Dosimetric characterization of a novel intracavitary mold applicator for Ir-192 high dose rate endorectal brachytherapy treatment

作者：Poon Emily^*; Reniers Brigitte; Devic Slobodan; Vuong Te; Verhaegen Frank

来源：Medical Physics, 2006, 33(12): 4515-4526.

DOI：10.1118/1.2364054

• Ir-192
• intracavitary brachytherapy
• GEANT4
• Monte Carlo
• GAFCHROMIC (TM) EBT film

The dosimetric properties of a novel intracavitary mold applicator for Ir-192 high dose rate (HDR) endorectal cancer treatment have been investigated using Monte Carlo (MC) simulations and experimental methods. The 28 cm long applicator has a flexible structure made of silicone rubber for easy passage into cavities with deep-seated tumors. It consists of eight source catheters arranged around a central cavity for shielding insertion, and is compatible for use with an endocavitary balloon. A phase space model of the HDR source has been validated for dose calculations using the GEANT4 MC code. GAFCHROMIC (TM) EBT model film was used to measure dose distributions in water around shielded and unshielded applicators with two loading configurations, and to quantify the shielding effect of a balloon injected with an iodine solution (300 mg I/mL). The film calibration procedure was performed in water using an Ir-192 HDR source. Ionization chamber measurements in a Lucite phantom show that placing a tungsten rod in the applicator attenuates the dose in the shielded region by up to 85%. Inserting the shielded applicator into a water-filled balloon pushes the neighboring tissues away from the radiation source, and the resulting geometric displacement reduces the dose by up to 53%; another 8% dose reduction can be achieved when the balloon is injected with an iodine solution. All experimental results agree with the GEANT4 calculations within measurement uncertainties. 2006 American Association of Physicists in Medicine.

• 出版日期2006-12