AimsTo characterize patient radiation doses from nuclear myocardial perfusion imaging (MPI) and the use of radiation-optimizing ‘best practices’ worldwide, and to evaluate the relationship between laboratory use of best practices and patient radiation dose.Methods and resultsWe conducted an observational cross-sectional study of protocols used for all 7911 MPI studies performed in 308 nuclear cardiology laboratories in 65 countries for a single week in March–April 2013. Eight ‘best practices’ relating to radiation exposure were identified a priori by an expert committee, and a radiation-related quality index (QI) devised indicating the number of best practices used by a laboratory. Patient radiation effective dose (ED) ranged between 0.8 and 35.6 mSv (median 10.0 mSv). Average laboratory ED ranged from 2.2 to 24.4 mSv (median 10.4 mSv); only 91 (30%) laboratories achieved the median ED ≤ 9 mSv recommended by guidelines. Laboratory QIs ranged from 2 to 8 (median 5). Both ED and QI differed significantly between laboratories, countries, and world regions. The lowest median ED (8.0 mSv), in Europe, coincided with high best-practice adherence (mean laboratory QI 6.2). The highest doses (median 12.1 mSv) and low QI (4.9) occurred in Latin America. In hierarchical regression modelling, patients undergoing MPI at laboratories following more ‘best practices’ had lower EDs.ConclusionMarked worldwide variation exists in radiation safety practices pertaining to MPI, with targeted EDs currently achieved in a minority of laboratories. The significant relationship between best-practice implementation and lower doses indicates numerous opportunities to reduce radiation exposure from MPI globally.
This study describes the cross-calibration of two Hologic bone densitometers, one using a fan-beam X-ray source (QDR4500/A) and the other a pencil-beam source (QDR1000/W). The QDR4500/A allows spine and hip measurements to be made at three principal speeds. Results from two spine phantoms and 154 patients showed no significant difference in the absolute values or precision between speeds. The middle speed (taking 1 min to scan an adult lumbar spine) was used for the comparison between the instruments. The two densitometers were compared using two spine phantoms and 182 patients. In vivo measurements were made of all lumbar spine, hip, forearm and whole body sites. Regression lines, constrained to pass through the origin, were calculated. Slopes for total bone mineral density (BMD) for each scan type ranged between 0.994 and 1.029, the best value being found for forearm (1.000). Scatter graphs of the individual points were generated and showed results slightly worse than would be expected from repeat measurements on a single machine (79-88% fell within the expected 2 SD range). A trend for the QDR4500/A to overestimate BMD at low values and underestimate it at high values was seen in the femoral neck. The trend was more significant in the lumbar spine. There was an overestimate of total hip BMD throughout the range. Slopes of the regression lines for area and bone mineral content (BMC) were used to improve cross-calibration between the systems on a site-to-site basis, after which the results improved to a level consistent with repeat measurements on a single machine (81-94% within 2 SD). At present only global, rather than site-specific, correction factors can be employed for the spine and hip and no overall improvement in cross-calibration was possible. We conclude that although global correction factors allow adequate cross-calibration to be achieved, improvements could be made by the use of scan-site-specific factors.
Objectives: To establish worldwide and regional diagnostic reference levels (DRLs) and achievable administered activities (AAAs) for SPECT MPI.Background: Reference levels serve as radiation dose benchmarks to compare individual laboratories against aggregated data, helping to identify sites in greatest need of dose reduction interventions. DRLs for SPECT myocardial perfusion imaging (MPI) have previously been derived from national or regional registries. To date there have been no multi-regional reports of DRLs for SPECT MPI from a single standardized dataset.Methods: Data were submitted voluntarily to the International Atomic Energy Agency Nuclear Cardiology Protocols Study (INCAPS), a cross-sectional, multinational registry of MPI protocols. 7,103 studies were included. DRLs and AAAs were calculated by protocol for each world region and for aggregated worldwide data. Results:The aggregated worldwide DRLs for rest/stress or stress/rest studies employing Tc-99m labelled radiopharmaceuticals were 11.2 mCi (1 st dose) and 32.0 mCi (2 nd dose) for 1-day protocols, and 23.0 mCi (1 st dose) and 24.0 mCi (2 nd dose) for multi-day protocols.Corresponding AAAs were 10.1 mCi (1 st dose) and 28.0 mCi (2 nd dose) for 1-day protocols, and 17.8 mCi (1 st dose) and 18.7 mCi (2 nd dose) for multi-day protocols. For stress-only Tc-99m studies, the worldwide DRL and AAA were 18.0 mCi and 12.5 mCi, respectively. Stress-first imaging was used in 26-92% of regional studies except in North America where it was used in just 7% of cases. Significant differences in DRLs and AAAs were observed between regions. Conclusions:This study reports reference levels for SPECT MPI for each major world region from one of the largest international registries of clinical MPI studies. Regional DRLs may be useful in establishing or revising guidelines or simply comparing individual laboratory protocols
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