目的：通过Delta4模体验证在Truebeam加速器上执行的体部立体定向放射治疗（Stereotacic Body Radiation Therapy,SBRT）计划,评价SBRT治疗计划执行过程的可靠性。方法：按抽签法在Eclipse10.0治疗计划系统中选取40例SBRT治疗计划,将选...目的：通过Delta4模体验证在Truebeam加速器上执行的体部立体定向放射治疗（Stereotacic Body Radiation Therapy,SBRT）计划,评价SBRT治疗计划执行过程的可靠性。方法：按抽签法在Eclipse10.0治疗计划系统中选取40例SBRT治疗计划,将选取的治疗计划移植到Delta4模体进行剂量计算,得到计算后的剂量分布,再与Delta4模体实际测量得到的剂量分布进行比较,运用γ分析验证两者剂量分布的一致性,以电离室验证治疗计划中心点的绝对剂量。结果：所有Delta4验证的SBRT治疗计划,采用γ（3%,3 mm）标准进行分析时,通过率均〉98%（98.9%~100%）;当用更为严格的γ（2%,2 mm）标准进行分析时,其通过率均〉90%（91.2%~98%）。SBRT治疗计划用电离室在模体中心点处进行的绝对剂量验证,其计算值和测量值的误差均〈2%（-0.8%~1.5%）。结论：在Truebeam加速器上执行的无均整滤过器6MV X射线SBRT治疗计划是安全可靠的,Delta4是一个用于验证无均整滤过器模式弧形旋转治疗计划的理想设备。展开更多
The capability of the TrueBeam treatment system to deliver step and shoot IMRT plans at low dose rates was evaluated. Beam characteristics during low dose rates (5 to 100 MU/min) were evaluated for consistency using a...The capability of the TrueBeam treatment system to deliver step and shoot IMRT plans at low dose rates was evaluated. Beam characteristics during low dose rates (5 to 100 MU/min) were evaluated for consistency using a planar ion chamber array. MU constancy, linearity, and beam profile symmetry were all found to be equivalent within 0.5%. The response of the Scandi Dos Delta 4 system was also evaluated at low dose rates of using static open beams compared to ion chamber measurements, and step and shoot IMRT plans comparing 5 - 20 MU/min and 100 MU/min dose rates, with a maximum observed absolute dose difference of 0.8% and equivalence margin of 0.2%. The Gamma Index and measurement reproducibility were also found to be equivalent.展开更多
<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system ...<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system (TPS) for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. <strong>Methods:</strong> For beam modeling, percent depth dose curves, profiles and output factors for jaw-collimated fields and stereotactic cones as well as X-jaws transmission were measured. For multi-leaf collimator (MLC) modeling, MLC model parameters such as offset, gain, curvature, leaf tip width, tongue and groove and transmission were determined and output factors for MLC-collimated fields were measured. Absolute dose calibration was also performed. For beam model and MLC model validation, the American Association of Physicists in Medicine Task Group-119 plans, clinical SRS and SBRT plans and end-to-end testing were performed. <strong>Results:</strong> Beam characteristics of the 6 MV FFF beam agreed well with those in the literature. Validation results showed that our beam model and MLC model were acceptable for SRS and SBRT treatments. <strong>Conclusions:</strong> The technical information and dosimetric data provided in this study will be a useful reference for other clinics/institutions which will commission the same machine energy in the RayStation TPS.展开更多
Objective:To investigate the characteristics of peripheral doses outside electron-beam applicators in Varian TrueBeam linacs.Method:Peripheral doses outside the electron applicator were measured for 6-,9-and 12-MeV be...Objective:To investigate the characteristics of peripheral doses outside electron-beam applicators in Varian TrueBeam linacs.Method:Peripheral doses outside the electron applicator were measured for 6-,9-and 12-MeV beams at the maximum dose depth(Dmax)for each energy source and at a source-to-surface distance(SSD)of 100 cm.Measurements were performed using EBT3 films in solid water phantoms.The impact of field size on the penumbra width and peripheral doses was studied using various cutouts,including 3 cm×3 cm,6 cm×6 cm,and 10 cm×10 cm in a 10 cm×10 cm applicator with the gantry and collimator at 0°.The influence of the applicator size was investigated using a circular cutout of 5 cm in diameter for various applicator sizes,including 6 cm×6 cm,10 cm×10 cm,15 cm×15 cm,20 cm×20 cm,and 25 cm×25 cm,at Dmax for each energy,while keeping the gantry and collimator angle at 0°.The measured dose profiles were compared with the Eclipse treatment planning system(TPS)predicted dose profiles.The effect of varying gantry angles(0°,90°,and 270°)for a 3 cm×3 cm cutout in a 10 cm10 cm applicator for each energy source and varying collimator angles(0°,90°,and 270°)for a 10 cm×10 cm field were investigated to determine their effects on the penumbra widths and peripheral doses.Results:Both the penumbra width and peripheral dose values increased with energy across different field sizes,gantry angles,collimator angles,and applicator sizes.Root mean square deviation(RMSD)analysis indicated minimal differences between the measured profiles and TPS data.Peripheral doses remained below 5%of the maximum dose approximately 10–15 mm away from the field edges,suggesting the potential for implementing additional shielding where required.Conclusions:This study highlights the importance of considering peripheral doses in electron radiotherapy.It is important to note the impact on healthy tissues beyond the treatment area to ensure patient safety and prevent the long-term side effects of treatment.These findings emphasize the necessity of implementing appropriate measures to minimize peripheral doses.展开更多
文摘The capability of the TrueBeam treatment system to deliver step and shoot IMRT plans at low dose rates was evaluated. Beam characteristics during low dose rates (5 to 100 MU/min) were evaluated for consistency using a planar ion chamber array. MU constancy, linearity, and beam profile symmetry were all found to be equivalent within 0.5%. The response of the Scandi Dos Delta 4 system was also evaluated at low dose rates of using static open beams compared to ion chamber measurements, and step and shoot IMRT plans comparing 5 - 20 MU/min and 100 MU/min dose rates, with a maximum observed absolute dose difference of 0.8% and equivalence margin of 0.2%. The Gamma Index and measurement reproducibility were also found to be equivalent.
文摘<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system (TPS) for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. <strong>Methods:</strong> For beam modeling, percent depth dose curves, profiles and output factors for jaw-collimated fields and stereotactic cones as well as X-jaws transmission were measured. For multi-leaf collimator (MLC) modeling, MLC model parameters such as offset, gain, curvature, leaf tip width, tongue and groove and transmission were determined and output factors for MLC-collimated fields were measured. Absolute dose calibration was also performed. For beam model and MLC model validation, the American Association of Physicists in Medicine Task Group-119 plans, clinical SRS and SBRT plans and end-to-end testing were performed. <strong>Results:</strong> Beam characteristics of the 6 MV FFF beam agreed well with those in the literature. Validation results showed that our beam model and MLC model were acceptable for SRS and SBRT treatments. <strong>Conclusions:</strong> The technical information and dosimetric data provided in this study will be a useful reference for other clinics/institutions which will commission the same machine energy in the RayStation TPS.
文摘Objective:To investigate the characteristics of peripheral doses outside electron-beam applicators in Varian TrueBeam linacs.Method:Peripheral doses outside the electron applicator were measured for 6-,9-and 12-MeV beams at the maximum dose depth(Dmax)for each energy source and at a source-to-surface distance(SSD)of 100 cm.Measurements were performed using EBT3 films in solid water phantoms.The impact of field size on the penumbra width and peripheral doses was studied using various cutouts,including 3 cm×3 cm,6 cm×6 cm,and 10 cm×10 cm in a 10 cm×10 cm applicator with the gantry and collimator at 0°.The influence of the applicator size was investigated using a circular cutout of 5 cm in diameter for various applicator sizes,including 6 cm×6 cm,10 cm×10 cm,15 cm×15 cm,20 cm×20 cm,and 25 cm×25 cm,at Dmax for each energy,while keeping the gantry and collimator angle at 0°.The measured dose profiles were compared with the Eclipse treatment planning system(TPS)predicted dose profiles.The effect of varying gantry angles(0°,90°,and 270°)for a 3 cm×3 cm cutout in a 10 cm10 cm applicator for each energy source and varying collimator angles(0°,90°,and 270°)for a 10 cm×10 cm field were investigated to determine their effects on the penumbra widths and peripheral doses.Results:Both the penumbra width and peripheral dose values increased with energy across different field sizes,gantry angles,collimator angles,and applicator sizes.Root mean square deviation(RMSD)analysis indicated minimal differences between the measured profiles and TPS data.Peripheral doses remained below 5%of the maximum dose approximately 10–15 mm away from the field edges,suggesting the potential for implementing additional shielding where required.Conclusions:This study highlights the importance of considering peripheral doses in electron radiotherapy.It is important to note the impact on healthy tissues beyond the treatment area to ensure patient safety and prevent the long-term side effects of treatment.These findings emphasize the necessity of implementing appropriate measures to minimize peripheral doses.
