MONTE CARLO SYMULATION CHARACTERISTICS OF MODEL 6711 BRACHYTHERAPY SEED: EFFECTS OF ENERGY SPECTRUM AND PHANTOM DIMENSIONS

Abstract

It is important to determine specified dose distributions of radioactive seed sources of brachytherapy in both phantom material and treated tissues. Dosimetric features and specific dose distribution functions of Model 6711 brachytherapy seed which is frequently used in prostate cancer treatments, have been given in literature. In the present study decay spectrum of radioactive material and variations of phantom dimensions which are foreseen to affect dosimetric specifications of the seed, were investigated and results were performed by Monte Carlo simulation. In simulation using separate decay spectrum and mono energy, differences were noted between interval of 1-68 percent. Also in calculations of phantom dimensions variations, deviations were not observed more than 0.1 percent by normalization to 1 as expected.

Keywords

• Brachytherapy, Monte Carlo, Model 6711, EGSnrc, I-125,

MODEL 6711 BRAKYTERAPY KAYNA?ININ MONTE CARLO SYMÜLASYONU KARAKTERYSTYKLERY: ENERJY SPEKTRUMU VE FANTOM BÜYÜKLÜ?ÜNÜN ETKYLERY

Öz

Brakiterapide kullanylan radyoaktif kaynaklaryn gerek doku içerisinde gerekse fantom metaryelindeki özelle?mi? doz da?ylymlarynyn hassas olarak bilinmesi tedavi planlamalarynda önemlidir. Prostat kanseri tedavisinde syklykla tercih edilen Model 6711 kayna?ynyn dozimetrik özellikleri ve ilgili doz da?ylymlaryny ifade eden fonksiyonlary literatürde verilmi? durumdadyr. Bu çaly?mada bu kayna?a özel parametreleri etkileyece?i öngörülen, radyoaktif malzemenin bozunum spektrumu ve kullanylan simülasyon fantomunun büyüklü?üne ait de?i?imler incelenerek etkileri Monte Carlo simulasyonu kullanylarak ortaya konmu?tur. Bozunum spektrumu ve tek enerji kullanylarak yapylan çaly?malarda parametreler arasynda %1 ile %68 orasnynda de?i?en farklar görülmü?tür. Fantom geni?liklerinin de?i?iminden kaynaklanan hesaplarda parametrelerin bire normalizasyonlarynda beklendi?i gibi %0,1 den büyük farklar gözlenmemi?tir.

Anahtar Kelimeler

• Brakiterapi, Monte Carlo, Model 6711, EGSnrc, I-125,