background: absolute dosimetry of external beam radiotherapy is carried out by the use of ionization chambers. these chambers must be calibrated at a standard dosimetry laboratory before any use in clinical dosimetry. the secondary standard dosimetry laboratory of iran (ssdl) has the duty of calibrating the ionization chambers used in radiotherapy centers in iran. materials and methods: the pre...

background: the assessment of rbe quantity in the treatment of cancer tumors with proton beams in treatment planning systems (tps) is of high significance. given the significance of the issue and the studies conducted in the literature, this quantity is fixed and is taken as equal to 1.1. objective: the main objective of this study was to assess rbe quantity of proton beams and their variations...

introduction intensity-modulated radiotherapy (imrt) is becoming an increasingly routine treatment method. imrt can be delivered by use of conventional multileaf collimators (mlcs) and/or physical compensators. one of the most important factors in selecting an appropriate imrt technique is integral dose. integral dose is equal to the mean energy deposited in the total irradiated volume of the p...

Introduction BNCT is an effective method to destroy brain tumoral cells while sparing the healthy tissues. The recommended flux for epithermal neutrons is 109 n/cm2s, which has the most effectiveness on deep-seated tumors. In this paper, it is indicated that using D-T neutron source and optimizing of Beam Shaping Assembly (BSA) leads to treating brain tumors in a reasonable time where all IAEA ...

Introduction: Radiotherapy is one of the treatment options for locally advanced prostate cancer, however with standard radiation doses it is not always very effective. One of the strategies to improve the efficiency of radiotherapy is increasing the dose. In this study to increase tumor local control rates a new radiotherapy method, known as dose painting (DP) was investigated....

introduction in radiography, dose and image quality are dependent on radiographic parameters. the problem is caused from incorrect use of radiography equipment and from the radiation exposure to patients much more than required. therefore, the aim of this study was to implement a quality-control program to detect changes in exposure parameters, which may affect diagnosis or patient radiation do...

The biased coin up-and-down design (BCD) is used to allocate doses in phase I clinical trials. The BCD requires that the treatment response or the toxicity evaluation is observed quickly. In trials with a long treatment evaluation, the BCD will lead to long trial duration because a new patient cannot be enrolled until the preceding patient has completed the evaluation period. We propose a simpl...