Volumetric Modulated Arc Therapy: Planning and Evaluation for Prostate Cancer Cases

Journal Article · Thu Apr 15 04:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.03.033· OSTI ID:21372213

Zhang, Pengpeng ^[1]; Happersett, Laura; Hunt, Margie; Jackson, Andrew ^[1]; Zelefsky, Michael ^[2]; Mageras, Gig ^[1]

---

1. Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
2. Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

Purpose: To develop an optimization method using volumetric modulated arc therapy (VMAT) and evaluate VMAT plans relative to the standard intensity-modulated radiotherapy (IMRT) approach in prostate cancer. Methods and Materials: A single gantry rotation was modeled using 177 equispaced beams. Multileaf collimator apertures and dose rates were optimized with respect to gantry angle subject to dose-volume-based objectives. Our VMAT implementation used conjugate gradient descent to optimize dose rate, and stochastic sampling to find optimal multileaf collimator leaf positions. A treatment planning study of 11 prostate cancer patients with a prescription dose of 86.4 Gy was performed to compare VMAT with a standard five-field IMRT approach. Plan evaluation statistics included the percentage of planning target volume (PTV) receiving 95% of prescribed dose (V95), dose to 95% of PTV (D95), mean PTV dose, tumor control probability, and dosimetric endpoints of normal organs, whereas monitor unit (MU) and delivery time were used to assess delivery efficiency. Results: Patient-averaged PTV V95, D95, mean dose, and tumor control probability in VMAT plans were 96%, 82.6 Gy, 88.5 Gy, and 0.920, respectively, vs. 97%, 84.0 Gy, 88.9 Gy, and 0.929 in IMRT plans. All critical structure dose requirements were met. The VMAT plans presented better rectal wall sparing, with a reduction of 1.5% in normal tissue complication probability. An advantage of VMAT plans was that the average number of MUs (290 MU) was less than for IMRT plans (642 MU). Conclusion: The VMAT technique can reduce beam on time by up to 55% while maintaining dosimetric quality comparable to that of the standard IMRT approach.

• OSTI ID: 21372213
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 5 Vol. 76; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BODY
COLLIMATORS
CONTROL
DISEASES
DOSE RATES
GLANDS
MALE GENITALS
MEDICINE
NEOPLASMS
NUCLEAR MEDICINE
OPTIMIZATION
ORGANS
PLANNING
PROSTATE
RADIOLOGY
RADIOTHERAPY
THERAPY