Verification of a pencil beam based treatment planning system: output factors for open photon beams shaped with MLC or blocks

New challenging dosimetric approaches, such as narrow beams and 3D algorithms, are being used in radiotherapy. In this paper two quality control (QC) procedures are reported. The first one concerns the QC of the dosimetry of small x-ray beams, generally carried out by using silicon detectors. The comparison of dose values obtained by a silicon diode, a diamond detector, and radiochromic films shows that for x-ray beams of high energy, the silicon diode can give an overestimation of the output factors in phantom, up to 4%. This is due to the higher than unit density silicon diode and the surrounding envelope that restore the lateral electron equilibrium. About the 3D algorithms for breast treatment planning, a quality control test has been adopted to verify the accuracy of the computed dosimetry when “loss of scatter” occurs. The results show a sensible agreement (within 1.5%) between computed and experimental data.

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Commissioning a Superposition Dose Calculation Model for 6 MV Photon Beams on a Radiotherapy Treatment Planning System

Clinical Oncology ◽

10.1016/j.clon.2007.01.399 ◽

2007 ◽

Vol 19 (3) ◽

pp. S40 ◽

Cited By ~ 1

Author(s):

P. Ambolt ◽

J. Bowden ◽

M. Cooper ◽

A. Henry ◽

S. McCormack ◽

...

Keyword(s):

Treatment Planning ◽

Dose Calculation ◽

Calculation Model ◽

Planning System ◽

Treatment Planning System ◽

Photon Beams ◽

Radiotherapy Treatment Planning ◽

Radiotherapy Treatment

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Analyzing the Treatment Delivery Accuracy of the uRT Treatment Planning System and uRT-Linac 506C by Use of AAPM TG 119 Test Cases

10.21203/rs.3.rs-556651/v1 ◽

2021 ◽

Author(s):

DaZhen Jiang ◽

Dajiang Wang ◽

Jiuling Shen ◽

Jun Zhang ◽

Cheng Chen ◽

...

Keyword(s):

Treatment Planning ◽

Photon Beam ◽

Planning System ◽

Treatment Planning System ◽

Maximum Deviation ◽

High Dose ◽

Photon Beams ◽

Position Accuracy ◽

Collapsed Cone ◽

Beam Mode

Abstract ObjectiveThe objective of this study was to investigate accuracy of the United Imaging Healthcare's uRT treatment planning system (uRT-TPS), by creating AAPM TG 119 test plans with respectively IMRT and VMAT techniques by homogeneous and heterogeneous phantom. Materials and MethodsThe plans were delivered to the homogeneous and heterogeneous phantom using the United Imaging Healthcare's uRT-Linac 506C. The overall dose calculation accuracy by uRT-TPS with Collapsed Cone Convolution (CC) and Monte Carlo (MC) algorithm was measured and analyzed by creating IMRT and VMAT plans for the 5 test geometries specified in TG 119, by using two kinds of beams FF photon beam and FFF photon beam. The point doses were measured with a Farmer type ion chamber and the fluences were measured with films respectively. Results The result of position accuracy was shown that the worst position accuracy is 0.36 mm and the repeated positioning accuracy of MLC field location was less than 0.25mm. The symmetry deviation of MLC was less than 0.08mm. In this study, the CLs of sMLC, dMLC and VMAT plans with FF photon beams were 2.74%, 2.12%, and 1.36% respectively. As for FFF photon beams, they were 3.76%, 2.14% and 2.90% respectively, whereas the counterpart CL specified in TG119 were 4.5% for the high dose regions and 4.7% for OAR regions. The CLs of Gamma Passing rates for sMLC, dMLC and VMAT plans were 4.59%, 5.35% and 2.15% for FF beam mode, and were 1.82%, 6.12% and 4.82% for FFF beam mode. For the heterogeneous phantom, the maximum deviation is 2.35% for CC and 2.63% for MC algorithm respectively.Conclusion Based on this analysis which were performed in accordance with the TG 119 recommendations, it is evident that the URT treatment planning system and URT-Linac 506C have commissioned IMRT and VMAT techniques with adequate accuracy. and all uRT_TPS treatment plans were recognized as clinically acceptable.

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The Commissioning and Validation of EclipseTM Treatment Planning System on a Varian VitalBeamTM Medical Linear Accelerator for Photon and Electron Beams

Frontiers in Biomedical Technologies ◽

10.18502/fbt.v8i2.6514 ◽

2021 ◽

Author(s):

Samira Yazdani ◽

Fateme Shirani Takabi ◽

Abolfazl Nickfarjam

Keyword(s):

Treatment Planning ◽

Linear Accelerator ◽

Electron Beams ◽

Planning System ◽

Treatment Planning System ◽

Patient Treatment ◽

Depth Dose ◽

Tps Commissioning ◽

Calculated Dose ◽

Output Factors

Purpose: Commissioning of a linear accelerator is a process of acquiring a set of data used for patient treatment. This article presents the beam data measurement results from the commissioning of a VitalBeamTM linac. Materials and Methods: Dosimetric properties for 6,10, and 15 MV photon beams and 6, 9, 12, and 16 MeV electron beams have been performed. Parameters, including Percentage Depth Dose (PDD), depth dose profile, symmetry, flatness, quality index, output factors, and the vital data for Treatment Planning System (TPS) commissioning were measured. The imported data were checked by CIRS phantom accordingly to IAEA TRS-430, TECDOC. Eight different positions of CIRS phantom CT were planned and treated. Finally, the calculated dose at a determined position was compared with measuring data to TPS validation. Results: After comparing 84 points in a different plan, the 83 points were in agreement with the criteria, and just for one point in 15 MV failed. Conclusion: Commissioning of dose and field flatness and symmetry are in tolerance intervals given by Varian. This proves that the studied lines meet the specification and can be used in clinical practice with all available electron and photon energies.

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SU-E-T-381: Evaluation of Calculated Dose Accuracy for Organs-At-Risk Located at Out-Of-Field in a Commercial Treatment Planning System for High Energy Photon Beams Produced From TrueBeam Accelerators

Medical Physics ◽

10.1118/1.4924742 ◽

2015 ◽

Vol 42 (6Part18) ◽

pp. 3421-3421

Author(s):

L Wang ◽

G Ding

Keyword(s):

Treatment Planning ◽

Organs At Risk ◽

High Energy ◽

Planning System ◽

Treatment Planning System ◽

High Energy Photon ◽

Photon Beams ◽

Energy Photon ◽

Calculated Dose ◽

Dose Accuracy

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Evaluation of Delta4DVH Anatomy in 3D Patient-Specific IMRT Quality Assurance

Technology in Cancer Research & Treatment ◽

10.1177/1533033820945816 ◽

2020 ◽

Vol 19 ◽

pp. 153303382094581

Author(s):

Du Tang ◽

Zhen Yang ◽

Xunzhang Dai ◽

Ying Cao

Keyword(s):

Quality Assurance ◽

Treatment Planning ◽

Treatment Plan ◽

Planning System ◽

Treatment Planning System ◽

Patient Specific ◽

Pencil Beam ◽

Ion Chamber ◽

Passing Rate ◽

Gamma Passing Rate

Purpose: To evaluate the performance of Delta4DVH Anatomy in patient-specific intensity-modulated radiotherapy quality assurance. Materials and Methods: Dose comparisons were performed between Anatomy doses calculated with treatment plan dose measured modification and pencil beam algorithms, treatment planning system doses, film doses, and ion chamber measured doses in homogeneous and inhomogeneous geometries. The sensitivity of Anatomy doses to machine errors and output calibration errors was also investigated. Results: For a Volumetric Modulated Arc Therapy (VMAT) plan evaluated on the Delta4 geometry, the conventional gamma passing rate was 99.6%. For a water-equivalent slab geometry, good agreements were found between dose profiles in film, treatment planning system, and Anatomy treatment plan dose measured modification and pencil beam calculations. Gamma passing rate for Anatomy treatment plan dose measured modification and pencil beam doses versus treatment planning system doses was 100%. However, gamma passing rate dropped to 97.2% and 96% for treatment plan dose measured modification and pencil beam calculations in inhomogeneous head & neck phantom, respectively. For the 10 patients’ quality assurance plans, good agreements were found between ion chamber measured doses and the planned ones (deviation: 0.09% ± 1.17%). The averaged gamma passing rate for conventional and Anatomy treatment plan dose measured modification and pencil beam gamma analyses in Delta4 geometry was 99.6% ± 0.89%, 98.54% ± 1.60%, and 98.95% ± 1.27%, respectively, higher than averaged gamma passing rate of 97.75% ± 1.23% and 93.04% ± 2.69% for treatment plan dose measured modification and pencil beam in patients’ geometries, respectively. Anatomy treatment plan dose measured modification dose profiles agreed well with those in treatment planning system for both Delta4 and patients’ geometries, while pencil beam doses demonstrated substantial disagreement in patients’ geometries when compared to treatment planning system doses. Both treatment planning system doses are sensitive to multileaf collimator and monitor unit (MU) errors for high and medium dose metrics but not sensitive to the gantry and collimator rotation error smaller than 3°. Conclusions: The new Delta4DVH Anatomy with treatment plan dose measured modification algorithm is a useful tool for the anatomy-based patient-specific quality assurance. Cautions should be taken when using pencil beam algorithm due to its limitations in handling heterogeneity and in high-dose gradient regions.

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