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A comparison of patient position displacements from body surface laser scanning and cone beam CT bone registrations for radiotherapy of pelvic targets
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science.
2014 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 53, no 2, p. 268-277Article in journal (Refereed) Published
Abstract [en]

Background and purpose

Optical surface detection has attractive features as a mean in radiotherapy for patient positioning tasks such as set-up, monitoring and gating. To aid in hitting radiotherapy targets the correlation between detected surface displacements and internal structure displacements is crucial. In this study, we compare set-up displacements derived from a body surface laser scanning (BSLS) system to displacements derived from bone registrations with a cone beam computed tomography (CBCT) system in order to quantify the accuracy and applicability of BSLS for fractionated treatments in the pelvic region.

Material and methods

Displacements from concurrent BSLS and CBCT registrations were compared for 40 patients treated in the pelvic region for a total of 170 set-ups. Surface data captured by BSLS at the first treatment fraction (BSLSref) was used as main reference for the BSLS system, while bony structures from the planning CT were used as a reference for the CBCT method. As comparison, the patient outline extracted from the planning CT was used as BSLS reference (CTref). The displacements detected by the CBCT system (skin-marks-only) was also used for comparison.

Results

The mean differences (+/- 1 SD) between the BSLS and CBCT displacements were -0.01 (+0.17) cm, 0.00 (+0.21) cm and 0.01 (+0.17) cm in the lateral, longitudinal and vertical directions, respectively. The median length of the difference was 0.26 cm (0.24-0.29 cm, 95% CI). The median of the difference between CBCT and BSLS displacements based on CTref was 0.37 cm (0.30-0.39 cm) and the median for skin-marks-only was 0.38 cm (0.34-0.42 cm).

Conclusions

The BSLS system is a good supplement to the CBCT system for accurate set-up for fractions when no CBCT is deemed necessary for pelvic targets. Inter-fractional skin movement in relation to bone was estimated to be 0.2 cm in the lateral (X), longitudinal (Y) and vertical direction (Z), respectively.

Place, publisher, year, edition, pages
2014. Vol. 53, no 2, p. 268-277
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-217646DOI: 10.3109/0284186X.2013.802836ISI: 000329522000014OAI: oai:DiVA.org:uu-217646DiVA, id: diva2:695862
Available from: 2014-02-12 Created: 2014-02-04 Last updated: 2020-12-16
In thesis
1. Patient Positioning in Radiotherapy Using Body Surface Scanning
Open this publication in new window or tab >>Patient Positioning in Radiotherapy Using Body Surface Scanning
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

External radiotherapy uses ionising radiation to damage the DNA of the tumour cells and thereby inhibit their uncontrolled proliferation. The technical development regarding imaging and visualisation for radiotherapy has increased considerably during the last decades. By a submillimetre accuracy, a body surface laser scanning (BSLS) system maps the patient body contour in the treatment position by scanning a transversal laser line and detecting its reflection. A treatment plan is created for each patient to find a treatment that delivers a high dose to the tumour whilst keeping the dose to the surrounding normal tissue as low as possible. The setup done for treatment planning must be reproduced in the treatment room. Commonly patient skin-marks are aligned to room lasers to setup the patient in the treatment position. The setup is then verified by the BSLS and a cone-beam CT (CBCT) system. For left-sided-breast cancer patients, the dose to radiosensitive parts of the heart can be decreased by letting the patient take a deep breath and hold it in deep inspiration breath-hold (DIBH) position during treatment. The BSLS system can guide the patient to this position via visual and audial instructions to the patient. The breathing trace of a lung cancer patient can be monitored by the BSLS system to estimate the quality of the images used for treatment planning and also to support the treatment target definition process. The number of application of the BSLS system has increased over the years. Together with its increased accuracy and robustness, surface scanning has now reached a level where it can be used as a primary setup system, replacing skin-marks (paper I), guiding left-sided breast cancer patient to a reproducible DIBH position (paper II) and lung tumour motion can be determined more accurately (paper III and IV).

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2021. p. 45
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1711
Keywords
Radiotherapy, positioning, body surface, laser scanning, cancer, SGRT, ITV, lung cancer, surrogate, tumour motion, 4DCT
National Category
Cancer and Oncology
Research subject
Medical Radiophysics
Identifiers
urn:nbn:se:uu:diva-427519 (URN)978-91-513-1097-8 (ISBN)
Public defence
2021-02-19, H:son Holmdahlsalen, Akademiska sjukhuset, ing. 100, 751 85 Uppsala, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2021-01-28 Created: 2020-12-16 Last updated: 2021-03-04

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Wikström, KennethNilsson, KristinaIsacsson, UlfAhnesjö, Anders

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