Fast Monte Carlo simulation for total body irradiation using a teletherapy unit

• DOI: 10.1120/jacmp.v14i3.4214
• Publication Date: 2017-02-27T23:05:58Z
• Authors: Xiaodong Liu; Danielle Lack; Joseph T. Rakowski; Cory Knill; Michael Snyder
• Keywords: Phantoms, Imaging; Radiotherapy Planning, Computer-Assisted; Radiotherapy Dosage; 03 medical and health sciences; 0302 clinical medicine; Neoplasms; Humans; Cobalt Radioisotopes; Radioisotope Teletherapy; Monte Carlo Method; Algorithms; Whole-Body Irradiation

Our institution delivers TBI using a modified Theratron 780 60Co unit. Due to limitations of our treatment planning system in calculating dose for this treatment, we have developed fast Monte Carlo code calculate distributions within the patient. The algorithm is written C and uses voxel density information from CT images heterogeneous media. To test algorithm, film-based measurements were made separately simple water phantom with high-density insert RANDO then compared doses calculated by algorithm. In addition, separate simulation GEANT4 was run both film in-house simulation. All results analyzed RIT113 analysis software. Simulations accurately predict depth maximum at 0.5 cm. measured PDD along central axis beam closely matches generated code, deviating on average only 3% phantom. Dose planes inside had mean difference 4.9% cross-profile measurement. phantom, gamma pass rates vary between 91% 99% 3 mm, 3%, >99% 5 5% four measured. Profiles taken across simulations resulted relative differences < 2% all profiles each slice presented here potentially viable method delivered treatments center. While not yet refined enough be primary planning, its current resolution determines distribution one patient few hours, provides clinically useful TBI. With appropriate optimization, could implemented as first-line option