LAUSR

Purpose QA experience on stereotactic plans with Dolphin transmission detector and compass DVH analysis program. Methods 12 spine SBRT, 20 lung SBRT and 25 SRS/SRT patients were prepared non-coplanar VMAT field plans in the Monaco 5.11 treatment planning system. Patient QA was measured with the Dolphin transmission detector and evaluated by gamma index analysis in the DVH-based Compass 4.0.27 program. Gamma index values were calculated according to the criteria of 3%-3 mm, 2%-2 mm, 1%-1 mm and 3%-1 mm as dose difference and distance to agreement in QA of stereotactic plans. For a more detailed analysis, average gamma index values were calculated. In addition,1 cm, 2 cm, 3 cm and 4 cm margins were given to the PTV to form the gamma analysis volumes. Results Differences between Monaco TPS and Dolphin in SRS/SRT plans, PTV1: 5.1%, PTVaverage: 8.1% and PTV99: 9.2%. Differences between Compass and Dolphin in SRS/SRT plans, PTV1: 2.9%, PTVaverage: 4.8% and PTV99: 6.5%. Differences between Monaco TPS and Dolphin in lung SBRT plans, PTV1: 3.5%, PTVaverage: 2.2% and PTV99: 2.6%. Differences between Compass and Dolphin in Lung SBRT plans, PTV1: 2.7%, PTVaverage: 2% and PTV99: 2.6%. Differences between Monaco TPS and Dolphin in spine SBRT plans, PTV1: −1.9%, PTVaverage: −5.8% and PTV99: −6.8%. Differences between Compass and Dolphin in spine SBRT plans, PTV1: 3.3%, PTVaverage: −0.47% and PTV99: −1.1%. When average gamma values are examined in the regions formed with 1,2,3,4 cm margins in SRS/SRT/SBRT plans: 3%–3 mm 0.34–0.6, 2%–2 mm 0.51–0.83, 1%–1 mm 0.92–1.15, 3%–1 mm 0.36–0.86. In 2D gamma analysis, SRS/SRT was 96%, lung SBRT was 88% and spine SBRT was 84.1% according to the criteria of %2–2 mm. SRS/SRT was 93%, lung SBRT was 83% and spine SBRT was 72.4% according to the criteria of %3–1 mm. Conclusions DVH-based analysis has a crucial role in validating stereotactic plans. Assessment of QA from differences in PTV and OAR doses is one of the best verification methods.It is more accurate to analyze according to the criteria of 3–1 mm and 2–2 mm because it has high heterogeneity and gradient index in stereotactic plans. We do a more comprehensive analysis with average gamma. The main reason for differences between Monaco and Compass with dolphin measurement is that the plans have high dose gradients and high dose heterogeneity. Especially differences in small volume PTVs have been increasing.