Magnetic resonance guided adaptive post prostatectomy radiotherapy: Accumulated dose comparison of different workflows.

PURPOSE: The aim of this study was to assess the use of magnetic resonance guided adaptive radiotherapy (MRgART) in the post-prostatectomy setting; comparing dose accumulation for our initial seven patients treated with fully adaptive workflow on the Unity MR-Linac (MRL) and with non-adaptive plans generated offline. Additionally, we analyzed toxicity in patients receiving treatment. METHODS: Seven patients were treated with MRgART. The prescription was 70-72 Gy in 35-36 fractions. Patients were treated with an adapt to shape (ATS) technique. For each clinically delivered plan, a non-adaptive plan based upon the reference plan was generated and compared to the associated clinically delivered plan. A total of 468 plans were analyzed. Concordance Index of target and Organs at Risk (OARs) for each fraction with reference contours was analyzed. Acute toxicity was then assessed at six-months following completion of treatment with Common Terminology for Adverse Events (CTCAE) Toxicity Criteria. RESULTS: A total of 246 fractions were clinically delivered to seven patients; 234 fractions were delivered via MRgART and 12 fractions delivered via a traditional linear accelerator due to machine issues. Pre-treatment reference plans met CTV and OAR criteria. PTV coverage satisfaction was higher in the clinically delivered adaptive plans than non-adaptive comparison plans; 42.93% versus 7.27% respectively. Six-month CTCAE genitourinary and gastrointestinal toxicity was absent in most patients, and mild-to-moderate in a minority of patients (Grade 1 GU toxicity in one patient and Grade 2 GI toxicity in one patient). CONCLUSIONS: Daily MRgART treatment consistently met planning criteria. Target volume variability in prostate bed treatment can be mitigated by using MRgART and deliver satisfactory coverage of CTV whilst minimizing dose to adjacent OARs and reducing toxicity.

Equity should know no borders: The role of Australasian radiation oncologists in supporting radiation oncology services in low- and middle-income countries in the Asia-Pacific.

The rapid rise in cancer incidence within the world's poorest nations highlights the need for equitable access to evidence-based cancer care. It has been previously demonstrated that radiotherapy is a cost-effective and necessary tool in cancer treatment. However, globally there is a growing divide between demand and supply of radiotherapy services. In low- and middle-income countries, this resource gap is particularly problematic. By region, the Asia-Pacific has been demonstrated to have the highest absolute deficit in radiotherapy services. Radiation oncologists in Australia and New Zealand are geographically well positioned to assist departments within the Asia-Pacific to help to reduce these inequities. The Asia-Pacific Radiation Oncology Special Interest Group (APROSIG) aims to support oncology professionals in the Asia-Pacific to develop safe and sustainable cancer services. Members have already contributed to multiple projects throughout the region, supported by grants and departmental funding. However, the backbone of support comes from volunteers sharing their time and expertise. The Australasian oncological community has the skills and knowledge to help not only those within our borders but also beyond. Such efforts provide the potential to develop valuable clinical, educational, research and leadership experiences whilst establishing networking opportunities throughout the most populated regions of the world. More options for growth and work in global health must be investigated, encouraging future trainees to consider a role within the global cancer community. Without prompt and continued action, the resource deficit is likely to grow and the inequity in accessing radiotherapy and other cancer services further magnified.