scholarly journals Systematic end-to-end testing of multiple target treatments using the modular RUBY phantom

2021 ◽  
Author(s):  
Leonie Brodbek ◽  
Jana Kretschmer ◽  
Katrin Büsing ◽  
Hui Khee Looe ◽  
Bjoern Poppe ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Monte Carlo Algorithm ◽  
Planning System ◽  
Treatment Planning System ◽  
Detector Response ◽  
Multiple Target ◽  
Collapsed Cone ◽  
End To End ◽  
Dose Measurements ◽  
Single Isocenter

Abstract The RUBY head phantom in combination with the System QA insert MultiMet can be used for simultaneous point dose measurements at an isocentric and two off-axis positions. This study investigates the suitability of the system for systematic integral end-to-end testing of single-isocenter multiple target stereotactic treatments. Several volumetric modulated arc therapy plans were optimized on a planning CT of the phantom positioned in a stereotactic mask on the stereotactic treatment board. The plans were created for three artificial spherical target volumes centred around the measurement positions in the MultiMet insert. Target diameters between 5 and 40 mm were investigated. Coplanar and non-coplanar plans were optimized using the collapsed cone algorithm of the Oncentra Masterplan treatment planning system and recalculated with the Monte Carlo algorithm of the Monaco treatment planning system. Measurements were performed at an Elekta Synergy linear accelerator. The head phantom was positioned according to clinical workflow comprising immobilization and CBCT imaging. Simultaneous point dose measurements at all target positions were performed with three PinPoint 3D chambers (type 31022) as well as three microDiamond (type 60019) detectors and compared to the treatment planning system calculations. Furthermore, the angular dependence of the detector response was investigated to estimate the associated impact on the measured point dose values. Considering all investigated plans, PTV diameters and positions, the point doses calculated with the Monaco treatment planning system and the microDiamond measurements differed within 3.5%, whereas the PinPoint 3D showed differences of up to 6.9%. Point dose differences determined in comparison to the Oncentra Masterplan dose calculations were larger. The RUBY system was shown to be suitable for end-to-end testing of complex treatment scenarios such as single-isocenter multiple target plans.

scholarly journals Benchmarking techniques for stereotactic body radiotherapy for early-stage glottic laryngeal cancer: LINAC-based non-coplanar VMAT vs. Cyberknife planning

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
You Zhang ◽  
Tsuicheng Chiu ◽  
Jeffrey Dubas ◽  
Zhen Tian ◽  
Pam Lee ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Laryngeal Cancer ◽  
Statistical Significance ◽  
Dose Calculation ◽  
Monte Carlo Algorithm ◽  
Planning System ◽  
Treatment Planning System ◽  
Conformity Index ◽  
Plan Quality ◽  
Significant Difference

Abstract Introduction Stereotactic body radiation therapy (SBRT) was found effective in treating laryngeal cancer with only five treatment fractions by a recent clinical trial (NCT01984502, ClinicalTrials.gov). Nevertheless, this trial used the Cyberknife system, which is not widely accessible enough to benefit all patients affected by laryngeal cancer. Our study investigates the feasibility of larynx SBRT treatment planning on a conventional gantry-based LINAC and compares its plan quality with that from the Cyberknife. Materials & methods Ten larynx SBRT cases were originally treated by Cyberknife using fixed cones in our institution, with plans created and optimized using the Monte-Carlo algorithm in the MultiPlan treatment planning system. These cases were retrospectively planned in the Eclipse planning system for a LINAC with the same prescription dose. We used volumetric modulated arc therapy (VMAT) for larynx SBRT planning in Eclipse and incorporated non-coplanar arcs to approach the Cyberknife’s large solid angle delivery space. We used both anisotropic analytical algorithm (AAA) and Acuros XB (AXB) algorithm for dose calculation and compared their accuracy by measurements on an in-house larynx phantom. We compared the LINAC VMAT plans (VMAT-AAA and VMAT-AXB) with the original Cyberknife plans using dosimetric endpoints such as the conformity index, gradient indices (R50, R20), OAR maximum/mean doses, and the monitor units. Results Phantom measurement showed that both the AAA and the AXB algorithms provided adequate dose calculation accuracy (94.7% gamma pass rate on 2%/2 mm criteria for AAA vs. 97.3% for AXB), though AXB provided better accuracy in the air cavity. The LINAC-based VMAT plans achieved similar dosimetric endpoints as the Cyberknife planning, and all plans met the larynx SBRT dosimetric constraints. Cyberknife plans achieved an average conformity index of 1.13, compared to 1.20 of VMAT-AXB and 1.19 of VMAT-AAA. The VMAT plans spared the thyroid gland better with average Dmean of 2.4 Gy (VMAT-AXB) and 2.7 Gy (VMAT-AAA), as compared to 4.3 Gy for Cyberknife plans. The VMAT-AAA plans had a slightly lower contralateral arytenoid Dmax (average: 15.2 Gy) than Cyberknife plans (average: 17.9 Gy) with statistical significance, while the contralateral arytenoid Dmax was similar between VMAT-AXB and Cyberknife plans with no statistically significant difference. Cyberknife plans offered slightly better R50 (average: 5.0) than VMAT-AXB (5.9) and VMAT-AAA (5.7) plans. The VMAT plans substantially reduced the plan MUs to less than 1/3 of the Cyberknife plans, and the differences were statistically significant. The other metrics were similar between VMAT and Cyberknife plans with no statistically significant differences. Conclusions Gantry-based LINACs can achieve similar plan quality to Cyberknife systems. Treatment outcome with both methods remains to be investigated.

Evaluating small field dosimetry with the Acuros XB (AXB) and analytical anisotropic algorithm (AAA) dose calculation algorithms in the eclipse treatment planning system

2019 ◽  
Vol 18 (4) ◽  
pp. 353-364
Author(s):  
Sepideh Behinaein ◽  
Ernest Osei ◽  
Johnson Darko ◽  
Paule Charland ◽  
Dylan Bassi
Keyword(s):  
Treatment Planning ◽  
Planning System ◽  
Treatment Planning System ◽  
Patient Specific ◽  
Average Dose ◽  
Water Phantom ◽  
Acuros Xb ◽  
Small Fields ◽  
Dose Measurements ◽  
The Brain

AbstractBackground:An increasing number of external beam treatment modalities including intensity modulated radiation therapy, volumetric modulated arc therapy (VMAT) and stereotactic radiosurgery uses very small fields for treatment planning and delivery. However, there are major challenges in small photon field dosimetry, due to the partial occlusion of the direct photon beam source’s view from the measurement point, lack of lateral charged particle equilibrium, steep dose-rate gradient and volume averaging effect of the detector response and variation of the energy fluence in the lateral direction of the beam. Therefore, experimental measurements of dosimetric parameters such as percent depth doses (PDDs), beam profiles and relative output factors (ROFs) for small fields continue to be a challenge.Materials and Methods:In this study, we used a homogeneous water phantom and the heterogeneous anthropomorphic stereotactic end-to-end verification (STEEV) head phantom for all dose measurements and calculations. PDDs, lateral dose profiles and ROFs were calculated in the Eclipse Treatment Planning System version 13·6 using the Acuros XB (AXB) and the analytical anisotropic algorithms (AAAs) in a homogenous water phantom. Monte Carlo (MC) simulations and measurements using the Exradin W1 Scintillator were also accomplished for four photon energies: 6 MV, 6FFF, 10 MV and 10FFF. Two VMAT treatment plans were generated for two different targets: one located in the brain and the other in the neck (close to the trachea) in the head phantom (CIRS, Norfolk, VA, USA). A Varian Truebeam linear accelerator (Varian, Palo Alto, CA, USA) was used for all treatment deliveries. Calculated results with AXB and AAA were compared with MC simulations and measurements.Results:The average difference of PDDs between W1 Exradin Scintillator measurements and MC simulations, AAA and AXB algorithm calculations were 1·2, 2·4 and 3·2%, respectively, for all field sizes and energies. AXB and AAA showed differences in ROF of about 0·3 and 2·9%, respectively, compared with W1 Exradin Scintillator measured values. For the target located in the brain in the head phantom, the average dose difference between W1 Exradin Scintillator and the MC simulations, AAA and AXB were 0·2, 3·2 and 2·7%, respectively, for all field sizes. Similarly, for the target located in the neck, the respective dose differences were 3·8, 5·7 and 3·5%.Conclusion:In this study, we compared dosimetric parameters such as PDD, beam profile and ROFs in water phantom and isocenter point dose measurements in an anthropomorphic head phantom representing a patient. We observed that measurements using the W1 Exradin scintillator agreed well with MC simulations and can be used efficiently for dosimetric parameters such as PDDs and dose profiles and patient-specific quality assurance measurements for small fields. In both homogenous and heterogeneous media, the AXB algorithm dose prediction agrees well with MC and measurements and was found to be superior to the AAA algorithm.

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

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.

scholarly journals Rectal dosimetry in intracavitary applications of cervix carcinoma: Comparison of two methods

2002 ◽  
Vol 10 (4) ◽  
pp. 253-259 ◽  
Author(s):  
Milutin Baucal ◽  
Jovan Babic ◽  
Zoran Kuzmanovic
Keyword(s):  
Treatment Planning ◽  
The Other ◽  
Planning System ◽  
International Commission ◽  
Treatment Planning System ◽  
Cervix Carcinoma ◽  
Rectal Dose ◽  
High Doses ◽  
Dose Measurements ◽  
Made In

BACKGROUND: Brachytherapy of cervix carcinoma often results in high doses to surrounding structures, such as rectum and bladder. Therefore, these organs should be closely monitored. Purpose of this work was to evaluate rectal marker made in our institution for rectal dose measurements by comparing it with the method recommended in ICRU (International Commission on Radiation Units and Measurements) Report 38. METHODS: In this work rectal dosimetry was performed by two different methods. In one, rectal marker made in Institute of Oncology Sremska Kamenica was used, while in the other method recommended in ICRU Report 38 dose on ICRU rectal point was measured A total of 34 applications using Microselectron HDR and its standard applicator set were performed in a prospective way. The prescribed dose was 7.6 Gy to point A for each application. Rectal doses were calculated by Nucletron Plato Treatment Planning System. RESULTS: Differences found between the means of ICRU point R and rectal marker points Rref and Rmax were significant (P<0.002 and P<0.00002). The same result was obtained for Rref and Rmax pair (P<0.003). CONCLUSION: Maximal doses obtained using rectal marker were in most cases high- er than those obtained by ICRU method. It conforms well to several CT-based dosimetry studies where rectum dose was found to be higher from that obtained by ICRU method.

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