Patient positioning in radiotherapy based on surface imaging using time of flight cameras. Issue 8 (28th July 2016)

• Record Type: Journal Article
• Authors: Gilles, M.; Fayad, H.; Miglierini, P.; Clement, J. F.; Scheib, S.; Cozzi, L.; Bert, J.; Boussion, N.; Schick, U.; Pradier, O.; Visvikis, D.
• Is Part Of: Medical physics. Volume 43:Issue 8(2016)Part 1
• Page Start: 4833
• Page End: 4841
• Publication Date: 2016-07-28
• Subjects: biomedical optical imaging -- cancer -- lung -- medical image processing -- pneumodynamics -- radiation therapy -- stereo image processing; Treatment strategy -- Visual imaging -- Cancer -- Pneumodyamics, respiration -- Image forming and processing -- Movement; Radiation therapy -- Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Stereoscopic television systems; Details thereof; radiotherapy -- patient positioning -- surface imaging -- marker‐less device -- time of flight -- iterative closest point; Medical imaging -- Cameras -- Cancer -- Calibration -- Lungs -- Surface structure -- Infrared detectors -- Surface reconstruction -- Dosimetry; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4959536
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: To evaluate the patient positioning accuracy in radiotherapy using a stereo‐time of flight (ToF)‐camera system. Methods: A system using two ToF cameras was used to scan the surface of the patients in order to position them daily on the treatment couch. The obtained point clouds were registered to (a) detect translations applied to the table (intrafraction motion) and (b) predict the displacement to be applied in order to place the patient in its reference position (interfraction motion). The measures provided by this system were compared to the effectively applied translations. The authors analyzed 150 fractions including lung, pelvis/prostate, and head and neck cancer patients. Results: The authors obtained small absolute errors for displacement detection: 0.8 ± 0.7, 0.8 ± 0.7, and 0.7 ± 0.6 mm along the vertical, longitudinal, and lateral axes, respectively, and 0.8 ± 0.7 mm for the total norm displacement. Lung cancer patients presented the largest errors with a respective mean of 1.1 ± 0.9, 0.9 ± 0.9, and 0.8 ± 0.7 mm. Conclusions: The proposed stereo‐ToF system allows for sufficient accuracy and faster patient repositioning in radiotherapy. Its capability to track the complete patient surface in real time could allow, in the future, not only for an accurate positioning but also a real time tracking of any patient intrafraction motion (translation, involuntary, and breathing).