In current study, the relative biological effectiveness (RBE) values relevant to the various IODINE RADIOISOTOPES, have been assessed to compare the performance of the MCSD and GEANT4-DNA Monte Carlo codes at low energy regions. After the calculation of the Auger electrons energy spectrum, obtained from the IODINE RADIOISOTOPES including 123I, 124I, and 125I through the GEANT4 Monte Carlo code, the calculation of the RBE values was performed through the GEANT4-DNA extension by considering the B-DNA model. In addition, the RBE values were also estimated by the MCDS code in completely aerobic conditions. The results of this study showed that employing the GEANT4-DNA-option4 physics by GEANT4-DNA extension in the physical stage provides near results in comparison with MCDS code for the radiobiological assessments and RBE estimation. The obtained highest difference values in this study were related to the use of GEANT4-DNA-option2 physics which varies from 22.30% to 24.60% for the studied RADIOISOTOPES. Since double strand damages along the DNA molecule can eventually lead to the cell death, and due to the appropriable agreement between the calculated results of RBEDSB values through the MCDS and GEANT4-DNA codes, it can be deduced that the MCDS code provides accurate results for the radiation induced DNA damage.

Background: The 131I radioisotope is used for diagnosis and treatment of hyperthyroidism and thyroid cancer. In optimized IODINE therapy, a specific dose must be reached to the thyroid gland with minimum radiation to the cervical spine, cervical vertebrae, neck tissue, subcutaneous fat and skin. Dose measurement inside the alive organ is difficult, therefore the aim of this research was dose calculation in the organs by MCNPX code.Materials and Methods: First of all, the input file for MCNPX code has been prepared to calculate F6 and F8 tallies for ellipsoidal thyroid lobes with long axes is tow times of short axes which the 131I is distributed uniformly inside the lobes. Then the code has been run for F6 and F8 tallies for variation of lobe volume from 1 to 25 milliliters. From the output file of tally F6, the gamma absorbed dose in ellipsoidal thyroid, spinal neck, neck bone, neck tissue, subcutaneous fat layer and skin for the volume lobe variation from 1 ml to 25 ml have been derived and the graphs are drew. As well as, form the output of F8 tally the absorbed energy of beta in thyroid and soft tissue of neck is obtained and listed in the table and then absorbed dose of bate has been calculated.Results: The results of this research show that for constant activity in thyroid, the absorbed dose of gamma decreases about 88.3% in thyroid, 6.9% at soft tissue, 19.3% in adipose layer and 17.4% in skin, but it increases 32.1% in spinal of neck and 32.3% in neck bone when the lobe volume varied from 1 to 25 milliliters. For the same situation, the beta absorbed dose decreases 95.9% in thyroid and 64.2% in soft tissue.Conclusion: For the constant activity in thyroid by increasing the thyroid volume, absorbed dose of gamma in thyroid and soft tissue of neck, adipose layer under the skin and skin of neck decreased, but it increased at spinal of neck and neck bone. Also, by increasing of the lobe volume in constant activity, the beta absorbed dose reduced. Therefore, whatever the thyroid lobe is small the administered value of 131I increased to induce the suitable dose.

Background: To evaluate the effects of probe positioning on radioactive IODINE uptake (RAIU) measurements and 131I quantification in Graves disease (GD) patients. Materials and Methods: We performed a cross-sectional study in GD patients between May 9 and June 27, 2013. 24 hr-RAIU was measured. Measurement A was the reference measurement and was obtained with the probe parallel to the bottom of the thyroid cartilage. Measurements B, C, D, and E were obtained by moving the probe 2.5 cm to the left, 5 cm to the left, 2.5 cm vertically upward, and 5 cm vertically upward, respectively. The 131I doses were calculated. Non-reference measurements were compared with measurement A using the paired t-test or Wilcoxon signed-rank test. Results: A total of 63 GD patients (17 men, 40.3±13.6 years old) were enrolled. Among them, 57 patients had 24 hr-RAIU measurement and 37 patients chose the 131I treatment. Significant changes were observed in 24 hr-RAIU and 131I dose between measurement A (24 hr-RAIU 60.40±12.67% and median 131I dose 8.17 mCi) and measurement E (24 hr-RAIU 48.67±11.74% and median 131I dose 9.50 mCi) (P<0.05). In one patient, the 24 hr-RAIU was 20.3% lower in measurement E compared with that in measurement A, resulting in a 30 mCi increase in the calculated 131I dose. Conclusions: The vertically upward movement by a distance of a radius of the collimator could affect the 24 hr-RAIU measurement and thus cause inaccurate calculation of the 131I dose.

in patients with thyroid papillary carcinoma, performing an effective radioactive IODINE ablation after total thyroidectomy requires adequate levels of serum thyrotropin. Administration of recombinant human thyroid stimulating hormone (rhTSH) is the current established method for patients with insufficient serum TSH levels four to six weeks after surgery and levothyroxine discontinuation. Two major problems with rhTSH are its cost and availability in most countries worldwide. We have used propylthiouracil (PTU), a routine antithyroid drug, for the first time to induce a TSH rise. Our patient was a 33-year-old woman with remnant thyroid tissue of 11. 5×4 mm after thyroidectomy. Her TSH was 12.7 mIU/ml, five weeks after surgery, and rose to 30. 0 mIU/ml after a 10 day trial of PTU. RadioIODINE uptake index also increased from 28% to 56%. RadioIODINE ablation was successfully done and patient showed no sign of recurrence or metastasis after 4 years. We propose that anti-thyroid drugs may be considered for post-operative induction of TSH rise in patients considered for radioIODINE ablation of thyroid cancer. This may increase the chance of successful ablations with least possible cost.

It is necessary to know the exact value of radioisotope activity in the field of radio-pharmaceutical therapy or diagnostic applications. Dose calibrators are usually utilized in the nuclear medical centers for this purpose. Because of the sophisticated technology used in dose calibrators and due to the limited demand, only a few American and European companies supply the dose calibrators, thereby, the very high prices, a dose calibrator makes it uneconomical for the medical centers to purchase. This paper introduces a brief description of the design and construction of a dose calibrator along with an assessment of a thorough experiment results. The detector of the dose calibrator is a chamber that works in the current mode. The ionization area of the chamber has two cylinder spaces filled with argon gas. The electrometer of this system has been designed in a way that it can measure very low currents of a few femtoamperes (10-15 A). The results of experiments and practitioners’ reports showed that the device is able to measure the activity of γ and b sources with high accuracy in a wide range. Measuring low activities, having high accuracy, low cost, and being user friendly are some advantages of this device.

Two RADIOISOTOPES of 18F (T1/2=109. 7 min, Iβ += 97%, Eβ += 0. 63 MeV), and 13N (T1/2=10min, Iβ +=100%, Eβ +=0. 96 MeV) decay almost completely via positron emission. Due to this characteristic, these RADIOISOTOPES are used in PET (positron emission tomography) camera for detection of cancer cells. In this article, after calculating the excitation function for nuclear reactions leading to the 18F, 18O (p, n) 18F, and 13N, 16O (p, α ) 13N formation using the ALICE-91 nuclear code and by a comparison of the results with the experimental data, the best range of energy to produce with a cyclotron accelerator and the amount of heat deposited to the target material, was determined. For the waste heat removal, a miniature heat exchanger was designed and manufactured. A thermal design of the heat exchanger by the Aspen HTFS+ software was created, and its mechanical plan sheet was drawn using the SolidWorks software. After the fabrication of the heat exchanger and recirculation liquid target located at the liquid target room, 13N was produced via pure water proton bombardment with 17. 5 MeV energies verifying the theoretical calculations.

RADIOISOTOPES, as a new achievement in the environmental sciences, have found significant development in water resources management, especially in dating, aquifer recharge management, and the role of contaminants in water resources pollution. Due to the quantitative and qualitative critical condition of groundwater resources in Kashan plain, having accurate isotopic data from water resources can be effective in proper management of water resources in this region. In this paper, while present the groundwater sampling, preparation and analysis methods for measuring 3H and 14C, we have investigated the age of groundwater resources in Kashan plain. For this aim, 11 groundwater samples for tritium by enrichment method and 3 samples for carbon-14 were analyzed. The results showed that the amount of tritium in the groundwater resources of Kashan plain is less than 0. 08 TU which indicates that the water resources are old. Also, carbon-14 results showed that the age of groundwater resources in Kashan plain varies between 10, 000 and 21, 000 years. The results showed that by moving toward the northeast of the aquifer (aquifer’ s outlet), the age of the water resources decreased, which indicating that the paleo deep-waters were mixed with the freshwater waters. In general, by mowing toward the southwest and west of the aquifer to northeast of the aquifer, groundwater age decreases.