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

Sean P Hassan; Jeremiah de Leon; Vikneswary Batumalai; Zoe Moutrie; Louise Hogan; Yuanyuan Ge; Phillip Stricker; Michael G Jameson

doi:10.1002/acm2.14253

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

J Appl Clin Med Phys. 2024 Apr;25(4):e14253. doi: 10.1002/acm2.14253. Epub 2024 Feb 23.

Authors

Sean P Hassan¹, Jeremiah de Leon¹, Vikneswary Batumalai^{1

2}, Zoe Moutrie^{1

2

3

4}, Louise Hogan^{1

5}, Yuanyuan Ge¹, Phillip Stricker^{2

6

7

8

9}, Michael G Jameson^{1

2

10}

Affiliations

¹ GenesisCare, St Vincent's Hospital, Sydney, New South Wales, Australia.
² Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia.
³ South Western Sydney Cancer Services, New South Wales Health, Sydney, Australia.
⁴ Ingham Institute for Applied Medical Research, Sydney, Australia.
⁵ GenesisCare, Murdoch, Western Australia, Australia.
⁶ Western Sydney University, Penrith, New South Wales, Australia.
⁷ St Vincent's Prostate Cancer Research Centre, Darlinghurst, New South Wales, Australia.
⁸ Garvan Institute, Darlinghurst, Sydney, New South Wales, Australia.
⁹ University of Sydney, Camperdown, New South Wales, Australia.
¹⁰ Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.

Abstract

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.

Keywords: MRL; MR‐Linac; adaptive radiotherapy; post‐prostatectomy radiotherapy; prostate cancer; radiotherapy.

MeSH terms

Humans
Magnetic Resonance Spectroscopy
Male
Prostatectomy
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted* / methods
Radiotherapy, Intensity-Modulated* / methods
Workflow