Introduction: Thyroid cancer is at the ninth from ten of common malignant cancer. A man has higher risk to get Thyroid cancer that a woman has. This organ is lain near human neck. The use of radioactive I-131, I-123 and Tc-99m for diagnosis of thyroid cancer has a risk where other organs around Thyroid will accept dose of radiation. One of the risks is large dose which is accep...

introduction: nowadays new radiochromic films have an essential role in radiotherapy dosimetry. properties such as high sensitivity, good reproducibility, high spatial resolution, easy readout and portability have made them attractive for dosimetry, especially in high-dose-gradient regions. material and methods: in this study, electron-beam dose distributions in homogenous and heterogeneous pha...

as a result of being hydrogenous moderators, several landmine detection methods based onnuclear techniques have been suggested in recent years. because of elastic scattering and moderating neutrons from hydrogen atoms in landmines, detection of backscattered neutron shows an anomaly in the reflected thermal neutrons count when a detector scans over a mine. on landmine detection using neutron so...

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...

background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...

The Monte Carlo method was used to calculate the photon detection efficiency and energy resolution curves for a 1.500 100 NaI(Tl) scintillator detector (crystal þ housing þ photomultiplier tube material equivalent) exposed to gamma rays in the energy range from 20 keV to 662 keV. This work aims to design a precise computational model, based in Monte Carlo simulation, which can be used in practi...

This work presents experimental dosimetry results for a new 103Pd brachytherapy seed, in accordance with the AAPM TG-43U1 recommendation that all new low-energy interstitial brachytherapy seeds should undergo one Monte Carlo (MC) and at least one experimental dosimetry characterization. Measurements were performed using TLD-GR200A circular chip dosimeters using standard methods employing thermo...

Introduction: In recent decades, several Monte Carlo codes have been introduced for research and medical applications. These methods provide both accurate and detailed calculation of particle transport from linear accelerators. The main drawback of Monte Carlo techniques is the extremely long computing time that is required in order to obtain a dose distribution with good statistical accuracy. ...

In view of assessing natural radioactivity with on-site quantitative gamma spectrometry, efficiency calibration of NaI(Tl) detectors is investigated. A calibration based on Monte Carlo simulation of detector response is proposed, to render reliable quantitative analysis practicable in field campaigns. The method is developed with reference to contact geometry, in which measurements are taken pl...

The manganese bath method for measuring the neutron emission rate of radionuclide sources requires corrections to be made for emitted neutrons which are not captured by manganese nuclei. The Monte Carlo particle transport code MCNP has been used to calculate the fractions of neutrons that escape from the boundaries of the tank, that are captured by the steel cavity in which the source is housed...