TY - JOUR
T1 - Dosimetry of a sonolucent material for an ultrasound-compatible gynecologic high-dose-rate brachytherapy cylinder using Monte Carlo simulation and radiochromic film
AU - Van Elburg, Devin J.
AU - Roumeliotis, Michael
AU - Morrison, Hali
AU - Rodgers, Jessica R.
AU - Fenster, Aaron
AU - Meyer, Tyler
N1 - Funding Information:
Disclosure: T.M. and M.R. have ownership interest in Okolo Health, a brachytherapy company. The remaining authors have nothing to disclose. This work was supported by the Alberta Cancer Foundation , the Alberta Innovates Graduate Studentship , and the Canadian Institutes of Health Research .
Publisher Copyright:
© 2021 American Brachytherapy Society
PY - 2021/1/1
Y1 - 2021/1/1
N2 - Purpose: he purpose of this study was to study the dosimetric characterization of sonolucent material “TPX” to be used toward gynecologic high-dose-rate brachytherapy treatments using ultrasound-compatible cylinders in non–model-based dose calculation workflows. Methods: Monte Carlo simulations were performed using EGSnrc application egs_brachy in cylinders of polymethylpentene (TPX) plastic, water, and PMMA. Simulations were performed of five 192Ir sources placed longitudinally in ∼3.7 cm diameter, 5.0 cm length cylinders (matching physical cylinders used in film measurements). TPX and PMMA dose distributions and percentage depth dose curves were compared relative to water. Film measurements were performed to validate egs_brachy simulations. TPX and PMMA cylinders were placed in a water tank using 3D-printed supports to position film radially and touching the surface of the cylinders. The same five 192Ir dwell positions were delivered as simulated in egs_brachy. Results: The egs_brachy and film percentage depth doses agreed within film uncertainties. The egs_brachy relative dose difference between TPX and water was (0.74 ± 0.09)% and between PMMA and water was (-0.79 ± 0.09)% over the dose scoring phantom. Dose differences for TPX and PMMA relative to water were less than ± 1% within 5 cm of the cylinder surface. Conclusions: In a solid sonolucent sheath of TPX, the dosimetric differences are comparable with PMMA and other applicator materials in clinical use. No additional uncertainty to dose calculation is introduced when treating through TPX cylinders compared with current applicator materials, and therefore, it is acceptable to perform gynecologic brachytherapy treatments with a sonolucent sheath inserted during radiation delivery.
AB - Purpose: he purpose of this study was to study the dosimetric characterization of sonolucent material “TPX” to be used toward gynecologic high-dose-rate brachytherapy treatments using ultrasound-compatible cylinders in non–model-based dose calculation workflows. Methods: Monte Carlo simulations were performed using EGSnrc application egs_brachy in cylinders of polymethylpentene (TPX) plastic, water, and PMMA. Simulations were performed of five 192Ir sources placed longitudinally in ∼3.7 cm diameter, 5.0 cm length cylinders (matching physical cylinders used in film measurements). TPX and PMMA dose distributions and percentage depth dose curves were compared relative to water. Film measurements were performed to validate egs_brachy simulations. TPX and PMMA cylinders were placed in a water tank using 3D-printed supports to position film radially and touching the surface of the cylinders. The same five 192Ir dwell positions were delivered as simulated in egs_brachy. Results: The egs_brachy and film percentage depth doses agreed within film uncertainties. The egs_brachy relative dose difference between TPX and water was (0.74 ± 0.09)% and between PMMA and water was (-0.79 ± 0.09)% over the dose scoring phantom. Dose differences for TPX and PMMA relative to water were less than ± 1% within 5 cm of the cylinder surface. Conclusions: In a solid sonolucent sheath of TPX, the dosimetric differences are comparable with PMMA and other applicator materials in clinical use. No additional uncertainty to dose calculation is introduced when treating through TPX cylinders compared with current applicator materials, and therefore, it is acceptable to perform gynecologic brachytherapy treatments with a sonolucent sheath inserted during radiation delivery.
KW - 3D ultrasound
KW - Dosimetry
KW - Gynecologic brachytherapy
KW - High-dose-rate brachytherapy
KW - Transvaginal ultrasound
UR - http://www.scopus.com/inward/record.url?scp=85092254363&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85092254363&partnerID=8YFLogxK
U2 - 10.1016/j.brachy.2020.08.024
DO - 10.1016/j.brachy.2020.08.024
M3 - Article
C2 - 33039331
AN - SCOPUS:85092254363
SN - 1538-4721
VL - 20
SP - 265
EP - 271
JO - Brachytherapy
JF - Brachytherapy
IS - 1
ER -