background: the purpose of this work was to investigate the use of polyvinyl chloride (pvc) dyed with methyl red as a high dose radiation dosimetry. materials and methods: commercial pvc films from sabic made from resins pvc57s with thickness of 60 µm and methyl red with a molecular weight of 269.31 were used. irradiation was carried out using a 60co γ-ray generator with sources arranged in rec...

BACKGROUND Radiotherapy plays an important role in the management of most malignant and many benign primary central nervous system (CNS) tumors. Radiotherapy affects both tumor cells and uninvolved normal cells; so, it is important to estimate absorbed dose to organs at risk in this kind of treatment. The aim of this study was to determine the absorbed dose to chiasma, lens, optic nerve, retina...

Introduction: The CT machine utilizes a bowtie filter to shape the X-ray beam and remove lower energy photons. Configuration of this bowtie filter is complex and its geometry is often not available in detail. It causes the CT dose index (CTDI) be with the different values in measurement versus Monte Carlo simulation studies and other analytical calculations. It is important esp...

Introduction Radon is a colorless and tasteless gas which exists in most soils. It is a substance that poses a potential risk for lung cancer in case a person is exposed to high levels over long periods of time. The Environmental Protection Agency (EPA) estimates that 90% of lung cancers per year are caused by radon. The aim of this paper is to estimate the absorbed doses of 222Rn by MCNPX simu...

Background: Radioiodine therapy has proven to be an effective method in the treatment of patients with differentiated thyroid carcinoma after thyroidectomy. The scope of this study is to describe a method to obtain the dose of organs using medical internal radiation dosimetry (MIRD) method. At the end, the results of MIRD calculations were compared with thermoluminescent dosimeter (TLD...

introduction in order to treat uveal melanoma , first, radioactive seeds are laid on a silicone- made substance which is called silastic after that they are inserted in the plaque, and finally, this plaque containing silicone-made substance is stitched to the sclera surface. the dose gradient within the tumor and healthy tissues can be varied due to changing the silastic thickness between scler...

Various types of radiation detectors are used to measure relative dose distributions for therapeutic electron and photon beams. Most detectable signals from a radiation detector are correlated to the energy imparted δε to the detector [1]. This, in turn, is related to the absorbed dose in the detector, Ddet. Table I lists types of radiation detectors, their signals, and their relationship to th...

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: Breast cancer is the most common cancer among women. Brachytherapy is one of the ways to treat breast cancer. In brachytherapy treatments, high-dose sources are used in interstitial placement. Here, Iridium-192 is used. This source emits gamma rays with energies ranging from 136 kV to 1060 kV electron volts. The activity of the used spring is 10 Ci. The simulated ...

The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, ...