---

Background: The anatomic position and proven radiosensitivity of the thyroid make it an organ of concern in dental X-ray examinations. A National Radiation Protection Department (NRPD)-sponsored pilot study carried out in the Dental Radiology Department of RUMS., to assess if the radiation dose in panoramic radiographies could be reduced without significant impairment of the subjective image quality.

Materials and Methods: Thermoluminescent dosimetry (TLD) is widely acknowledged to be the recommended method for measuring entrance surface doses (ESD). In this study, ESD was measured using LiF thermoluminescent dosimeters (TLD-100) on the thyroid of 40 patients who had referred to the School of Dentistry , Rafsanjan University of Medical Sciences. Patients were not exposed to any additional radiation and the radiographs were used for diagnostic
purposes. TLDs were calibrated with radiation energies similar to those commonly used in orthopantomography.

Results: The overall mean ESD on the thyroid in orthopantomography was 0.071 ± 0.012 mGy (ranged from 0.01 to 0.40 mGy). The mean ESD for radiographies performed with 66 kVp (20 patients) and 68 kVp (20 patients) were 0.072 ± 0.019, and 0.070 ± 0.016 respectively. No statistically significant difference was found between these means.

Conclusions: The measured surface doses in our study are inconsistent with the only one
already reported about the same experiment. However, due to lack of national diagnostic reference levels for orthopantomography, it is not clear whether in case of the PM 2002 CC unit used in this experiment, reducing the radiation dose to a level that still keeps a diagnostically acceptable image quality is necessary. Iran . J. Radiat. Res., 2004 2 (1): 21-26

---

ABSTRACT

Background: Osteoid osteoma is a benign bony neoplasm and its classic treatment is surgery. In the r ecent decades percutaneous laser therapy was suggested to be replaced by surgery. In this study we have reviewed the results of the first applications of interstitial laser photocoagulation (ILP) for treatment of osteoid osteoma in Iranian patients.

Materials and Methods: In this case series study, we evaluated 9 known cases of osteoid osteoma that were referred for ILP from orthopedic section of Imam Khomeini hospital during 2001 and 2002. Diagnosis was confirmed by plain X-ray, CT, isotope & MR scan. ILP was done by interventional radiologists of medical imaging center. Percutaneous ILP was performed by Nd-Yag laser, using 400-1000 joules energy (according to nidus size) and adjusting on 2 watts power.

Results: The procedure was successful in all patients. We had pain relief in 24 hours. Follow up from 5 months to one year showed no recurrence.

Conclusion: The procedure is a safe and effective method for patients and could be applied for proper cases.

---

Background: Since 1996 the assessment of environmental gamma radiation dose in residential areas of Iranian towns and cities has been accomplished for 10 counties. As a practical method and based on the results of a pilot study, in order to attribute the final results to the whole residential area of a town five stations were selected for every town. The location of individual station was studied closely to comply with recommended conditions in the literature. Materials and Methods: RDS-110 was employed to measure gamma dose rate for one hour. Average annual dose rates plus conversion coefficients were employed to estimate gonad, bone marrow, equivalent and effective dose. Result: Minimum and maximum annual bone marrow and gonad dose equivalent attributed to environmental gamma are 0.24 mSvy-1 (for both tissues) and 1.44 and 1.46 mSvy-1, respectively. Conclusion: Average gonad and bone marrow doses for North Khorasan, Boshehr and Hormozgan provinces were less than the corresponding values for normal area. Iran. J. Radiat. Res., 2009 7 (1): 41-47

---

Background: The Poly-Allyl Diglycol Carbonate (PADC) detector is of particular interest for development of a fast neutron dosimeter. Fast neutrons interact with the constituents of the CR-39 detector and produce H, C and O recoils, as well as (n, α) reaction. These neutron- induced charged particles contribute towards the response of CR-39 detectors. Material and Methods: Electrochemical etching was used to enlarge track diameter which was made by low energy recoil protons. Before electrochemical etching, a chemical etching was performed for 1 hour. The responses were also calculated by Monte Carlo simulations, using MCNPX code in different energy bins considering H, C and O recoils. The total registered efficiency and partial contributions of the efficiency, due to interactions with each constituent of CR-39, were calculated. Results: The optimized condition of etchant was obtained to be 6N KOH 15kV.cm^-1, and 6 hours etching time. The obtained results show that track efficiency of CR-39 was a function of incident neutron energy. The tracks caused by O and C recoil nuclei were negligible for neutron energies lower than 1 MeV. At neutron energies lower than 1 MeV, only recoil protons would have sufficient energy to leave visible tracks. But, O and C recoils had important contributions in overall response of PADC at neutron energies of few MeV. Conclusion: The efficiency of a CR-39 based dosemeter could be calculated by MCNPX code and the results were in a good agreement with experimental results in energy range of ²⁴¹Am – Be bare source and ²⁴¹Am-Be was softened with a spherical polyethylene moderator of radius of 20 cm. Iran. J. Radiat. Res., 2011 9(2): 95-102

---

Background: One of the key techniques for the preparation of ¹²⁵I seeds is adsorption of ¹²⁵I onto silver bits coated by palladium (pd). Carriers played an important role in the adsorption of ¹²⁵I on palladium. KI is used as a carrier for fixing of ¹²⁵I onto silver wire bits coated with palladium. Materials and Methods: Three procedures KI, KOH, NH₄OH were investigated for adsorption of ¹²⁵I activity by different carriers. Results: Adsorptions percentage of ¹²⁵I on treated silver beads showed about 85% by using KI as a carrier, the KOH showed 74% and 65% for NH₄OH. Conclusion: The results indicated that, the use of KI as a carrier was suitable for adsorption of ¹²⁵I on treated silver seeds with Pd than KOH and NH₄OH. Iran. J. Radiat. Res., 2012 10(2): 105‐107

---

Background: Radon (²²²Rn) Measurement in the residential environments is very important because of its effecting on human health and causing cancer in the respiratory system. ²²²Rn is individually responsible for half of the natural radiation received in humans and influences on human by breathing. Hence, this study was undertaken to access the ²²²Rn level in the dormitories of Kerman university of medical science (southeast of Iran) to ensure its safety level. Materials and Methods: In this study, for measuring ²²²Rn level in seven dormitories of the Kerman University of Medical Sciences, the Lucas cell technique was used. This study was undertaken during the winter because of the high concentration of radon in this season due to closed building ambience. Results: In this study, the highest measured radon gas rate was 24.5 Bq/m³ in Boustan (1). Average concentrations of the radon gas in all dormitories were 4.7 Bq/m³, which is lower than the standard level. Conclusion: The results of this study showed that the ²²²Rn level in all dormitories was lower than the normal amount (48 Bq/m³) as well as the standard level. Iran. J. Radiat. Res., 2012 10 (3‐4): 171‐175

---

Background: Small photon fields are increasingly used in modern radiotherapy especially in intensity modulated radiation therapy (IMRT) and stereotactic radiosurgery (SRS) treatments. Accurate beam profile and central axis depth doses measurements of such beams are complicated due to the electron disequilibrium. Hence the EBT2 (external beam therapy) Gafchromic film was used for dosimetry of small circular photon beams because of its high spatial resolution. The results of EBT2 film were compared with PinPoint measurements and Monte Carlo calculations. Materials and Methods: Four small field sizes (5, 10, 20 and 30 mm diameters) were produced by circular cones coupled to a Varian Clinac-2100 linear accelerator at 6MV photon beam energy. Experimental measurements were carried out using two dosimeters: The Gafchromic EBT2 film and the 0.015 cm3 PinPoint ionization chamber (PTW, type 31006). The EGSnrc/BEAMnrc code was used to calculate dosimetric parameters for the above small fields. Results: The results showed that the PDD values measured by EBT2 film had maximum local differences 4% and 3% with PinPoint measurements and MC calculations respectively. The measurements of penumbra (80-20%) at 5 cm depth in a water phantom and SSD=100 cm by EBT2 film were up to 0.8 and 0.4 mm smaller than PinPoint measurements and MC calculation respectively. Our results show good agreement between EBT2 film measurements and MC calculation for small field output factors but PinPoint measurements need correction factors. Conclusion: This study showed that the Gafchromic EBT2 film is suitable detector for small field dosimetry especially for penumbra and output factor measurements.

---

Background: Rhabdomyosarcoma is a rare malignant soft tissue sarcoma and the most common sarcoma of childhood. The purpose of this study was to investigate the distribution of age and sex of patients, pathological subtypes and to determine the role of staging and classification of RMS on treatment outcome. Materials and Methods: This retrospective study included patients who diagnosed with RMS in Cancer Institute between 2006 and 2013. We used the Kaplan Meier and life table methods to estimate survival rate. STATA statistical software ver. 11.2 was used for statistical analyses. Results: Thirty patients with a mean age of 15.1 years (±SD =18.1) were evaluated.66.6 Percent were males. Median follow-up for survivors was 57.3 months (±SD=32.4). Survival rates of patients were as follows: 6 months (94%), 1 year (87%), 3 years (69%), and 5 years (50%). The pathology review classified of tumors as botryoid (6.7%), spindle cell (6.7%), embryonal (40%), alveolar (33.3%) and undifferentiated (13.3%). 3 years survival for patients with international classification III (alveolar and undifferentiated) was 70%, International classification II (embryonal) was 67%. Due to small sample size, we can’t report 3 years survival for international classification I (botryoid and spindle cell). Conclusion: Our results support early age of onset (>50% of RMS cases are diagnosed before age 10 years). Age of diagnosis often gives key facts about clinical behavior and has a noticeable effect on 5 year survival it is a prognostic factor in RMS. Disease extent as well as age and histology affect survival.

---

Background: Accurate small radiation field dosimetry is essential in modern radiotherapy techniques such as stereotactic radiosurgery (SRS) and intensity modulated radiotherapy (IMRT). Precise measurement of dosimetric parameters such as beam profile, percentage depth doses and output factor of these beams are complicated due to the electron disequilibrium and the steep dose gradients. In the present work the MAGIC polymer gel was used for dosimetry of small circular photon beams. The results of MAGIC were compared with EBT2 measurements and Monte Carlo (MC) calculations. Materials and Methods: Experimental measurements were made by mentioned dosimeters in four small field sizes 5, 10, 20 and 30 mm. The BEAMnrc code based on EGSnrc was used for simulation to calculate dosimetric parameters at these small fields. The phantoms were irradiated in a 6 MV photon beam Varian 2100C linear accelerator at SSD=100 cm. gel readout performed by 3 Tesla MRI scanner. Results: The results showed that the Percent depth dose (PDD) values measured and calculated by EBT2 film and MC had maximum local differences 4% and 5% with PDD values measured by MAGIC for field size of 5mm respectively. These differences decreased for larger field sizes. The measurements of output factor and penumbra (80%-20%) and (90%-10%) showed good agreement between the measurements and MC calculation. Conclusion: This study showed that the MAGIC polymer gel based on high resolution MRI images is useful detector for small field dosimetry but its agreement with MC is less than agreement of EBT2 film with MC.

---