Introduction In this study, effective Dose equivalent for the public due to internal exposure to 222radon (222Rn) was evaluated in three regions of Ramsar, a northern coastal city in Iran. Materials and Methods Measurements were carried out using a radon monitoring device. Outdoor and indoor radon concentrations were measured within 24 hours with an integration interval of 3 hours. Regions were selected with respect to our previous study on areas of Ramsar with high levels of environmental background radiation. Results This study showed that indoor 222Rn concentration reached to 465 Bq/m3 in one of the selected regions (Talesh Mahalleh) in early morning (5-8 a. m. ). Our study also showed that the average effective Dose equivalents (due to both indoor and outdoor exposures) in the selected regions (Talesh Mahalleh, Sadat Mahalleh, and Chaparsar) were 9. 5± 2. 8, 5. 1± 2. 1, and 3. 2± 1. 2 mSv/y, respectively. Conclusion It is clear that the annual effective Dose from internal exposure to 222Rn in areas of Ramsar with high levels of natural radiation was significantly higher than the maximum annual effective Dose permissible for public.

Introduction: Microdosimeters are helpful for Dose equivalent measurement in unknown radiation fields. The favorable physical and mechanical properties of the detector-grade chemical vapor deposition diamond materials have made the diamond microdosimeters suitable candidate for radioprotection applications in space. The purpose of this work is the investigation of the Dose equivalent response of a typical diamond microdosimeter with laser-induced graphitized electrodes for use in space radiation fields.Materials and Methods: The Geant4 Monte Carlo simulation toolkit was applied to simulate the particle transport within the microdosimeter, and to determine the mean chord length and the Dose equivalent response of the microdosimeter, based on the lineal energy dependent quality factor.results: The linear stopping power of the protons and alpha particles with energies higher than 5 MeV and 10 MeV respectively can be estimated within 20% of deviation using the microdosimeter response. The fluence to Dose equivalent conversion coefficients calculated affirms that there is an adequate agreement between the calculated coefficients and other research group results.Conclusion: The reasonable agreement between the Dose equivalents calculated in this study and the results reported by other researchers confirmed that this type of microdosimeter could be a promising candidate suitable for the measurement of the Dose equivalent in space radiation fields.

Background: To quantify the influence of photon Dose-calculation algorithm selection on the cervical esophagus (CE) Dose indices and the derived equivalent uniform Dose (EUD) and normal-tissue complication probability (NTCP) for acute esophagitis in patients with head-and-neck cancer (HNC). Materials and Methods: The Fast Photon Effective Path (FPEP) and Collapsed-Cone Convolution Superposition (CCCS) algorithms on the Prowess Panther treatment planning system were compared for 30 patients (six tumor sites). The Lyman-Kutcher-Burmann (LKB) model was used to calculate the EUDs and NTCPs. Results: On average, the more simplistic FPEP algorithm overestimated the mean Dose to CE planning organ-at-risk volumes (PRVs) by 2. 0% (p = 0. 003). The average absolute difference in mean Dose was 2. 7% and the maximum difference was 9. 3%. The V5Gy, V10Gy, V15Gy, V20Gy, V25Gy and V30Gy values were significantly higher with FPEP, while the point-Dose and D2cc hot spots were similar. In turn, the Dose differences led to an underestimation of the LKB-model prediction of the EUD by 1. 4% (p = 0. 297). The mean absolute difference in EUD was 4. 5% and the maximum difference was 15. 3%. In the 14-50 Gy mean Dose range, the resulting NTCPs with FPEP were lower on average by 2. 6% than CCCS (p = 0. 041). Conclusions: In the group of HNC patients considered in this study, the EUD and NTCP for acute esophagitis showed to be moderately sensitive to the choice of Dose-calculation algorithm. Despite an overestimated mean Dose by the simpler algorithm, the NTCP underestimation, which can be large in some patients, is of clinical concern.

One of the challenges of individual dosimetry in Iran is the absence of standard radiation fields with different energies for calibration. For dosimetry in the photon fields, only the standard fields of Co-60 and Cs-137 sources, located in the (SSDL) can be utilized. This study aims to determine energy response of a personal thermoluminescence dosimeter (TLD) designed for determining the personal Dose-equivalent, Hp(10), in order to investigate whether the calibration curve in the Co-60 gamma field can be utilized for assessing the Dose-equivalent in the photon fields with different energies. To do this, first, the TLD dosimeters (an appropriate plastic badge including a TLD-100 chip) are irradiated with a few Hp(10) values using the Co-60 source in the Karaj SSDL. The badges are placed on a water phantom (slab), one meter distant from the source. Then, MCNP4C code is used to calculate the energy response at 662 keV and 1.25 MeV energies. Next, these responses are validated with the experimental data. Finally, the calculation is carried out for several other energies in the range of 20 keV to 1.25 MeV. Obtained results show that for the energies more than 400 keV, The response of the dosimeter is independent of the photon energy, within 10% uncertainty. On the other hand, for the energies smaller than 400 keV, a significant dependence on the energy is observed; such that in 40 keV the response is about 2 times larger than that at 1.25 MeV. Consequently, a method to reduce this uncertainty is needed.