Journal
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
Volume 89, Issue 5, Pages 1121-1128Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.ijrobp.2014.04.051
Keywords
-
Funding
- Canadian Institutes of Health Research (CIHR) Fellowship
- U.S. National Institutes of Health [5RO1CA124714-02]
- National Cancer Institute of Canada [18207]
- Canadian Institutes of Health Research (CIHR) [202477]
Ask authors/readers for more resources
Purpose: The dosimetric impact of dose probability based planning target volume (PTV) margins for liver cancer patients receiving stereotactic body radiation therapy (SBRT) was compared with standard PTV based on the internal target volume (ITV). Plan robustness was evaluated by accumulating the treatment dose to ensure delivery of the intended plan. Methods and Materials: Twenty patients planned on exhale CT for 27 to 50 Gy in 6 fractions using an ITV-based PTV and treated free-breathing were retrospectively evaluated. Isotoxic, dose escalated plans were created on midposition computed tomography (CT), representing the mean breathing position, using a dose probability PTV. The delivered doses were accumulated using biomechanical deformable registration of the daily cone beam CT based on liver targeting at the exhale or mean breathing position, for the exhale and midposition CT plans, respectively. Results: The dose probability PTVs were on average 38% smaller than the ITV-based PTV, enabling an average +/- standard deviation increase in the planned dose to 95% of the PTV of 4.0 +/- 2.8 Gy (9 +/- 5%) on the midposition CT (P<.01). For both plans, the delivered minimum gross tumor volume (GTV) doses were greater than the planned nominal prescribed dose in all 20 patients and greater than the planned dose to 95% of the PTV in 18 (90%) patients. Nine patients (45%) had 1 or more GTVs with a delivered minimum dose more than 5 Gy higher with the midposition CT plan using dose probability PTV, compared with the delivered dose with the exhale CT plan using ITV-based PTV. Conclusions: For isotoxic liver SBRT planned and delivered at the mean respiratory, reduced dose probability PTV enables a mean escalation of 4 Gy (9%) in 6 fractions over ITV-based PTV. This may potentially improve local control without increasing the risk of tumor underdosing. (C) 2014 Elsevier Inc.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available