Dataset Information

1.5 T MR-linac planning study to compare two different strategies of rectal boost irradiation.

ABSTRACT:

Purpose

To compare treatment plans of two different rectal boost strategies: up-front versus adaptive boost at the 1.5 T MR-Linac.

Methods

Patients with locally advanced rectal cancer (LARC) underwent standard neoadjuvant radiochemotherapy with 50.4 Gy in 28 fractions. T2-weighted MRI prior and after the treatment session were acquired to contour gross tumor volumes (GTVs) and organs at risk (OARs). The datasets were used to simulate four different boost strategies (all with 15 Gy/5 fractions in addition to 50.4 Gy): up-front boost (5 daily fractions in the first week of treatment) and an adaptive boost (one boost fraction per week). Both strategies were planned using standard and reduced PTV margins. Intra-fraction motion was assessed by pre- and post-treatment MRI-based contours.

Results

Five patients were included and a total of 44 MRI sets were evaluated. The median PTV volumes of the adaptive boost were significantly smaller than for the up-front boost (81.4 cm³ vs 44.4 cm³ for PTV with standard margins; 31.2 cm³ vs 15 cm³ for PTV with reduced margins; p = 0.031). With reduced margins the rectum was significantly better spared with an adaptive boost rather than with an up-front boost: V60Gy and V65Gy were 41.2% and 24.8% compared with 59% and 29.9%, respectively (p = 0.031). Median GTV intra-fractional motion was 2 mm (range 0-8 mm).

Conclusions

The data suggest that the adaptive boost strategy exploiting tumor-shrinkage and reduced margin might result in better sparing of rectum and anal canal. Individual margin assessment, motion management and real-time adaptive radiotherapy appear attractive applications of the 1.5 T MR-Linac for further testing of individualized and safe dose escalation in patients with rectal cancer.

SUBMITTER: Bonomo P

PROVIDER: S-EPMC7732969 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

1.5 T MR-linac planning study to compare two different strategies of rectal boost irradiation.

Bonomo Pierluigi P Lo Russo Monica M Nachbar Marcel M Boeke Simon S Gatidis Sergios S Zips Daniel D Thorwarth Daniela D Gani Cihan C

Clinical and translational radiation oncology 20201203

<h4>Purpose</h4>To compare treatment plans of two different rectal boost strategies: up-front versus adaptive boost at the 1.5 T MR-Linac.<h4>Methods</h4>Patients with locally advanced rectal cancer (LARC) underwent standard neoadjuvant radiochemotherapy with 50.4 Gy in 28 fractions. T2-weighted MRI prior and after the treatment session were acquired to contour gross tumor volumes (GTVs) and organs at risk (OARs). The datasets were used to simulate four different boost strategies (all with 15 Gy ...[more]

PMID: 33336086

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Dataset Information

1.5 T MR-linac planning study to compare two different strategies of rectal boost irradiation.

Purpose

Methods

Results

Conclusions

Publications

1.5 T MR-linac planning study to compare two different strategies of rectal boost irradiation.

Similar Datasets

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