Sean Blancher, Abstract Co-Author: Nothing to Disclose

Jose Eduardo Villarreal- Barajas PhD, Presenter: Nothing to Disclose

To present the design, construction and testing of a polyurethane-pvc  pelvis anthropomorphic phantom for brachytherapy dose distribution studies

The accurate design of an anthropomorphic phantom of the pelvic region was achieved by using a plaster template molded from the RandoTM humanoid phantom. This template was latter filled with a thick (~ 12 cm) layer of polyurethane which makes up the majority of the phantom, forming a permanent outer shell that holds the pelvic bones (pvc) in situ. CT of the pelvic phantom reveled a consistent outer shell of -10 +/- 30 HU and pvc-bones of 570 +/- 30 HU. Two cavities to mimic the rectum and the vagina (4 and 5 cm diameter respectively) were "carved" within the pelvic phantom. The vaginal cavity was designed to accommodate the insertion of brachytherapy applicator (tandem and ovoids). For the successful measurement of dose delivery, the phantom was prepared to accommodate the insertion and removal of LiF thermoluminescent dosemeters. To allow for different configurations of dosimeters and the possibility of testing different treatment regimes, the phantom was made reusable by filling the applicator insertion with gelatin. For testing a simple treatment using a three channel Fletcher vaginal applicator and a 11.3 Ci HDR brachytherapy source was used. Four rectal points and eight applicator points were scored using LiF powder (TLD-100) contained in plastic cylinders1cm in length and 3mm diameter.  

  The absorbed dose to water calculated using the TG-43 formalism correlated reasonably well (within the measurement uncertainties) with the TLD measurements performed on the pelvic phantom. However,  a small (~ 7%) but systematic overestimation of the calculated rectal doses was observed.

The pelvic anthropomorphic phantom can be effectively used for the commissioning, testing and training of brachytherapy treatment systems. The initial investigation into the ability of the TG43 formalism to accurately predict absorbed dose to water showed good agreement with measurements performed using TLD-LiF dosemeters.  

An anthropomorphic phantom of the pelvic region has the potential to improve the effectiveness of the commissioning, quality control and training of brachytherapy treatments systems.

Blancher, S, Villarreal- Barajas, J, Design, Construction, and Testing of a Pelvis Anthropomorphic Phantom for Brachytherapy Dose Distribution Studies.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034299.html