Implications of Projections for Infrastructure Planning
Interpreting the results
The projections should be treated as baseline numbers rather than as the maximum linac numbers required.
The model developed by the Allen Consulting Group to predict the number of linacs required across Australia assumes that capacity needs equal demand. However, queuing theory (mathematical study of waiting times) proves that capacity needs to exceed mean demand to avoid the build-up of waiting times, including in radiotherapy11. Research into the required percentage of spare capacity needed to keep radiotherapy waiting times to treatment short found that about 10% spare capacity is required to ensure that 86% of patients are able to start radiotherapy within a week of completing the treatment planning process12.
Meeting the target utilisation rate should therefore incorporate an additional 10% capacity in linear accelerator numbers to negate increases in the waiting times for treatment. This would mean that to meet the 52.3% target utilisation rate in 2022, at least 27 additional linacs would be needed extra to the projected number of 267 linacs to create this needed spare capacity.
It is possible that the lack of spare capacity allocation in previous calculations of linac requirements by service planners has resulted in unrealistic expectations regarding throughput and waiting times.
Linac requirements in each jurisdiction
Projected linac requirements for each State and Territory are not included in the Plan. There are two key reasons for this:
Some jurisdictions have very low linac numbers and therefore the model is of limited use;
While the national linac projections are robust, linac numbers at jurisdiction level should be based on local population characteristics and numbers.
There are existing benchmarks for planning radiotherapy services on a population basis2. For every 1,000 cases of cancer in a population, 523 patients would need radiation as an optimal part of their management. Considering the average linac throughput (patients that can be treated in a year), for every 600 new cases of cancer, a linac is required.