COMPARISON OF ISODOSE DISTRIBUTIONS IN CANINE BRAIN IN HETEROGENEITY‐CORRECTED VERSUS UNCORRECTED TREATMENT PLANS USING 6 MV PHOTONS

作者：Jeri‐Anne Lyons, Donald Ε. Thrall, Amy F. Pruitt · 发表于：Veterinary Radiology & Ultrasound · 年份：2007 · DOI：10.1111/j.1740-8261.2007.00245.x · 被引用次数：5 · 研究领域：Advanced MRI Techniques and Applications、Advanced Radiotherapy Techniques、MRI in cancer diagnosis

Magnetic resonance (MR) images may be useful for radiation planning due to greater contrast resolution. One disadvantage of MR images for radiation planning is the inability to incorporate electron density information into the dose calculation algorithm. To assess the magnitude of this problem, we evaluated radiation dose distribution in canine brain by comparing computed tomography (CT)-based radiotherapy plans with and without electron density correction. Computerized radiotherapy plans were generated for 13 dogs with brain tumors using 6 MV photons. A tissue-contouring program was used to outline the gross tumor volume (GTV) and the planning target volume (PTV) for each patient. Two treatment plans were generated for each dog. First, the plan was optimized without heterogeneity correction. Then the heterogeneity correction was implemented without changing any other plan parameters. Isodose distributions and dose volume histograms (DVHs) were used to compare the two plans. The D95 (dose delivered to 95% of the volume) within the PTV was calculated for each treatment plan and differences in the D95s were compared. The mean D95s without and with heterogeneity correction were 49.1 +/- 0.7 and 48.9 +/- 1.0Gy, respectively. The absolute mean percent dose difference without and with heterogeneity correction was 1.0 - 0.9% (-1.3-3.2%) and was not considered to be clinically significant. We found no clinically significant difference between CT-based radiotherapy plans without and w...