TG‐69: Radiographic film for megavoltage beam dosimetry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134818/1/mp6779.pd

Comparison of apparent diffusion coefficient maps to T2-weighted images for target delineation in cervix cancer brachytherapy

Purpose: T2-weighted (T2W) magnetic resonance imaging (MRI) has been used for target delineation in cervix cancerbrachytherapy. The objective of this study was to examine the feasibility of using diffusion-weighted magnetic resonanceimaging (DWI) for target delineation as compared against T2W imaging. Material and methods: Fifteen cervix cancer patients, implanted with tandem and ovoid applicators, underwentT2W turbo-spin echo imaging and DWI with a maximum diffusion factor of 800 sec/mm2 on a 1.5-T MR scanner. Appa -rent diffusion coefficient (ADC) maps were derived from the DWI. The gross tumor volume was manually delineatedon the T2W and ADC datasets for each patient. The agreement between T2W- and ADC-delineated volumes was assessedusing the Dice similarity coefficient (DSC). An algorithm was developed to compare the edge contrast of the delineatedvolumes on T2W images and ADC maps by calculating the percentage difference in the intensity values of selectedregions of pixels inside versus outside the target contour. Results: ADC-delineated volumes were generally smaller than T2W-delineated volumes, yielding a low DSC of 0.54± 0.22. ADC maps were found to display superior definition of the target volume edge relative to T2W images, yieldinga statistically significant difference between the mean edge contrast on ADC (12.7 ± 7.7%) versus that on T2W images(4.6 ± 3.2%; p = 0.0010). Conclusions: These results suggest that incorporating the use of DWI for cervix cancer brachytherapy may yieldgross tumor volumes that are different from those based on T2W images alone

Outcomes of iodine-125 plaque brachytherapy for uveal melanoma with intraoperative ultrasonography and supplemental transpupillary thermotherapy

To assess the impact on local tumor control of intraoperative ultrasonographic plaque visualization and selective application of transpupillary thermotherapy (TTT) in the treatment of posterior uveal melanoma with iodine-125 (I-125) episcleral plaque brachytherapy (EPB). Retrospective analysis of 526 patients treated with I-125 EPB for posterior uveal melanoma. Clinical features, dosimetric parameters, TTT treatments, and local tumor control outcomes were recorded. Statistical analysis was performed using Cox proportional hazards and Kaplan-Meier life table method. The study included 270 men (51%) and 256 women (49%), with a median age of 63 years (mean, 62 years; range, 16-91 years). Median dose to the tumor apex was 94.4 Gy (mean, 97.8; range, 43.9-183.9) and to the tumor base was 257.9 Gy (mean, 275.6; range, 124.2-729.8). Plaque tilt >1 mm away from the sclera at plaque removal was detected in 142 cases (27%). Supplemental TTT was performed in 72 patients (13.7%). One or 2 TTT sessions were required in 71 TTT cases (98.6%). After a median follow-up of 45.9 months (mean, 53.4 months; range, 6-175 months), local tumor recurrence was detected in 19 patients (3.6%). Local tumor recurrence was associated with lower dose to the tumor base (P=.02). Ultrasound-guided plaque localization of I-125 EPB is associated with excellent local tumor control. Detection of plaque tilt by ultrasonography at plaque removal allows supplemental TTT to be used in patients at potentially higher risk for local recurrence while sparing the majority of patients who are at low risk. Most patients require only 1 or 2 TTT sessions

Essentials and guidelines for clinical medical physics residency training programs: executive summary of AAPM Report Number 249

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135475/1/acm20004.pd