Background: Natural radioactivity in materials under certain conditions can reach the hazardous radiological levels. So, it becomes necessary to study the natural radioactivity in different materials to assess the dose for the population in order to know the health risks and to have a baseline for future changes in the environmental radioactivity due to human activities.Materials and Methods: The present study deals with the measurement of radioactivity using “Y-ray spectrometry” from naturally occurring radionuclides in the soil, stone and sand samples used as building materials in North-Eastern Haryana state of India. The places are in the vicinity of Shivalik range of Himalayas.Results: The activity concentrations for 226Ra, 232Th and 40K varied from 18±1.5 to 156±6Bqkg-1, 23±1 to 300±5Bqkg-1 and 32±0.5 to 1705±14 Bqkg-1 respectively in various samples. The absorbed dose rate in soil, sand and stone samples is investigated at 1 m above ground level. Ra equivalents, Internal and external hazard indices have also been calculated.Conclusion: The natural radioactivity levels measured in the samples under present study are below the recommended limits except for black stone (SB) and red stone (SR). However, these samples satisfy the universal standards.

Introduction: The rapid use of computed tomography (CT) scan is of great concern, due to increase in patients’ dose. Optimization of CT protocol is a vital issue in dose reduction. This study aimed to optimize radiation dose in cranial CT and assess modifications in image quality under radiation dose reduction. Material and Methods: A poly(methyl methacrylate) phantom was used for quality control test on CT scanners. Data of 214 scan parameters, dose indicators; volume CT dose index (CTDIvol) and dose-length product (DLP) of patients who underwent cranial CT scans were collected. The data were grouped into three, with respect to the slice numbers of 24, 28, and 32. Tube voltage (kVp) and slice thickness were constant; (110 kVp and 4. 8 mm, respectively), at variable tube currents (mAs). A one-sample t-test was used to compare the dose indicator values of the hospital protocol with a recommended protocol. Scan parameters were optimized for radiation dose against image quality. Results: Increased mAs resulted in increased CTDIvol and DLP at constant kVp and slice thickness. Moreover, dose indicators recorded the lowest and highest values at the slice numbers of 24 and 32, respectively. An increase in slice numbers affected dose indicators. Dose indicators recorded significant reduction (P<0. 001) in comparison to the recommended protocol. Conclusion: Optimization of CT protocol considers radiation dose and image quality. Radiologists adopted protocols acquired with lower scan parameters and dose indicators lower than the recommended achievable dose limit of 58 mGy.

Background: People who have been administrated radiopharmaceuticals could be a source of radiation to their relatives, medical nurses, and people who are in contact with them. The aim of this work was to estimate radiation dose received by nuclear medicine nurses. Materials and Methods: In this study, the dose rates at various distances of 5 – 100 cm from 70 patients, who were administered diagnostic amounts of 201Tl-Chloride and 99mTc-MIBI, were measured using an ionization chamber. For determination of external radiation dose to the nurses, three different time intervals were used for measurements.  Results: The maximum values of external dose rates of 201Tl and 99mTc-MIBI were 11.2 µSv/h ±2.3 and 43.1µSv/h ±11.9 respectively, at 5cm from the patients. Significant exposure from patients after injection of 99mTc-MIBI was limited to the day of administration. Departure dose rate of 201Tl fell gradually; so, it became significant by 3 days after administration. Maximum and average absorbed dose of nuclear medicine staff from 201Tl, was 4.6 and 2.7 µSv/h, and for 99mTc-MIBI was 18.1 and 9.8 µSv/h in each scan.  Conclusion: Significant exposure from the patients is limited to the few hours after administration, therefore patients should be recommended to urinate frequently before leaving the nuclear medicine department.

The coronary artery disease is a common and major cause of death. Invasive coronary angiography is currently the "gold standard" investigation to detect obstructive coronary artery lesions but carries a small risk of serious complications.The mortality risk of invasive coronary angiography (ICA) is about 0.13% which is approximately twice the risk of multi-detector CT (MDCT) angiography (0.07%). MDCT angiography has enabled the detection of coronary artery disease noninvasively. The measured mean effective dose has been measured to be significantly higher in past studies. MDCT angiography radiation dose was clearly more than that of ICA, which has led to a concern about the increasing use of MDCT angiography. Since there was not any study about the radiation dose in patients doing MDCT angiography in Iran and according to the importance of this subject, we performed a study in 134 patients referred for MDCT angiography of the coronary arteries in one of the biggest MDCT angiography centers, using 64-slice MDCT (SIEMENS SOMATOM Sensation 64). The patients were divided into two groups, with or without a previous history of CABG. Total mean effective dose and CTDI were 15.24 mSv and 51.80 mSv, respectively that were similar to previous studies in other parts of the world. Measured quantities were higher in patients who had a history of CABG (20.92 mSv and 13.99 mSv). Our study shows that if the scanning parameters are adjusted for the patient, the radiation dose could be reduced down to 50%.

In diagnostic radiology, entrance surface air kerma (ESAK) is one of the patient radiation dose quantities, and the effective dose is used as an estimator of possible risk for radiation exposure level. Calculation of the ESAK and effective dose requires both X-ray machine parameters and patient exposure parameters. Due to the high performance of smartphones and the increase in mobile applications, this study aimed to develop a mobile application to estimate the ESAK and effective dose in general radiography. The ESAK calculator was then developed using Android studio software, which is a standalone application operating on Android operating system version 5.0 or higher. X-ray machine parameters are initially required for calculating X-ray output. For the ESAK and effective dose calculation, exposure parameters for each examination are needed. The results showed that the average score of satisfaction was 4.64±0.13, which was very satisfactory. In conclusion, the ESAK calculator could be used for estimating ESAK and effective dose for individual radiographic examination.

Background: Hot lab is a specially designed room in a nuclear medicine hospital where the radiopharmaceuticals are delivered, stored and prepared for dispensing. 99 Mo/ 99m Tc-generator is the major source in the hot lab used for various medical imaging. It is important to maintain a standard for hot lab procedures to optimize the patient care and minimize radiation exposure to all nuclear medicine personnel, patients, public, as well as environment. Materials and Methods: The radiation doses in the hot lab were measured by GM and NaI Detectors for about 12 months. Package surface doses and generator surface doses were also measured. An increase in the counted rate above background was considered for the study. A constant distance was made in every step. Results: At the receipt date, the 99 Mo/ 99m Tc-generator surface dose (450±150 ?Gy/hr) found to be nearly six times higher than the package surface dose (80±20 ?Gy/hr). The dose rate at the outer surface of the fume-hood glass found to be 80±15 ?Gy/hr in the 1 st day of generator placement, whereas at the 2 nd day it was 70±12 ?Gy/hr; showing a gradual decline in dose rate during 3 rd (50±10 ?Gy/hr), 4 th (40±9 ?Gy/hr), 5 th day (30±6 ?Gy/hr) and 6 th day (25±4 ?Gy/hr). Conclusion: In the 1 st day of a generator storing in the hot lab, the dose rate found to be 3-4 times higher than the 6 th days. The dose rate at various places indicated poor performance of the fume-hood glass. The study emphasizes on the need of growing awareness among all the radiation workers and encouraging the safe working practices in nuclear medicine.

Background: Concern about radiation risk of computed tomography (CT) scan as a diagnostic modality has increased in recent years. Diagnostic reference levels (DRLs) is one of the tools to optimizing radiation dose of patients. CTDIv (Volume Computed tomography dose index) and DLP (Dose Length product) are used for assessment of DRLs. The CTDIv under/overestimate the patient dose. AAPM has introduced SSDE (Size-specific dose estimates) for estimation of patient. In this study, the DRLs of head and abdomen-pelvis CT examinations of adults is determined using CTDIv, DLP and SSDE. Materials and Methods: 680 CT examinations of head and abdomen-pelvis were collected from PACS (Picture archiving and communication system) in Imam Khomeini and Mostafa Khomeini hospitals. The Deff, CF and SSDE calculated using AAPM TG-204 and TG-220. Statistics analysis calculated using SPSS version 18. Results: For abdomenpelvis third quartile of CTDIV, SSDE and DLP was 9. 96, 13. 58 and 527 and values of 27. 62, 26. 79 and 402. 90 are determined for head, respectively that are lower than national DRLs. Also, calculated conversion factor (CF) for head and abdomen-pelvis was 0. 97 ±,0. 75and 1. 45 ±,0. 17, respectively. Conclusion: DRLs were lower than other studies in this study. Using the AEC (Auto Exposure Control) and different kVp in this hospitals can help optimization of patient dose. The SSDE must be calculable by radiographers to more accurate estimation of patient dose using CFs.

Introduction Intensity-Modulated Radiotherapy (IMRT) is becoming an increasingly routine treatment method. IMRT can be delivered by use of conventional Multileaf Collimators (MLCs) and/or physical compensators. One of the most important factors in selecting an appropriate IMRT technique is integral dose. Integral dose is equal to the mean energy deposited in the total irradiated volume of the patient. The aim of the present study was to calculate and compare the integral dose in normal and target organs in two different procedures of IMRT: Step-and-Shoot (SAS) and compensator-based IMRT. Materials and Methods In this comparative study, five patients with prostate cancer were selected. Module Integrated Radiotherapy System was applied, using three energy ranges. In both treatment planning methods, the integral dose dramatically decreased by increasing energy. Results Comparison of two treatment methods showed that on average, the integral dose of body in SAS radiation therapy was about 1. 62% lower than that reported in compensator-based IMRT. In planning target volume, rectum, bladder, and left and right femoral heads, the integral doses for SAS method were 1. 01%, 1. 02%, 1. 11%, 1. 47%, and 1. 40% lower than compensator-based IMRT, respectively. Conclusion Considering the treatment conditions, the definition of dose volume constraints for healthy tissues, and the equal volume of organs in both treatment methods, SAS radiation therapy by providing a lower integral dose seems to be more advantageous and efficient for prostate cancer treatment, compared to compensator-based IMRT.