Automated registration of large deformations for adaptive radiation therapy of prostate cancer

Journal Article · Wed Apr 15 04:00:00 EDT 2009 · Medical Physics

DOI:https://doi.org/10.1118/1.3095777· OSTI ID:22095335

Godley, Andrew; Ahunbay, Ergun; Cheng, Peng; Li, X. Allen ^[1]

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1. Department of Radiation Oncology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226 (United States)

Available deformable registration methods are often inaccurate over large organ variation encountered, for example, in the rectum and bladder. The authors developed a novel approach to accurately and effectively register large deformations in the prostate region for adaptive radiation therapy. A software tool combining a fast symmetric demons algorithm and the use of masks was developed in C++ based on ITK libraries to register CT images acquired at planning and before treatment fractions. The deformation field determined was subsequently used to deform the delivered dose to match the anatomy of the planning CT. The large deformations involved required that the bladder and rectum volume be masked with uniform intensities of -1000 and 1000 HU, respectively, in both the planning and treatment CTs. The tool was tested for five prostate IGRT patients. The average rectum planning to treatment contour overlap improved from 67% to 93%, the lowest initial overlap is 43%. The average bladder overlap improved from 83% to 98%, with a lowest initial overlap of 60%. Registration regions were set to include a volume receiving 4% of the maximum dose. The average region was 320x210x63, taking approximately 9 min to register on a dual 2.8 GHz Linux system. The prostate and seminal vesicles were correctly placed even though they are not masked. The accumulated doses for multiple fractions with large deformation were computed and verified. The tool developed can effectively supply the previously delivered dose for adaptive planning to correct for interfractional changes.

• OSTI ID: 22095335
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 4 Vol. 36; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BLADDER
CAT SCANNING
COMPUTER CODES
DEFORMATION
IMAGE PROCESSING
IMAGES
NEOPLASMS
PLANNING
PROSTATE
RADIATION DOSES
RADIOTHERAPY
RECTUM