Journal of Basic Research in Medical Sciences

en Calculation of Photoneutron Contamination of Varian linac with New Target in Tissue Equivalent Phantom Using Monte Carlo Simulation Medical physics Medical physics پژوهشي Research Introduction: In this research, a new material (Ti2V0.7Cu97.3) was proposed for the target of medical linear accelerators (linacs) to reduce the production of unwanted photoneutrons in the radiotherapy. So, the fluence, dose equivalent and kerma of the photoneutrons were calculated in a soft tissue phantom. Materials and Methods: The medical linac was the Varian 2100 C/D 18 MV, which its tungsten target was replaced with a new multi-metal target (Ti2V0.7Cu97.3). Desired quantities were computed in a ICRU soft tissue phantom, using the Monte Carlo code MCNPX (v. 2.6). Results: The ratio of the maximums of fluence, kerma, and dose equivalent of photoneutrons along the central axis of the ICRU phantom with new target rather than tungsten target were 72 %, 59 % and 61 %, respectively. Average of the Ratio of fluence, kerma, and dose equivalent in inner area (distances less than 5 cm from central axis) at different depths of the phantom with new target rather than tungsten target were 78 %, 70 % and 75 %, respectively. Uncertainties at all points were less than 5 % (except for a few points which were less than 10 %). Conclusion: This work showed that applying Ti2V0.7Cu97.3 alloy for the target of linac, can reduce the produced photoneutrons up to 38 % by an applicable and inexpensive way.   MCNPX, Photoneutron contamination, Simulation, Target of linac 31 41 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-657-1&slc_lang=en&sid=1 Mojtaba Cheraghian mojtaba.cheraghian61@gmail.com 10031947532846007619 10031947532846007619 No Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran, Iran Tayyeb Pourfallah tpourfallah@gmail.com 10031947532846007620 10031947532846007620 Yes Department of Biochemistry, Biophysics and Genetics, Medical College, Mazandaran University of Medical Sciences, Sari 48157-33971, Iran Amir Abbas Sabouri-Dodaran sabouri@pnu.ac.ir 10031947532846007621 10031947532846007621 No Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran, Iran Mehrdad Gholami gholami.mehrdad@lums.ac.ir 10031947532846007622 10031947532846007622 No Department of Medical Physics, School of Allied Medical Sciences, Lorestan University of Medical Sciences, Khorramabad 68138-33946, Iran