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Showing 4 results for Radiation Protection
Review on radiation protection in diagnostic radiology
Vahid Karami , Mansour Zabihzadeh ,
Volume 74, Issue 7 (10-2016)
Abstract

Discovery of x-ray and using of it for medical imaging have produced tremendous outcomes for diagnosis and treatment of diseases. More than 10 million diagnostic radiological procedures and 100,000 nuclear medicine exams are being performed daily around the world. According to the national commission on radiological protection and measurements (NCRP)-report 160, medical x-ray is contribute to approximately 95% of all radiological examinations that is responsible for 74% of the collective dose to the US population. Despite of unique benefits of ionizing radiations, in the field of radiation protection, they are associated with potential risks such as cancer and genetically abnormalities. The cancer risk attributable to diagnostic radiology is estimated about 0.6% to 3%. It is estimated that the radiation dose from diagnostic x-ray procedures are annually responsible for 7,587 and 5,695 cases of radiation induced cancer in the population of Japan and US, respectively. Although the radiation dose associated with most radiological procedures are very low, but rapid increasing use of radiography procedures during two past decades have been concerned due to the cancer risk associated with ionizing radiations. On the base of linear no-threshold (LNT) model of dose-response curve, any level of exposure is dangerous. Deoxyribonucleic acid (DNA) is the main target of ionizing radiation. For radiological exposure with low dose, the stochastic effects such as genetic damages and leukemia are concerned. According to the recommendations of the radiation protection regulatory organizations, radiological procedure must be done with respect to social and economic factors in which exposure of patient and population kept as low as reasonable and achievable. Hence, prescription of a radiological test is acceptable only when its advantages are higher than its damages. Optimizing the different parameters such as: collimating the primary beam field to the area of diagnostic interest, exposure conditions (high kVp and low mAs), projections, exposure time and shielding can reduce the patients' exposure besides the saving of image quality. Following the radiation protection guidelines can considerably decrease the exposure risks.


Evaluation of the anode heel effect on the testes dose during pelvic radiography
Vahid Karami , Mansour Zabihzadeh , Nasim Shams , Mehrdad Gholami ,
Volume 75, Issue 2 (5-2017)
Abstract

Background: Anode heel effect refers to reduction of radiation intensity in the anode side of X-ray tube. This variation in radiation intensity across the anode-cathode of X-ray tube can be benefited for decrease radiation exposure in some radiological examinations. The aim of this study was to evaluate the effect of anode heel orientation on the radiation dose received by the testes in male patients undergoing pelvic radiography.

Methods: This is a cross-sectional study, conducted at one of the teaching hospitals of Ahvaz, Jundishapur University of Medical Science Ahvaz, Iran, from September 2015 to March 2016. In order to measure the profile of radiation intensity variation, 13 paired sets of high radiosensitive cylindrical lithium fluoride thermo-luminescent dosimeters (TLD) aligned on the cathode-anode central axis upon the table and then irradiated using routine exposure parameters. The anode of X-ray tube was positioned toward the feet for 40 patients and toward the head for 39 patients undergoing pelvic radiography. For measure the entrance skin dose (ESD), 8 TLD chips were located on the central point of the radiation field and 5 TLDs were located on the testes position to measure the dose received.

Results: Radiation intensity profile showed that radiation intensity decrease from the cathode to the anode side. Discrepancy of radiation intensity on central axis of cathode-anode was calculated about 35%. The radiation dose received by the testes was 26.74% lower for patients the anode directed toward the feet, compared to the patients in which the anode directed toward the head (FTC: 1.260±0.296 mGy, FTA: 0.923±0.167 mGy, P<0.05). There was no meaningful difference for the measured ESD of pelvis between two groups of patients (FTC: 1.256±0.315 mGy, FTA: 1.195±0.205 mGy, P=0.788).

Conclusion: In pelvic radiography, positioning of testes directed to the anode of X-ray tube can decrease the receive dose.

Estimation and assessment of the effective doses for radiosensitive organs in women undergoing chest CT scans with or without automatic exposure control system
Daryoush Khorramian , Soroush Sistani , Amin Banaei , Salar Bijari ,
Volume 75, Issue 7 (10-2017)
Abstract
Background: There are several techniques for reducing the delivered dose from CT (Computed tomography) scanning such as the automatic exposure control (AEC). This technique modulates the tube current regarding the patient size and weight. The aim of this study was to estimate the effect of the AEC on the radiosensitive organs effective doses in women undergoing chest CT scanning.
Methods: This study was a cross-sectional, analytical and quantitative study that was performed during 3 months in the imaging section of the Firoozgar educational and therapeutic hospital (belonging to Shahid Beheshti University of Medical Sciences) in the spring of 2017. CT scan exposure parameters were gathered and registered for 54 women undergoing chest CT scan. 25 of these scans were performed using AEC system and 29 of them were performed without using AEC. CT dose indexes in the center and peripheral regions of the standard phantom were calculated using the exposure parameters. Weighted CT dose index was also calculated and effective organ doses were obtained using CT-Expo software, version 2 (Medizinische Hochschule, Hannover, Germany) for two mentioned groups. In addition, noise was measured for these two groups as an image quality parameter.
Results: Calculated weighted CT dose indexes were 9.94 mGy and 12.46 mGy using AEC system and without using AEC, respectively. The calculated effective doses were equal to 5.4 mSv and 6.3 mSv using AEC and without using AEC, respectively. Maximum organ effective doses were 15, 14, 14 and 14 mSv for breast, esophagus, lung and thymus respectively in the non-using AEC system imaging technique.
Conclusion: Our measurements indicated a decrease about 15% in weighted CT dose index (from 12.46 to 9.94 mGy) using AEC system. Beside of this fact, the noise increased about 11.3% (from 4.2 to 4.74) using AEC system. So, it can be said that using of AEC was an effective way for dose reduction in women undergoing chest CT scanning, and the additional noise was in the acceptable range.

Evaluation of radiation protection principles and 10-day rule observance for women prone to pregnancy: brief report
Mohsen Shoja, Mohadese Soleimani, Maryam Ameriyan , Niloufar Asbaghipour , Peyman Hejazi Hejazi ,
Volume 77, Issue 2 (5-2019)
Abstract
Background: Today, with the increasing use of ionizing radiation like X-rays in diagnosis and treatment of diseases, the risk of fetal exposure in pregnant women also increases. Therefore, protecting pregnant women from ionizing radiation is essential and is considered as the standard criterion for Medical Radiation Center. So the aim of this study was to investigate the observance of protective principles and 10-day rule in imaging of susceptible women.
Methods: This cross-sectional study was carried out at the Radiography Centers of Semnan University of Medical Sciences, Iran, from July 2017 to September 2017. First, patients who were under radiography, were asked about the knowledge of the radiographers about the 10-day rule and radiation protection. Then a questionnaire with 12 questions was given to the radiographers in radiology and CT scan center. Finally, the existence of protection guidelines for pregnant women was determined by asking manager and checking at the moment.
Results: The patient's question about pregnancy failed about 19%, which did not have a significant relationship with patients' singleness (P=0.0004). Also the mean scores for the knowledge of radiographers about radiation protection were 14.21±0.96, which did not have a significant relationship with their work record and place of employment and their educational level (P=0.09). On the other hand, in half of the radiography centers, the written radiation protection guidelines were not available.
Conclusion: Principles of radiation protection and 10-day rule for radiography of women who were prone to pregnancy were desirable but due to importance of radiation protection, the rules should be more carefully implemented.

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