What health system factors influence progression from basic to advanced radiotherapy capability across different income settings? A scoping review.

Radiotherapy is an essential component of cancer treatment, yet access to advanced radiotherapy techniques — including IMRT, IGRT, SABR, adaptive radiotherapy, and respiratory motion management — remains deeply unequal across global health systems. Disparities are especially pronounced in sub-Saharan Africa and low- and middle-income countries (LMICs), where infrastructure, workforce, financing, and governance constraints limit progression beyond basic techniques. Existing approaches to global radiotherapy disparities have focused primarily on technology access — equipment numbers, procurement costs, and infrastructure deficits. While these are real constraints, this framing obscures a more complex picture. Progression from basic to advanced radiotherapy requires an alignment of workforce capability, governance arrangements, financing systems, organisational culture, and learning infrastructure. This scoping review therefore adopts a health system capability perspective, asking what system-level factors enable or constrain that progression across diverse income settings. The Consolidated Framework for Implementation Research (CFIR) provides a structured analytic lens for organising identified determinants. Findings will inform the development of a conceptual framework for subsequent empirical comparative case study research. This review is distinct from a related student project developing a survey instrument at organisational level in UK settings; the present review operates at health system level across multiple income contexts.