Fast time-of-flight camera based surface registration for radiotherapy patient positioning

Abstract

The proposed solution is able to solve surface registration problems with an accuracy suitable for radiotherapy cases where external surfaces offer primary or complementary information to patient positioning. The system shows promising dynamic properties for its use in gating/tracking applications. The overall system is competitive with commonly-used surface registration technologies. Its main benefit is the usage of a cost-effective off-the-shelf technology for surface acquisition. Further strategies to improve the registration accuracy are under development.

Real-Time Range Imaging in Health Care: A Survey

“…The focus of early solutions was on setup verification, restricting the automatic patient alignment to a fine-scale positioning and thus still requiring a manual setup initialization [9,13]. The first ToF-based systems for automatic patient setup in RT were proposed by Schaller et al [15] and Placht et al [10]. However, these systems rely on rigid surface registration techniques and thus do not account for deformations induced by respiratory motion.…”

“…As the underlying iterative closest point (ICP) algorithm [16,17] for these surface registration techniques is susceptible to local minima, the methods are restricted to resolving small initial misalignments. Targeting fully-automatic patient setup, Bauer et al and Placht et al proposed feature-based approaches that are capable to cope with gross initial misalignments [8,10]. Both rely on matching feature descriptors that encode the local surface topography.…”

“…first fraction [10]. Bauer et al proposed a multi-modal surface registration scheme that enables a direct alignment of intra-fractional structured light data (Microsoft Kinect) to a reference shape extracted from pre-fractional tomographic planning data [8].…”

“…Conventionally, this alignment is performed in a two-step procedure, comprising (1) manual coarse patient setup using laser cross-hairs and skin markers, and (2) position verification and refinement using radiographic imaging. Over the past years, systems for non-radiographic patient setup and monitoring in RT have been proposed using different RI technologies, including active stereo vision [9], ToF imaging [10], structured light [8,11,12], and light sectioning [13,14]. These systems estimate the rigid transformation that aligns the intra-fractionally acquired external body surface of the patient with a given reference shape extracted from tomographic planning data.…”

Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery

“…used for AR applications (Koch et al, 2009). In the context of biomedical applications ToF cameras have been used as an imaging modality for respiratory motion gating (Schaller et al, 2008) and patient positioning (Placht et al, 2012;Schaller et al, 2009) in radiotherapy as well as for building patient-specific respiratory motion models Wentz et al, 2012).…”