B. Tas’s research while affiliated with Istanbul Yeni Yüzyıl University and other places

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.

Purpose Our propose was assesing the dosimetric accuracy and reliability of TBI treatment by using linac-based VMAT in 27 patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL) and aplastic anemia (AA). Methods Patients underwent TBI radiotherapy treatment with a linac-based VMAT technique on the coach. The VMAT-TBI technique consisted of three isocentres and three overlapping arcs. If patients were taller than 120 cm, we added one or two more overlapping arcs for feet to gantry CT sets. We eliminated high dose junction region after fusion of two CT sets via bias dose properties of Monaco® 5.11 TPS (Elekta AB, Sweden). Each treatment plans were recalculated with 3 mm, 6 mm, 9 mm and 12 mm longitidudinal misallignment of second and third overlapping arcs. Also, the quality assurance comprised the verification of the irradiation plans via DVH based 3D patient QA system which was Dolphin® and Compass® (IBA Dosimetry, Germany). Results When we recalculated plan’s with longitidudinal misallignments, we obtained an average %2.0 ± 0,7, %2,9 ± 1,5, %6,5 ± 1,7 and %7,1 ± 1,8 higher mean lungs doses, %2,6 ± 1,6, %9,8 ± 3,9, %15,4 ± 4,4 and %23,0 ± 3,5 higher maximum lung doses and %3,7 ± 1,4, %11,8 ± 3,3, %20,4 ± 3,8 and %22,8 ± 4,1 higher point doses with each 3 mm, 6 mm, 9 mm and 12 mm longitidudinal misallignments. When we compared plan and DVH based 3D patient QA results, we determined an average difference %3,4 ± 1,3 mean kidneys doses, %0,8 ± 0,7 mean lungs doses and %0,9 ± 0,4 higher mean target doses. Conclusions Our results show that linac-based VMAT is reliable treatment for TBI. DVH based 3D patient QA dose verification is possible with linac-based VMAT and we determined high dosimetric accuracy for OARs and target between treatment plan and delivered dose.

Purpose Radiotherapy is an effective treatment method for managing breast cancer, but patients may have cardiac disease as a late radiation effect after completing radiotherapy. The left anterior descending coronary artery (LAD) dose and mean heart dose are playing a major role for cardiac disease. We aimed to compare deep inspiration breath-hold (DIBH) and free breathing (FB) techniques dosimetrically for left breast radiotherapy while using VMAT method. Methods Sixteen early stage left breast cancer patient’s treatment planning were performed using Monaco 5.11® TPS (Elekta AB, Sweden) for DIBH and FB techniques. We used Catalyst® (C-RAD AB, Sweden) optical surface guided radiotherapy gating device for DIBH technique. The prescribe dose was 60 Gy to tumor bed and 46 Gy to breast in 28 fractions by simultane integrated boost (SIB). We aimed to achieve a similar dose conformality for PTV (tumor bed) and PTV (whole breast) while optimizing two technique’s plan, then we compared mean heart dose, max. heart dose, mean LAD dose, V20 Gy, V10 Gy and V5 Gy doses percentage of lung volume. Results A statistically significant interaction existed between heart, LAD doses and DIBH technique. We determined an average %20 lower max. heart doses, %32 lower mean heart doses and %27 lower mean LAD doses with DIBH technique, also, an average lung volume were enlarged %66. We didn’t determine significant percentage difference for V20 Gy, V10 Gy and V5 Gy doses of lung volume between two techniques. Conclusions However, we achieved an average 3.7 Gy mean heart doses, 9.2 Gy mean LAD doses and 42.4 Gy max. heart doses with FB technique by using VMAT method, Darby et al. [1] have shown that the relative risk of ishemic heart disease increases with %7.4 per Gy increased mean heart dose. Hence, we even reduced significantly mean heart, max. heart and mean LAD doses with DIBH technique. Therefore, DIBH technique while using VMAT method may reduce cardiac disease possibility for left breast radiotherapy.

Purpose: To report the feasibility, accuracy, and reliability of volumetric modulated arc therapy (VMAT)-based total-body irradiation (TBI) treatment in patients with acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL). Materials and methods: From 2015 to 2018, 30 patients with AML or ALL were planned and treated with VMAT-based TBI, which consisted of three isocenters and three overlapping arcs. TBI dose was prescribed to 90% of the planning treatment volume (PTV) receiving 12 Gy in six fractions, at two fractions per day. Mean lung and kidney doses were restricted less than 10 Gy, and maximum lens dose less than 6 Gy. Quality assurance (QA) comprised the verification of the irradiation plans via dose-volume histogram (DVH) based 3D patient QA system. Results: Average mean lung dose was 9.7 ± 0.2 Gy, mean kidney dose 9.6 ± 0.2 Gy, maximum lens dose 4.5 ± 0.4 Gy, mean PTV dose 12.7 ± 0.1 Gy, and heterogeneity index of PTV was 1.16 ± 0.02 in all patients. Grade 3 or more acute radiation toxicity was not observed. When comparing plan and DVH-based 3D patient QA results, average differences of 3.3% ± 1.3 in mean kidney doses, 1.1% ± 0.7 in mean lung doses, and 0.9% ± 0.4 in mean target doses were observed. Conclusion: Linac-based VMAT increased the dose homogeneity of TBI treatment more than extended SSD techniques. Partial cone-beam CT and optical surface-guided system assure patient positioning. DVH-based 3D patient dose verification QA was possible with linac-based VMAT showing small differences between planned and delivered doses. It is feasible, accurate, and reliable.

Purpose Portal imaging is performed before the radiotherapy treatment to ensure that the target volume and patient position are correct. Three-dimensional images are obtained and patient positioning can be done very precisely and accurately with ConeBeamCT. So patients are irradiated with extra radiation except for treatment with ConeBeamCT. In addition, the patient can be positioned with a laser-based surface scanning system Catalyst.The patient’s body is scanned with the optical laser system and the patient is positioned according to the scan results with Catalyst. In our study, the differences between the shift values obtained by ConeBeamCT and Catalyst surface scanning were compared. Methods IMRT or VMAT plans are prepared for 22 breast cancer patients in Monaco 5.11 treatment planning system. Two partial VMAT fields or six IMRT fields were used in the plans. 22 patients were positioned with a C-RAD laser-based surface scan in 389 fractions and then three-dimensional images were obtained with ConeBeamCT. Results ConeBeamCT images were evaluated with the XVI program. The average difference between the Catalyst and XVI shift values were found in the lateral direction X (cm): 0.24 ± 0.21, in the longitudinal direction Y (cm): 0.36 ± 0.29, in the vertical direction Z(cm): 0.23 ± 0.20. The maximum difference between Catalyst and XVI shift values were found in the lateral direction X (cm): 1.28, in the longitudinal direction Y (cm): 1.54, in the vertical direction Z (cm): 1.30. Conclusions In Breast CA Radiotherapy, target volume should be irradiated accurately for treatment success. Moreover, the right positioning of the patient has a very important role to success treatments. During this procedure, a laser-based surface scanning system can be used to reduce the radiation dose implemented to the patient for portal. Several fraction ConeBeamCT and Catalyst should be used simultaneously and if the difference is small, the number of ConeBeamCT should be reduced and the C-RAD surface scan system should be used, taking into account the entire treatment of the patient.