SU-F-T-61: Treatment Planning Observations for the CivaSheet Directional Brachytherapy Device Using VariSeed 9.0

Journal Article · Wed Jun 15 04:00:00 EDT 2016 · Medical Physics

DOI:https://doi.org/10.1118/1.4956196· OSTI ID:22642309

Rivard, MJ ^[1]; Rothley, DJ ^[2]

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1. Tufts University School of Medicine, Boston, MA (United States)
2. Cancer Treatment Centers of America, Newnan, GA (United States)

Purpose: The VariSeed 9.0 brachytherapy TPS is recently available and has new features such as ability to rotate a brachytherapy source away from normal to the imaging plane. Consequently, a dosimetric analysis was performed for a directional brachytherapy source (CivaSheet) with tests of this functionality and experiences from clinical treatment planning were documented. These observations contribute to safe, practical, and accurate use of such new software features. Methods: Several tests were established to evaluate the new rotational feature, specific to the CivaSheet for the first patients treated using this new brachytherapy device. These included suitability of imaging slice-thickness and in-plane resolution, window/level adjustments for brachytherapy source visualization, commissioning the source physical length for performing rotations, and using different planar and 3D window views to identify source orientation. Additional CivaSheet-specific tests were performed to determine the dosimetric influence on target coverage: changing the source tilt angle, source positioning in the treatment plan based on the CivaSheet rectangular array of CivaDots, and influence of prescription depth on the necessary treatment margin for adequate target coverage. Results: Higher imaging-resolution produced better accuracy for source orientation and positioning, with sub-millimeter CT slice-thickness and in-plane resolution preferred. Source rotation was possible only in sagittal or coronal views. The process for validating source orientation required iteratively altering rotations then checking them in the 3D view, which was cumbersome given the absence of quantitative plan documentation to indicate orientation. Given the small Pd-103 source size, influence of source tilt within 30° was negligible for <1.0 cm. Influence of source position was important when the source was positioned in/out of the adjacent source plane, causing changes of 15%, 7%, and 3% at depths of 0.5, 0.7, and 1.0 cm. Conclusion: The new TPS rotational feature worked well, but several issues were identified to improve the treatment planning process. Research supported in part by CivaTech Oncology, Inc. for Dr. Rivard.

• OSTI ID: 22642309
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 43; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
ACCURACY
BIOMEDICAL RADIOGRAPHY
BRACHYTHERAPY
COMMISSIONING
COMPUTER CODES
COMPUTERIZED TOMOGRAPHY
ITERATIVE METHODS
PALLADIUM 103
PATIENTS
PLANNING
SPATIAL RESOLUTION
THICKNESS