Strategies for Online Organ Motion Correction for Intensity-Modulated Radiotherapy of Prostate Cancer: Prostate, Rectum, and Bladder Dose Effects

Journal Article · Sun Nov 15 04:00:00 EST 2009 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.04.034· OSTI ID:21367529

Rijkhorst, Erik-Jan ^[1]; Lakeman, Annemarie; Nijkamp, Jasper; Bois, Josien de; Herk, Marcel van; Lebesque, Joos V; Sonke, Jan-Jakob ^[1]

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1. Department of Radiation Oncology, Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands)

Purpose: To quantify and evaluate the accumulated prostate, rectum, and bladder dose for several strategies including rotational organ motion correction for intensity-modulated radiotherapy (IMRT) of prostate cancer using realistic organ motion data. Methods and Materials: Repeat computed tomography (CT) scans of 19 prostate patients were used. Per patient, two IMRT plans with different uniform margins were created. To quantify prostate and seminal vesicle motion, repeat CT clinical target volumes (CTVs) were matched onto the planning CTV using deformable registration. Four different strategies, from online setup to full motion correction, were simulated. Rotations were corrected for using gantry and collimator angle adjustments. Prostate, rectum, and bladder doses were accumulated for each patient, plan, and strategy. Minimum CTV dose (D{sub min}), rectum equivalent uniform dose (EUD, n = 0.13), and bladder surface receiving >=78 Gy (S78), were calculated. Results: With online CTV translation correction, a 7-mm margin was sufficient (i.e., D{sub min} >= 95% of the prescribed dose for all patients). A 4-mm margin required additional rotational correction. Margin reduction lowered the rectum EUD(n = 0.13) by approx2.6 Gy, and the bladder S78 by approx1.9%. Conclusions: With online correction of both translations and rotations, a 4-mm margin was sufficient for 15 of 19 patients, whereas the remaining four patients had an underdosed CTV volume <1%. Margin reduction combined with online corrections resulted in a similar or lower dose to the rectum and bladder. The more advanced the correction strategy, the better the planned and accumulated dose agreed.

• OSTI ID: 21367529
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 75; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
BLADDER
BODY
CAT SCANNING
COMPUTERIZED TOMOGRAPHY
CORRECTIONS
DIAGNOSTIC TECHNIQUES
DIGESTIVE SYSTEM
DISEASES
DOSES
GASTROINTESTINAL TRACT
GLANDS
INTESTINES
LARGE INTESTINE
MALE GENITALS
MEDICINE
MOTION
NEOPLASMS
NUCLEAR MEDICINE
ORGANS
PROSTATE
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
RECTUM
ROTATION
THERAPY
TOMOGRAPHY
URINARY TRACT