Stewart Gaede

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Papers by Stewart Gaede

MOESM1 of Assessment of precision irradiation in early non-small cell lung cancer and interstitial lung disease (ASPIRE-ILD): study protocol for a phase II trial

Additional file 1. Â Summary of SABR-related mortality and ILD-specific toxicity. Reproduced from... more

MOESM3 of Assessment of precision irradiation in early non-small cell lung cancer and interstitial lung disease (ASPIRE-ILD): study protocol for a phase II trial

Additional file 3.Â ASPIRE-MRI Sub-study (London Site Only).

Additional file 1 of Stereotactic ablative radiotherapy for the comprehensive treatment of 1–3 Oligometastatic tumors (SABR-COMET-3): study protocol for a randomized phase III trial

Additional file 1 Appendix 1. World Health Organization Trial Registration Dataset. Appendix 2. D... more

MOESM2 of Assessment of precision irradiation in early non-small cell lung cancer and interstitial lung disease (ASPIRE-ILD): study protocol for a phase II trial

Additional file 2.Â Consent Form for the ASPIRE-ILD Study.

MOESM5 of Assessment of precision irradiation in early non-small cell lung cancer and interstitial lung disease (ASPIRE-ILD): study protocol for a phase II trial

Additional file 5. Flowchart of Enrollment and Central Review.

Additional file 1: of Stereotactic ablative radiotherapy for the comprehensive treatment of 4â 10 oligometastatic tumors (SABR-COMET-10): study protocol for a randomized phase III trial

Dose Constraints. Dose Constraints for Treatment Planning. (DOC 123 kb)

Trainee Name: Supervisor(s): Structured tr ct: Title: Assessing Myocardial Perfusion after Cardiac Irradiation using Dynamic Contrast Enhanced Hybrid PET/ MRI

INTRODUCTION: Breast cancer accounts for 25% of total yearly female cancer mortalities. Adjuvant ... more INTRODUCTION: Breast cancer accounts for 25% of total yearly female cancer mortalities. Adjuvant radiation therapy of the breast plays a vital role to breast cancer treatment and has shown to improve both local control and overall survival. However, patients with left-sided breast cancer are at an increased risk of coronary artery disease due to the proximity of the heart to the high radiation dose. Using hybrid PET/MR imaging, cardiac abnormalities, changes in myocardial viability, and coronary artery disease can be assessed noninvasively. A previous canine study done in our lab demonstrated that hybrid PET/MRI detected an increase in PET 13N-NH3 myocardial perfusion and was associated with a global inflammatory response after a low radiation dose exposure. However, the rest and adenosine induced stress 13N-NH3 myocardial blood flow (MBF) propagated in different trends starting from 1 month onwards after cardiac irradiation. Hence, further investigation was done in the dynamic contrast enhanced MR (DCE-MR) imaging data acquired simultaneously in our canine model to assess the change in myocardial perfusion. HYPOTHESIS: We believe DCE-MR imaging acquired would detect changes in myocardial perfusion in our canine model after cardiac irradiation. METHOD: 5 canines performed dual bolus Gd-DTPA DCE-MR imaging at baseline, 1 week, 1 month, 3 months, 6 months after cardiac external beam irradiation. Rest and adenosine induced stress scan were conducted utilizing the fast gradient echo sequence on the 3T hybrid PET/MR scanner at St. Joseph's hospital. Axial slices of the myocardium were contoured on ITK-snap according to 17 segment cardiac model. With left ventricle selected as the arterial input function (AIF), myocardial tissue curves were fitted using MATLAB with Toft's model to determine volume transfer constant Ktrans. Ktrans data were sorted into regions supplied with respective coronary arteries (LAD, LCX or Both arteries). Since Ktrans =extraction fraction*MBF, paired T-tests were performed with 13N-NH3 MBF versus extraction fraction (assumed 0.5) multiplied with Ktrans determined from separated bolus curve fittings. RESULT: P-values obtained from paired sample T-tests of 13N-NH3 MBF vs 0.5 *1st MR Gd-DTPA bolus Ktrans and that of 13N-NH3 MBF vs 0.5 *2nd MR Gd-DTPA bolus Ktrans for all coronary artery supplied regions under rest and stress scans were less than 0.05. This proved the presence of AIF signal saturation from left ventricle blood pool. DCE-MR Ktrans rest and stress data propagated in different trends starting from 1month post radiotherapy. CONCLUSION: Dual peaks Toft's model curved fitting instead of separated peaks curve fitting for determining myocardial Ktrans values was necessary for accurate myocardial perfusion quantification especially for dual bolus GD-DTPA injection scans due to signal saturation in the AIF. In this animal model study, we were not able to acquire same propagating trends in both PET MBF and MR Ktrans imaging.

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Inter-observer and intra-observer reliability for lung cancer target volume delineation in the 4D-CT era

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 2010

BACKGROUND AND PURPOSE To investigate inter-observer and intra-observer target volume delineation... more BACKGROUND AND PURPOSE To investigate inter-observer and intra-observer target volume delineation (TVD) error in 4D-CT imaging of thoracic tumours. MATERIALS AND METHODS Primary and nodal gross tumour volumes (GTV) of 10 lung tumours on the 10 respiratory phases of a 4D-CT scan were contoured by six radiation oncologist observers. Inter-observer and intra-observer variability were assessed by the coefficient of variation (COV) and the volume overlap index (VOI). ANOVA was performed to assess differences in inter-observer and intra-observer variability based on patient case difficulty, respiratory phase, physician seniority, and physician observer. RESULTS VOI analysis determined that inter-observer was a more significant source of error than intra-observer variability. VOI improved with the use of 4D-CT as compared to conventional CT. ANOVA analysis for COVs found case difficulty (easy versus difficult) to be significant for inter-observer primary tumour and intra-observer nodal dis...

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Technical Note: Volumetric computed tomography for radiotherapy simulation and treatment planning

Journal of Applied Clinical Medical Physics

Abstract Purpose For lung and liver tumors requiring radiotherapy, motion artifacts are common in... more Abstract Purpose For lung and liver tumors requiring radiotherapy, motion artifacts are common in 4D‐CT images due to the small axial field‐of‐view (aFOV) of conventional CT scanners. This may negatively impact contouring and dose calculation accuracy and could lead to a geographic miss during treatment. Recent advancements in volumetric CT (vCT) enable an aFOV up to 160 mm in a single rotation, which may reduce motion artifacts. However, the impact of large aFOV on CT number required for dose calculation needs to be evaluated before clinical implementation. The objective of this study was to determine the utility of a 256‐slice vCT scanner for 4D‐CT simulation by evaluating image quality and generating relative electron density (RED) curves. Methods Images were acquired on a 256‐slice GE Revolution CT scanner with 40 mm, 80 mm, 120 mm, 140 mm, and 160 mm aFOV. Image quality was assessed by evaluating CT number linearity, uniformity, noise, and low‐contrast resolution. The relationship between each quality metric and aFOV was assessed. Results CT number linearity, uniformity, noise, and low‐contrast resolution were within the expected range for each image set, except CT number in Teflon and Delrin, which were underestimated. Spearman correlation coefficient (ρ) showed that the CT number for Teflon (ρ = 1.0, p = 0.02), Delrin (ρ = 1.0, p = 0.02), and air (ρ = 1.0, p = 0.02) was significantly related to aFOV, while all other measurements were not. The measured deviations from expected values were not clinically significant. Conclusion These results suggest that vCT can be used for CT simulation for radiation treatment planning.