Dosimetric Parameters Estimation for I-125 (model 6711) Brachytherapy Source

Determining dose distribution around the applied sources in brachytherapy, especially ones with low-energy is so crucial in treatment designing. In this study dosimetric parameters of a brachytherapy source I-125 (model6711) were calculated using Monte Carlo simulation method.A homogeneity water phantom with dimensions of 30´30´30 cm 3 were simulated with MCNPX(2.6.0) code. A brachytherapy source I-125 (model6711) considering its details (materials, dimensions and its emitted spectrum) was located in the center of phantom. Positioning the source inside the vacuum sphere its air kerma strength, S k , was calculated. Recommende

Radiological protection in the Neonatal Intensive Care Units (NICUs): a retrospective and observational audit at two teaching hospitals

Introduction: Portable chest and abdomen x-rays are the most common x-ray procedures performed during hospitalization in the Neonatal Intensive Care Units (NICUs). These x-rays contribute to radiation exposure to several radiosensitive tissues, causing increased concerns about patients’ safety. This study aims to assess the status of radiological protection in the NICUs at two teaching hospitals supervised by Dezful University of Medical Sciences (DUMS), Dezful, Iran. Methods: A retrospective and observational study was performed at two teaching hospitals of DUMS comprising three NICUs. Six radiologic technology students were invited and agreed to participate in this audit. The students were asked to attend as observers in the NICUs and record the radiation safety principle observances specified in the checklist. We also supplemented data from an observational study with a retrospective survey of the images at the picture archiving and communication system (PACS) database. Results: 230 neonatal chest and abdomen x-rays from 65 hospitalized neonates were investigated during 57 work shifts in the observational survey. In all, 90.1%, 80% and 13% of the chest, abdomen and chest/abdomen x-rays had unsatisfactory beam restriction, respectively. The protective shielding tools were available; however, they were not commonly applied to the patients. Most of the personnel used fixed exposure parameters of 42 kVp and 3.2 mAs. In the retrospective study, 498 portable x-rays were retrieved from the PACS database, in which only 17.5% and 0.4% of images have adequate beam restriction and evidence of shielding, respectively. Conclusion: Our study is commensurate with previous literature and emphasizes that neonates in the investigated hospitals are receiving avoidable excessive radiation exposure, mainly due to inappropriate beam restriction

Letter to Editor: Poor collimation in digital radiology: A growing concern

No Abstrac

Review on radiation protection in diagnostic radiology

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

Efficacy of Increasing Focus to Film Distance (FFD) for Patient’s Dose and Image Quality in Pediatric Chest Radiography

Background: Increasing the x-ray focus to film distance (FFD) has been advocated as an effective method to reduce the patients’ radiation dose. The aim of this study was to investigate the efficacy of this technique in patients' dose and image quality in pediatric chest x-ray.Material and methods: Sixty pediatric patients were x-ray imaged at FFDs of 100 and 130 cm. Dose measurements were performed using thermo-luminescent dosimeters (GR200). The quality of images was independently assessed using the anatomical criteria recommended by the European guidelines.Results: Increasing the FFD from 100 to 130 cm has reduced the entrance skin dose (ESD) of patients by 32.2% (p 0.05).Conclusion: Increased FFD to 130 cm reduce the pediatric radiation dose with no significant changes in image quality

Evaluation of the Prevalence and Utility of Gonad Shielding in Pediatrics Undergoing Pelvic X-Ray

Background: Gonad shielding has been recommended during pelvic x-rays since the 1950s. The popular method of gonad shielding is placement a lead shield in the midline of the pelvis. The aim of this study was to evaluate the prevalence and utility of gonad shielding in pediatrics undergoing pelvic x-rays.Materials and MethodsFollowing study approval, we retrospectively retrieved data from the digital image library of ten radiology depertments of Khuzestan provience-Iran to identify pediatric patients who underwent pelvic x-ray (anteriorposterior [AP] view). All the images were reviewed for the probable evidence of gonad shield. If there was evidence of shielding, the accuracy positioning of the shield was also investigated by a single assistant radiologist.ResultsIn all 1745 pelvic x-rays (942 girls and 803 boys) were identified of which the shield was present in 51 (5.41%) radiographs of girls and 132 (16.43%) radiographs of boys. When a shield was present; the shields has adequate positioning only in 8 (15.68%) radiographs in girls and 59 radiographs in boys. Inaccurate placement and absence of gonad shields were more common in girls than the boys. Due to the shield has concealed the anatomical criteria of the pelvis, retakes of the examination was required in 11 (21.56%) radiographs of girls and 14 (10.6%) radiographs of boys.ConclusionThe current methods of gonad shielding in girls pelvic x-ray was not effective nor is justifiable. We  no longer advocate of gonad shielding during girls pelvic x-ray. However in boys it is controversial and depends on the skill and effort of radiographers

Optimization of Radiological Protection in Pediatric Patients Undergoing Common Conventional Radiological Procedures: Effectiveness of Increasing the Film to Focus Distance (FFD)

Background Increasing the x-ray film to focus distance (FFD), has been recommended as a practical dose optimization tool for patients undergoing conventional radiological procedures. In the previous study, we demonstrated a 32% reduction in absorbed dose is achievable due to increasing the FFD from 100 to 130 cm during pediatric chest radiography. The aim of this study was to examine whether increasing the FFD from 100 to 130 cm is equally effective for other common radiological procedures and performing a literature review of published studies to address the feasibility and probable limitations against implementing this optimization tool in clinical practice. Materials and Methods Radiographic examination of the pelvis (AP view), abdomen (AP view), skull (AP and lateral view), and spine (AP and lateral view), were taken of pediatric patients. The radiation dose and image quality of a radiological procedure is measured in FFD of 100 cm (reference FFD) and 130 cm (increased FFD). The thermo-luminescent dosimeters (TLD) were used for radiation dose measurements and visual grading analysis (VGA) for image quality assessments. Results: Statistically significant reduction in the ESD ranged from 21.91% for the lateral skull projection to 35.24% for the lateral spine projection was obtained, when the FFD was increased from 100 to 130 cm (P0.05). Conclusion Increasing the FFD from 100 to 130 cm has significantly reduced radiation exposure without affecting on image quality. Our findings are commensurate with the literatures and emphasized that radiographers should learn to use of an updated reference FFD of 130 cm in clinical practice

Survey of the Use of X-ray Beam Collimator and Shielding Tools during Infant Chest Radiography

Background The use of shielding tools and X-ray beam collimator has extensively been advocated as effective methods to reduce radiation exposure to patients underwent radiological procedures. The aim of this study was to address the use of these protection measures during infant chest radiography. Material and Methods 348digital and/or analogue infant chest radiographs were reviewed that performed between October-  and December 2015 at four main hospitals of Khuzestan-Iran province to assessment the beam collimation. For each radiograph the area between current and acceptable collimation was calculated. Thirty eight radiographers were deeply interviewed to investigate the actual use of shielding tools and the main reasons for not using of them. Results Only 54 (15.5%) radiographs [33(61%) analogues and 21(39%) digital] have satisfactory collimation. The total means area of diagnostic interest (ADI) and the region outside ADI for each radiograph was estimated 171 and 86 cm2, respectively. The irradiated region outside the ADI was significantly larger in digital than in analogue images (mean of 103 cm2 vs. 54 cm2; P < 0.05). Shielding tools were used regularly only by 5% of radiographers. Conclusion The radiosensitive organs of infants located outside of ADI in hospitals investigated are at risk. Adherence to safety guideline urgently recommends

Analytical investigation of magnetic field effects on Proton lateral deflection and penetrating depth in the water phantom: A relativistic approach

Background: Integrated proton therapy - MRI systems are capable of delivering high doses to the target tissues near sensitive organs and achieve better therapeutic results; however, the applied magnetic field for imaging, influences the protons path, changes the penetration depth and deflects the particles, laterally, leading to dose distribution variations. Objective: To determine the effects of a magnetic field on the range and the lateral deflection of protons, analytically. Methods: An analytical survey based on protons energy and range power law relation, without using small angle assumption was done. The penetration depth and lateral deflection of protons with therapeutic energy ranges 60- 250 MeV in the presence of uniform magnetic fields of 0-10T intensities, were calculated analytically. Calculations were done for relativistic conditions with Mathematica software version 7.0, and MATLAB 7.0 was applied to plot curves and curve fittings. Results: In the presence of a magnetic field, the depth of Bragg peak was decreased and it was shifted laterally. A second order polynomial model with power equation for its coefficients and a power model with quadratic polynomial coefficients predicted the maximum lateral deflection (ymax) and maximum penetration depth (zmax) variations with energy and magnetic field intensity, respectively. Conclusion: The applied correction for deflection angle will give more reliable results in initial energy of 250 MeV and 3T magnetic field intensity. For lower energies and magnetic field intensities the differences are negligible, clinicall

Dose Reduction to the Thyroid Gland in Pediatric Chest Radiography

Background  It is remain a main concern that pediatric chest radiographies contribute to the significant radiation exposure to the thyroid gland as a more susceptible organ to radiation induced cancer. The aim of this study was to evaluate the entrance surface dose (ESD) of pediatric chest radiography compared to the diagnostic reference levels (DRL) and evaluation the efficacy of the lead (Pb) shield in radiation dose reduction to the thyroid gland.Materials and Methods After assessing each patient against specific inclusion-exclusion criteria, 40 pediatric patients who were undergoing anterior-posterior (AP) projection of the chest x-ray were considered eligible for this study. The ESD of the chest and also ESD of thyroid gland with and without a 1 mm butterfly-shaped lead shield which placed on the thyroid gland were measured using high sensitive thermo luminescent dosimeters (TLD-GR 200).Results The average of ESD for chest radiography was 0.068+ 0.006 mGy (0.021 - 0.232 mGy). The unshielded average thyroid ESD was 0.065 + 0.003 mGy compared to the shielded average thyroid ESD of 0.001 + 0.0005 mGy. The use of Pb-shield produced a statistically significant decrease in the average thyroid dose by about 97% (P< 0.001). Conclusion The use of Pb-thyroid shield in the AP projection of pediatric chest radiography has potential to reduced radiation dose without compromising image quality