Developing a Theoretical Framework for Equitable Diagnostic Imaging Access in Rural Nigeria: Systems, Policy, and Geographical Dimensions

Access to diagnostic imaging services in rural Nigeria is profoundly inequitable, with over 70 percent of the country's imaging infrastructure concentrated in urban centres serving less than 40 percent of the population. Despite policy commitments to universal health coverage, no theoretically grounded framework for achieving equitable imaging access in the rural Nigerian context has been developed. This study develops an original theoretical framework for equitable diagnostic imaging access in rural Nigeria. A sequential explanatory mixed-methods design is applied: phase one conducts a national diagnostic imaging access mapping study documenting facility-to-population ratios, modality distribution, operational status, and referral patterns across 774 local government areas using GIS-based spatial analysis; phase two applies qualitative interpretive methodology through 50 in-depth interviews and eight focus groups with rural community members, radiographers, health managers, and policy makers to understand access determinants; phase three uses these data to develop and validate the framework through iterative expert consultations. The original Equitable Rural Imaging Access Framework (ERIA Framework) identifies three interconnected access dimensions: Availability (facility distribution), Affordability (cost and financing mechanisms), and Acceptability (cultural and communication appropriateness), structured within a Systems Strengthening environment model. The framework specifies 24 actionable evidence-based policy levers targeted at each dimension. Available rural radiology access literature from Nigeria identifies geographic distribution inequity as more severe than financing inequity, reversing the priority assumption common in global health literature. The Penchansky and Thomas Access Framework and the WHO Health Systems Framework provide the theoretical foundations. Keywords: equitable access, diagnostic imaging, rural Nigeria, access framework, health policy.