Global linear accelerator requirements and personalised country recommendations: a cross-sectional, population-based study

The Linear Accelerator Shortage Index (LSI) is a practical tool for prioritising the deployment of linear accelerators (LINACs) in various regions within a country. The LSI reflects the ratio of LINAC demand to current availability. The aim of this study was to use the LSI to predict global LINAC needs and classify countries according to the degree of radiotherapy shortage (LINAC shortage grade). In this cross-sectional, population-based study of globally representative, country-level data, we sourced regional LINAC distribution, numbers of radiotherapy centres, and cancer incidence data for 181 countries from the Directory of Radiotherapy Centers and Global Cancer Observatory 2022 databases. Current gross domestic product and gross national income per capita in US dollars were obtained from the World Bank. We calculated an LSI for each country to assess the relative demand and supply of radiotherapy by dividing LINAC use by 450 and multiplying by 100. An LSI of 100 or less indicates no shortage (450 or fewer patients per LINAC), whereas an LSI greater than 100 signals a shortage, with higher values indicating more severe deficits. We categorised countries by LINAC shortage grade: grade 0 (LSI ≤100, no shortage), grade 1 (LSI 101–130, low need), grade 2 (LSI 131–300, high need), grade 3 (LSI >300, excessive need), or grade 4 (no existing LINACs). We estimated LINAC requirements until 2045 using the LSI and Global Cancer Observatory data. We determined future investment costs according to the LSI for each country. As of the data cutoff on Sept 15, 2024, the global median LSI was 130 (IQR 96–319), suggesting a shortage of 30% in radiotherapy capacity. Significant disparities in median LSI were observed across income levels: low-income countries had a median LSI of 1523 (528–2247), lower-middle-income countries 399 (183–685), upper-middle-income countries 133 (104–198), and high-income countries 96 (83–127; p