Patterns and trends of population radiation exposure and projected the risk of exposure-induced death from gamma camera examinations in Yazd Province.

INTRODUCTION: The use of nuclear medicine examinations as imaging modalities has recently increased. This study aimed to assess the radiation dose delivered to patients from common diagnostic nuclear medicine examinations and estimate the risk of exposure-induced death (REID). In addition, the frequency of nuclear medicine procedures were evaluated from 2015-2018. MATERIALS AND METHODS: The data were collected from adult patients who had undergone cardiac, skeletal, renal, lacrimal, and thyroid imaging. For each patient, the effective dose was calculated using dose conversion factors, and REID was estimated using PCXMC. The frequency of examinations between 2015 and 2018 was obtained from the hospital information system (HIS). RESULTS: The highest estimated effective dose was attributed to the scans of myocardial stress (8.09 ± 1.28 mSv), myocardial rest (5.59 ± 1.27 mSv), and thyroid imaging (3.93 ± 0.55 mSv). In addition, cardiac stress examination had the highest REID values for solid cancers (212.5 ± 67.5) and bone scans had the highest REID values for leukemia (11.5 ± 2.5). A large increase in the number of myocardial perfusion scans was a significant contributor to an increase in collective effective dose from 23.37 man-Sv in 2015 to 49.47 man-Sv in 2018, a compound annual growth rate (CAGR) of 26%. CONCLUSION: Although the annual frequency and per capita effective dose of nuclear medicine procedures in Yazd Province increased continuously, they were comparably lower than those reported for other countries. Despite this, the cancer risks of nuclear medicine scans at the individual level are negligible (around 0.01% excess fatal cancer risk), yet the increasing tendency for these examinations could be of concern.

ESTIMATION OF DIAGNOSTIC REFERENCE LEVELS AND ACHIEVABLE DOSES FOR PEDIATRIC PATIENTS IN COMMON COMPUTED TOMOGRAPHY EXAMINATIONS: A MULTI-CENTER STUDY.

This study was conducted to determine first local diagnostic reference levels (DRLs) and achievable doses (ADs) for pediatric patients during the most common computed tomography (CT) procedures in Yazd province. The DRL was obtained based on volume CT dose index (CTDIvol) and dose length product (DLP) for four various age groups of children. Data were collected from the most commonly performed pediatric CT scans, including abdomen-pelvis, chest, brain and sinus examinations, at six high-loaded institutes. The patients' data (766 no.) in terms of CTDIvol and DLP were obtained from four age groups: ≤1-, 1-5-, 5-10- and 10-15-y-old. The 75th percentiles of CTDIvol and DLP were considered as DRL values and the 50th percentiles were described as ADs for those parameters. Consequently, the acquired DRLs were compared with other national and international published values. The DRLs in terms of CTDIvol for abdomen-pelvis, chest, brain and sinus examinations were 3, 8, 9 and 10 mGy; 4, 5, 5 and 5 mGy; 25, 28, 29 and 38 mGy; and 23, 24, 26 and 27 mGy for four different age groups of ≤1-, 1-5-, 5-10- and 10-15-y-old, respectively. The DRL values in terms of DLP were 75, 302, 321 and 342 mGy.cm; 109, 112, 135 and 170 mGy.cm, 352, 355, 360 and 481 mGy.cm; and 206, 211, 228 and 245 mGy.cm, respectively, for the mentioned age groups. In this study, the DRL and AD values in the brain examination were greater among the other studied regions. The DRL plays a critical role in the optimization of radiation doses delivered to patients and in improving their protection. This study provides the local DRLs and ADs for the most common pediatric CT scanning in Yazd province to create optimum situation for the clinical practice.

Radiation dose and risk of exposure-induced death associated with common computed tomography procedures in Yazd Province.

PURPOSE: This survey was conducted to evaluate the radiation dose delivered to the patients through different CT procedures along with its corresponding risks in Yazd province. METHOD: Data for the five most common procedures were collected from six institutions from September 2017. The effective dose for each patient was estimated by ImpactDose software. The risk of exposure-induced death (REID) was calculated by coupling the BEIR VII model and ICRP 103 data for the Asian population. RESULTS: The median effective doses for the five most common procedures, in descending order, were as follows: 5.19 mSv for abdomen-pelvis, 3.30 mSv for routine chest, 3.00 mSv for chest HRCT, 0.76 mSv for Brain and 0.47 mSv for sinus. Averaged over all the procedures, the ratio of maximum to minimum of effective dose was 90-fold. The highest associated risk was tied to high-resolution CT scans for women which was estimated to be 1 exposure-induced death related to 2096 scans performed on a 20-year old patient. CONCLUSION: The estimated effective doses for all the procedures except sinus were comparably low, however, the variations among patient doses, even for a given procedure, were substantially high, indicating that further optimization processes need to be undertaken. Moreover, it was estimated that approximately 2000 scans of abdomen-pelvis performed on 20 year-old women could result in 1 radiation-induced cancer death, which in large scales may cause drastic health issues. In this regard, several approaches, one of which is the implementation of DRLs, can be suggested to reduce the collective dose from CT scans.

ESTABLISHMENT OF LOCAL DIAGNOSTIC REFERENCE LEVELS FOR COMMON PROCEDURES OF COMPUTED TOMOGRAPHY IN YAZD PROVINCE.

OBJECTIVE: The aim of this study was to propose first established diagnostic reference levels (DRLs) in computed tomography (CT) for adults, based on volume-averaged CTDI and dose length product (DLP) metrics in Yazd Province. MATERIALS AND METHODS: Six multislice CT scanners located at diverse areas of Yazd Province and seven common procedures were selected for the present study. For each procedure, at least twenty patients 18 years and older were sampled at each institution. For each patient, dose report data and scan parameters as well as patient's information were abstracted from picture archiving and communication system. RESULTS: Proposed DRLs in terms of computed tomography dose index (mGy) and DLP (mGy.cm) were as follows: brain (42, 527), sinus (25, 220), neck (14, 264), abdomen-pelvis (11, 295), routine chest (8, 247), CT pulmonary angiogram (32, 261) and chest HRCT (11, 455), respectively, slightly lower compared to other investigations. CONCLUSION: The proposed DRLs in this study should be considered as the local DRLs for the seven most common adult CT examinations in Yazd province so as to optimize the patient dose while maintaining acceptable image quality for the clinical task.

European trends in radiology: investigating factors affecting the number of examinations and the effective dose.

The advances in technology have led to a growing trend in population exposure to radiation emerging from the invention of high-dose procedures. It is, for example, estimated that annually 1.2% of cancers are induced by radiological scans in Norway. This study aims to investigate and discuss the frequency and dose trends of radiological examinations in Europe. European Commission (EC) launched projects to gain information for medical exposures in 2004 and 2011. In this study, the European Commission Radiation Protection (RP) reports No. 154 and 180 have been reviewed. The RP 154 countries' data were extracted from both reports, and the average variation trend of the number of examinations and effective doses were studied. According to the results, plain radiography and fluoroscopy witnessed a reduction in the frequency and effective dose per examination. Nevertheless, European collective dose encountered an average increase of 23%, which resulted from a growing tendency for implementation of high-dose procedures such as CT scans and interventional examinations. It is worth noting that most of the CT procedures have undergone an increase in effective dose per examination. Although demand and dose per examination in some radiological procedures (such as intravenous urography (IVU) have been reduced, population collective dose is still rising due to the increasing demand for CT scan procedures. Even though the individual risks are not considerable, it can, in a large scale, threaten the health of the people at the present time. Due to this fact, better justification should be addressed so as to reduce population exposure.