Background: Neutron contamination in our environment can cause harmful bio-logical effects on human body. Therefore, many efforts have been made to construct a neutron Dosimeter to estimate the received dose. Objective: To design a simple neutron Dosimeter. Methods: The primary Dosimeter had 3He as a spherical thermal neutron detector encircled by paraffin 10 cm in radius. Then, the paraffin sphere was replaced with ICRU that contains soft tissue and dose equivalent determined as a desired output. Finally, an appropriate relation between counts and dose equivalent was found. Results: Results on the energies below 1 MeV demonstrated the similarity of changing process of these two quantities, so they could relate to each other with an adequate factor. To find the best fit, different factors considered and the smallest c2 (goodness of fit) was 1.17×105 At the next step, two covers of cadmium and gado-linium, separately, put around the detector to improve c2, which was 2.51×104 for cadmium cover and 6.33×103 for gadolinium cover. As we see, gadolinium cover fits the curves of counts and equivalent dose in a better way. Conclusion: Applying this simple Dosimeter lead us to estimate whole body dose equivalent.

Background: Thermoluminescence dosimetry is one of the dosimetry procedures used widely as routine and personal Dosimeters. In order to extend this kind of Dosimeters, dental tissue has been examined and was found promising as a TLD Dosimeter. Materials and Methods : In this study, 70 health teeth were collected. The only criterion, which was considered for selection of the teeth, was the healthiness of them regardless of age and gender of the donors. All collected samples were washed and cleaned and milled uniformly. The final powder had a uniform grain size between 100 – 300 micrometer. The sample was divided into four groups. Group A and B were used for measurement of density and investigation of variation of thermoluminescent characteristics with temperature respectively. Groups C and D were used for investigation of variation of thermoluminescent intensity with dose and fading of this intensity with time . In all cases the results obtained with dental tissue were compared to a standard LiF, TLD Dosimeter. Results : It was found that, average density of the dental tissue was 1.570 g/cm3, which is comparable to density of LiF, which is 1.612 g/cm3. It was also concluded that the range of 0-300 oC, dental tissue has a simple curve with two specific peaks at 140 and 250 oC respectively.The experiment also showed that, the variation of relative intensity versus dose is linear in the range of 0.04 – 0.1Gy . The fading rate of dental tissue is higher than LiF but still in the acceptable range (14% per month in compare to 5.2% per month) Conclusion : Dental tissue as a natural Dosimeter is comparable with TLD and can be used in accidental events with a good approximation

Background: An effec ve polymer gel Dosimeter can be fabricated by varying the composi on of its chemical components. Materials and Methods: The MAGAT gel Dosimeter formula ons that used different composi ons of Methacrylic acid (MAA) and gela n were extensively inves gated in the present study according to the R2– dose response and R2– dose sensi vity. The irradia on of MAGAT gel was performed by 6-MV photon beam at a dose range 1 to 10 Gy and was imaged by 1. 5T Magne c Resonance Imaging (MRI). The dose response of MAGAT gel Dosimeter was obtained from spin-spin relaxa on rate (R2) of MRI signal. Results: The MAGAT gel Dosimeter composed of 5% gela n and 6% MAA gave the highest sensi vity (1. 1180 s-1Gy-1). Conclusion: Understanding the effects of the composi onal changes will help to clarify the mechanisms involved in the dose response of the MAGAT gel Dosimeter.

Introduction: The PAGAT polymer gel Dosimeter melts at 30oC and even at room temperature during the summer, so it needs to be kept in a cool place such as a refrigerator. To increase the stability of the PAGAT gel, different amounts of agarose were added to the PAGAT gel composition and the PAGATA gel was manufactured. Material and Methods: The PAGATA gel vials were irradiated using a Co-60 machine. Then, the samples were evaluated using a 1.5 T Siemens MRI scanner. The ingredients of the PAGATA normoxic gel Dosimeter were 4.5% N-N' methylen-bis-acrylamide, 4.5% acrylamide, 4.5% gelatine, 5 mM tetrakis (THPC), 0.01 mM hydroquinone (HQ), 0.5% agarose and 86% de-ionized water (HPLC). Results: Melting point and sensitivity of the PAGAT gel Dosimeter with addition of 0.0, 0.3, 0.5, 1.0, 1.5 and 2.0% of agarose were measured, in which the melting points were increased to 30, 82, 86, 88, 89 and 90oC and their sensitivities found to be 0.113, 0.1059, 0.125, 0.122, 0.115 and 0.2 S-1 Gy-1 respectively.Discussion and Conclusions: Adding agarose increased the sensitivity and background R2 of the evaluated samples. The optimum amount of agarose was found to be 0.5% regarding these parameters and also the melting point of the gel Dosimeter. A value of 0.5% agarose was found to be an optimum value considering the increase of sensitivity to 0.125 and melting point to 86°C but at the expense of increasing the background R2 to 4.530.

Introduction: Different dosimetric modalities (e.g., ionization chambers, semiconductors, TLDs, radiographic films) often have some problems determining isodose curves and percentage depth doses in high dose gradient regions. Research has been ongoing to develop portable high resolution dosimetry devices with accurate absolute dosimetry capabilities and easy data analysis. The ‘PRESAGE’ Dosimeter is a type of polymer Dosimeters with improved characteristics in comparison with older polymer Dosimeters. It is solid, insensitive to oxygen, and can be made in different shapes. This work presents the fabrication process for a PRESAGE Dosimeter and optimization of its radiation sensitivity.Material and Methods: The PRESAGE gel was formed in two steps. In the first step, Leuco Malachite Green was dissolved in a free radical initiator (carbon tetrachloride; CCl4) and a polyol, referred to as ‘Part B’ was added to the solution. The second step consisted of mixing the Leuco dye, a free radical initiator, and a catalyst with ‘Part B’ (a commercially available polyol), then blending them with Part A in equal proportions, placing the blended materials in an appropriate mold, and incubating at an optimal temperature under a pressure of 60 psi for 18 to 24 hours. After this period, the solution turned solid and was subsequently exposed using a cobalt-60 unit. Finally, the PRESAGE gel was read using a spectrophotometer.Results: The results showed that by changing the percentage of both Leuco dye and CCl4 to 4%, an optimum sensitivity of 0.0144 units/Gy can be reached. Discussion and Conclusion: Our results showed that the response function of the PRESAGE Dosimeter is linear between 2.5 to 55 Gy. Using different material percentages to make the PRESAGE gel can result in a sensitivity variation ranging from 0.0099 to 0.0144 units/Gy.

This study aimed to produce a personal Dosimeter to connect the electronic devices to transfer the dosimetry data online including dose rate data and integral dose. At first, an electronic board was designed. Afterwards, the board was simulated using Altium Designer software. Then, the microcontroller programming was performed using Code Vision software. The performance of the elements was tested using Proteus Design Suite software and the circuit diagnosis and testing were practically implemented. Afterwards, the calibration factor and the count-to-dose conversion coefficient were obtained using an ionization chamber in the Secondary Standard Dosimetry Laboratory of Iran. Furthermore, dose distribution as a function of distance to the source, was obtained using the produced Dosimeter and was compared using a calibrated ionization chamber. To this purpose, an unmitigated Cs-137 source, a Cs-137 source with a 22 mm Pb shield, and a Cs-137 source with a 22 mm plus 18 mm shield were used. The results showed a calibration factor of 0. 99 ± 0. 02 for the designed Dosimeter. Calibration results showed that the produced Dosimeter passed the ISO/IEC 17025: 2005 criteria. Furthermore, the dose distribution results demonstrated negligible differences of less than 0. 01% between the produced Dosimeter and the reference ionization chamber. It was concluded that the produced Dosimeter could be used as a reference and standard Dosimeter in laboratories, for monitoring and dosimetry of ionizing photon radiations.

Thennoluminescence Dosimeters are well known for their widespread applications in dosimetry specially neutron dosimetry. In low neutron fluences it is usual to use (n, a) reaction for direct measurement of neutron fluence, but in higher values, some gray filters are necessary. And also supralinearity because of the high absorbed dose makes the direct reading of TLDs difficult. After anealing of Dosimeters the absorbed dose from the internal activity was used as a mass for neutron fluence. In this work thermal neutron fluence in the range between 1011 and 1013 n/cm2 in the reactor core of Tehran Research Reactor was measured using TLD-600 thennoluminescence Dosimeters. The influence of irradiation-induced damage effect on the response of TLDs and their subsequent readings have been minimized. The measurements were made reproducible in this manner. The induced TL-light reader due to self-activity in TLD-600 dependens on the neutron fluence caused a conveniently: measurable TL glow curve. The accumulated TL-light was measured after storage periods of 24, 48 and 72 hours. A short theoretical treatment is also presented at this work.

Background: In this work, we investigated the effect of adding 0.3% w/w of the non-toxic substance agarose to the Dosimeter formulation of genipin radiochromic gel, which was named LCA-GENA (Low Concentration Agarose-GENipin and Agarose) gel Dosimeter.  Materials and Methods: A compact linear accelerator with a beam quality of 6 MV and a dose rate of  200 cGy/min irradiated the produced gel Dosimeters in a dose range of 0-10 Gy. A UV-Visible spectrophotometer was used to read out the irradiated gel Dosimeters. Calibration curves for both absorbance peak and area-under-spectrum responses were investigated. Furthermore, the physical and radiological characteristics of the new formulation were investigated. Results: The results showed that the dose sensitivity of the LCA-GENA gel Dosimeter under the irradiated conditions is (8.4 ± 0.15) × 10-3 cm-1 Gy-1. Results showed adding the abovementioned percentage of agarose will increase the melting point of the genipin gel Dosimeter from 24°C to 28°C. Also, an investigation of the radiological properties of the novel formulation revealed that this radiochromic gel is water equivalent. Conclusion: From the obtained results, it is verified that adding 0.3% w/w agarose to the genipin gel Dosimeter leads to an increase in the melting point of the original genipin gel Dosimeter, easier fabrication, and lower price than that of higher agarose concentrations. The mentioned features make this gel suitable for dosimetry applications in clinical and radiotherapy environments.

Introduction: One of the problems in chemical Dosimeters such as Trimesic acid is the liquid environment which makes it difficult to use. Chemical Dosimeter merged into a bed of gel can help to partly overcome this problem. According to the importance of stability of Dosimeter response after irradiation, in this study, the parameters of gelatin- Trimesic acid Dosimeter in the range of doses of a one fraction of radiotherapy was assessed in days one, two, three and four after irradiation.Materials and Methods: After the gel construction at a concentration of 1 mM and a pH of 2.2, it was poured into Perspex vials which opening was tight with parafilm and wrapped in an aluminum foil to eliminate light and was divided into 5 groups to be irradiated with 6 MV photons of linac 24h after the gel synthesis. To do so, vials were place at the isocenter of the linac in a SSD of 100cm and field size of 10×10 cm2. The delivered doses were from 0-200 cGy and vials were kept at the temperature of 4˚C after the irradiation. The procedure of reading the vials were performed using a spectroflourimeter (Jasco 6200) from one to four days after irradiation in excitation wavelengths of 370, 380, 390, 410, 420 and 450 nm.Results: After obtaining the emission spectrum from the spectroflourimeter, the emission spectrum was analyzed and it was found that there is a peak in the wavelengths of 377, 387, 396, 416, 427 and 457 nm seen in one day after irradiation and the most stable response belongs to the first day after irradiation.Conclusion: The results of this study showed that the combined gelatin- Trimesic acid Dosimeter in the first day after irradiation has the highest and most stable response and according to its characteristics, has the potential to be assessed as a clinical Dosimeter.