Which Criteria Should We use to Determine an Adequate Number of Linear Accelerators in Emerging Economy Countries

Abstract

In the age of limited resources, knowing the number of linear accelerators (LINACS) is paramount for designing and planning comprehensive coverage for a population. As important guidelines for the actual prediction of the number of LINACS, a wide range of directions are found in the literature. These guidelines vary depending on total population size, cancer incidence, cancer types, fractions per year, and machine workload. Knowing which guidelines to use, and which one fits the population's needs, is key to the best utilization of resources. In Oman, we have a stable population with minimal rates of immigration/emigration. The current needs of LINACS are met so we have a unique opportunity to test some of these guidelines and see which one most accurately predicts the correct number needed. The results should help emerging economies use a similar approach in estimating their needs. This study was conducted to estimate the demand for radiotherapy services needed in Oman taking into consideration the most common methods and recommendations available in the literature. The calculation methods analyzed: COCIR - targets a density of 7 radiation therapy units per million; ESTRO/QUARTS - 1 LINAC per 400 patients/year or 1 LINAC per 180,000 persons; and IAEA method that uses a combination of cancer incidence, number of treatment fractions per cancer type, and machine workload. The population demographics with cancer incidence were extracted from the Oman Cancer Registry data 2019 (total number of cases and cancer types). For the density of LINAC units per million population, we used the 2019 population of 4.603 million. For the workload calculation, we used 4 fractions/hour in an 8-hour shift and 248 working days. The calculations included the total number of cancer cases, average number of fractions per year, machine workload, rate of patients receiving radiotherapy per cancer type, the optimal number of fractions per treatment course, retreatment rate, and radiotherapy utilization rate per cancer type. Based on most frequent cancer incidence (1,437 cases), the total number of fractions per year is 22,920. The workload of machines was 7,936 fractions/year. If calculations included total number of cancer types (2,039) and average number of fractions per patient based on average number of fractions per cancer site, the total number of fractions is 27,715. If the reirradiation ratio included the number of fractions per year, a total of 34,644 (25% increase). For the COCIR, ESTRO/QUARTS, and IAEA recommendations, the range is 2.8 to 32 of required LINACS for adequate coverage in Oman (respectively 32; 4 to 25; and 2.8). The analysis of recommended guidelines for calculating the required number of LINACS in Oman showed a wide range. While in practice we know currently the number of LINACS required for our population is 5, for emerging economies 1 LINAC per 400 patients/year, or the IAEA calculation methods are the closest approximation to the actual needs.