Advances and potential of optical surface imaging in radiotherapy

Abstract

This article reviews the recent advancements and future potentials of optical surface imaging (OSI) in clinical applications as a four-dimensional (4D) imaging modality for surface-guided radiotherapy (SGRT), including OSI systems, clinical SGRT, and OSI-based clinical research. The OSI is a non-ionizing radiation imaging modality, offering real-time 3D surface imaging with a large field of view (FOV) suitable for in-room interactive patient setup and real-time motion monitoring during radiotherapy. So far, most clinical SGRT applications have focused on treating superficial breast cancer or deep-seated brain cancer in rigid anatomy, because the skin surface can serve as tumor surrogates and the procedures for breast treatments with deep-inspiration breath-hold (DIBH) and cranial stereotactic radiosurgery (SRS) and radiotherapy (SRT) are well developed. When using the skin surface as a body-position surrogate, SGRT promises to replace traditional tattoo-based setup, but radiographical image-guided radiotherapy (IGRT) is still necessary, especially for stereotactic body radiotherapy (SBRT). SGRT studies in other anatomical sites have shown slightly better accuracy and performance than tattoo-based setup. To infer internal tumor motion, recent studies have shown the clinical potential of OSI-based spirometry to measure dynamic tidal volume as a tumor motion surrogate and Cherenkov surface imaging to guide and assess treatment delivery. As OSI provides complete datasets of body position, deformation, and motion, it offers an opportunity to replace fiducial-based optical tracking systems. Therefore, SGRT has great potentials for further clinical applications. In this review, the OSI technology, applications, and potentials are discussed since its first introduction to radiotherapy in 2005, including technical characterization, different commercial systems, and major clinical applications, including clinical implementation of tattoo-less SGRT. The clinical research for OSI-based tumor tracking is reviewed, including OSI-based spirometry to feed a tumor tracking model. After all, the ongoing clinical research has created more SGRT opportunities for clinical applications beyond the current scope.

Real-time liver tumor localization via combined surface imaging and a single x-ray projection

“…To address the above challenges/limitations, in this work another real-time imaging modality was utilized to improve the tumor localization accuracy and robustness, especially for large motion. Besides on-board x-ray imaging, optical surface imaging provides another real-time imaging modality that can monitor a large FOV (up to 110 × 140 × 240 cm 3 ) with a sub-millimeter detectability (Meeks et al 2005, Hoisak and Pawlicki 2018, Padilla et al 2019, Freislederer et al 2020, Al-Hallaq et al 2022, Li 2022. With the non-ionizing light sources and high frame rates of monitoring systems [10-24 Hz (Al-Hallaq et al 2022)], opitcal imaging can continuously monitor patients' body surface in real-time without incurring additional dose.…”

In Silico Studies of the Impact of Rotational Errors on Translation Shifts and Dose Distribution in Image-Guided Radiotherapy

“…In addition, it can also be combined with the gating technique via free-breath or breath-hold to achieve a static breast target for more accurate radiotherapy. 27,28 Second, an auxiliary positioning line can be added, and the fixation device of the breast bracket can be selected in combination with a thermoplastic shell. Third, radiation physicists and technologists should pay more attention to possible rotational setup errors in the pitch direction, such as quality control of the breast bracket and couch sag.…”

Feasibility of surface‐guidance combined with CBCT for intra‐fractional breath‐hold motion management during Ethos RT

“…[9][10][11] Surface imaging, in general, has been actively used for routine patient positioning and is effective for deepinspiration breath-hold (DIBH) treatment in radiation therapy (surface-guided radiation therapy: SGRT). [12][13][14][15] For example, Naumann et al reported a surface-guided position verification and monitoring combined with CBCT for stereotactic body radiotherapy (SBRT)-DIBH of 10 patients (3 lung and 7 liver cases). 16 In addition, surface imaging was used to manage intra-fractional respiratory-related motion.…”

“…Surface imaging, in general, has been actively used for routine patient positioning and is effective for deep‐inspiration breath‐hold (DIBH) treatment in radiation therapy (surface‐guided radiation therapy: SGRT) 12–15 . For example, Naumann et al.…”