Abstract
Purpose or Objective
The introduction of online adaptive MR-guided radiotherapy enables stereotactic body radiation therapy (SBRT) of upper abdominal tumors. The aim of this study was to evaluate the feasibility of MR-guided SBRT on a 1.5T MR-linac in a first group of patients with unresectable malignancies in the upper abdomen.
Materials and Methods
Patients with unresectable, pathology-proven upper abdominal malignancies who were treated at the UMC Utrecht (April 2019-December 2020) were identified in the prospective ‘Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-linac’ (MOMENTUM) study. Feasibility of treatment was arbitrarily defined as an on-table time of ≤60 minutes for >75% of delivered fractions and successful completion of >95% of fractions as scheduled. Treatment-related toxicity and tumor stability on CT-imaging were assessed.
Results
Twenty-five consecutive patients with a median follow-up time of 7 (range 1 to 20) months were treated with 35 Gray (n=4) and 40 Gray (n=21) in five fractions over two weeks. For all fractions, contours were adapted based on the daily anatomy of the tumor and organs-at-risk and delivered within a median on-table time of 47 minutes/fraction (range 30-74). In 98/117 fractions (84%), adapted treatment was completed within one hour. All patients received the scheduled irradiation dose as planned. No acute grade 3 toxicity or higher was reported. Tumor stability is shown in figure 1.
Conclusion
Online adaptive MR-guided SBRT on a 1.5T MR-linac is feasible in patients with unresectable malignancies in the upper abdomen. Dose escalation studies, followed by comparative studies, are needed to determine the optimal radiation dose needed.
The introduction of online adaptive MR-guided radiotherapy enables stereotactic body radiation therapy (SBRT) of upper abdominal tumors. The aim of this study was to evaluate the feasibility of MR-guided SBRT on a 1.5T MR-linac in a first group of patients with unresectable malignancies in the upper abdomen.
Materials and Methods
Patients with unresectable, pathology-proven upper abdominal malignancies who were treated at the UMC Utrecht (April 2019-December 2020) were identified in the prospective ‘Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-linac’ (MOMENTUM) study. Feasibility of treatment was arbitrarily defined as an on-table time of ≤60 minutes for >75% of delivered fractions and successful completion of >95% of fractions as scheduled. Treatment-related toxicity and tumor stability on CT-imaging were assessed.
Results
Twenty-five consecutive patients with a median follow-up time of 7 (range 1 to 20) months were treated with 35 Gray (n=4) and 40 Gray (n=21) in five fractions over two weeks. For all fractions, contours were adapted based on the daily anatomy of the tumor and organs-at-risk and delivered within a median on-table time of 47 minutes/fraction (range 30-74). In 98/117 fractions (84%), adapted treatment was completed within one hour. All patients received the scheduled irradiation dose as planned. No acute grade 3 toxicity or higher was reported. Tumor stability is shown in figure 1.
Conclusion
Online adaptive MR-guided SBRT on a 1.5T MR-linac is feasible in patients with unresectable malignancies in the upper abdomen. Dose escalation studies, followed by comparative studies, are needed to determine the optimal radiation dose needed.
| Original language | English |
|---|---|
| Pages (from-to) | S1008-S1009 |
| Journal | Radiotherapy and Oncology |
| Volume | 161 |
| Issue number | S1 |
| DOIs | |
| Publication status | Published - Aug 2021 |