Establishment of diagnostic reference levels in cardiac computed tomography

Abstract

The aim of this study was to determine diagnostic reference levels (DRLs) for cardiac computed tomography (CCT) in Jordan. Volume computed tomography dose index (CTDI vol ) and dose-length product (DLP) were collected from 228 CCTs performed at seven Jordanian hospitals specialized in cardiac CT. DRLs for cardiac CT were defined at the 75th percentile of CTDI vol and DLP. CTDI vol and DLP were collected from 30 successive cardiac CT in each center except for one center (18 scans). The 75th percentile of the CTDI vol and the DLP of the centers calculated from mixed retrospective and prospective gated modes were 47.74 milligray (mGy) and 1035 mGy/cm, respectively. This study demonstrated wide dose variations among the surveyed hospitals for cardiac CT scans; there was a 5.1-fold difference between the highest and lowest median DLP with a range of 223.2-1146.7 mGy/ cm. Differences were associated with variations in the mAs and kVp. This study confirmed large variability in CTDI vol and DLP for cardiac CT scans; variation was associated with acquisition protocols and highlights the need for dose optimization.DRLs are proposed for CCT; there remains substantial potential for optimization of cardiac CT examinations for adults in Jordan. K E Y W O R D S CCT, CTDI vol , DLP, DRL, Jordan 1 | INTRODUCTION Radiation doses differ between hospitals for standard-sized patients undergoing the same examination. 1 These dose variations are "primarily attributable to local choices regarding technical parameters, rather than patient, institution, or machine characteristics." Computed tomography (CT) has a large range of scanning options that lead to a large variation in patient radiation doses. Several factors affect radiation dose to patients undergoing cardiac computed tomography (CCT) procedures. 2 Concerns have been raised about the radiation exposure of CCT. Recently, prospective gated mode (PGM) was developed to reduce radiation dose. PGM, also known as "step-and-shoot" or "sequential scan mode," 3 has been developed as an alternative mode to standard helical (spiral) scanning with retrospective electrocardiographic gating with the aim of decreasing radiation dose during CCT to patients with stable heart rates. Previous work by other authors has identified key contributors to variations in dose as radiographic settings, equipment factors, the level of quality assurance in place, radiographer training, radiographer experience, as well as patient body habitus. 4,5 Dose optimization requires identification of which factors are the greatest contributor to variations in dose. Once the contribution of factors is established, operators can consider corrective action in a cost-effective manner. 4 ---

Establishment of diagnostic reference levels in low-dose renal computed tomography

“…Regarding the range of doses recorded, large variations were evident across the surveyed hospitals in reported CTDI vol and DLP values. This is in line with previous work, which has shown that variations may occur depending on CT scanner design (43,45) and the protocol employed (45–47). The particular make and model of the CT scanner may lead to some variation in doses owing to inherent differences such as filtration, beam geometry, number of detector rows, scattered X-rays, and noise value calculations (48,49).…”

“…Routine quality control is conducted for scanners in Jordan (43). Automated tube current modulation and iterative reconstruction were used in all systems except hospitals 6 and 12.…”

Applying the AAPM 293 report to estimate the absorbed dose during head computed tomography: using head circumference for rapid dose estimation

“…Emerging evidence demonstrates a patient’s absorbed dose depends on the computed tomography (CT) scanner radiation dose output during CT examinations ( 1 - 3 ). The most common scanner output dose metrics for CT systems are the volumetric CT dose index (CTDI vol ) and dose-length product (DLP) ( 4 , 5 ). CTDI vol and DLP indicate the absorbed dose of polymethyl methacrylate (PMMA) phantoms with defined diameters of 16 and 32 cm for the head and body, respectively ( 6 - 9 ).…”

Radiation dose for 320‐row dose‐modulated dynamic coronary CT angiography

“…While this may be a new noninvasive method for detecting functional coronary stenosis, it risks increasing radiation exposure. Therefore, we aim to verify and compare the dose of radiation exposure for 320‐row dynamic CCTA with that for standard CCTA and the latest CCTA diagnostic reference levels (DRLs) for Japan and Western countries 16,17 …”

“…Therefore, we aim to verify and compare the dose of radiation exposure for 320-row dynamic CCTA with that for standard CCTA and the latest CCTA diagnostic reference levels (DRLs) for Japan and Western countries. 16,17 2 | METHODS…”