A Comparison of the Use of Bony Anatomy and Internal Markers for Offline Verification and an Evaluation of the Potential Benefit of Online and Offline Verification Protocols for Prostate Radiotherapy

Journal Article · Thu May 01 04:00:00 EDT 2008 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.09.002· OSTI ID:21124180

Hansen, Vibeke N ^[1]; Parker, Christopher ^[2]; Evans, Phil M ^[1]; Norman, Andrew ^[3]; Miles, Elizabeth ^[4]; Harris, Emma J ^[1]; Del-Acroix, Louise; Smith, Elizabeth; Keane, Richard ^[4]; Khoo, Vincent S; Thompson, Alan C; Dearnaley, David P ^[2]

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1. Joint Department of Physics and Radiotherapy, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)
2. Academic Unit of Urology, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)
3. Department of Computing, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)
4. Department of Radiotherapy, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)

Purpose: To evaluate the utility of intraprostatic markers in the treatment verification of prostate cancer radiotherapy. Specific aims were: to compare the effectiveness of offline correction protocols, either using gold markers or bony anatomy; to estimate the potential benefit of online correction protocol's using gold markers; to determine the presence and effect of intrafraction motion. Methods and Materials: Thirty patients with three gold markers inserted had pretreatment and posttreatment images acquired and were treated using an offline correction protocol and gold markers. Retrospectively, an offline protocol was applied using bony anatomy and an online protocol using gold markers. Results: The systematic errors were reduced from 1.3, 1.9, and 2.5 mm to 1.1, 1.1, and 1.5 mm in the right-left (RL), superoinferior (SI), and anteroposterior (AP) directions, respectively, using the offline correction protocol and gold markers instead of bony anatomy. The subsequent decrease in margins was 1.7, 3.3, and 4 mm in the RL, SI, and AP directions, respectively. An offline correction protocol combined with an online correction protocol in the first four fractions reduced random errors further to 0.9, 1.1, and 1.0 mm in the RL, SI, and AP directions, respectively. A daily online protocol reduced all errors to <1 mm. Intrafraction motion had greater impact on the effectiveness of the online protocol than the offline protocols. Conclusions: An offline protocol using gold markers is effective in reducing the systematic error. The value of online protocols is reduced by intrafraction motion.

• OSTI ID: 21124180
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 1 Vol. 71; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ANATOMY
CARCINOMAS
CORRECTIONS
ERRORS
IMAGES
PROSTATE
RADIOTHERAPY
VERIFICATION