U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT                     Examinations

Kanal, Kalpana M.; Butler, Priscilla F.; Sengupta, Debapriya; Bhargavan-Chatfield, Mythreyi; Coombs, Laura P.; Morin, Richard L.

doi:10.1148/radiol.2017161911

Cited by 280 publications

(208 citation statements)

References 15 publications

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“…Low-contrast detectability is a little lower in the NR mode compared with MDCT, but only a slight dose increase results in the same low-contrast detectability. At our institution, radiation exposure of abdominal MDCT scans is below the achievable levels used in many countries [20,21]; the median (1st and 3rd quartiles) of the CTDI vol and DLP used clinically over the last year on our MDCT was 3 mGy (2.3-4.8 mGy) and 155 mGy cm (116-252 mGy cm), respectively. The slight dose increase necessary to achieve the same low-contrast detectability with the UHRCT in high-resolution modes will not raise The low-contrast detectability of the high-resolution modes is lower than that of the MDCT at the same CTDI vol ; to make it comparable, an extra dose of about 23% is needed.…”

Section: Discussionmentioning

confidence: 83%

Physical evaluation of an ultra-high-resolution CT scanner

et al. 2020

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Objectives To evaluate the technical performance of an ultra-high-resolution CT (UHRCT) system. Methods The physico-technical capabilities of a novel commercial UHRCT system were assessed and compared with those of a current-generation multi-detector (MDCT) system. The super-high-resolution (SHR) mode of the system uses 0.25 mm (at isocentre) detector elements (dels) in the in-plane and longitudinal directions, while the high-resolution (HR) mode bins two dels in the longitudinal direction. The normal-resolution (NR) mode bins dels 2 × 2, resulting in a del-size equivalent to that of the MDCT system. In general, standard procedures and phantoms were used to perform these assessments.Results The UHRCT MTF (10% MTF 4.1 lp/mm) is twice as high as that of the MDCT (10% MTF 1.9 lp/mm), which is comparable to the MTF in the NR mode (10% MTF 1.7 lp/mm). The width of the slice sensitivity profile in the SHR mode (FWHM 0.45 mm) is about 60% of that of the MDCT (FWHM 0.77 mm). Uniformity and CT numbers are within the expected range. Noise in the high-resolution modes has a higher magnitude and higher frequency components compared with MDCT. Low-contrast visibility is lower for the NR, HR and SHR modes compared with MDCT, but about a 14%, for NR, and 23%, for HR and SHR, dose increase gives the same results. Conclusions HR and SHR mode scanning results in double the spatial resolution, with about a 23% increase in dose required to achieve the same low-contrast detectability. Key Points • Resolution on UHRCT is up to twice as high as for the tested MDCT.• With abdominal settings, UHRCT needs higher dose for the same low-contrast detectability as MDCT, but dose is still below achievable levels as defined by current diagnostic reference levels. • The UHRCT system used in normal-resolution mode yields comparable resolution and noise characteristics as the MDCT system.

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Section: Discussionmentioning

confidence: 83%

Physical evaluation of an ultra-high-resolution CT scanner

et al. 2020

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“…The ICRP and some national bodies have discussed using the 50 th percentile as an optimisation target, an 'achievable dose'. 19,24,28 The ICRP has also suggested that facilities with dose levels below the 25th percentile should pay particular attention to ensure that image quality is adequate. 19 Table 3 shows the 25th and 50th percentiles of the FRL distributions for CTDI vol and DLP along with the NDRLs (75th percentiles).…”

Section: A Recent Australianmentioning

confidence: 99%

Updated Australian diagnostic reference levels for adult CT

Lee¹,

Beveridge²,

Sanagou³

et al. 2020

J of Medical Radiation Sci

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Introduction In 2018, ARPANSA published updated national DRLs for adult CT, which were first published in 2012, and augmented the national DRL categories. This paper presents the updated national DRLs and describes the process by which they were produced. Methods Examine patient survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS). Determine the quartiles of the distributions of median survey dose metrics with categorisation by procedure type. Engage a liaison panel representing the radiology professions to review procedure categories and recommend revised national DRLs. The revised NDRL procedure categories are: head (non‐contrast brain (trauma/headache)), cervical spine (Non‐contrast (trauma)), soft‐tissue neck (post‐contrast (oncology)), chest (post‐contrast (oncology)), abdomen–pelvis (post‐contrast (oncology)), kidney–ureter–bladder (non‐contrast (suspected renal colic)), chest–abdomen–pelvis (post‐contrast (oncology)) and lumbar spine (non‐contrast (degenerative pain)). Results The existing six procedure categories were revised and refined. Updated Australian national diagnostic reference levels for adult CT were recommended and endorsed for eight procedure categories: head (52 mGy/880 mGycm), cervical spine (23 mGy/470 mGycm),soft‐tissue neck (17 mGy/450 mGycm), chest (10 mGy/390 mGycm), abdomen–pelvis (13 mGy/600 mGycm), kidney–ureter–bladder (13 mGy/600 mGycm), chest–abdomen–pelvis (11 mGy/940 mGycm) and lumbar spine (26 mGy/670 mGycm). The updated national DRLs are between 12 and 26% lower than the previous DRLs for dose‐length product and between 13 and 63% lower for volume computed tomography dose index. Conclusions Australian national DRLs for adult CT have been reviewed and revised. The revised national DRLs are lower, better reflecting current practice among imaging facilities in Australia. The revised Australian national DRLs are similar to those in other developed countries.

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“…Kanal et al (13) published diagnostic reference and achievable dose index levels for abdominopelvic CT of 19 mGy and 13 mGy, respectively, which represent volume CT dose index values corresponding to the 75th and 50th percentile of patient data in their CT dose index registry (14), to be used for dose optimization (13,15). The American Association of Physicists in Medicine also published abdominopelvic CT protocols for differently sized patients that use a similar dose range (16).…”

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confidence: 99%

Observer Performance with Varying Radiation Dose and Reconstruction Methods for Detection of Hepatic Metastases

et al. 2018

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Purpose: To estimate the ability of lower dose levels and iterative reconstruction (IR) to display hepatic metastases that can be detected by radiologists. Materials and Methods: Projection data from 83 contrast agent–enhanced CT examinations were collected. Metastases were defined by histopathologic analysis or progression and regression. Lower radiation dose configurations were reconstructed at five dose levels with filtered back projection (FBP) and IR (automatic exposure control settings: 80, 100, 120, 160, and 200 quality reference mAs [QRM]). Three abdominal radiologists circumscribed metastases, indicating confidence (confidence range, 0–100) and image quality. Noninferiority was assessed by using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis (noninferiority limit, −0.10) and reader agreement rules, which required identification of metastases identified at routine dose, and no nonlesion localizations in patients negative for metastases, in 71 or more patient CT examinations (of 83), for each configuration. Results: There were 123 hepatic metastases (mean size, 1.4 cm; median volume CT dose index and size-specific dose estimate, 11.0 and 13.4 mGy, respectively). By using JAFROC figure of merit, 100 QRM FBP did not meet noninferiority criteria and had estimated performance difference from routine dose of −0.08 (95% confidence interval: −0.11, −0.04). Preset reader agreement rules were not met for 100 QRM IR or 80 QRM IR, but were met for doses 120 QRM or higher (ie, size-specific dose estimate ≥ 8.0 mGy). IR improved image quality (P < .05) but not reader performance. Other than 160 QRM IR, lower dose levels were associated with reduced confidence in metastasis detection (P < .001). Conclusion: For detection of hepatic metastases by using contrast-enhanced CT, dose levels that corresponded to 120 quality reference mAs (size-specific dose estimate, 8.0 mGy) and higher performed similarly to 200 quality reference mAs with filtered back projection.

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U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT Examinations

Cited by 280 publications

References 15 publications

Physical evaluation of an ultra-high-resolution CT scanner

Physical evaluation of an ultra-high-resolution CT scanner

Updated Australian diagnostic reference levels for adult CT

Observer Performance with Varying Radiation Dose and Reconstruction Methods for Detection of Hepatic Metastases

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