Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

Chu, Philip; Yu, Sophronia; Wang, Yifei; Seibert, J. Anthony; Cervantes, Luisa F.; Kasraie, Nima; Chu, Cameron A.; Smith‐Bindman, Rebecca

doi:10.1007/s00247-021-05227-0

Cited by 9 publications

(1 citation statement)

References 17 publications

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“…As DLCT scanning parameters in this study, a tube voltage of 120 kV, a current of 250 mAs, a DLP of 717.47 (SD, 41.52) mGYÂcm, and a CTDI vol of 36 mGy were used for conventional CT to view the pediatric brain, which were similar to or slightly lower than diagnostic reference levels for the CT radiation dose in China (804 mGy for the DLP and 39 mGYÂcm for CTDI vol ) 28 and other countries. [29][30][31][32][33][34] The CTDI vol is the dose of the standard American College of Radiology head phantom according to the reference phantom selection in pediatric CT; 19,35 the DLP is the actual radiation dose received by the patient. There was no significant difference in DLP between the 6 year and younger and older than 6-year subgroups in the 250-mAs group, while there was a significant difference in DLP between the 6 year and younger and older than 6-year subgroups in the 180-mAs group.…”

Section: Discussionmentioning

confidence: 99%

Dual-Layer Detector Head CT to Maintain Image Quality While Reducing the Radiation Dose in Pediatric Patients

Tan,

Zhang,

Sun

et al. 2023

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: Radiation exposure in the CT diagnostic imaging process is a conspicuous concern in pediatric patients. This study aimed to evaluate whether 60-keV virtual monoenergetic images of the pediatric cranium in dual-layer CT can reduce the radiation dose while maintaining image quality compared with conventional images. MATERIALS AND METHODS:One hundred six unenhanced pediatric head scans acquired by dual-layer CT were retrospectively assessed. The patients were assigned to 2 groups of 53 and scanned with 250 and 180 mAs, respectively. Dose-length product values were retrieved, and noise, SNR, and contrast-to-noise ratio were calculated for each case. Two radiologists blinded to the reconstruction technique used evaluated image quality on a 5-point Likert scale. Statistical assessment was performed with ANOVA and the Wilcoxon test, adjusted for multiple comparisons.RESULTS: Mean dose-length product values were 717.47 (SD, 41.52) mGyÂcm and 520.74 (SD, 42) mGyÂcm for the 250-and 180-mAs groups, respectively. Irrespective of the radiation dose, noise was significantly lower, SNR and contrast-to-noise ratio were significantly higher, and subjective analysis revealed significant superiority of 60-keV virtual monoenergetic images compared with conventional images (all P , .001). SNR, contrast-to-noise ratio, and subjective evaluation in 60-keV virtual monoenergetic images were not significantly different between the 2 scan groups (P . .05). Radiation dose parameters were significantly lower in the 180-mAs group compared with the 250-mAs group (P , .001).CONCLUSIONS: Dual-layer CT 60-keV virtual monoenergetic images allowed a radiation dose reduction of 28% without imagequality loss in pediatric cranial CT.ABBREVIATIONS: CNR ¼ contrast-to-noise ratio; CTDI vol ¼ volume CT dose index; DECT ¼ dual-energy CT; DLCT ¼ dual-layer CT; DLP ¼ dose-length product; GWMA ¼ assessment of GM-WM differentiation; PFAA ¼ assessment of artifacts in posterior fossa; SSA ¼ assessment of the subcalvarial space; SAI ¼ subcalvarial artifact index; VMI ¼ virtual monoenergetic image

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Section: Discussionmentioning

confidence: 99%

Dual-Layer Detector Head CT to Maintain Image Quality While Reducing the Radiation Dose in Pediatric Patients

Tan,

Zhang,

Sun

et al. 2023

AJNR Am J Neuroradiol

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Dose length product to effective dose coefficients in children

et al. 2023

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Background The most accurate method for estimating effective dose (the most widely understood metric for tracking patient radiation exposure) from computed tomography (CT) requires time-intensive Monte Carlo simulation. A simpler method multiplies a scalar coefficient by the widely available scanner-reported dose length product (DLP) to estimate effective dose. Objective Develop pediatric effective dose coefficients and assess their agreement with Monte Carlo simulation. Materials and methods Multicenter, population-based sample of 128,397 pediatric diagnostic CT scans prospectively assembled in 2015–2020 from the University of California San Francisco International CT Dose Registry and the University of Florida library of highly realistic hybrid computational phantoms. We generated effective dose coefficients for seven body regions, stratified by patient age, diameter, and scanner manufacturer. We applied the new coefficients to DLPs to calculate effective doses and assessed their correlations with Monte Carlo radiation transport-generated effective doses. Results The reported effective dose coefficients, generally higher than previous studies, varied by body region and decreased in magnitude with increasing age. Coefficients were approximately 4 to 13-fold higher (across body regions) for patients <1 year old compared with patients 15–21 years old. For example, head CT (54% of scans) dose coefficients decreased from 0.039 to 0.003 mSv/mGy-cm in patients <1 year old vs. 15–21 years old. There were minimal differences by manufacturer. Using age-based conversion coefficients to estimate effective dose produced moderate to strong correlations with Monte Carlo results (Pearson correlations 0.52–0.80 across body regions). Conclusions New pediatric effective dose coefficients update existing literature and can be used to easily estimate effective dose using scanner-reported DLP.

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Large variation in radiation dose for routine abdomen CT: reasons for excess and easy tips for reduction

Smith-Bindman,

Kang,

Chu

et al. 2023

Eur Radiol

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Objective To characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT. Methods We retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds. Results A total of 748,846 CTs were performed using 1033 unique protocols. When sorted by patient size, patients with larger abdominal diameters had increased dose and effective mAs (milliampere seconds), even after adjusting for patient size. When sorted by size-adjusted dose, patients in the highest versus the lowest decile in size-adjusted DLP received 6.4 times the average dose (1680 vs 265 mGy-cm) even though diameter was no different (312 vs 309 mm). Effective mAs was 2.1-fold higher, unadjusted CTDIvol 2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6–40%. Conclusion There are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction. Clinical relevance Radiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients. Key Points • Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized. • The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common. • kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches.

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Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

Cited by 9 publications

References 17 publications

Dual-Layer Detector Head CT to Maintain Image Quality While Reducing the Radiation Dose in Pediatric Patients

Dual-Layer Detector Head CT to Maintain Image Quality While Reducing the Radiation Dose in Pediatric Patients

Dose length product to effective dose coefficients in children

Large variation in radiation dose for routine abdomen CT: reasons for excess and easy tips for reduction

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