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Review
. 2024 Mar 19;16(6):1206.
doi: 10.3390/cancers16061206.

Adaptive Radiotherapy: Next-Generation Radiotherapy

Olga Maria Dona Lemus  1 , Minsong Cao  2 , Bin Cai  3 , Michael Cummings  1 , Dandan Zheng  1
Affiliations
Review

Adaptive Radiotherapy: Next-Generation Radiotherapy

Olga Maria Dona Lemus et al. Cancers (Basel). .

Abstract

Radiotherapy, a crucial technique in cancer therapy, has traditionally relied on the premise of largely unchanging patient anatomy during the treatment course and encompassing uncertainties by target margins. This review introduces adaptive radiotherapy (ART), a notable innovation that addresses anatomy changes and optimizes the therapeutic ratio. ART utilizes advanced imaging techniques such as CT, MRI, and PET to modify the treatment plan based on observed anatomical changes and even biological changes during the course of treatment. The narrative review provides a comprehensive guide on ART for healthcare professionals and trainees in radiation oncology and anyone else interested in the topic. The incorporation of artificial intelligence in ART has played a crucial role in improving effectiveness, particularly in contour segmentation, treatment planning, and quality assurance. This has expedited the process to render online ART feasible, lowered the burden for radiation oncology practitioners, and enhanced the precision of dynamically personalized treatment. Current technical and clinical progress on ART is discussed in this review, highlighting the ongoing development of imaging technologies and AI and emphasizing their contribution to enhancing the applicability and effectiveness of ART.

Keywords: CBCT; IGRT; MRgRT; PET; adaptive radiotherapy; adaptive replanning; personalized medicine; treatment adaptation.

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Conflict of interest statement

Cao reported receiving personal fees from ViewRay Inc. and Varian Medical Systems Inc., outside the current study. Cummings and Zheng reported having research agreements with Varian Medical Systems Inc., outside the current study. The funders had no role in the design of this study; in the collection, analyses, or interpretation of data; in the writing of this manuscript; or in the decision to publish the results.

Figures

Figure 4
Figure 4
(a) Initial plan met all organ-at-risk constraints for a patient with a pancreatic tumor (blue color wash) based on the anatomy from the initial CT simulation. (b) Application of the plan to the daily MRI set resulted in a violation of hard duodenal (green color wash) constraints. (c) Daily adaptive planning achieved the resolution of the OAR constraint violation to the duodenum (marked with arrows) while preserving target volume coverage. Reprinted/adapted with permission from “Simulated Online Adaptive Magnetic Resonance–Guided Stereotactic Body Radiation Therapy for the Treatment of Oligometastatic Disease of the Abdomen and Central Thorax: Characterization of Potential Advantages” by Henke et al. 2016, International Journal of Radiation Oncology* Biology* Physics, 96(5), Copyright 2016 by Elsevier [23].
Figure 1
Figure 1
Illustrated here is a schematic comparing the anatomical changes and consequences of different radiation procedures between a simulation day (A1–A5) and a treatment day (B1–B5). Panels A1 and B1 depict the changes in shape and movement of the tumor (shown in red) and two organs at risk (represented in blue and green). This could be similar to a case of prostate cancer or cervical cancer (tumor), with bladder (OAR1) and rectum (OAR2) OARs. Panels A2–A5 and B2–B5 depict the volume that has been treated (indicated in yellow) on both the simulated anatomy and the anatomy on the day of therapy for the 2D treatment (2), 3D conformal (3), IMRT with IGRT (4), and ART (5) techniques, respectively.
Figure 2
Figure 2
General workflow of ART.
Figure 3
Figure 3
Example MR-based (A), CBCT-based (B), and PET-based (C) online ART systems, featuring the integration of corresponding imaging system with a 6MV FFF LINAC, installed at University of California Los Angeles, University of Rochester, and University of Texas Southwestern Medical Center, respectively.
Figure 5
Figure 5
HyperSight CBCTs. The upper panel compares a simulation CT vs. a HyperSight CBCT (HAL 4.0 with a 6 s acquisition) of the abdomen. HyperSight CBCT shows comparable image contrast as the simulation CT and minimal streaking artifacts from gas pockets and breathing motion. The lower panel compares a conventional CBCT vs. a HyperSight CBCT (breath hold with a 6 s acquisition) of the thorax. The HyperSight CBCT shows much better image contrast and mitigated streaking artifacts and noise. Used with permission from Varian Medical Systems (https://medicalaffairs.varian.com/hypersight, accessed on 31 January 2024).
Figure 6
Figure 6
A representative SCINTIX radiation plan specifically designed for the treatment of lung conditions.
See this image and copyright information in PMC

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