Related Experiment Video
Updated: Feb 6, 2026

Author Spotlight: Improving Radiation Therapy Access with Radiation Planning Assistant
Published on: October 6, 2023
Clinical indication-based diagnostic reference levels in CT: a systematic review
Abdul Alim1,2, Sook Sam Leong3,4, Ann Erynna Lema Thomas Sudin1
1Center for Medical Imaging Studies, Universiti Teknologi MARA, Puncak Alam, Selangor, Malaysia.
Objectives:
A growing number of national diagnostic reference levels based on clinical indications (NDRLci) in CT have been implemented worldwide since the International Commission on Radiological Protection's 2017 recommendation. This study aims to compare NDRLci practices, identify influencing factors and propose evidence-based recommendations for NDRLci development, based on the literature published between 1996 and 2025.
Design:
Systematic review.
Setting:
A systematic literature search was conducted in PubMed, Web of Science and Scopus from 1996 to 24 august 2025. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis framework was followed to report the study selection process in this review. Joanna Briggs Institute's critical appraisal tools were used to evaluate the articles critically.
Participants:
Adult patients undergoing CT scans for various clinical indications.
Intervention:
Clinical indication-based CT protocols with reported NDRLci values as CT dose index volume and dose length product (DLP).
Primary And Secondary Outcome Measures:
The primary outcomes were NDRLci values reported for various clinical indications. The secondary outcomes were CT technology, protocol parameters and patient characteristics influencing NDRLci.
Result:
A total of 4146 articles were identified. 410 full texts were examined and 11 studies were included in the systematic review. 25 clinical indications across seven anatomical regions were identified across 11 included studies. The NDRLci for urinary stones and cerebrovascular accident had the highest number of references, while flank pain and occlusion had the lowest number. The highest NDRLci in DLP was found for total body CT in severe trauma (3830 mGy cm) and the lowest for sinusitis (70 mGy cm).
Conclusion:
Several factors contribute to dose discrepancies for the same clinical indications in CT imaging, including kilovolt peak and milliampere-second, scan length, number of phases, patient size, reconstruction algorithm, CT scanner age and specifications, underscoring the need for standardised and optimised CT protocols. This review highlighted several challenges, which emphasise the importance of international organisations to standardise the development of NDRLci to improve comparability across countries.
Prospero Registration Number:
CRD42024603574.
Related Concept Videos
Indicators
Pericarditis II: Clinical Features and Diagnostic Tests
Atherosclerosis II: Clinical Manifestations and Diagnostic Tests
Aneurysm II: Clinical Manifestations and Diagnostic Studies
Myocarditis II: Clinical Features and Diagnostic Tests
Mitral Regurgitation II: Clinical Features and Diagnostic Tests

