Elsevier

Academic Radiology

Volume 28, Issue 2, February 2021, Pages 217-224
Academic Radiology

Original Investigation
Patient-based Performance Assessment for Pediatric Abdominal CT: An Automated Monitoring System Based on Lesion Detectability and Radiation Dose

https://doi.org/10.1016/j.acra.2020.01.018Get rights and content

Rationale and Objective

To deploy an automated tool for evaluating pediatric body computed tomography (CT) performance utilizing metrics of radiation dose and image quality for the task of liver lesion detection.

Materials and Methods

This IRB approved retrospective investigation used 507 IV-contrast-enhanced abdominopelvic CT scans of pediatric patients (<18 years) between June 2014 and November 2017 acquired on three scanner models from two manufacturers. The scans were evaluated in terms of radiation metrics (CTDIvol, DLP, and SSDE) as well as task-based performance based on the clinical task of detecting a 5 mm liver lesion with a 10 HU attenuation difference from background liver. An informatics algorithm extracted a previously-validated quantitative detectability index (d′) from each case reflective of the likelihood of detecting a liver lesion. The results were analyzed in terms of the relationship between d′ and radiation dose metrics.

Results

There was minimal SSDE variability by age. Median SSDE at 100 kV on one scanner model was 5.2 mGy (5.0–5.4 mGy interquartile range). However, when assessing image quality by applying d′, the age groups separated such that the younger patients had higher d′ values than older patients. Similar trends were seen in all scanners.

Conclusions

An automated method to assess clinical image quality for pediatric CT provided a metric of image quality that varied as expected across ages (i.e., higher quality for younger patients). This tool affords the establishment of a quality reference level that, in addition to dose estimations currently available, would allow for enhanced assessment (e.g., facilitated audit) of CT imaging performance.

Section snippets

INTRODUCTION

A necessary consequence of computed tomography (CT) is the exposure of patients to ionizing radiation with consequent potential radiation-related risks (1, 2, 3, 4, 5, 6, 7, 8). While there are numerous resources dedicated to improving CT in children which emphasize appropriate radiation exposure, there is an increasing requirement for establishment of CT monitoring programs (9). This includes requirements and guidance standards established in Europe with the Directive Euratom/2013/59 (10), the

Clinical Cases

The study population consisted of 507 clinically-performed, contrast-enhanced AP CT scans of patients ages 0–<18 years (Fig 1) that were protocoled based on age and weight through a color-coded system (29). All studies were performed at a large academic medical center between June 2014 and November 2017. The studies were from three scanner models: Siemens SOMATOM Definition Flash (n = 364, Erlangen, Germany), GE Discovery CT750 HD (n = 53, Waukesha, WI), and GE LightSpeed VCT (n = 90, Waukesha,

RESULTS

Radiation dose in CTDIvol for a given kV trended slightly positively across ages. On Scanner 1, median CTDIvol at 100 kV was 3.0 mGy (2.8–3.3 mGy interquartile range [IQR]) and at 120 kV was 5.5 mGy (4.9–6.6 mGy IQR). On Scanner 2, median CTDIvol at 120 kV was 2.2 mGy (1.9–2.5 mGy IQR). On Scanner 3, median CTDIvol at 120 kV was 2.3 mGy (2.0–2.6 mGy IQR). Overall, the CTDIvol for the oldest age group on all scanners was approximately 1.35-fold the youngest age group. All aggregate median values

DISCUSSION

Automation of CT quality assessment facilitates potential integration with existing dose information into a more comprehensive and efficient assessment of CT practice. We deployed a tool which affords an automated method for quality quantification of pediatric body CT examinations for a reference diagnostic task—the detection of a small, focal liver lesion by combining published methodologies. Our study was based on a proven assumption that the detectability index metric correlates with higher

REFERENCES (42)

  • M Bhargavan-Chatfield et al.

    The ACR computed tomography dose index registry: the 5 million examination update

    J Am Coll Radiol

    (2013)
  • R Morin et al.

    ACR dose index registry

    J Am Coll Radiol

    (2011)
  • P Butler et al.

    Diagnostic reference levels for adult patients in the United States

    J Am Coll Radiol

    (2018)
  • A Berrington de Gonzalez et al.

    Relationship between paediatric CT scans and subsequent risk of leukaemia and brain tumours: assessment of the impact of underlying conditions

    Br J Cancer

    (2016)
  • J Boice

    Radiation epidemiology and recent paediatric computed tomography studies

    Ann ICRP

    (2015)
  • The Joint Commission. Diagnostic Imaging Standards....
  • H Harvey et al.

    Informed consent for radiation risk from CT is unjustified based on the current scientific evidence

    Radiology

    (2015)
  • WY Huang et al.

    Paediatric head CT scan and subsequent risk of malignancy and benign brain tumour: a nation-wide population-based cohort study

    Br J Cancer

    (2014)
  • N Journy et al.

    Are the studies on cancer risk from CT scans biased by indication? Elements of answer from a large-scale cohort study in France

    Br J Cancer

    (2015)
  • L Krille et al.

    Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study

    Radiat Environ Biophys

    (2015)
  • J Mathews et al.

    Cancer risk in 680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians

    BMJ

    (2013)
  • Radiological protection and safety in medicine. A report of the International Commission on Radiological Protection

    Ann ICRP

    (1996)
  • 59/EURATOM of 5 December 2013 laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122

    Off J Eur Union

    (2013)
  • California State Senate. SB 1237. 2010 [updated 02/19/2010]; Available from:...
  • US Food and Drug Administration. White paper: initiative to reduce unnecessary radiation exposure from medical imaging....
  • Centers for Medicare & Medicaid Services. Quality Measures. [updated April 06, 2012, June 01, 2018]; Available from:...
  • Boone J, Strauss K, Cody D, et al. Size specific dose estimates (SSDE) in pediatric and adult body CT examinations....
  • European Society of Radiology. PiDRL-European diagnostic reference levels for paediatric diagnostic imaging...
  • McCollough C, Bakalyar D, Bostani M, et al. Use of water equivalent diameter for calculating patient size and...
  • Diagnostic reference levels in medical imaging

    ICRP Publication 135. Ann ICRP

    (2017)
  • National Council on Radiation Protection Measurements. Reference levels and achievable doses in medical and dental...
  • Cited by (6)

    • Oncology-specific radiation dose and image noise reference levels in adult abdominal-pelvic CT

      2023, Clinical Imaging
      Citation Excerpt :

      This automated, direct measure of an image quality metric provides yet another level of detail for practices when refining protocols and they report further objective automated measures that are feasible for reporting in the future such as noise texture and spatial resolution. Such efforts have been extended across large cohorts of facilities,9 extended to the likelihood of lesion detection,10 and validated to be reflective of radiologists preference11 and, more importantly, diagnostic accuracy.12,13 The purpose of our study was to provide oncology-specific adult abdominal-pelvic CT reference levels for radiation dose and image noise from a high-volume, oncologic, tertiary referral center.

    • Medical physics 3.0: A renewed model for practicing medical physics in clinical imaging

      2022, Physica Medica
      Citation Excerpt :

      But troubleshooting, as commonly practiced, is sporadic and only address the most noticeable problems. Latest technologies in dose and performance monitoring enable physicists to systematically analyze the output of the imaging examinations [9–12] (Fig. 1). These analyses can ensure that the actual output of the imaging technology matches expectations in terms of quality and safety surrogates, diagnostic performance [13], and consistency of the operation.

    View full text