Comparative Analysis of Radiation Dose in Digital vs. Conventional Radiography

Thesis Abstract

The rapid transition from conventional radiography to digital systems promises improvements in image quality, workflow efficiency, and diagnostic accuracy, yet it also raises concerns about patient radiation exposure and dose optimization across diverse clinical settings. This study addresses the problem of whether digital radiography (DR) delivers a statistically significant reduction in patient radiation dose compared with conventional film-screen radiography (FSR), while accounting for modality-specific workflow differences, imaging protocols, and patient factors. The aim is to quantify and compare entrance skin dose (ESD) and effective dose (ED) between DR and FSR, and to identify determinants of dose variation across radiographic examinations. The specific objectives are (1) to measure and compare ESD and ED for common diagnostic projections (chest PA, abdomen AP, and extremities) in DR and FSR; (2) to evaluate the influence of exposure parameters (kVp, mAs, and source-to-image distance) and patient-related factors (BMI and age) on dose outcomes; (3) to assess compliance with established dose optimization guidelines (e.g., AAPM, ICRP, and national DRLs) in both modalities; (4) to determine whether digital post-processing and detector efficiency contribute to dose differences; and (5) to develop evidence-based recommendations for dose optimization in mixed-modality radiography services. The methodology adopts a cross-sectional, comparative design conducted in three tertiary hospitals with centralized radiology departments. The population comprises adult outpatients and inpatients undergoing standard radiographic examinations in DR and FSR. A total of 600 radiographic examinations (300 DR and 300 FSR) will be sampled using stratified random sampling across the selected projections. Data collection will integrate dosimetric measurements, imaging protocol audits, and patient demographics. ESD will be measured directly using calibrated dosimeters placed at the skin entry point during routine practice, while ED will be estimated via the Bureau of Radiological Health-converted effective dose coefficients. Exposure parameters (kVp, mAs, focal spot size), patient body mass index (BMI), age, and projection type will be recorded from radiology information systems. Instruments will include (1) calibrated thermoluminescent dosimeters (TLD-100) or digital dosimeters for ESD, (2) standardized protocol checklists, and (3) a data collection form integrated with the hospital picture archiving and communication system (PACS). Validity and reliability will be ensured through pilot testing, inter-rater calibration for protocol audits, and calibration of dosimetric devices prior to data collection. Data analysis will employ descriptive statistics to summarize dose metrics, followed by inferential analyses using independent-samples t-tests or Mann-Whitney U tests for group comparisons, and multiple linear regression to quantify associations between dose outcomes and predictors such as modality, BMI, projection, and exposure parameters. Analysis will adjust for potential confounders using stratification by projection and age groups. A sensitivity analysis will test the robustness of ED estimations under alternative conversion factors. The study will also apply a mixed-effects model to account for clustering by imaging room and technologist. Theoretical framing will be guided by the Principle of ALARA (As Low As Reasonably Achievable) and the Technology Acceptance Model to interpret adoption-related differences in dose practices between DR and FSR. Key expected findings include (a) DR will demonstrate lower mean ESD and ED for chest and abdominal projections but may show variable results for extremities depending on detector efficiency and exposure latitude; (b) kVp and BMI will emerge as significant predictors of dose across modalities, with higher BMI associated with increased dose, particularly in FSR; (c) adherence to dose optimization guidelines will be higher in DR settings due to automated exposure control but may be offset by overexposure in cases of suboptimal technique settings; (d) detector characteristics (indirect vs. direct conversion, noise handling) and post-processing will contribute meaningfully to dose differences. The study contributes to knowledge by providing contemporary, cross-modality evidence on radiation dose performance in real-world radiography practice, informing protocol optimization, equipment procurement decisions, and policy development for DR deployment. It will offer actionable recommendations standardized exposure protocols aligned with patient size, routine audit of detector performance, calibration of automatic exposure control systems, and continued education for radiographers on dose instrumentation and optimization. The findings will support targeted strategies to maximize ALARA outcomes while maintaining diagnostic quality, and will identify areas where additional regulatory guidance or DRLs may be warranted to harmonize practice across imaging departments.