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. 2021 May 17;13(5):e15075.
doi: 10.7759/cureus.15075.

Implementation of Stereotactic MRI-Guided Adaptive Radiotherapy (SMART) for Hepatobiliary and Pancreatic Cancers in the United Kingdom - Fifty in Five

Andrew Gaya  1 , Philip Camilleri  2 , Adam Nash  3 , Donna Hughes  3 , James Good  4
Affiliations

Implementation of Stereotactic MRI-Guided Adaptive Radiotherapy (SMART) for Hepatobiliary and Pancreatic Cancers in the United Kingdom - Fifty in Five

Andrew Gaya et al. Cureus. .

Abstract

The first MRIdian® MR linear accelerator (MR-Linac; ViewRay, Oakwood Village, Ohio) in the United Kingdom went live in December 2019 following a record installation time. Stereotactic MRI-guided Adaptive Radiotherapy (SMART) has since been implemented and has advantages of excellent soft tissue definition of both target and organs at risk (OARs), real-time target and OAR visualisation on cine-MRI, daily recontouring of target and critical OARs with live online plan adaptation/re-optimisation, and automatic respiratory-gated treatment delivery. We present a multi-disciplinary narrative and technical description of how this innovative technique was implemented for hepatobiliary (HPB) cancers. In particular, we explain how a collaborative approach and desire to push the boundaries and improve outcomes enabled 50 patients to be treated in the first five months, many with technically challenging tumours not always deliverable on other platforms. Physics, dosimetry, radiographer, and clinician perspectives on implementing SMART are presented. MRIdian® single fraction lung stereotactic ablative radiotherapy (SABR) will shortly be implemented along with innovative research in conjunction with our academic partners.

Keywords: hepatobiliary tumours; liver metastases; mr-linac; mridian®; pancreatic cancer; stereotactic radiotherapy.

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Conflict of interest statement

The authors have declared financial relationships, which are detailed in the next section.

Figures

Figure 1
Figure 1. Installation of the MRIDian bore
Figure 2
Figure 2. Cholangiocarcinoma OAR Overlap
Cholangiocarcinoma OAR overlap (PTVhigh) volume with 100% isodose line conforming to PTVhigh (PTV-Visceral OAR+5 mm and Vessels) 130% hot spot in the GTV. brown = visceral OAR; purple = blood vessels; cream = visceral OAR + margin; black = PTV; red = PTVprescribe; green = 3 cm ring structure around PTV OAR: organ at risk; PTV: planning target volume; GTV: gross tumour volume
Figure 3
Figure 3. Cholangiocarcinoma OAR and PTV
Cholangiocarcinoma OAR overlap (PTVhigh) volume with 100% isodose line conforming to PTVhigh (PTV-VisceralOAR+5 mm and Vessels) 130% hot spot in the GTV. brown = visceral OAR; purple = blood vessels; cream = visceral OAR + margin; black = PTV; red = PTVprescribe; green = 3 cm ring structure around PTV OAR: organ at risk; PTV: planning target volume; GTV: gross tumour volume
Figure 4
Figure 4. Treatment of Three Liver Metastases
The two superior metastases and inferior met. The inferior volume shows down to the 50% isodose and the local OARs (a) at the time of planning and (b) at the time of treatment. See also Figure 5 OAR: organ at risk
Figure 5
Figure 5. Three Liver Metastases Treatment Plan
Two superior volumes and an inferior volume. Illustrates the change in position with breath-hold and variation in the position of OARs during treatment (compared to at the time of planning in Figure 4).
Figure 6
Figure 6. Three Liver Metastases Treatment - Cine View Images
Tumour outlined in blue, with the breath-hold target in red. The 0.35T image is grainy at four frames per second, but the Primovist contrast enables accurate delineation and tracking of the target.
Figure 7
Figure 7. MRIDian Adaptive Workflow
See this image and copyright information in PMC

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