Radiation Protection Research Papers

TRANSPORT AND SHIELDING OF IONISING RADIATION

by Johann van Rooyen

TEXTBOOK ON TRANSPORT AND SHIELDING OF IONISING RADIATION.

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Guidelines for Patient Radiation Dose Management

by Alan Cohen

2009, Journal of Vascular and Interventional Radiology

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Cancer consequences of the Chernobyl accident: 20 years on

by Andre Bouville and

2006, Journal of Radiological Protection

26 April 2006 marks the 20th anniversary of the Chernobyl accident. On this occasion, the World Health Organization (WHO), within the UN Chernobyl Forum initiative, convened an Expert Group to evaluate the health impacts of Chernobyl.... more

Table 2. Distribution of doses to clean-up workers as recorded in state Chernoby] registries (UN Chernobyl! Forum 2006).

Table 3. Estimates of thyroid doses (Goulko et al 1996, Likhtarov et al 2005, Minenko 2000 UNSCEAR 2000).

Table 4. Number of cases of thyroid cancer diagnosed between 1986 and 2002, by country and ag at exposure. * Cancer Registry of Belarus, 2006. > Cancer subregistry of the Russian National Medical and Dosimetric Registry, 2006. © Cancer Registry of Ukraine, 2006.

* Including approximately 1900000 persons from Belarus, 2000000 from Russia and 1300000 from Ukraine (UNSCEAR 2000). > For the period 1986-2005. ~ Strict control zones (included in the areas with deposition density >37 kBq m7’). Table 1. Estimates of mean effective doses (mSv) for population groups of interest (Cardis et a 1996, UNSCEAR 2000).

Figure 1. Annual incidence of childhood, adolescent and adult thyroid cancer in Belarus (courtesy of Yu E Demidchik). (Thiec fionre ic in calanr anly in the electranic vercan)

*N.A.: not available. 6 OR: odds ratio. Table 5. Summary of the case-control and cohort studies, and of the most recent ecological study of thyroid cancer following the Chernobyl accident: comparison with a combined analysis of data on populations with external exposures.

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ISSSD 2017 Proccedings Volume 2

by Hector Rene Vega-Carrillo

In-extenso papers published on the ISSSD 2017 proccedings

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ISSSD 2017 Proccedings Volume 1

by Hector Rene Vega-Carrillo

In-extenso papers published on the ISSSD 2017 proccedings

relation to the exposure time for both CR plates.

Fig. 2. Maniqui ginecologico dentro de una esfera de aire. gamma en la malla, en unidades de y/cm’.

Figura 14.- Detector de superficie esférico colocado a 75 cm de la fuente, utilizando como filtro el blindaje del tubo de rayos X con un blanco de Tungsteno (W). September 26 to 30, 2017. Santo Domingo, Dominican Republic.

cada electron emitido (Qe), de neutrones producidos en el LINAC de 18 MV.

Figura 26.- Efecto de la filtracion con aluminio en el espectro de energias para IPEM78.

Tabla 2.- Fluencia de neutrones, por historia, en los 6 detectores En la tabla 2 se presentan las fluencias de neutrones, por historia, en los 6 detectores.

Figura 1.- Espectro tipico producido por electrones con energia cinética de 100 keV golpeando un objetivo de Tungsteno. a) espectros lineales caracteristicos sobrepuestos al espectro Bremsstralung. b) muestra solamente el espectro Bremsstralung bajo diversas condiciones: la curva 1 es para un objetivo delgado, produciendo un haz de intensidad constante; las curvas 2, 3 y 4 son para un blanco grueso, la curva 2 representa un espectro no filtrado (dentro del tubo de rayos X), la curva 3 representa un haz de rayos X filtrado por una ventana de tubo de rayos X y la curva 4 representa un haz de rayos X filtrado por la ventana del tubo de rayos X y una filtracion adicional [Podgorsak 2010]. intensidades que se extienden sobre el rango de energias, como se muestra en la figura 1.

Figura 25.- Espectros de energias obtenido con MCNP con blanco de Mo y Ro.

llustraci6n 1 Fraccién de espectro electromagnético comprendido desde el Ultravioleta (UV) hasta el Infrarrojo Cercano (NIR). visible (entre 350 y 700 nm, Ilustracion 1).

Table 4.- Absorbed and Effective Dose in CT scan the high-resolution lung and whole body scans, are presented in Table 4. The results of Absorbed Dose and Effective Dose, as well as the associated uncertainties for

Figure 3.- Semicircular plates of acrylic of polymethylmethacrylate. that were used to determine the resolution of the CR plates are presented in Figure 3. [Nacimento de Carvalho, 2013], 10 mm and 5 mm of thick and 90 mm of diameter. The plate:

Figure 3.- Silver K-alpha intensities at different depths. nanoparticle doped volume at different depths from the surface of the phantom.

Figure 5.- PMMA plate with calcium agglomerates.

Figura 4.1. Curva de brillo ideal mostrando los tres puntos seleccionados para su analisis. matemiatico, se tiene (Ty, [y), (12 Lb) y (14 14).

Figure 4.- Samples of calctum agglomerates separated by size.

Table 2.- Tissue weighting factors according to ICRP 103 *Remaining tissues: Adrenals, extrathoracic region, gall bladder, heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, prostate (“), small intestine, spleen, thymus, uterus/cervix (@).

Figura 4.2. Curva de brillo del Y203:Ce 0.5%. Exposicion: 36.0 R. September 26 to 30', 2017. Santo Domingo, Dominican Republic.

reported in previous studies when a silver salt was used as the modifier (Mattea et al., 2017 modification to the stability of the FGD or severe changes to their optical properties, as

Tabla 4.2. Parametros cinéticos de la curva de brillo mostrada en la Figura 4.2. Por ultimo, la Figura 4.7 muestra todos los picos reconstruidos, asi como el ruido de la sefial.

Table 1. — Parameters used in the Whole Body scan protocol * Automatic Exposure Control (AEC)

4.2.2 Ejemplo de Deconvolucion de una Curva de Brillo Escogimos la curva de brillo 1.2.4, correspondiente al dosimetro marcado con el cédigo 1.2 (Y203:Ce 0.5%. Exposicion: 36.0 R), la cual podemos observar en la Figura 4.2.

arreglo lineal de fuentes radiactivas y van disminuyendo con la distancia, como 1/r’. tasas de dosis durante el tratamiento de CACU por modalidad de B-LDR.

Figura 4.4. Pico 1 de la curva de brillo analizada. cuenta que esta compuesta por varios picos y ruido.

Figura 4.3. Curva de brillo reconstruida a partir de los datos obtenidos reconstruyo la curva que se muestra en la Figura 4.2.

Figura 9.- SpekCalc. Espectros de energia con un blanco de Tungsteno (W).

Figure 9.- TL glow curves of sample C taken after 30 seconds of UV irradiation and three individual TL peaks obtained by peak-fitting using Gaussian lines. TL glow curves collected 24 hours after UV irradiation. September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Figura 4b. Porcentaje de recuperacion de Pu-242.

Figure 3: Peak-to-peak amplitude EPR versus microwave power. Peak-to-peak amplitude was normalized. September 26 to 30, 2017. Santo Domingo, Dominican Republic.

‘At 0.15 pulse width and 75 W rsp. OW average anode input powe

Figure 2: XRD patterns for sample A (black line) and B (red line). (m) assigned to rhombohedral phase Lanthanum aluminate (LaAlO3) and (c) for lanthanum hydroxide (La(OH)3). September 26 to 30, 2017. Santo Domingo, Dominican Republic.

Figure 4: Comparison between EPR versus pre-heating temperature and TL curve.

“The symbol -- indicates values less than 0.00001 w/w.

Figura 22.- Espectros de energias obtenidos con IPEM Report 78 para un blanco de Molibdeno (Mo).

Figura 7.- Geometria resultante del tubo de rayos X en MCNP, visualizada con MCNPX Visual Editor Version X_24E. Vacio adentro del tubo, aire adentro del cuarto y fuera del tubo con paredes de concreto baritado. September 26 to 30, 2017. Santo Domingo, Dominican Republic.

Table 3. Absorbed dose values (CTDI)09) in mGy. Table 4. Weighted and volumetric dose indexes in mGy.

Figure 2 reports the photon mass absorption coefficient and total stopping power for the

Figure 12.- TL glow curves of sample B taken after 1 (black curve), 5 (red curve), 15 (green curve) and 30 seconds (blue curve) UV irradiation. September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Table 4.- HU ratio with respect to water for the different irradiated and non-irradiated ge dosimeters.

Figura 23.- Espectros de energias obtenidos con IPEM Report 78 para un blanco de Rodio (Ro).

sample. rure 1: Main peak shape (g=2.00216). The inset show the details of the spectrum near the base line . A spectral feature with an orthorhombic symmetry can be seem.

Figura 4.5. Sefial residual al sustraer el pico | de la curva. la cual se observa un pico de mas baja temperatura y ruido a mas alta temperatura.

Tabla 6. Resultados obtenidos en los LOD y AMD de Pu-239 y Pu-242.

Figura 6.- Dimensiones en mm del tubo de rayos X SIEMENS P135/30R [OEM 2017]. cual muestra en la figura 6 sus dimensiones principales. En MCNP se utilizaron los componentes principales del tubo de rayos X, como I:

Figura 10.- Resultados de la simulacién con los parametros que usa IPEM Report 78.

Figure 2: High-field peak shape showing a spectrum with g,=1.17869, g,=1.18304 and g,=1.19459 September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Figura 1. Espectro Raman de las nanoparticulas sin recubrir (negro) y recubiertas (rojo). Se puede observar el efecto de SERS en el espectro de las nanoparticulas recubiertas de oro.

Figura 16.- Detector de superficie esférico colocado a 75 cm de la fuente, utilizando como filtro el grosor del vidrio de 3 milimetros del tubo de rayos X con un blanco de Tungsteno (W). September 26 to 30t, 2017. Santo Domingo, Dominican Republic.

Table 5. — Effective Dose from '*F-FDG injection

September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Figura 27.- Efecto de la filtracion con aluminio en el espectro de energias para SpekCalec.

Table 3.- Values of the coefficients of the fitting curves for both CR plates. Table 4.- Estimated saturation time for each CR plate.

En la figura 3 se muestra la fluencia de los neutrones monoenergéticos que llegan al detecto1

Figure 1. Alderson phantom positioned into the PET/CT scanner rotation time of 1 s, sweeping from the top of the head until the root of the thigh.

Figure 4.- Relative intensity (normalized at 1 mm depth) of detected K-alpha line positioning the 2% w/w AgNP-infused Fricke gel dosimeter at different water-equivalent depths. as a function of the water-equivalent depth at which AgNPs were located.

Figure 6: FTIR spectra for samples A(blue line), B(green line), C(black line) and D(red line).

Figure 11.- TL glow curves of sample A taken after 1 (black curve), 5 (red curve), 15 (green curve) and 30 seconds (blue curve) UV irradiation. LaA1lO3 /La(OH)3 crystals irradiated with different doses are shown in Figures 11 to 14. radiation, the maximum saturation is achieved. TL glow curve of pure and carbon doped

Table 2.- Gel dosimeter mass density and dose range. Gel dosimeter samples were irradiated with photon beams produced by 3kW Siemens Kristalloflex generator [Valente et a/., 2016] with electrical current and accelerating voltages within 5-60mA and 20-60kVp, respectively. The dose rate was measured by means of calibrated ionization chambers: farmer type (PTW-Freiburg 30013) and pinpoint (PTW- Freiburg 30006) obtaining (635.44 +0.8) cGy/min at sample position accounting for all Gel dosimeter samples were irradiated with photon beams produced by 3kW Siemens Kristalloflex generator [Valente et a/., 2016] with electrical current and accelerating voltages

Tabla 2. Condiciones operacionales para analisis de Pu usando ICP-SFMS

respectively. Thus the best TL response for UV fields was found to sample C.

Figure 3: XRD patterns for sample C (black line) and D (red line). (m) assigned to rhombohedral phase Lanthanum aluminate (LaAlO3) and (c) for lanthanum hydroxide (La(OH)s).

Figura 3.7. Respuesta TL de los dosimetros estudiados.

Figura 18.- Detector de superficie esférico colocado a 75 cm de la fuente, utilizando como filtro el grosor del vidrio del tubo de rayos X con un blanco de Tungsteno (W). articulas los resultados se muestran en las siguientes figuras.

Figura 24.- Efecto del blanco de Mo y Ro en el espectro de energias con IPEM78.

Figure 2. — Irradiated area in the HR Lung protocol. radiation dose. After scans, the film strips were scanned with an output resolution of 300 ppi. The image:

Figura 8.- IPEM Report 78. Espectros de energia para un blanco de Tungsteno (W).

Table 2: Percentage of each material observed in XRD patterns The UV-Vis absorption spectra were collected and the spectrograms plotted in Fig. 4, for samples A and B, and in Fig. 5 for samples C and D. Strong absorption bands, for wavelengths ranging from 190 to 220 nm, have been observed for all samples. These absorption peaks are assigned to the F center formation. Interestingly, a more intense absorption band, centered around 230 nm, is observed only for carbon doped samples. Finally, it is possible to see a wide absorption around 270 nm that has lower intensity, which is The UV-Vis absorption spectra were collected and the spectrograms plotted in Fig. 4, for

Figure 2. - Positioning of the newborn chest phantom in the CT scanner isocenter. ‘rom the CTDIi99 values measured at the central and peripheral openings of the phanthoms it

Figura 5. Espectro de neutrones con estructura ICRP74 para haz de electrones de 18 MeV.

Figura 17.- Espectro de energias resultantes con los parametros de la geometria mostrada en la figura 16.

Figure 7.- TL glow curves of sample A taken after 30 seconds of UV irradiation and three individual TL peaks obtained by peak-fitting using Gaussian lines. TL glow curves collected 24 hours after UV irradiation. September 26 to 30', 2017. Santo Domingo, Dominican Republic.

Figura 20.- Detector de volumen (tejido equivalente de 20 cm de grosor) colocado a 75 cm dé la fuente, utilizando como filtro una ventana del blindaje del tubo de rayos X con un blanc« de Tungsteno (W). September 26 to 30, 2017. Santo Domingo, Dominican Republic.

ICRP 106, 2008 September 26 to 30, 2017. Santo Domingo, Dominican Republic.

Figura 6. Distribucion de los electrones de 18 MeV interactuando con la laminilla. dispersion de los electrones en la laminilla.

significant increase in OSL and TL sensitivity (Yukihara 2011.). FTIR spectra to all samples, for wavenumbers ranging from 400 to 4000 cm” are shown in

Figure 3.- Dose-response curve for PAGAT (top left), NIPAM (top right), ITABIS (bottom left) and Fricke (bottom right) dosimeters along with corresponding linear fit. Error bars indicate 95% of confidence. acquisition and corresponding tomography reconstruction.

AgNP concentration [%ow/w] Norm. total dose [a.u.] Table 1.- Dosimetry effect due to AgNP presence in Fricke gel dosimeters.

Figure 13.- TL glow curves of sample C taken after 1 (black curve), 5 (red curve), 15 (green curve) and 30 seconds (blue curve) UV irradiation.

llustracion 2 Vista esquematica de los efectos de absorcion y dispersion. dependen y son determinadas respectivamente por el coeficiente de absorci6n y el coeficiente contacto con el tejido. La cantidad de absorcion y dispersion de una longitud de onda y tejid cromoforos); la dispersion a su vez consiste en el cambio de direccion provocado al entrar en

Figura 3.6. Curva de brillo adquirida durante el protocolo de lectura. conjunto.

cada dosimetro con relacion a la carga liberada en funcion de la exposicion aplicada.

September 26 to 30%, 2017. Santo Domingo, Dominican Republic. The TL responses of these two samples are shown in Figures 16 and 17. The linear fitting

Figura 3. Curva de calentamiento magnético para las nanoparticulas sin recubrir y recubiertas. September 26 to 30%, 2017. Santo Domingo, Dominican Republic. 4.- Discusion

Figure 17.- TL output intensities for sample C between 0.042 -0.63mJ/cm’, and linear fitting (red line). Each point corresponds to average of three measurements. September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Figura 4a. Porcentaje de recuperacion de Pu-239.

Figure 10.- TL glow curves of sample D taken after 30 seconds of UV irradiation and three individual TL peaks obtained by peak-fitting using Gaussian lines. TL glow curves collected 24 hours after UV irradiation.

Tabla 3.2. Identificacion de los dosimetros

Figura 3. Espectros de los fotones producidos con el haz de electrones de 18 MeV.

Figure 1. - Positioning of the pencil chamber inside the openings 3, 6, 9, 12 and central of the pediatric chest phantom. placed in the gantry.

Figura 2. Sintonizacion de m/z de Pu usando Aridus-ICP-SFMS. muestra durante el analisis.

images was 4095, which represents the highest value of the scale for both CR plates.

ina distancia de 1 metro de la fuente. En la Fig. 5 se muestra la interfaz de usuario de este

Table 2. Protocol parameters for optimized image acquisitions.

Figura 28.- Espectros de rayos X obtenido con MCNP al variar el grosor del filtro de Al utilizando los parametros de IPEM Report 78.

Tabla 1: Distribucién de tasa de dosis absorbida en puntos de tratamiento B-LDR inferior) de la fuente radiactiva con la misma actividad.

Figura 19.- Espectro de energias resultantes de la geometria mostrada en la figura 18.

Table 3.- Absorbed dose per unit activity administered (mGy/MBq) ISSSD 2017 Proccedings

Ilustraci6n 3 Coeficiente de absorcion de los cromoforos en los tejidos September 26 to 30, 2017. Santo Domingo, Dominican Republic.

llustraci6n 4 Render de prototipo a desarrollar e imagen de visualizaci6n de vasos obtenida con el prototipo personal de la salud.

Table 1. Parameters for central slice irradiation. cm in the central region of the adult phantom and optimized pediatric protocols with 120 kV

Figura 13.- Espectro de energias resultantes de la geometria mostrada en la figura 12.

Table 3: Image noise for pediatric phantom with optimized protocol.

Figure 5: UV-Vis absorption spectra of unirradiated samples C (black line) and D(red line) indicating the absorption bands attributed to F and F’ centers. September 26 to 30%, 2017. Santo Domingo, Dominican Republic.

Figure 4.- Typical CT slices of the scanned pack of vials along with reference (water anc aluminum) samples at 110 kVp.

Tabla 3.4. Resultado de las mediciones dosimétricas

Figure 8.- TL glow curves of sample B taken after 30 seconds of UV irradiation and three individual TL peaks obtained by peak-fitting using Gaussian lines. TL glow curves collected 24 hours after UV irradiation.

Figura 1. Calibracién en energia de uno de los detectores del espectrometro alfa empleado la fuente radiactiva de referencia MRC2008-013, realizandose 10 repeticiones con un tiempo de recuento de 10 min. September 26 to 30, 2017. Santo Domingo, Dominican Republic.

Figure 5: Peak-to-peak amplitude EPR versus delivered dose. Peak-to-peak amplitude was normalized analysis for high-field peak is depicted.

Figura 11.- Resultados de la simulacion con los parametros que usa SpekCalc.

Figura 12.- Detector de superficie esférico con radio de 75 cm, sin filtracién y blanco de Tungsteno (W).

Figura 2.4. Solucion de la ecuacion (2.8), Ti es independiente de la concentracion inicial de De la ecuacion (2.8) obtenemos

Tabla 1.- Fluencia de fotones en los detectores En las figuras 4 y 5 se muestran los espectros de neutrones, por historia, en los cuatro

en la figura 1. Utilizando métodos Monte Carlo, con el cddigo MCNP5 [X-5 Monte Carlo Team, 2003], s lisefid un modelo simple del cabezal de un LINAC [NCRP, 1984] con fuente mono snergética de electrones de energias de 12 y 18 MeV y una laminilla dispersora de tungsten ‘1 cm diametro y 0.05 cm de espesor), que se ubicé a 6 cm debajo del centro como se muestr: on la figura 1. (1 cm diametro y 0.05 cm de espesor), que se ubicé a 6 cm debajo del centro como se muestra

Figura 4. Espectro de neutrones con estructura ICRP74 para haz de electrones de 12 MeV.

Fig. 1. Cilindro vaginal de lucita dentro del maniqui ginecoldgico. R; (de izquierda a derecha) representan el recto.

Tabla 3.1. Parametros de irradiacion de la maquina de rayos X En cada sesion, cada grupo de dosimetros recibid uno de los niveles de radiacion antes

Tabla 3. Condiciones operacionales optimizadas de Aridus-HR-ICP-MS alcanzada en el método 3 fue ~2 fg por muestra.

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Scientific Aspects of Polymer Electrolyte Fuel Cell Durability and Degradation

by Fernando Garzón

2007, Chem. Rev

Automobile manufacturers and fuel cell developers have produced PEMFCs for many years, but recent significant technological advances have left two major remaining challenges to widespread fuel cell use: cost and lifetime, which are... more

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Optimización del estudio radiológico de la escoliosis

by Cesar Fontecha

2014, Medicina Clínica

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CT Radiation Dose and Iterative Reconstruction Techniques

by Ranish Khawaja

2015, AJR. American journal of roentgenology

Key Points 1. CT radiation dose optimization is one of the major concerns for the scientific community. 2. CT image quality is dependent on the selected image reconstruction algorithm. 3. Iterative reconstruction algorithms have reemerged... more

Fig. 6—7-year-old girl with weight loss and diarrhea. A-D, Coronal abdominal CT images at 4.3 mGy (baseline volume CT dose index) (A) and 1.3 mGy (reduced dose) (B-D) and reconstructed with filtered backprojection (FBP) (B), Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare) (C), and Model-Based Iterative Reconstruction (MBIR, GE Healthcare) (D). There is marked improvement in image quality with MBIR at 1.3 mGy compared with FBP and ASIR images.

Fig. 1—73-year-old man with pulmonary nodule (arrows). A-D, Transverse chest CT images acquired at 7 mGy (baseline volume CT dose index) (A) and at 1.6 mGy (reduced dose) (B—D) and reconstructed with various iterative reconstruction techniques. At 1.6 mGy, pulmonary nodule was depicted optimally on iterative reconstruction images with SafeCT (Medic Vision) (B), Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare) (C), and Model-Based Iterative Reconstruction (MBIR, GE Healthcare) (D) techniques.

Note—CTDI,,, = volume CT dose index, SNR = signal-to-noise ratio, CNR = contrast-to-noise ratio, FBP = filtered back projection, ASIR = Adaptive Statistical Iterative Reconstruction (GE Healthcare), MBIR = Model-Based Iterative Reconstruction (GE Healthcare), IRIS = Iterative Reconstruction in Image Space (Siemens Healthcare), SAFIRE = Sinogram-Affirmed Iterative Reconstruction (Siemens Healthcare). TABLE |: Tabulated Summary of Iterative Reconstruction Technique and Radiation Dose in Different Body Region: and in Children

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Fiducial markers and spacers in prostate radiotherapy: current applications

by Michael Chao and

2014, BJU International

To review the use of fiducial markers and spacers in prostate radiotherapy (RT).

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ISSSD 2017 Proccedings Volume 3

by Hector Rene Vega-Carrillo

In-extenso papers published on the ISSSD 2017 proccedings

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RADIATION SAFETY AWARENESS AMONG MEDICAL DOCTORS AT NORTH OKKALAPA GENERAL AND TEACHING HOSPITAL YINN MAR HLAING

by nay win Aung

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Review of NASA Approach to Space Radiation Risk Assessments for Mars Exploration

by francis cucinotta

2015, Health Physics

Long duration space missions present unique radiation protection challenges due to the complexity of the space radiation environment, which includes high charge and energy particles and other highly ionizing radiation such as neutrons.... more

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Irradiation as a Food Preservation Method in Nigeria: Prospects and Problems

by SULEMAN KAMALDEEN OLASUNKANMI and

Food irradiation is a food preservation method which involves the process of exposing foodstuffs to a source of energy capable of stripping electrons from individual atoms in the targeted material (ionizing radiation). This method of food... more

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Onde elettromagnetiche Come proteggersi-I-prima parte

by liliana bordoni

Siamo da sempre immersi in campi elettromagnetici naturali dovuti al moto di agitazione termica degli atomi (magnetismo terrestre, radiazioni solari, atmosfera e fenomeni metereologici ) e ai nostri stessi corpi che irradiano energia... more

Siamo da sempre immersi in campi elettromagnetici naturali dovuti al moto di agitazione termica degli atomi (magnetismo terrestre, radiazioni solari, atmosfera e fenomeni metereologici ) e ai nostri stessi corpi che irradiano energia nelle diverse bande di frequenza .
E’ nei campi elettromagnetici -presenti ovunque intorno a noi, ma invisibili all’occhio umano- che avvengono le comunicazioni a distanza; gli oggetti interagiscono senza toccarsi .
Tutta la materia è perlopiù vuota e caratterizzata da una emissione di campo elettromagnetico derivante dai nuclei atomici che scambiano energia attraverso le particelle subatomiche all’interno dell’atomo stesso.
Una piccolissima massa crea una quantità enorme di energia come nelle reazioni di fissione e di fusione nucleari .
“L’universo non è fatto da cose, ma da reti di energia vibratoria che emergono da qualcosa di ancora più profondo e sottile”. W. Heisenberg, fisico quantistico
Tutto ciò che c'è sul nostro pianeta emette calore sotto forma di radiazione elettromagnetica. Le radiazioni si propagano sotto forma di onda con specifiche caratteristiche (lunghezza, periodo, velocità, frequenza.)
L’uomo emette un campo elettromagnetico
Ogni essere genera ed emette un campo elettromagnetico.
Una carica positiva sulla sommità della testa e una negativa sotto i piedi …
Ogni organo del corpo emette il suo campo elettromagnetico come somma dei campi generati dalle varie cellule che lo compongono.
Ogni cellula è in grado di eseguire migliaia di trasformazioni molecolari ogni secondo.
I circa cinquanta trilioni di cellule del nostro corpo comunicano fra di loro alla velocità della luce.
Il DNA umano è una sede di informazioni trasmesse e ricevute tramite la modulazione del campo elettromagnetico .
Entriamo continuamente in interazione con altri campi: le onde sonore, ad esempio, generando movimento dell’aria, modulano il campo elettromagnetico che influenza e modifica quelli circostanti, compreso quello umano.
Qualsiasi tipo di frequenza può interagire con la banda del corpo umano, a qualsiasi livello.

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Radiation Protection in Interventional Radiology

by Michael Fitzgerald

2001, Clinical Radiology

There is growing concern regarding the radiation dose delivered during interventional procedures, particularly in view of the increasing frequency and complexity of these techniques. This paper reviews the radiation dose levels currently... more

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Safe radioisotope thermoelectric generators and heat sources for space applications

by Nigel Bannister

2008, Journal of Nuclear …

Several isotopes are examined as alternatives to 238 Pu that is traditionally used in radioisotope thermoelectric generators (RTGs) and heating units (RHUs). The radioisotopes discussed include 241 Am, 208 Po, 210 Po, and 90 Sr. The aim... more

GPHS module mass & thermal output isotope comparison Fig. 11. A thermal performance and fuel mass comparison of substitute isotope candidates (excluding 7!°Po) when used to fuel a GPHS module in contrast to the current yerformances of the GPHS modules fuelled by 77PuQ3.

Physical properties of 5 W, prototype breadboard model for a low mass reduced radiation RTG

Fig. 17. Comparison of MCNPX [24] derived results for the masses of modelled systems fuelled by oxygen-enriched 741AmO, in oxide form and in tungsten based cermets relative to those of devices with similar dose rates fuelled by oxygen-enriched 738PuO, in oxide form and tungsten cermets. These system masses are illustrated as a function of source thermal output power and dose rate equivalence. The tungsten volume fraction for cermet based sources are listed in the key.

Americium Dioxide & Tungsten Internal Cermet Fig. 9. Prototype hexagonal encapsulated cermet geometry. A tungsten carbide outer jacket surrounds a central americium dioxide/tungsten cermet. The outer jacket has a hexagonal exterior geometry with facet widths of 30mm so as to facilitate direct coupling with thermoelectric modules.

Fig. 12. A thermal performance and fuel mass comparison of all substitute isotope candidates when used to fuel a GPHS module in contrast to the performances of the GPHS modules fuelled 7?8PuO.

Fig. 1. SNAP-27 RTG deployed on the lunar surface during the Apollo 16 mission ial We Following the SNAP programmes, the US developed the multi- hundred watt (MHW) RTG systems to provide power to the Lincoln experimental satellites LES 8 and 9 and Voyager 1 and 2 spacecraft. These devices were fuelled by 24 pressed spheres of 778PuOz, each with an activity of 3.2 kCi. Each sphere was encapsulated within a cladding of iridium alloy and housed individually within a filament wound carbon-carbon impact shell. All 24 assembled spheres were housed within a cylindrical POCO graphite aeroshell for re-entry protection [6]. The thermoelectric conversion was performed using

Fig. 5. Total neutron yield per gram of 741AmO, compound matrix based on an average « energy of 5.46 MeV. If a reduction in the total neutron yields for both AmO, and PuO, is required for safety, chemical processing of the materials

A general purpose heat source (GPHS) module is a composite carbon body that houses a total of four fuel pellets and as a whole acts as an aero-impact shell. The isotope fuel for the GPHS-RTG is in the form of plutonium dioxide (?7®PuO) at approximately 80% density. The fuel is pressed into pellets with an approximate length and diameter of 27.6mm [9]. Each pellet has approximately 0.55 mm of iridium alloy (DOP-26) cladding [9] that is used to maintain the structural integrity of the pellet both under normal operating conditions and under impact. The iridium cladding also

Alternative isotope study results for the replacement of the current PuO, fuel in the GPHS module Data for oxygen-enriched oxides and oxides of natural oxygen composition is given for ?*®PuO, and *41AmO, fuelled modules. ‘>’ Signifies that a practically unlimited annual exposure time is permissible. Table 2

Fig. 8. Spark plasma sintering (SPS) principal schematic showing the consolidation of powdered material through neck formation and applied pressure [42) The overall setup consists of a conductive (graphite) die into which the powder mixture is formed, a press and a high power pulsed DC circuit. The die, and ultimately, the powder mixture it- self form the completing component for the DC circuit. The geom- etry of the die determines the radial geometry of the pressed/ sintered cermet. The powdered fuel (in oxide form) and tungsten metal powders, typically less than 10 pm in grain size, are mixed to the desired ratio. Once prepared, the mixture is loaded into the graphite die. The die is then put under compression in between two electrodes in a hydraulic press [40] in order to compact the In order to minimise thermal stresses across a fuel cermet, the geometry must be designed so as to minimise the temperature gra- dient across the cermet radius. Finite element modelling (FEM) and

Fig. 13. Schematic of the laboratory breadboard model of a low mass, reduced radiation (LMRR)-RTG demonstration model.

Fig. 6. Total neutron yield per gram of ??®PuO, compound matrix based on an average « energy of 5.49 MeV.

Fig. 7. A plot of calculated system performances for theoretical RTGs with a beginning of mission power output of 5 We fuelled by candidate alternative reduced radiatio isotopes. These performances are compared to that of a similar device fuelled by 7**Pu.

Fig. 3. Spontaneous fission (S.F.) neutron yield per gram of 74!Am. This S.F. spectrum was generated using the Monte Carlo N-Particle transport code MCNPX version 6 [24], the statistics from which were derived from the calculation of 1 x 10° spontaneous fission events.

Fig. 4. Spontaneous fission (S.F.) neutron yield per gram of 7?Pu. This S.F. spectrum was generated using the Monte Carlo N-Particle transport code MCNPX version 6 [24], the statistics from which were derived from the calculation of 1 x 10° spontaneous fission events.

Fig. 14. Comparison of MCNPX [24] derived results for the dose rates of modelled systems fuelled by 741AmO) (natural oxygen composition) in oxide form and in tungsten based cermets relative to those of devices with similar dose rates fuelled by 778PuO, (natural oxygen composition) in oxide form and tungsten cermets. These system masses are illustrated as a function of source thermal output power and dose rate equivalence. The tungsten volume fraction for cermet-based sources are listed in the key.

* Based on a 5% conversion efficiency. > Calculated from data presented by Bennett et al. [5] for current materials (approx. 25-30 years old). © Very low probability of emission. Summary of the key properties of the isotopes presented

Fig. 16. Comparison of MCNPX [24] derived results for the dose rates of modelled systems fuelled by oxygen-enriched 741Am0O, in oxide form and in tungsten based cermets relative to those of devices with similar dose rates fuelled by oxygen-enriched 7?°PuO, in oxide form and tungsten cermets. These system masses are illustrated as a function of source thermal output power and dose rate equivalence. The tungsten volume fraction for cermet based sources are listed in the key.

Fig. 10. Three-dimensional drawing of the GPHS module MCNPX [24] geometry model.

Fig. 15. Comparison of MCNPX [24] derived results for the masses of modelled systems fuelled by 741AmO, (natural oxygen composition) in oxide form and in tungsten based cermets relative to those of devices with similar dose rates fuelled by 7?8PuO2 (natural oxygen composition) in oxide form and tungsten cermets. These system masses are illustrated as a function of source thermal output power and dose rate equivalence. The tungsten volume fraction for cermet based sources are listed in the key.

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Proteksi Radiasi dan Radiobiologi dalam Pelayanan Radiologi Diagnostik

by Arif Jauhari

Pendahuluan Pemeriksaan diagnostik radiologi telah menjadi bagian yang tidak dapat dipisahkan dari kehidupan kita sehari-hari, terutama penatalaksanaan klinis pasien di dalam pelayanan kesehatan. Sejak ditemukannya sinar-X oleh Roentgen... more

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Radiation Protection in X-Ray Computed Tomography: Literature Review

by Khalid Alsafi

Dose reduction in CT should be optimized by adjustment of scan parameters (tube current, peak tube voltage and pitch) according to patient weight or age, and weight-adapted CT protocols have been suggested and published. For the purpose... more

Dose reduction in CT should be optimized by adjustment of scan parameters (tube current, peak tube voltage and pitch) according to patient weight or age, and weight-adapted CT protocols have been suggested and published. For the purpose of minimizing radiation exposure, noisier images, if sufficient for radiological diagnosis, should be accepted. Optimized study quality also depends on region scanned and study indication. Other dose reduction strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Guidelines to optimize the protection of patients during CT procedures have been provided by various international organizations [5-7]. All guidelines include reference doses that are described as diagnostic reference levels (DRLs) or guidance levels that assist in the optimization of radiation protection of the patient and permit comparisons of the performance of different CT scanners and techniques. Full optimization of CT requires implementing quality assurance program and optimization of both scanner and CT operator factors including the use of tube current modulation and other dose saving protocols. Radiation health effects Two primary detrimental health effects are associated with ionizing radiation: stochastic effects and deterministic effects. A stochastic effect of radiation is one in which the probability of the effect, rather than its severity, increases with radiation dose. Radiation-induced cancer and genetic effects are stochastic in nature. On contrary, deterministic effects occur when radiation dose exceeds certain threshold [8,9]. In CT examinations, the entrance skin doses are approximately 40 mGy for head examinations and approximately 20 mGy for body examinations [10]. As far as deterministic effects (tissue reactions) are concerned, ICRP notes that 'in the absorbed dose range up to around 100 mGy (low LET or high LET) no tissues are judged to express clinically relevant functional impairment [8,11]. Accordingly, deterministic effects are not expected for any patient undergoing a standard diagnostic CT examination. Below the threshold for the induction of deterministic effects, the principal concern of any radiation exposure is the induction of stochastic (random) risks. In diagnostic radiology, these stochastic radiation risks are carcinogenesis and genetic effects that would appear in the offspring of an irradiated individual. The principal concern for any patient undergoing a diagnostic CT examination is the risk of developing a radiation-induced cancer, which may be fatal or nonfatal. The total patient risk is related to the Abstract The aim of this study was to evaluate radiation protection techniques in computed tomography (CT) scanning, address concerns on the increased population exposure during CT procedures, and provide a review on dose management and optimization procedures. Radiation protection in CT requires regular dose surveys and optimization of CT exposure parameters, establishing and/or implementing diagnostic references (DRLs), implementation of a comprehensive quality assurance program, reference dose levels, and CT dose saving protocols. Patient dose reduction of 40-60%, 50%, 20-30%, 20-40%, 30-50% can be achieved using tube current modulation, beam filters, thyroid and breast shields, low tube voltage for abdominal CT, automatic pitch adaptation; respectively. CT users are strongly encouraged to take advantage of these dose reduction techniques while maintaining diagnostic image quality. Current review provides updated radiation protection measures for minimizing patient radiation dose in CT without adversely affecting the quality of diagnostic information.

Table 1: Published adult DRLs for CTDI., (mGy) and DLP (mGy- cm). vol

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Radiation Protection and Mitigation by Natural Antioxidants and Flavonoids: Implications to Radiotherapy and Radiation Disasters

by Masoud Najafi and

Background: Nowadays, ionizing radiations are used for various medical and terroristic aims. These purposes involve exposure to ionizing radiations. Hence, people are at risk for acute or late effects. Annually, millions of cancer... more

Fig. (1). Mechanisms of radiation toxicity in normal tissues. Ionizing radiation cause generation of ROS and cells death, leading to initiation of inflammatory responses and chronic free radical production. These are associated with several side effects in irradiated normal tissues such as fibrosis, pneumonitis, dermatitis, ulcer and etc. Suppression of oxidative damage and other factors involved in these side effects by various agents such as flavonoids can help the management of radiation toxicity. for 8 weeks. Also, this study showed that upregulation of NOX4 and NOX2 is responsib e for continuous ROS pro- duction and genomic instability in bone marrow cells. More- over, their results showed that inhibition of NOX4 can pro- tect mice similar to a potent rad ine) [19, 20]. Other studies con ioprotector (N-acety production through stimulation of redox interactions key role in the development of both early and late e cyste- firmed that continuous ROS plays a ffect of IR [21-23]. Weyemi et al. showed that inactivation of both NOX4 and NOX5 can mitigate tive DNA damage in irradiated ROS production and human fibroblast cel oxida- s [24]. In animal model, it has shown that upregulation of pro- oxidant enzymes such as NOX1, NOX4, COX-2, iNOS and also increased superoxide production by mitochondria are involved in the development of pneumonitis and fibrosis [25- 27]. Similar results have shown for intestinal cells, vascular endothelial cells, mice brain, etc [28-30]. characteristics of radioprotectors in these two cases are not similar. For example, in radiotherapy, it is very important that the administered agent does not cause the protection of tumor cells. Both radioprotectors and mitigators should have minimal toxicities and protect normal tissues especially radi- osensitive organs such as hematopoietic and gastrointestinal [4]. Although the search for radioprotectors has been on for a long time, there has been more emphasis on the development of radiation mitigators with high efficiency. The most im- portant focus in this issue is mitigation of radiosensitive or- gans such as bone marrow and gastrointestinal system [5].

Table 1. Different herbal and natural antioxidants for radioprotection.

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CT effective dose per dose length product using ICRP 103 weighting factors

by Walter Huda and

2011, Medical Physics

Purpose: To generate effective dose per unit dose length product ͑E/DLP͒ conversion factors incorporating ICRP Publication 103 tissue weighting factors. Methods: Effective doses for CT examinations were obtained using the IMPACT Dosimetry... more

TABLE II. Comparison of E/DLP conversion factors for 16 cm diameter and 32 cm diameter phantoms computed using ICRP 103 weighting factors for selectec CT examinations and those obtained from AAPM Report No. 96 (Ref. 9). E/DLP conversion factors pertain to the same phantom «20 size.

Fic. 2. CT effective dose average ratio of E93/Eg) for 4 cm wide scans performed along the patient long axis z (at the center of the beam).

Fic. 1. Mathematical phantom in the IMPACT software used to simulate CT effective dose. Superimposed on the phantom is a 4 cm beam width centered at z=52 cm in the breast region (i.e., from z=50 cm to z=54 cm).

TABLE I. Ratios of effective doses from ICRP 103 and ICRP 60 for patients undergoing selected CT examina- tions.

TABLE III. Comparison of E,9;/E¢o ratios obtained in this study and the data presented by Deak er al. (Ref. 25). scan length, weighting factors, and (any) patient size correc- tion factors that may be applied.””*° version factors assume that the x-ray tube output is constant for the complete patient CT examination. The current prac- tice, however, is to modulate the current as the x-ray rotates around the patient, as well as changing the tube current as the patient moves through the gantry.'° X-ray tube current modulation has been successfully introduced into clinical practice in the past decade and been shown to result in pa- tient dose savings with no apparent loss of image quality or diagnostic performance.” Recent studies have been per- formed on how tube current modulation will affect E/DLP conversion factors when imaging normal size adults.7*~4 When scanning a Rando phantom, use of tube current modu- lation would reduce E/DLP factors in the head by ~2%, in the chest by ~9%, and in the abdomen/pelvis by ~71% 4

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Évaluation des connaissances des prescripteurs de scanner en matière de radioprotection des patients

by Alban Gervaise and

2011, Journal de Radiologie

Dosimétrie ; Prescripteur ; Radiation ionisante ; Radioprotection ; Scanner

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The risks of risk-based regulation: Insights from the environmental policy domain

by Henry Rothstein and

2006, Environment International

Risk-based regulation has become increasingly popular in recent years. Proponents argue that it facilitates robust governance, contributing to efficient and effective use of regulatory resources and delivering interventions in proportion... more

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Biological effects of electromagnetic fields

by GHADA G A AMER

2012, AFRICAN JOURNAL OF BIOTECHNOLOGY

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Conventional and new lead-free radiation shielding materials for radiation protection in nuclear medicine: A review

by Noorfatin Aida Amin

2019, Radiation Physics and Chemistry

Gamma ray is an energetic ionising radiation that can damage living cells as it slows down and transfers its energy to surrounding cells. Lead and concrete have been used as radiation shielding materials. However, it shows that lead... more

Fig. 2. Comparison of lightweight gamma shielding materials. Retrieved from Timothy P Martinez and Cournoyer (2001) From the reported novel work for the development of advanced, non-toxic, synthetic radiation shielding aggregate, a conclusion can be

Fig. 1. Comparison of gamma shielding materials. Retrieved from Timothy P Martinez and Cournoyer (2001).

Fig. 3. Variation of linear attenuation coefficient (in cm) with photon energy in a range of 0.015-15 Mev for heavy metal oxide glasses; 70 BiO2: 30 SiOz, 70 BaO:30 SiOz, 70 Biz03:30 B203, 70 PbO:30 SiOz, and 10 ZnO:30 Bi2O3: 60 B2O3 (Retrieved from Singh et al., 2014).

Atomic number and density of lead, tungsten, and bismuth. Table 1

Cost comparison of radiation shielding materials. * Brick dimensions are 2” x 4” x 8” (5cm xX 10cm x 20cm). Table 2

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Radiation safety program for the cardiac catheterization laboratory

by Charles Chambers

2011, Catheterization and Cardiovascular Interventions

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Monte Carlo simulation of x-ray spectra in diagnostic radiology and mammography using MCNP4C

by Adib Habib

2004, Physics in Medicine and Biology

The general purpose Monte Carlo N-particle radiation transport computer code (MCNP4C) was used for the simulation of x-ray spectra in diagnostic radiology and mammography. The electrons were transported until they slow down and stop in... more

Figure 1. Geometry of the experimental set-up used for Monte Carlo simulation of x-ray spectra and assessment of anode heel effect. The position of detectors for calculation of exposure around the target (A) and anode heel (B) is also shown.

Figure 7. Comparison of transmission curves produced by MCNP4C and IPEM report 78 fot (a) tungsten target between 50 and 140 kV and (b) molybdenum target at 30 kV.

‘Distance between focal spot and measurement point. ’ X-ray spectrum data. ’ Transmission curve data. | Radiation intensity data. Table 1. Summary of x-ray tube parameters investigated in this work using MCNP4C-based Monte Carlo simulations.

Figure 8. Comparison of simulated and measured on- and off-axis x-ray spectra for 100 kV tube voltage. (a) Central axis, (b) 6° cathode side and (c) 6° anode side.

Figure 3. Comparison of x-ray spectra for various tube voltages produced by MCNP4C and measured data by Fewell et al (1981) and Bhat et al (1998). (a) 50 kV, (b) 80 kV, (c) 100 kV. Monte Carlo simulation of x-ray spectra using MCNP4C

Figure 2. (a) Comparison of x-ray spectra produced by MCNP4C and IPEM report 78 for various tube voltages. (b) Same as (a) for 140 kV tube voltage with 0.1 mm Cu additional filter.

Monte Carlo simulation of x-ray spectra using MCNP4C SSDL laboratory of the IAEA (Pernieka et al 1997). They reported 0.348 mm AI for first HVL while we calculated 0.35 mm (—0.6% difference). Note that there are some differences between their experimental set-up (0.8 mm Be filter, 0.03 mm Mo filter, 20° Mo target angle) and our simulation set-up (1 mm Be filter, 0.035 mm Mo filter, 12° Mo target angle). According to our estimation, the 8° difference in target angle produces 3.8% difference in the first HVL.

Figure 4. Comparison of x-ray spectra using various tube voltage ripple factors in 80 kV produced by MCNP4C and IPEM report 78. the calculated spectra. To simulate ripple in MCNP4C, we used the following formulation for ripple factor and tube voltage (Boone and Seibert 1997):

Table 3. Variation in radiation exposure for various target angles and tube voltages in the useful x-ray beam. * From 6° anode side until 6° cathode side.

Figure 10. (a) Comparison of simulated and measured relative exposure values in different directions relative to the central axis (calculation points B in figure 1). (b) Relative exposure around the target (calculation points A in figure 1). (c) Normalized exposure on the axis perpendicular to the anode—cathode axis.

Figure 6. (a) Plots of 30 kV x-ray spectra simulated by MCNP4C for Mo target with 0.5 mm Be and 0.03 mm Mo filter produced for XNUM = | and 0.01. (b) Comparison between x-ray spectra produced by MCNP4C with XNUM = | and IPEM report 78 after manual setting of the intensity of characteristic photons in the MCNP4C spectra to match the value computed by IPEM.

Monte Carlo simulation of x-ray spectra using MCNP4C above. Note that a pure tungsten target was used in our simulation, while the targets used 1n the experimental measurements have some rhenium and molybdenum impurity. It is worth emphasizing that both el03 and ell treatments only take into account the highest Z component of the material for production of k-shell x-rays in MCNP (Briesmeister 2000). Thus, the tungsten k-shell masks the x-ray characteristic of added low Z impurities. Figure 4 shows the effect of tube voltage ripple on production of simulated x-ray spectra and its comparison with PEM report no. 78. Some authors modelled the tube voltage ripple by combining a number of spectra generated at different constant tube potentials, each one being weighted according to the time for which that tube potential occurs (Boone and Seibert 1997, Cranley et al 1997). In our experiments, we modelled the tube voltage ripple during Monte Carlo simulation of x-ray spectra by uniformly sampling from the tube voltage waveform (equation (2)). Similar to the results reported above, there is good agreement between simulated and calculated spectra apart from the small shift in characteristic photon energy for the reasons explained above. A 30% ripple is probably higher than most inverter generators as most of them produce ripple factors between 5% and 15% (Boone and Seibert 1997). —

Figure 11. Illustration of anode heel effect for different anode angles for (a) tungsten targe with tube voltages between 80 and 140 kV and for (b) molybdenum target with the tube voltages between 25 and 35 kV.

Figure 5. Comparison of 30 kV x-ray spectra produced by MCNP4C and IPEM report 78 for (a) Mo target with 0.5 mm Be and 0.03 mm Mo filter, (b) Mo target with 0.5 mm Be and 0.025 mm Rh and (c) W target with 0.5 mm Be and 1.2 mm Al. Monte Carlo simulation of x-ray spectra using MCNP4C

Monte Carlo simulation of x-ray spectra using MCNP4C Table 2. Comparison between measured, calculated (IPEM report 78) and simulated (MCNP4C) HVLs and mean spectrum energy for spectra produced using 12° target angle and different tube voltages. The percentage difference between IPEM and MCNP4C estimates is also shown.

(unit is photons cm~* or MeV cm~?), which is normalized to be per starting particle. We used the unit photons cm~? for spectra generation and MeV cm~? for exposure assessment in the part related to investigation of anode heel effect. The point detectors were arranged in the calculation points A and B shown in figure | to calculate the exposure around the target and study anode heel effect. Note that the arrangement of point detectors for the calculation of exposure in the axis perpendicular to the anode-cathode axis is not shown. According to the MCNP user manual (Briesmeister 2000), an uncertainty of less than 5% is required for point detector tally (F5) to produce a generally reliable confidence interval. The maximum uncertainty regarding the number of produced photons within each energy bin of widths 0.5, 1 and 2 keV is less than 2% in our simulations, the magnitude of which depends on the number of simulated electrons (in our case 4 x 107).

Figure 9. Simulated x-ray spectra for 140 kV tube voltage for various target angles. (a) Centra axis. (b) 6° cathode side. (c) 6° anode side.

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Radiation exposure in bone mineral density assessment

by Christopher Njeh

1999, Applied Radiation and Isotopes

Osteoporosis is a systematic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue which leads to diminished biomechanical competence of the skeleton and low-trauma or atraumatic fractures.... more

Osteoporosis is a systematic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue which leads to diminished biomechanical competence of the skeleton and low-trauma or atraumatic fractures. Due to increased awareness of the impact of osteoporosis on the elderly population, the use of bone densitometric techniques is becoming more widespread. Considerable progress has been made in the development of non-invasive methods for the assessment of the skeleton. While DXA and QCT are commonly used techniques, the popularity of other approaches such as RA, SXA and QUS is gaining grounds. QCT has an advantage over the other techniques in its ability to measure the true volumetric density of trabecular or cortical bone. We therefore present an overview of these current techniques for bone mineral density (BMD) measurements. In the second section we discuss the radiation doses incurred in BMD measurements by patients and methods for reducing patient and sta radiation exposure are given. Studies of radiation dose to patient from DXA con®rms that patient dose is small (0.08±4.6 mSv) compared to that given by many other investigations involving ionizing radiation. Fan beam technology with increased resolution has resulted in increase patient dose radiation dose (6.7±31 mSv) but this is still relatively small. Carrying vertebral morphometry using DXA also incurs less radiation dose (<60 mSv) than standard lateral radiographs QCT has radiation dose (25±360 mSv) comparable to simple radiological examination such as chest X-ray but lower than imaging CT. Radiation dose from other techniques such as RA and SXA are in the same order of magnitude as pencil beam DXA. For pencil beam DXA and SXA systems the time average dose to sta from scatter is very low even with the operator sitting as close as 1 m from the patient during measurement. However the scatter dose from fan beam DXA systems is considerable higher and approaches limits set by regulator bodies for occupational exposure. #

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Scientific Aspects of Polymer Electrolyte Fuel Cell Durability and Degradation

by Seizo Miyata and

2007, Chemical Reviews

Automobile manufacturers and fuel cell developers have produced PEMFCs for many years, but recent significant technological advances have left two major remaining challenges to widespread fuel cell use: cost and lifetime, which are... more

Figure 23. (a) TEM of freshly prepared MEA. (b) TEM of MEA after potential cycling at 80 °C to 1.2 V for 1500 cycles.%87

Figure 1. Trend in published literature for PEMFC long-term durability and degradation studies (1989-2006). The search criteric were “Proton Exchange Membrane Fuel Cell” plus “Polymer Electrolyte Fuel Cell (PEFC)” and “durability” for the blue bars. The searches were repeated, substituting “degradation” for “durabil- ity”, and these totals correspond to the red bars.

Table 5. Membrane Mechanical Cycle and Metrics

Figure 12. Chemical structures of polymer electrolyte membranes.

Table 4. MEA Chemical Stability and Metrics

Figure 22. X-ray powder diffraction pattern of the pristine Pt/ Vulcan powder sample collected at normal incidence compared to those of anode b and cathode c in the cycled Pt/Vulcan MEA sample collected at primary incidence. Reprinted with permission from ref 224. Copyright 2005 The Electrochemical Society.

Figure 7. Voltage losses of two 50 cm? equivalent cells run at 0.8 A/cm? for 1000 h on neat hydrogen and on the mixture of Table 7. Loadings: 0.2 mg/cm? Pt at each electrode. Nafion membrane N112. Temperature = 80 °C. psig: 30/30. From ref 45. 2 Includes dilution due to inert gas in stock mixtures.

Figure 8. Equilibrium concentration of dissolved platinum vs electrode potential from a mathematical model. Reprinted with permission from ref 143. Copyright 2003 The Electrochemical Society.

Figure 17. Logarithm of Pt solubility as a function of inverse temperature. Open square, Pt/C in HC10,;!46 open triangle, in 0.5 M H,SO,;?24 open diamond, Pt foil in 0.1 M HCl + HNO;;348 closed diamond, Pt foil in 96% H3P0,;349 open circle, Pt powder in 0.5 M H2SO,; closed circle,5°® Pt powder in 1 M H2S04.95°

Figure 25. Life test of a hydrogen/air fuel cell operating with a CoPPy catalyst cathode. Life test data for a cell with a pyrolized cobalt tetraphenyl porphyrin cathode are shown for comparison. Cell voltage, 0.40 V; cell temperature, 80 °C.592

Figure 4. Polarization curves of a H,/air fuel cell showing the effect of 30 ppm NHs injected into the fuel stream for a total of 15 h. After this period, the cell continued operating on neat hydrogen for an additional 88 h at a constant voltage of 0.5 V. T = 80 °C. Reprinted with permission from ref 43. Copyright 2002 The Electrochemical Society.

Figure 10. Electrode potentials for a cell driven to pass current after hydrogen flow is interrupted. Reproduced with permission from ref 147. Copyright 2004 Elsevier Sequoia SA.

Figure 2. Schematic cross section of a typical PEM fuel cell.

Kenichiro Ota is a Professor of the Chemical Energy Laboratory at the Graduate School of Engineering, Yokohama National University, | apan. He received his B.S.E. in Applied Chemistry from the University of Tokyo in 1968 and his Ph.D. from the University of Tokyo in 1973. He has worked on hydrogen energy and fuel cells since 1974, working on materials science for fuel cells and water electrolysis. He has published more than 150 original papers, 70 review papers, and 50 scientific books. He is now the president of the Hydrogen Energy Systems Society of J apan, the chairman of the Fuel Cell Research Group of the Electrochemical Society of J apan, and the chairman of the National Committee for the Standardization of the Stationary Fuel Cells. He is also a member of the National Committee for Nuclear Safety.

Figure 18. Logarithm of Pt solubility as a function of potential. Open square, Pt wire in 0.57 M HC1O, at 23 °C;!4* open triangle, PU/C in 0.5 M H»SO, at 80 °C;224 closed circle, Pt wire in buffer solutions;*47 open circle, Pt powder in 1 M H2SO, at 22 °C;35° open diamond, Pt powder in 1 M H2SO, at 35 °C;35° double triangle, Pt powder in 1 M H2SO, at 51 °C;356 double square, Pt powder in 1 M H,SO, at 76 °C;3°6 solid line, Pt foil in H3PO. at 196 °C;°49 dashed line, Pourbaix.?38

Table 6. Origin of Common Fuel and Air Impurities® effect is permanent unless rigorous recovery procedures have been attempted. Exposure to high potentials or repeated cyclic voltammetry (CV) sweeps (for catalyst poisons, such as S) and operation at high currents (for foreign cations, such as NH,*) should be performed to determine if the effects are permanent.

Rod Borup is a Team Leader in the fuel cell program at Los Alamos National Lab in Los Alamos, New Mexico. He received his B.S.E. in Chemical Engineering from the University of lowa in 1988 and his Ph.D. from the University of Washington in 1993. He has worked on fuel cell technology since 1994, working in the areas of hydrogen production and PEM fuel cell stack components. He has been awarded 12 U.S. patents, authored over 40 papers related to fuel cell technology, and presented over 50 oral papers at national meetings. His current main research area is related to water transport in PEM fuel cells and PEM fuel cell durability. Recently, he was awarded the 2005 DOE Hydrogen Program R&D Award for the most significant R&D contribution of the year for his team’s work in fuel cell durability and was the Principal Investigator for the 2004 Fuel Cell Seminar (San Antonio, TX, USA) Best Poster Award.

Figure 13. Hydrolytic reaction of the imide rings resulting in chain scission.

Figure 11. Schematic diagram illustrating the “reverse current” mechanism. Reprinted with permission from ref 153. Copyright 2006 The Electrochemical Society.

Table 8. Durability of Selected Membranes under Fuel Cell Operation

4 Activity in A/mg at 150 kPa absolute backpressure at 900 mV iR, corrected on H2/O2, 100% RH, 80 °C. » Polarization curve per USFCC “Single Cell Test Protocol” section A6. Table 3. Catalyst Support Cycle and Metrics

Figure 16. Logarithm of Pt solubility as a function of pH at room temperature. Open symbols, E > 0.8 V vs SHE; closed symbols, E < 0.8V vs SHE. Square, Pt/C in HC10,;!*6 closed circle, Pt wire in buffer solutions;3*’ closed triangle, Pt powder in buffer solu- tions;*4” closed diamond, Pt foil in diluted water;*48 open diamond, Pt foil in 0.1 M HCl + HNO;;348 open circle, Pt powder in H2S04.356

Table 2. Electrocatalyst Cycle and Metrics

Figure 26. Contact angle measurements of GDL materials before and after aging in various environments. Image is from ref 629.

Figure 5. Polarization curves of a 5 cm? FC whose anode was poisoned with 1 ppm H,S. Pt loadings were 0.2 mg Pt/cm? at each electrode. Curves prior to poisoning and after electrochemical cleaning are also shown. T = 80 °C. From ref 112.

Figure 6. CV of the anode after full poisoning with H2S. CV prior to poisoning is also shown for comparison. Scan rate = 100 mV/s. T = 80 °C. From ref 113.

Figure 15. Regions of stability for platinum vs potential and pH.238:339

Table 13. Solubility of Group 4 and 5 Metal Oxides and Oxynitrides

Minoru Inaba is a Professor at the Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, ] apan. He received his B.Sc. from the Faculty of Engineering, Kyoto University, in 1984 and his M.Sc. in 1986 and his Dr. Eng. in 1995 from the Graduate School of Engineering, Kyoto University. He has worked on electrochemical energy conversion systems including fuel cells and lithium-ion batteries at Kyoto University (1992-2002) and at Doshisha University (2002-pres- ent). His primary research interest is the durability of polymer electrolyte fuel cells (PEF Cs), in particular, membrane degradation, and he has been involved in NEDO R&D research projects on PEFC durability since 2001. He has authored over 140 technical papers and 30 review articles. Bryan Pivovar received his B.S. in Chemical Engineering from the University of Wisconsin in 1994. He completed his Ph.D. in Chemica Engineering at the University of Minnesota in 2000 under the direction o Profs, Ed Cussler and Bill Smyrl, studying transport properties in fuel cel electrolytes. He continued working in the area of polymer electrolyte fue cells at Los Alamos National Laboratory as a postdoc (2000-2001), as a technical staff member (2001-2005), and in his current position as é team leader (2005-present). In this time, Bryan’s research has expanded to include further aspects of fuel cell operation, including electrodes, subfreezing effects, alternative polymers, hydroxide conductors, fuel cel interfaces, impurities, water transport, and high-temperature membranes. Bryan has served at various levels in national and intemational conferences and workshops, including organizing a DOE sponsored workshop on freezing effects in fuel cells and an ARO sponsored workshop on alkaline membrane fuel cells, and he was co-chair of the 2007 Gordon Researct Conference on Fuel Cells.

Zempachi Ogumi is a Professor of the Electrochemistry Laboratory at the Graduate School of Engineering, Kyoto University, | apan. He received his Ph.D. from Kyoto University in 1975 after finishing Bachelor and Master courses in the Department of Industrial Chemistry, Graduate School of Engineering, Kyoto University. He has worked on lithium batteries and fuel cells, focusing on materials science and reactions in electrochemical energy conversion and storage. He is now the president of the Electrochemical Society of J apan.

Figure 14. Stress—strain curves of sulfonated poly(arylene ether sulfone) (BPSH) and Nafion 117 at dry and humidified conditions; the numbers in parentheses represent the weight basis water content. Reprinted with permission from ref 286. Copyright 2005 Wiley- VCH Verlag GmbH & Co.

Figure 24. Pt particle size distributions comparing the Pt particles in a fresh cathode with Pt in the cathodes of MEAs subjected to 0.1-1.2 V potential cycling for 1500 h, 80 °C, and 50% RH. Modified from ref 387.

Table 12. Summary of Potential Cycling Platinum Dissolution Rates Guilminot et al.%°’ reported detection of Pt?* ions (z = 2, 4) in the membrane of a cycled MEA using ultraviolet spectroscopy; however, Pt?* was also detected in the as- prepared MEA. Y asuda et al.22°3%8.369 studied electrochemi- cally cycled MEAs using TEM and cyclic voltammetry. The Yasuda papers presented strong evidence for platinum dissolution, diffusion of the dissolved platinum into the membrane, and reduction of the dissolved platinum as particles in the membrane near the membrane—cathode interface by dissolved hydrogen. However, neither group observed the dissolution phenomena directly, e.g., the existence of particles with decreased diameter. Darling and Meyers developed mathematical models for dissolution and redeposition of platinum in PEMFCs.'*!“4 They assumed that platinum dissolution is determined by potential, particle size, and coverage ratio by oxide. In their model, the oxide layer can protect the platinum from dissolution, but the kinetics of oxide formation are slow relative to the rate of dissolution, so rapid changes in potential can expose the bare platinum to corrosive potentials in the interim between the potential step and coverage of the surface with oxide. Changes of the ECSA, particle size distribution, and con- centration of ionic species during potential holding or cycling were calculated. There is a growing body of literature suggesting that platinum dissolution is a major factor limiting the lifetime of polymer electrolyte fuel cells, especially under varying load conditions and at the high potentials of the cathode, though considerably more information is needed in order to fully characterize the mechanisms of oxide formation, platinum dissolution, and redeposition.

Figure 21. Particle size as determined by XRD and measured electrochemical active surface area for various potential cycling experiments. Cell 80 °C, Hz 226% RH, air 100% RH. Reproduced with permission from ref 17. Copyright 2004 Elsevier Sequoia SA.

Table 11. Thermal Transition Temperatures of Various Polymer Electrolyte Membranes for Fuel C ells

Table 10. Peroxide Stability by Fenton’s Test

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Assessment of radiation dose awareness among pediatricians

by Rahim Moineddin

2006, Pediatric radiology

There is increasing awareness among pediatric radiologists of the potential risks associated with ionizing radiation in medical imaging. However, it is not known whether there has been a corresponding increase in awareness among... more

Table 1 Responses to questions on lifetime cancer risk from CT, discussion with parents and informed consent

Table 2 Estimated effective doses for a 5-year-old child (19 kg) at our institution were within a factor of four, and 40% believed this frequently requested examination was equivalent to 10 CXR or less.

Thank you for taking the time to complete this survey. Please return in the self addressed envelope supplied. © 2003 surgical specialties or general pediatric medicine. For the purposes of simplicity, we refer to our study group by the overall term “pediatricians”. (Fig. 1). Of these, 224 (40%) were staff (attending physicians/surgeons) at a large pediatric teaching hospita in specialties involving regular use of the diagnostic imaging department, 186 (34%) were clinical or research fellows undergoing higher training but having completed their statutory specialty training, and 145 (26%) were other pediatricians identified from the records of the provincia College of Physicians and Surgeons practicing in loca hospitals and/or clinics. All respondents were primarily involved in managing pediatric patients in medical or

12 The new 'multislice' CT technology allows faster scanning of children. Compared to previous single-slice helical scanners, the radiation dose is

Table 3 Recalled training regarding radiation doses in medical imaging (total no. of respondents 218)

g CT chest (3.6mSv, approx. 600 CXR-equivalent units) h CT neck/chest/abdo/pelvis (10.4mSv, approx. 1700 CXR-equivalent units)

(8.3 mSv, approximately 1,300 CXR-equivalent units). f CT head pre- and post-contrast medium (7 mSv, approximately 1,100 CXR- equivalent units). g CT chest (3.6 mSv, approximately 600 CXR- equivalent units). h CT neck/chest/abdomen/pelvis (10.4 mSv, approximately 1,700 CXR-equivalent units) b DMSA scan (1.9mSv, approx. 300 CXR-equivalent units) Fig. 2. Estimation of effective doses for a 5-year-old child in CXR- equivalent units (Q.11) (x-axis no. of CXR-equivalents, y-axis no. 01 respondents). a AP pelvis radiograph (0.06 mSv, 10 CXR-equivalent units). b DMSA scan (1.9 mSv, approximately 300 CXR-equivalent units). ec VCUG (0.4 mSv, approximately 65 CXR-equivalent units). d Abdominal US (no ionizing radiation). e CT abdomen/pelvis

f CT head pre- and post-contrast (7mSv, approx. 1100 CXR-equivalent units’ e CT abdomen/pelvis (8.3mSv, approx. 1300 CXR-equivalent units) f CT

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Shielding strategies for human space exploration

by francis cucinotta

1997

"500 kilometers from the lunar base, astronauts make quick work of a rare service call on one of the exploration-class teleoperated rovers. Drawing by Paul Hudson. Vehicle and suit design by Brand Griffin. Copyright 1993."

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A sentinel case series of cancer patients with occupational exposures to electromagnetic non-ionizing radiation and other agents

by Y. Stein

2011, European Journal of Oncology

Background. There are reports that intense prolonged occupational exposure to non-ionizing radiation may increase risks for cancer. We previously have reported a sentinel cluster, of 7 workers with high exposures and short latent periods,... more

Background. There are reports that intense prolonged occupational exposure to non-ionizing radiation may increase risks for cancer. We previously have reported a sentinel cluster, of 7 workers with high exposures and short latent periods, and individual patients with brain cancer high occupational exposures and short latent periods. We present a sentinel case series (n=47, 40M, 7F) of cancer patients, referred to our medical unit with occupational exposures to non-ionizing radiation of all types.
Objectives. Our aims were to report the findings on tumour types, age of first diagnosis, and latency, to describe their exposures and to examine the hypothesis that latencies for all tumour types (solid tissue, hematolymphatic, testicular) were coherently related to high occupational exposures starting at young ages.
Methods. We divided the patients into groups by latency. We categorized each patient’s exposures in regard to types of radiation, far or near field exposure and direct body contact. For some we had data on frequencies, for others we provided assessments. We also present the patient data categorized by age of diagnosis. We used a case-case type comparison to examine latencies for tumour types [solid, hematolymphatic (HL), testicular].
Results. 15 patients developed cancer with latent periods of less than 5 years and 12 patients with latent periods between 5 and 10 years. The remaining 20 patients had longer latent periods between first occupational exposure to EMF and diagnosis of cancer. 6 patients (12.7%) had multiple tumours. 12 patients (25.5%) reported cancer cases in co-workers. In the <5 years latency group there were 8 hematolymphatic cancers, 3 testicular cancers and 6 solid tumours [head & neck (includingbrain) and GI tract]. In all latency groups there were patients who were exposed to intense levels of electromagnetic fields (EMF), to several types of EMF, or to EMF in combination with ionizing radiation (IR) or other exposures, and patients who had direct body contact with the equipment, were in direct focus of high radiation, or worked in small, electronically dense environments. Case classification by age showed shorter latencies with younger ages, but this association is complicated by the fact that shorter latencies co-vary with younger ages especially for testicular tumours. But patients with testicular and hematolymphatic tumours had shorter latencies than those with solid tumours.
Conclusion. Many of the patients were young and had extremely short latent periods, especially for HL and testicular cancers. The fact that latent periods for testes were very short, HL longer and solid stil llonger suggests a coherent and biologically plausible pattern of latency in relation to the onset of exposure to EMF and other agents. The findings strengthen the hypothesis that these exposures may possibly be the major cause of many of these tumours. The findings state the case for (1) better modelling of exposure sources and penetration into the body and (2) preventive and protective measures based on control of exposure at source, barriers, and personal protection.
Eur.J.Oncol., 16(1),21-54,2011

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ANTROPOLOGÍA DEL CUERPO Y MEDICINA CRÍTICA: DEL ENCARNIZAMIENTO TERAPÉUTICO AL CONCEPTO DE MUERTE CLÍNICA; JUGANDO A SER DIOSES

by Adolfo Vasquez Rocca

2013, Rosebud – Critica, scrittura, Giornalismo – Anno III, Dublin, Ireland, julio, 2013. Dr. Adolfo Vásquez Rocca

RESUMEN: Las investigaciones aquí desarrolladas buscan una aproximación interdisciplinaria al fenómeno de la salud y la enfermedad, así como a la naturaleza de la práctica médica en la posmodernidad. La filosofía de la medicina se... more

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A Survey on the Radiation Protection Status among Radiology Staff

by Tahereh Khani

2018, Iranian Journal of Medical Physics

Introduction: Radiation exposure during radiological examination is a health concern, of which radiology professionals should be cognizant. We sought to evaluate the radiation protection knowledge, attitudes, and practice (KAP) amongst... more

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RADİASİYADAN MÜHAFİZƏ

by Azad Bayramov

Kitabda radioaktiv və elektromaqnit şüalanmanın insan orqanizminə təsiri öyrənilir. Nüvələrin radioaktiv parçalanması və praktikada istifadə olunan dozimetrik vahidlər qısa şəkildə işıqlandırılır, ionlaşdırma qabiliyyətinə malik... more

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Natural radioactivity and dose assessment for phosphate rocks from Wadi El-Mashash and El-Mahamid Mines, Egypt

by Atef El-Taher

2005, Journal of Environmental Radioactivity

The activity concentrations of 226 Ra, 232 Th and 40 K have been measured by gamma spectroscopy (sodium iodide NaI(Tl) detector) in phosphate rock samples, collected from the Wadi El-Mashash, a site located in the central eastern desert,... more

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THE CONCEPT OF RISK AND ALARA PRINCIPLE

by Kunle W Giwa

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Radiation Reloaded: Ecological Impacts of the Fukushima Daiichi Nuclear Accident - Five years later

by Kendra Ulrich

This Greenpeace report draws on a large body of scientific research in Fukushima-impacted areas over the past five years to bring to light the current ecological situation as a result of the March 2011 Fukushima Daiichi nuclear accident.... more

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p115 The Optically Stimulated Luminescence (OSL) Properties of Various Known Thermoluminescent (TL) Materials

by Kimberlee Kearfott

This paper reports on an investigation into the optically stimulated luminescence (OSL) properties of several known thermoluminescent materials, namely LiF:Mg,Ti, Li2B4O7:Cu, CaSO4:Tm, and CaF2:Mn. Samples were irradiated to air doses of... more

Fig. 6. Optically stimulated luminescence (OSL) response during blue light (A=470 nm) stimulation of samples irradiated to 1.5 Gy. Output is shown in counts per channel, with each channel representing 0.2 s. Fig. 5. Optically stimulated luminescence (OSL) response during infrared light (A=830 nm) stimulation of samples irradiated to 1.5 Gy. Output is shown in counts per channel, with each channel representing 0.2 s.

Fig. 7. Maximum recorded optically stimulated luminescence (OSL) signal versus dose for CaSO4:Tm. Samples were irradiated to 15, 150 and 1500 mGy and read out using blue light (A=470nm) stimulation (closed diamonds) and infrared light (A=830 nm) stimulation (closed squares). Output is shown in counts per channel, with a channel representing 0.2 s. Trendlines are plotted, showing a highly linear dose response under blue light stimulation and a slightly sub-linear dose response under IR stimulation. Error bars are plotted, showing the standard deviation of the signal over 10 count channels, i.e., the statistical counting error.

Fig. 2. Optically stimulated luminescence (OSL) response during blue light (A4=470 nm) stimulation of unirradiated samples. Output is shown in counts per channel, with each channel representing 0.2 s.

Fig. 1. Optically stimulated luminescence (OSL) response during infrared light (A=830 nm) stimulation of unirradiated samples. Output is shown in counts per channel, with each channel representing 0.2 s. The emitted luminescence as a function of time for materials irradiated to 1.5 Gy as a consequence of stimulation using IR and blue light are shown as Figs. 5 and 6, respectively. These data re- veal that all of the investigated TLD materials except for the CaF2:Mn demonstrated at least some OSL when stimulated by both IR and blue light, although the CaSO,:Tm was an order of magni- tude more responsive in this regard.

Fig. 4. Optically stimulated luminescence (OSL) response during blue light (A4=470 nm) stimulation of samples irradiated to 15 mGy. Output is shown in counts per channel, with each channel representing 0.2 s. Fig. 3. Optically stimulated luminescence (OSL) response during infrared light (A4=830nm) stimulation of samples irradiated to 15 mGy. Output is shown in counts per channel, with each channel representing 0.2 s.

Thermal annealing parameters used for material samples. This table indicates the equipment used as well as the heating parameters employed to anneal the samples of LiF:Mg,Ti; LizB407:Cu; CaSO4:Tm; and CaF2:Mn prior to subsequent irradiation and optically stimulated luminescence (OSL) readout.

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Quality assurance of computed and digital radiography systems

by Anita Dowling

2008, Radiation Protection Dosimetry

Computed radiography (CR) and digital radiography (DR) are replacing traditional film screen radiography as hospitals move towards digital imaging and picture archiving and communication systems (PACS). Both IPEM and KCARE have recently... more

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ISSSD 2017 Book of Abstracts

by Hector Rene Vega-Carrillo

2017, Book of abstracts of the ISSSD 2017

Abstracts submitted to the ISSSD 2017
Santo Domingo, Dominican Republic

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Proceedings of the 4th International Conference on Educational Data Mining, Eindhoven, The Netherlands, July 6-8, 2011

by Cristina Conati

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Historical development of radiation safety practices in radiology

by Ronald Kathren and

1989, RadioGraphics

Address reprint requests to Alien Brodsky, Sc.D., Allen B Consultants, Inc. 16412 Kipling Road, Derwood, MD. 20855-1927. Volume 9, Number 6, Monograph « November, 1989 e RadioGraphics 126

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UV radiation effects on pathogens and insect pests of greenhouse-grown crops

by Michael Raviv

2007, Photochemistry and Photobiology

Production of high-value crops is often performed under protected cultivation. In recent years various spectral modifications have been made in greenhouse covers. Two of the main reasons to modify the spectral characteristics of... more

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Prenatal exposure to ionizing radiation: sources, effects and regulatory aspects

by Paola Fattibene

2007, Acta Paediatrica

Knowledge and awareness of physicians and the general public concerning the risks of prenatal exposure to ionizing radiation are important when developing a correct attitude to ionizing radiation. This is particularly important in the... more

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Accurate skin dose measurements using radiochromic film in clinical applications

by Wamied Abdel-Rahman

2006, Medical Physics

Megavoltage x-ray beams exhibit the well-known phenomena of dose buildup within the first few millimeters of the incident phantom surface, or the skin. Results of the surface dose measurements, however, depend vastly on the measurement... more

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Radiation Protection in X-Ray Computed Tomography: Literature Review

by Khalid Alsafi

2016, International Journal of Radiology and Imaging Technology

The principal concern for any patient undergoing a diagnostic CT examination is the risk of developing a radiation-induced cancer, which may be fatal or nonfatal. The total patient risk is related to the

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Humex, a study on the survivability and adaptation of humans to long-duration exploratory missions, part I: Lunar missions

by D. Manzey

2003, Advances in Space Research

Space exploration programmes, currently under discussion in the US and in Europe, foresee human missions to Mars to happen within the first half of this century. In this context, the European Space Agency (ESA) has conducted a study on... more

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Radiation Protection

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