Volumetric Modulated Arc Therapy Planning for Primary Prostate Cancer With Selective Intraprostatic Boost Determined by {sup 18}F-Choline PET/CT
- Department of Medical Physics, University of Nevada Las Vegas, Las Vegas, Nevada (United States)
- Hamamatsu/Queen's PET Imaging Center and Departments of Radiation Oncology and Oncology Research, The Queen's Medical Center, Honolulu, Hawaii (United States)
Purpose: This study evaluated expected tumor control and normal tissue toxicity for prostate volumetric modulated arc therapy (VMAT) with and without radiation boosts to an intraprostatically dominant lesion (IDL), defined by {sup 18}F-choline positron emission tomography/computed tomography (PET/CT). Methods and Materials: Thirty patients with localized prostate cancer underwent {sup 18}F-choline PET/CT before treatment. Two VMAT plans, plan{sub 79} {sub Gy} and plan{sub 100-105} {sub Gy}, were compared for each patient. The whole-prostate planning target volume (PTV{sub prostate}) prescription was 79 Gy in both plans, but plan{sub 100-105} {sub Gy} added simultaneous boost doses of 100 Gy and 105 Gy to the IDL, defined by 60% and 70% of maximum prostatic uptake on {sup 18}F-choline PET (IDL{sub suv60%} and IDL{sub suv70%}, respectively, with IDL{sub suv70%} nested inside IDL{sub suv60%} to potentially enhance tumor specificity of the maximum point dose). Plan evaluations included histopathological correspondence, isodose distributions, dose-volume histograms, tumor control probability (TCP), and normal tissue complication probability (NTCP). Results: Planning objectives and dose constraints proved feasible in 30 of 30 cases. Prostate sextant histopathology was available for 28 cases, confirming that IDL{sub suv60%} adequately covered all tumor-bearing prostate sextants in 27 cases and provided partial coverage in 1 case. Plan{sub 100-105} {sub Gy} had significantly higher TCP than plan{sub 79} {sub Gy} across all prostate regions for α/β ratios ranging from 1.5 Gy to 10 Gy (P<.001 for each case). There were no significant differences in bladder and femoral head NTCP between plans and slightly lower rectal NTCP (endpoint: grade ≥ 2 late toxicity or rectal bleeding) was found for plan{sub 100-105} {sub Gy}. Conclusions: VMAT can potentially increase the likelihood of tumor control in primary prostate cancer while observing normal tissue tolerances through simultaneous delivery of a steep radiation boost to a {sup 18}F-choline PET-defined IDL.
- OSTI ID:
- 22458676
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 91, Issue 5; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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