Conversion coefficients for determination of dispersed photon dose during radiotherapy: NRUrad input code for MCNP

• Published in: PloS one Vol. 12; no. 3; p. e0174836
• Main Authors: Shahmohammadi Beni, Mehrdad, Ng, C Y P, Krstic, D, Nikezic, D, Yu, K N
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 31.03.2017; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Cancer; Cancer therapies; Computer simulation; Conversion; Dosimetry; Engineering and Technology; Health aspects; Laboratories; Materials science; Medicine and Health Sciences; Message passing; Models, Theoretical; Monte Carlo Method; Monte Carlo simulation; Organs; Patients; Photons; Physical Sciences; Physics; Radiation; Radiation dosage; Radiation therapy; Radiotherapy; Radiotherapy - methods; Risk factors; Tissues; United States
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0174836

Radiotherapy is a common cancer treatment module, where a certain amount of dose will be delivered to the targeted organ. This is achieved usually by photons generated by linear accelerator units. However, radiation scattering within the patient's body and the surrounding environment will lead to dose dispersion to healthy tissues which are not targets of the primary radiation. Determination of the dispersed dose would be important for assessing the risk and biological consequences in different organs or tissues. In the present work, the concept of conversion coefficient (F) of the dispersed dose was developed, in which F = (Dd/Dt), where Dd was the dispersed dose in a non-targeted tissue and Dt is the absorbed dose in the targeted tissue. To quantify Dd and Dt, a comprehensive model was developed using the Monte Carlo N-Particle (MCNP) package to simulate the linear accelerator head, the human phantom, the treatment couch and the radiotherapy treatment room. The present work also demonstrated the feasibility and power of parallel computing through the use of the Message Passing Interface (MPI) version of MCNP5.