Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, United States of America.
Phys Med Biol. 2022 Aug 9;67(16). doi: 10.1088/1361-6560/ac838f.
This article reviews the recent advancements and future potential 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 applications, 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 at any couch rotation 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 in these two clinical scenarios, and the procedures for breast treatments in free-breathing (FB) or at deep-inspiration breath-hold (DIBH), and for cranial stereotactic radiosurgery (SRS) and radiotherapy (SRT) are well developed. When using the skin surface as a body-position surrogate, SGRT promises to replace the traditional tattoo/laser-based setup. However, this requires new SGRT procedures for all anatomical sites and new workflows from treatment simulation to delivery. SGRT studies in other anatomical sites have shown slightly higher accuracy and better performance than a tattoo/laser-based setup. In addition, radiographical image-guided radiotherapy (IGRT) is still necessary, especially for stereotactic body radiotherapy (SBRT). To go beyond the external body surface and infer an 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. After all, SGRT has great potential for further clinical applications. In this review, OSI technology, applications, and potential are discussed since its first introduction to radiotherapy in 2005, including technical characterization, different commercial systems, and major clinical applications, including conventional SGRT on top of tattoo/laser-based alignment and new SGRT techniques attempting to replace tattoo/laser-based setup. The clinical research for OSI-based tumor tracking is reviewed, including OSI-based spirometry and OSI-guided tumor tracking models. Ongoing clinical research has created more SGRT opportunities for clinical applications beyond the current scope.
本文综述了光学表面成像（OSI）在临床应用中的最新进展和未来潜力，作为一种用于表面引导放射治疗（SGRT）的四维（4D）成像方式，包括 OSI 系统、临床 SGRT 应用以及基于 OSI 的临床研究。OSI 是一种非电离辐射成像方式，提供实时的 3D 表面成像，具有大视场（FOV），适用于房间内交互式患者摆位以及放射治疗过程中任何治疗床旋转时的实时运动监测。到目前为止，大多数临床 SGRT 应用都集中在治疗浅层乳腺癌或深部脑癌的刚性解剖结构上，因为在这两种临床情况下，皮肤表面可以作为肿瘤替代物，并且乳房治疗的程序在自由呼吸（FB）或深吸气屏气（DIBH）中，以及颅立体定向放射外科（SRS）和放射治疗（SRT）都得到了很好的发展。当使用皮肤表面作为身体位置替代物时，SGRT 有望替代传统的纹身/激光定位。然而，这需要为所有解剖部位开发新的 SGRT 程序，并从治疗模拟到交付的新工作流程。在其他解剖部位的 SGRT 研究表明，其准确性略高，性能更好比基于纹身/激光的定位。此外，影像学引导的放射治疗（IGRT）仍然是必要的，特别是对于立体定向体部放射治疗（SBRT）。为了超越外部身体表面并推断内部肿瘤运动，最近的研究表明，基于 OSI 的呼吸测量法作为肿瘤运动替代物来测量动态潮气量具有临床潜力，以及切伦科夫表面成像来指导和评估治疗交付。由于 OSI 提供了身体位置、变形和运动的完整数据集，因此它提供了替代基于基准的光学跟踪系统的机会。毕竟，SGRT 在临床应用中具有很大的潜力。在本文中，我们回顾了自 2005 年首次引入放射治疗以来 OSI 技术、应用和潜力，包括技术特征、不同的商业系统以及主要的临床应用，包括基于纹身/激光的配准之上的常规 SGRT 和试图替代纹身/激光的新型 SGRT 技术。还回顾了基于 OSI 的肿瘤跟踪的临床研究，包括基于 OSI 的呼吸测量和 OSI 引导的肿瘤跟踪模型。正在进行的临床研究为超出当前范围的临床应用创造了更多的 SGRT 机会。
