Achievable Radiation Dose Reduction with Comparable Image Quality in Chest Radiography

• Published in: Hong Kong journal of radiology : HKJR = Xianggang fang she ke yi xue za zhi 2014-09, Vol.17 (3), p.182-188
• Main Authors: Wan, AYH, Shih, MH, Lai, BMH, Chu, CY, Tang, KYK, Chan, RTM, Khoo, JLS
• Format: Article
• Language: English
• Subjects: Radiation; Radiography
• ISSN: 2223-6619; 2307-4620
• DOI: 10.12809/hkjr1413198

Objective: Chest radiography is one of the commonest radiological investigations utilised in various medical specialties. Although the radiation dose of a single chest radiography to the patient is relatively low, the contribution of the accumulated dose is substantial due to its frequent use in medical diagnoses. Optimisation of radiation dose and image quality, therefore, remains a challenging area in research and routine practice. The objective of this study was to evaluate the radiation dose in chest radiograph (CXR) taken with a sensitivity value of 400 (as in factory setting) and to perform quality assessment of the diagnostic applicability of dose-reduced CXRs obtained with a higher sensitivity value (of 600). Methods: CXRs performed in 100 consecutive adult patients attending a regional hospital in Hong Kong were reviewed. Images were taken with a sensitivity value of either 400 or 600 by an Agfa 85X CR System. Fifty patients were allocated to each acquisition technique and the assignment of this grouping was random. No significant mismatch with respect to patient body size was noted in the two groups. Diagnostic reference levels, estimated with dose area product derived from exposure measurements, were used to quantify the radiation dose. The difference in radiation dose between these two sets of images was statistically evaluated by the Student’s t test. The CXRs were reviewed and rated by two independent radiologists in random order. The image quality of CXRs was assessed by 10 criteria as stated in the European Guidelines On Quality Criteria for Diagnostic Radiographic Images. Differences in image quality ratings between the two acquisition techniques were statistically quantified by analysis of variance with repeated measures. The agreement ratio for each criterion between the two radiologists was calculated. Evaluation of the interobserver agreement for the overall mean score of image quality was performed using weighted Cohen’s Kappa statistics. Results: A statistically significant reduction in radiation dose of 32.8% (p