Online Adaptive MRI-Guided Stereotactic Body Radiotherapy for Pancreatic and Other Intra-Abdominal Cancers

Danny Lee, Paul Renz, Seungjong Oh, Min Sig Hwang, Daniel Pavord, Kyung Lim Yun, Colleen Collura, Mary McCauley, Athanasios Colonias, Mark Trombetta, Alexander Kirichenko

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

A 1.5T MRI combined with a linear accelerator (Unity®, Elekta; Stockholm, Sweden) is a device that shows promise in MRI-guided stereotactic body radiation treatment (SBRT). Previous studies utilized the manufacturer’s pre-set MRI sequences (i.e., T2 Weighted (T2W)), which limited the visualization of pancreatic and intra-abdominal tumors and organs at risk (OAR). Here, a T1 Weighted (T1W) sequence was utilized to improve the visualization of tumors and OAR for online adapted-to-position (ATP) and adapted-to-shape (ATS) during MRI-guided SBRT. Twenty-six patients, 19 with pancreatic and 7 with intra-abdominal cancers, underwent CT and MRI simulations for SBRT planning before being treated with multi-fractionated MRI-guided SBRT. The boundary of tumors and OAR was more clearly seen on T1W image sets, resulting in fast and accurate contouring during online ATP/ATS planning. Plan quality in 26 patients was dependent on OAR proximity to the target tumor and achieved 96 ± 5% and 92 ± 9% in gross tumor volume D90% and planning target volume D90%. We utilized T1W imaging (about 120 s) to shorten imaging time by 67% compared to T2W imaging (about 360 s) and improve tumor visualization, minimizing target/OAR delineation uncertainty and the treatment margin for sparing OAR. The average time-consumption of MRI-guided SBRT for the first 21 patients was 55 ± 15 min for ATP and 79 ± 20 min for ATS.

Original languageEnglish
Article number5272
JournalCancers
Volume15
Issue number21
DOIs
StatePublished - Nov 2023

Keywords

  • MRI in RT
  • MRI-Linac
  • MRI-guided SBRT
  • Unity
  • abdominal cancers
  • adapt-to-position
  • adapt-to-shape
  • online adaptive planning
  • pancreatic cancers
  • stereotactic body radiation treatment

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