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.

The retroneural approach: an alternative technique for lumbar transforaminal epidural steroid injections.

BACKGROUND: Compared with other available injection techniques for lumbar transforaminal epidural steroid injections (LTFESIs), the traditionally performed subpedicular approach is associated with a higher risk of spinal cord infarction, a rare but catastrophic complication. PURPOSE: To assess the short-term efficacy of the retroneural approach for computed tomography (CT)-guided LTFESIs with respect to different needle-tip positions. MATERIAL AND METHODS: This retrospective analysis included 238 patients receiving 286 CT-guided LTFESIs from January 2013 to January 2016. Short-term outcomes in terms of pain relief were assessed using the visual analogue scale (VAS) at baseline and 30 min after. The needle-tip location was categorized as extraforaminal, junctional, or foraminal relative to the neural foramen. Additionally, the distance from the needle tip to the nerve root was measured. RESULTS: A mean pain reduction of 3.22 points (±2.17 points) on the VAS was achieved. The needle-tip location was extraforaminal in 48% (136/286), junctional in 42% (120/286), and foraminal in 10% (28/286) of the cases. The mean distance from the needle tip to the nerve root was 3.83 mm (±3.37 mm). There was no significant correlation between pain relief and needle-tip position in relation to the neural foramen. Therapy success was not dependent on the distance between the needle tip and the nerve root. No major complications were observed. CONCLUSION: In our population treated with LTFESIs, the retroneural approach was shown to be an effective technique, with no significant differences in pain relief following different needle-tip positions.