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Höfel S, Liebig P, Fix MK, Drescher M, Zwicker F. Adapting a practical EPR dosimetry protocol to measure output factors in small fields with alanine. J Appl Clin Med Phys 2023; 24:e14191. [PMID: 37922380 PMCID: PMC10691647 DOI: 10.1002/acm2.14191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 10/12/2023] [Accepted: 10/17/2023] [Indexed: 11/05/2023] Open
Abstract
PURPOSE Modern radiotherapy techniques often deliver small radiation fields. In this work, a practical Electron Paramagnetic Resonance (EPR) dosimetry protocol is adapted and applied to measure output factors (OF) in small fields of a 6 MV radiotherapy system. Correction factors and uncertainties are presented and OFs are compared to the values obtained by following TRS-483 using an ionization chamber (IC). METHODS Irradiations were performed at 10 cm depth inside a water phantom positioned at 90 cm source to surface distance with a 6 MV flattening filter free photon beam of a Halcyon radiotherapy system. OFs for different nominal field sizes (1 × 1, 2 × 2, 3 × 3, 4 × 4, normalized to 10 × 10 cm2 ) were determined with a PinPoint 3D (PTW 31022) IC following TRS-483 as well as with alanine pellets with a diameter of 4 mm and a height of 2.4 mm. EPR readout was performed with a benchtop X-band spectrometer. Correction factors due to volume averaging and due to positional uncertainties were derived from 2D film measurements. RESULTS OFs obtained from both dosimeter types agreed within 0.7% after applying corrections for the volume averaging effect. For the used alanine pellets, volume averaging correction factors of 1.030(2) for the 1 × 1 cm2 field and <1.002 for the larger field sizes were determined. The correction factor for positional uncertainties of 1 mm was in the order of 1.018 for the 1 × 1 cm2 field. Combined relative standard uncertainties uc for the OFs resulting from alanine measurements were estimated to be below 1.5% for all field sizes. For IC measurements, uc was estimated to be below 1.0%. CONCLUSIONS A practical EPR dosimetry protocol is adaptable for precisely measuring OFs in small fields down to 1 × 1 cm2 . It is recommended to consider the effect of positional uncertainties for field sizes <2 × 2 cm2 .
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Affiliation(s)
- Sebastian Höfel
- Department of Chemistry and Konstanz Research School Chemical BiologyUniversity of KonstanzKonstanzGermany
- Klinik und Praxis für Strahlentherapie am Klinikum KonstanzKonstanzGermany
| | - Pauline Liebig
- Klinik und Praxis für Strahlentherapie am Klinikum KonstanzKonstanzGermany
| | - Michael K. Fix
- Division of Medical Radiation Physics and Department of Radiation Oncology, InselspitalBern University Hospital and University of BernBernSwitzerland
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical BiologyUniversity of KonstanzKonstanzGermany
| | - Felix Zwicker
- Klinik und Praxis für Strahlentherapie am Klinikum KonstanzKonstanzGermany
- Department of Radiation OncologyHeidelberg University HospitalHeidelbergGermany
- Clinical Cooperation Unit Molecular Radiation OncologyGerman Cancer Research Center (DKFZ)HeidelbergGermany
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Pokhrel D, Misa J, McCarthy S, Yang ES. Two novel stereotactic radiotherapy methods for locally advanced, previously irradiated head and neck cancers patients. Med Dosim 2023; 49:114-120. [PMID: 37867087 DOI: 10.1016/j.meddos.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/08/2023] [Accepted: 09/22/2023] [Indexed: 10/24/2023]
Abstract
To determine the feasibility and utility of conebeam CT-guided stereotactic radiotherapy for locally recurrent, previously irradiated head and neck cancer (HNC) patients on the Halcyon, a ring delivery system (RDS). This research aims to quantify plan quality, treatment delivery accuracy, and overall efficacy by comparing against novel clinical TrueBeam HyperArc method. Ten recurrent HNC patients who were treated at our institution on TrueBeam (6MV-FFF) for 30 to 40 Gy in 3 to 5 fractions with noncoplanar HyperArc plans were re-planned on Halcyon (6MV-FFF). These plans were re-planned with the same Acuros-based dose engine. Additionally, we used site-specific full/partial coplanar VMAT arcs. PTV coverage, mean dose to GTV, maximum dose to organs-at-risk (OAR), beam-on time (BOT), and quality assurance (QA) results were investigated and compared. Halcyon provided highly conformal HNC SRT plans with slightly superior mean PTVD99 coverage (96.7% vs 95.5%, p = 0.071), and slightly lower mean GTV dose (37.8 Gy vs 38.2 Gy, p = 0.241) when compared to the HyperArc plans. Differences in plan conformality and maximum dose to OARs were statistically insignificant. Due to Halcyon's coplanar geometry, D2cm was significantly higher (p = 0.001) but Halcyon did result in a reduced normal brain dose by 1 Gy on average and up to 5.2 Gy in some cases. Halcyon provided similar patient-specific QA pass rates with a 2%/2mm gamma criteria (98.2% vs 98.5%) and independent in-house Monte Carlo second check results (97.7% vs 98.2%), suggesting identical treatment delivery accuracy. Halcyon plans resulted in slightly longer beam-on time (3.16 vs 2.30 minutes, p = 0.010), however door-to-door patient time is expected to be <10 minutes. Compared to clinical TrueBeam HyperArc, Halcyon SRT plans provided similar plan quality and treatment delivery accuracy with a potentially faster overall treatment using fully automated patient setup and verification. Rapid delivery of recurrent HNC SRT may reduce intrafraction motion errors while also improving patient compliance and comfort. To provide high-quality of HNC SRT similar to HyperArc, we recommend Halcyon users consider commissioning this novel method. This method will be useful for remote and underserved patient cohorts including Halcyon-only clinics as well.
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Affiliation(s)
- Damodar Pokhrel
- Department of Radiation Medicine, Medical Physics Graduate Program, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
| | - Josh Misa
- Department of Radiation Medicine, Medical Physics Graduate Program, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Shane McCarthy
- Department of Radiation Medicine, Medical Physics Graduate Program, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Eddy S Yang
- Department of Radiation Medicine, Medical Physics Graduate Program, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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Pokhrel D, Smith M, Volk A, Bernard ME. Benchmarking halcyon ring delivery system for hypofractionated breast radiotherapy: Validation and clinical implementation of the fast-forward trial. J Appl Clin Med Phys 2023; 24:e14047. [PMID: 37221949 PMCID: PMC10476987 DOI: 10.1002/acm2.14047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/01/2023] [Accepted: 05/11/2023] [Indexed: 05/25/2023] Open
Abstract
PURPOSE The aim of this study was to demonstrate the feasibility and efficacy of an iterative CBCT-guided breast radiotherapy with Fast-Forward trial of 26 Gy in five fractions on a Halcyon Linac. This study quantifies Halcyon plan quality, treatment delivery accuracy and efficacy by comparison with those of clinical TrueBeam plans. MATERIALS AND METHODS Ten accelerated partial breast irradiation (APBI) patients (four right, six left) who underwent Fast-Forward trial at our institute on TrueBeam (6MV beam) were re-planned on Halcyon (6MV-FFF). Three site-specific partial coplanar VMAT arcs and an Acuros-based dose engine were used. For benchmarking, PTV coverage, organs-at-risk (OAR) doses, beam-on time, and quality assurance (QA) results were compared for both plans. RESULTS The average PTV was 806 cc. Compared to TrueBeam plans, Halcyon provided highly conformal and homogeneous plans with similar mean PTVD95 (25.72 vs. 25.73 Gy), both global maximum hotspot < 110% (p = 0.954) and similar mean GTV dose (27.04 vs. 26.80 Gy, p = 0.093). Halcyon provided lower volume of ipsilateral lung receiving 8 Gy (6.34% vs. 8.18%, p = 0.021), similar heart V1.5 Gy (16.75% vs. 16.92%, p = 0.872), V7Gy (0% vs. 0%), mean heart dose (0.96 vs. 0.9 Gy, p = 0.228), lower maximum dose to contralateral breast (3.2 vs. 3.6 Gy, p = 0.174), and nipple (19.6 vs. 20.1 Gy, p = 0.363). Compared to TrueBeam, Halcyon plans provided similar patient-specific QA pass rates and independent in-house Monte Carlo second check results of 99.6% vs. 97.9% (3%/2 mm gamma criteria) and 98.6% versus 99.2%, respectively, suggesting similar treatment delivery accuracy. Halcyon provided shorter beam-on time (1.49 vs. 1.68 min, p = 0.036). CONCLUSION Compared to the SBRT-dedicated TrueBeam, Halcyon VMAT plans provided similar plan quality and treatment delivery accuracy, yet potentially faster treatment via one-step patient setup and verification with no patient collision issues. Rapid delivery of daily APBI on Fast-Forward trial on Halcyon with door-to-door patient time < 10 min, could reduce intrafraction motion errors, and improve patient comfort and compliance. We have started treating APBI on Halcyon. Clinical follow-up results are warranted. We recommend Halcyon users consider implementing the protocol to remote and underserved APBI patients in Halcyon-only clinics.
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Affiliation(s)
- Damodar Pokhrel
- Department of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Mason Smith
- Department of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Alexander Volk
- Department of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Mark E. Bernard
- Department of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
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Saez J, Bar-Deroma R, Bogaert E, Cayez R, Chow T, Clark CH, Esposito M, Feygelman V, Monti AF, Garcia-Miguel J, Gershkevitsh E, Goossens J, Herrero C, Hussein M, Khamphan C, Kierkels RGJ, Lechner W, Lemire M, Nevelsky A, Nguyen D, Paganini L, Pasler M, Fernando Pérez Azorín J, Ramos Garcia LI, Russo S, Shakeshaft J, Vieillevigne L, Hernandez V. Universal evaluation of MLC models in treatment planning systems based on a common set of dynamic tests. Radiother Oncol 2023; 186:109775. [PMID: 37385376 DOI: 10.1016/j.radonc.2023.109775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 06/19/2023] [Accepted: 06/23/2023] [Indexed: 07/01/2023]
Abstract
PURPOSE To demonstrate the feasibility of characterising MLCs and MLC models implemented in TPSs using a common set of dynamic beams. MATERIALS AND METHODS A set of tests containing synchronous (SG) and asynchronous sweeping gaps (aSG) was distributed among twenty-five participating centres. Doses were measured with a Farmer-type ion chamber and computed in TPSs, which provided a dosimetric characterisation of the leaf tip, tongue-and-groove, and MLC transmission of each MLC, as well as an assessment of the MLC model in each TPS. Five MLC types and four TPSs were evaluated, covering the most frequent combinations used in radiotherapy departments. RESULTS Measured differences within each MLC type were minimal, while large differences were found between MLC models implemented in clinical TPSs. This resulted in some concerning discrepancies, especially for the HD120 and Agility MLCs, for which differences between measured and calculated doses for some MLC-TPS combinations exceeded 10%. These large differences were particularly evident for small gap sizes (5 and 10 mm), as well as for larger gaps in the presence of tongue-and-groove effects. A much better agreement was found for the Millennium120 and Halcyon MLCs, differences being within ± 5% and ± 2.5%, respectively. CONCLUSIONS The feasibility of using a common set of tests to assess MLC models in TPSs was demonstrated. Measurements within MLC types were very similar, but TPS dose calculations showed large variations. Standardisation of the MLC configuration in TPSs is necessary. The proposed procedure can be readily applied in radiotherapy departments and can be a valuable tool in IMRT and credentialing audits.
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Affiliation(s)
- Jordi Saez
- Hospital Clínic de Barcelona, Department of Radiation Oncology, Barcelona, Spain.
| | - Raquel Bar-Deroma
- Rambam Health Care Campus, Department of Radiotherapy, Division of Oncology, Haifa, Israel
| | - Evelien Bogaert
- Ghent University Hospital and Ghent University, Department of Radiation Oncology, Ghent, Belgium
| | - Romain Cayez
- Oscar Lambret Center, Department of Medical Physics, Lille, France
| | - Tom Chow
- Juravinski Hospital and Cancer Centre at Hamilton Health Sciences, Department of Medical Physics, Ontario, Canada
| | - Catharine H Clark
- National Physical Laboratory, Metrology for Medical Physics Centre, London TW11 0PX, UK; Radiotherapy Physics, University College London Hospital, 250 Euston Rd, London NW1 2PG, UK; Dept Medical Physics and Bioengineering, University College London, Malet Place, London WC1 6BT, UK
| | - Marco Esposito
- AUSL Toscana Centro, Medical Physics Unit, Florence, Italy; The Abdus Salam International Center for Theoretical, Trieste, Italy
| | | | - Angelo F Monti
- ASST GOM Niguarda, Department of Medical Physics, Milano, Italy
| | - Julia Garcia-Miguel
- Consorci Sanitari de Terrassa, Department of Radiation Oncology, Terrassa, Spain
| | - Eduard Gershkevitsh
- North Estonia Medical Centre, Department of Medical Physics, Tallinn, Estonia
| | - Jo Goossens
- Iridium Netwerk, Department of Medical Physics, Antwerp, Belgium
| | - Carmen Herrero
- Centro Médico de Asturias-IMOMA, Department of Medical Physics, Oviedo, Spain
| | - Mohammad Hussein
- National Physical Laboratory, Metrology for Medical Physics Centre, London TW11 0PX, UK
| | - Catherine Khamphan
- Institut du Cancer - Avignon Provence, Department of Medical Physics, Avignon, France
| | - Roel G J Kierkels
- Radiotherapiegroep, Department of Medical Physics, Arnhem/Deventer, the Netherlands
| | - Wolfgang Lechner
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
| | - Matthieu Lemire
- CIUSSS de l'Est-de-l'Île-de-Montréal, Service de Radio-Physique, Montréal, Canada
| | - Alexander Nevelsky
- Rambam Health Care Campus, Department of Radiotherapy, Division of Oncology, Haifa, Israel
| | | | - Lucia Paganini
- Humanitas Clinical and Research Center, Radiotherapy and Radiosurgery Department, Rozzano, Italy
| | - Marlies Pasler
- Lake Constance Radiation Oncology Center, Department of Radiation Oncology, Singen, Friedrichshafen, Germany; Radiotherapy Hirslanden, St. Gallen, Switzerland
| | - José Fernando Pérez Azorín
- Medical Physics and Radiation Protection Department, Gurutzeta-Cruces University Hospital, Barakaldo, Spain; Biocruces Health Research Institute, Barakaldo, Spain
| | | | | | - John Shakeshaft
- Gold Coast University Hospital, ICON Cancer Centre, Gold Coast, Australia
| | - Laure Vieillevigne
- Institut Claudius Regaud-Institut Universitaire du Cancer de Toulouse, Department of Medical Physics, Toulouse, France
| | - Victor Hernandez
- Hospital Sant Joan de Reus, Department of Medical Physics, Reus, Spain; Universitat Rovira i Virgili, Tarragona, Spain
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Pokhrel D, Mallory R, Bernard ME, Kudrimoti M. How much rotational error is clinically acceptable for single-isocenter/two-lesion lung SBRT treatment on halcyon ring delivery system (RDS)? J Appl Clin Med Phys 2023:e14068. [PMID: 37311070 DOI: 10.1002/acm2.14068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 05/17/2023] [Accepted: 05/28/2023] [Indexed: 06/15/2023] Open
Abstract
PURPOSE SBRT treatment of two separate lung lesions via single-isocenter/multi-target (SIMT) plan on Halcyon RDS could improve patient comfort, compliance, patient throughput, and clinic efficiency. However, aligning two separate lung lesions synchronously via a single pre-treatment CBCT scan on Halcyon can be difficult due to rotational patient setup errors. Thus, to quantify the dosimetric impact, we simulated loss of target(s) coverage due to small, yet clinically observable rotational patient setup errors on Halcyon for SIMT treatments. METHODS Seventeen previously treated 4D-CT based SIMT lung SBRT patients with two separate lesions (total 34 lesions, 50 Gy in five fractions to each lesion) on TrueBeam (6MV-FFF) were re-planned on Halcyon (6MV-FFF) using a similar arc geometry (except couch rotation), dose engine (AcurosXB algorithm), and treatment planning objectives. Rotational patient setup errors of [± 0.5⁰ to ± 3.0⁰] on Halcyon were simulated via Velocity registration software in all three rotation axes and recalculated dose distributions in Eclipse treatment planning system. Dosimetric impact of rotational errors was evaluated for target coverage and organs at risk (OAR). RESULTS Average PTV volume and distance to isocenter were 23.7 cc and 6.1 cm. Average change in Paddick's conformity indexes were less than -5%, -10%, and -15% for 1°, 2°, and 3°, respectively for yaw, roll, and pitch rotation directions. Maximum drop off of PTV(D100%) coverage for 2° rotation was -2.0% (yaw), -2.2% (roll), and -2.5% (pitch). With ±1° rotational error, no PTV(D100%) loss was found. Due to anatomical complexity: irregular and highly variable tumor sizes and locations, highly heterogenous dose distribution, and steep dose gradient, no trend for loss of target(s) coverage as a function of distance to isocenter and PTV size was found. Change in maximum dose to OAR were acceptable per NRG-BR001 within ±1.0° rotation, but were up to 5 Gy higher to heart with 2° in the pitch rotation axis. CONCLUSION Our clinically realistic simulation results show that rotational patient setup errors up to 1.0° in any rotation axis could be acceptable for selected two separate lung lesions SBRT patients on Halcyon. Multivariable data analysis in large cohort is ongoing to fully characterize Halcyon RDS for synchronous SIMT lung SBRT.
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Affiliation(s)
- Damodar Pokhrel
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Richard Mallory
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Mark E Bernard
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Mahesh Kudrimoti
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
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Pokhrel D, Mallory R, Bernard ME. The spatial accuracy of ring-mounted halcyon linac versus C-arm TrueBeam linac for single-isocenter/multi-target SBRT treatment. Med Dosim 2023:S0958-3947(23)00026-2. [PMID: 37059628 DOI: 10.1016/j.meddos.2023.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 02/01/2023] [Accepted: 03/14/2023] [Indexed: 04/16/2023]
Abstract
Stereotactic body radiotherapy (SBRT) treatment of oligometastatic lesions via single-isocenter/multi-target (SIMT) plan is more efficient than using multi-isocenter/multitarget SBRT. This study quantifies the spatial positioning accuracy of 2 commercially available LINAC systems for SIMT treatment pertaining to the potential amplification of error as a function of the target's distance-to-isocenter. We compare the Ring-Gantry Halcyon LINAC equipped with the fast iterative conebeam-CT (iCBCT) for image-guided SIMT treatment, and the SBRT-dedicated C-Arm TrueBeam with standard pretreatment CBCT imaging. For both systems, Sun Nuclear's MultiMet Winston-Lutz Cube phantom with 6 metallic BBs distributed at different planes up to 7 cm away from the isocenter was used. The phantom was aligned and imaged via CBCT, and then couch corrections were applied. To treat all 6 BBs, an Eclipse 10-field 3D-conformal Field-in-Field (2×2 cm2 MLC field to each BB) plan for varying gantry, collimator, and couch (TrueBeam only) positions was developed for both machines with 6MV-FFF beam. The plan was delivered through ARIA once a week. The EPID images were analyzed via Sun Nuclear's software for spatial positioning accuracy. On TrueBeam, the treatment plan was delivered twice: once with 3DoF translational corrections and once with PerfectPitch 6DoF couch corrections. The average 3D spatial positioning accuracy was 0.55 ± 0.30 mm, 0.54 ± 0.24 mm, and 0.56 ± 0.28 mm at isocenter, and 0.59 ± 0.30 mm, 0.69 ± 0.30 mm, and 0.70 ± 0.35 mm at 7 cm distance-to-isocenter for Halcyon, TrueBeam 3DoF, and TrueBeam 6DoF, respectively. This suggests there are no clinically significant deviations of spatial uncertainty between the platforms with the distance-to-isocenter. On both platforms, our weekly independent measurements demonstrated the reproducibility for less than 1.0 mm positional accuracy of off-axis targets up to 7 cm from the isocenter. Due to this, no additional PTV-margin is suggested for lesions within 7 cm of isocenter. This study confirms that Halcyon can deliver similar positional accuracy to SBRT-dedicated TrueBeam to off-axis targets up to 7 cm from isocenter. These results further benchmark the spatial uncertainty of our extensively used SBRT-dedicated TrueBeam LINAC for SIMT SBRT treatments.
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Affiliation(s)
- Damodar Pokhrel
- Department of Radiation Medicine, University of Kentucky, Lexington, KY 40536, USA.
| | - Richard Mallory
- Department of Radiation Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Mark E Bernard
- Department of Radiation Medicine, University of Kentucky, Lexington, KY 40536, USA
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Stanley DN, Harms J, Pogue JA, Belliveau JG, Marcrom SR, McDonald AM, Dobelbower MC, Boggs DH, Soike MH, Fiveash JA, Popple RA, Cardenas CE. A roadmap for implementation of kV-CBCT online adaptive radiation therapy and initial first year experiences. J Appl Clin Med Phys 2023:e13961. [PMID: 36920871 DOI: 10.1002/acm2.13961] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/12/2023] [Accepted: 02/23/2023] [Indexed: 03/16/2023] Open
Abstract
PURPOSE Online Adaptive Radiation Therapy (oART) follows a different treatment paradigm than conventional radiotherapy, and because of this, the resources, implementation, and workflows needed are unique. The purpose of this report is to outline our institution's experience establishing, organizing, and implementing an oART program using the Ethos therapy system. METHODS We include resources used, operational models utilized, program creation timelines, and our institutional experiences with the implementation and operation of an oART program. Additionally, we provide a detailed summary of our first year's clinical experience where we delivered over 1000 daily adaptive fractions. For all treatments, the different stages of online adaption, primary patient set-up, initial kV-CBCT acquisition, contouring review and edit of influencer structures, target review and edits, plan evaluation and selection, Mobius3D 2nd check and adaptive QA, 2nd kV-CBCT for positional verification, treatment delivery, and patient leaving the room, were analyzed. RESULTS We retrospectively analyzed data from 97 patients treated from August 2021-August 2022. One thousand six hundred seventy seven individual fractions were treated and analyzed, 632(38%) were non-adaptive and 1045(62%) were adaptive. Seventy four of the 97 patients (76%) were treated with standard fractionation and 23 (24%) received stereotactic treatments. For the adaptive treatments, the generated adaptive plan was selected in 92% of treatments. On average(±std), adaptive sessions took 34.52 ± 11.42 min from start to finish. The entire adaptive process (from start of contour generation to verification CBCT), performed by the physicist (and physician on select days), was 19.84 ± 8.21 min. CONCLUSION We present our institution's experience commissioning an oART program using the Ethos therapy system. It took us 12 months from project inception to the treatment of our first patient and 12 months to treat 1000 adaptive fractions. Retrospective analysis of delivered fractions showed that the average overall treatment time was approximately 35 min and the average time for the adaptive component of treatment was approximately 20 min.
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Affiliation(s)
- Dennis N Stanley
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Joseph Harms
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Joel A Pogue
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Jean-Guy Belliveau
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Samuel R Marcrom
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Andrew M McDonald
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Michael C Dobelbower
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Drexell H Boggs
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Michael H Soike
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - John A Fiveash
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Richard A Popple
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Carlos E Cardenas
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
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Yousif YAM, Gastaldo J, Baldock C. Golden beam data provided by linear accelerator manufacturers should be used in the commissioning of treatment planning systems. Phys Eng Sci Med 2022; 45:407-411. [PMID: 35604544 PMCID: PMC9125535 DOI: 10.1007/s13246-022-01134-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yousif A M Yousif
- North West Cancer Centre, Tamworth Hospital, 2340, Tamworth, NSW, Australia
| | - Jerome Gastaldo
- St George's Cancer Care Centre, 8140, Christchurch, New Zealand
| | - Clive Baldock
- Graduate Research School, Western Sydney University, 2747, Penrith, NSW, Australia.
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Mund K, Maloney L, Lu B, Wu J, Li J, Liu C, Yan G. Reconstruction of volume averaging effect-free continuous photon beam profiles from discrete ionization chamber array measurements using a machine learning technique. J Appl Clin Med Phys 2021; 22:161-168. [PMID: 34486800 PMCID: PMC8504600 DOI: 10.1002/acm2.13411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 01/07/2023] Open
Abstract
PURPOSE The use of the ionization chamber array ICProfiler (ICP) is limited by its relatively poor detector spatial resolution and the inherent volume averaging effect (VAE). The purpose of this work is to study the feasibility of reconstructing VAE-free continuous photon beam profiles from ICP measurements with a machine learning technique. METHODS In- and cross-plane photon beam profiles of a 6 MV beam from an Elekta linear accelerator, ranging from 2 × 2 to 10 × 10 cm2 at 1.5 cm, 5 cm, and 10 cm depth, were measured with an ICP. The discrete measurements were interpolated with a Makima method to obtain continuous beam profiles. Artificial neural networks (ANNs) were trained to restore the penumbra of the beam profiles. Plane-specific (in- and cr-plane) ANNs and a combined ANN were separately trained. The performance of the ANNs was evaluated using the penumbra width difference (PWD, the difference between the penumbra widths of the reconstructed and the reference profile). The plane-specific and the combined ANNs were compared to study the feasibility of using a single ANN for both in- and cross-plane. RESULTS The profiles reconstructed with all the ANNs had excellent agreement with the reference. For in-plane, the ANNs reduced the PWD from 1.6 ± 0.7 mm at 1.5 cm depth to 0.1 ± 0.1 mm, from 1.8 ± 0.6 mm at 5.0 cm depth to 0.1 ± 0.1 mm, and from 2.4 ± 0.1 mm at 10.0 cm depth to 0.0 ± 0.0 mm; for cross-plane, the ANNs reduced the PWD from 1.2 ± 0.4 mm at 1.5 cm depth, 1.2 ± 0.3 mm at 5.0 cm depth, and 1.6 ± 0.1 mm at 10.0 cm depth, to 0.1 ± 0.1 mm. CONCLUSIONS This study demonstrated the feasibility of using simple ANNs to reconstruct VAE-free continuous photon beam profiles from discrete ICP measurements. A combined ANN can restore the penumbra of in- and cross-plane beam profiles of various fields at different depths.
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Affiliation(s)
- Karl Mund
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Luke Maloney
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Bo Lu
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Jian Wu
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Jonathan Li
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Chihray Liu
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - Guanghua Yan
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
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10
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Pathak PK, Vashisht SK, Baby S, Jithin PK, Jain Y, Mahawar R, Sharan VGGK. Commissioning and quality assurance of Halcyon TM 2.0 linear accelerator. Rep Pract Oncol Radiother 2021; 26:433-444. [PMID: 34277097 PMCID: PMC8281907 DOI: 10.5603/rpor.a2021.0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 02/25/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Varian Medical Systems has introduced a new medical linear accelerator called HalcyonTM 2.0, which is based on the ring delivery system (RDS). It is a true IGRT machine having 6MV FFF photon energy. In addition to the planar and MV-CBCT imaging techniques it also has an option of ultra-fast kV-iCBCT which enhances the image reconstruction and improves the visualization of soft tissue. The field portals are shaped by a unique dual layer MLC with special stacked and staggered design which enables high modulation with low radiation leakage. Recently, we have commissioned our first Halcyon 2.0 machine. The aim of this work was to systematically investigate various parameters of a newly installed HalcyonTM 2.0 linear accelerator. MATERIALS AND METHODS Detailed measurements were conducted as per various guidelines. Also, the measurements were performed to fulfil the national regulatory requirements. Commissioning data of Halcyon 6 MV-FFF beam was performed in a water tank. For absolute measurements, a 0.6-cc waterproof Farmer chamber and electrometer were used. All relative measurements (PDDs, in-line, cross-line and angular profiles) were performed with 0.0125 cc point chamber. RESULTS All the tests were within the acceptable limit. Measured data were compared with factory data as well as the existing medical linear accelerator of the same category. The obtained results were quite satisfactory. CONCLUSIONS This study summarizes the commissioning experience with Halcyon linear accelerator. Evaluation of mechanical, radiation safety and dosimetric parameters were performed. The obtained parameters were well below the specified tolerance limits.
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Affiliation(s)
- Pushpraj K Pathak
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - S K Vashisht
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - S Baby
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - P K Jithin
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - Y Jain
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
| | - R Mahawar
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
| | - V G G K Sharan
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
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11
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Pokhrel D, Webster A, Stephen J, St Clair W. SBRT treatment of abdominal and pelvic oligometastatic lymph nodes using ring-mounted Halcyon Linac. J Appl Clin Med Phys 2021; 22:162-171. [PMID: 34032367 PMCID: PMC8200515 DOI: 10.1002/acm2.13268] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/18/2021] [Accepted: 04/14/2021] [Indexed: 12/31/2022] Open
Abstract
PURPOSE/OBJECTIVES This work seeks to evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter volumetric modulated arc therapy (VMAT) of abdominal/pelvic oligometastatic lymph nodes (LNs) stereotactic body radiation therapy (SBRT) on Halcyon Linac. MATERIALS AND METHODS After completing the in-house multitarget end-to-end phantom testing and independent dose verification using MD Anderson's single-isocenter/multi-target (lung and spine target inserts) thorax phantom, eight patients with two to three abdominal/pelvic oligometastatic LNs underwent highly conformal single-isocenter VMAT-SBRT treatment using the Halcyon Linac 6MV flattening filter free (FFF) beam. Targets were identified using an Axumin PET/CT scan co-registered with planning CT images and a single-isocenter was placed between/among the targets. Doses between 25 and 36.25 Gy in 5 fractions were delivered. Patients were treated every other day. Plans were calculated in Eclipse with advanced AcurosXB algorithm for heterogeneity corrections. For comparison, Halcyon VMAT-SBRT plans were retrospectively generated for SBRT-dedicated TrueBeam with a 6MV-FFF beam using identical planning geometry and objectives. Target coverage, conformity index (CI), dose to 2 cm away from each target (D2cm) and dose to adjacent organs-at-risk (OAR) were evaluated. Additionally, various treatment delivery parameters including beam-on time were recorded. RESULTS Phantom measurements showed acceptable spatial accuracy of conebeam CT-guided Halcyon SBRT treatments including compliance with MD Anderson's single-isocenter/multi-targets phantom credentialing results. For patients, the mean isocenter to tumor center distance was 3.4 ± 1.2 cm (range, 1.5-4.8 cm). The mean combined PTV was 18.9 ± 10.9 cc (range, 5.6-39.5 cc). There was no clinically significant difference in dose to LNs, CI, D2cm and maximal doses to OAR between single-isocenter Halcyon and Truebeam VMAT-SBRT plans, although, Halcyon plans provided preferably lower maximal dose to adjacent OAR. Additionally, total monitor units, beam-on time and overall treatment time was lower with Halcyon plans. Halcyon's portal dosimetry demonstrated a high pass rate of 98.1 ± 1.6% for clinical gamma passing criteria of 2%/2 mm. CONCLUSION SBRT treatment of abdominal/pelvic oligometastatic LNs with single-isocenter VMAT on Halcyon was dosimetrically equivalent to TrueBeam. Faster treatment delivery to oligometastatic LNs via single-isocenter Halcyon VMAT can improve clinic workflow and patient compliance, potentially reducing intrafraction motion errors for well-suited patients. Clinical follow-up of these patients is ongoing.
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Affiliation(s)
- Damodar Pokhrel
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - Aaron Webster
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - Joseph Stephen
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - William St Clair
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
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12
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Gao S, Chetvertkov MA, Cai B, Dwivedi A, Mihailidis D, Ray X, Netherton T, Court LE, Simon WE, Balter PA. Beam energy metrics for the acceptance and quality assurance of Halcyon linear accelerator. J Appl Clin Med Phys 2021; 22:121-127. [PMID: 34042271 PMCID: PMC8292713 DOI: 10.1002/acm2.13281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/25/2021] [Accepted: 04/22/2021] [Indexed: 11/12/2022] Open
Abstract
Purpose Establish and compare two metrics for monitoring beam energy changes in the Halcyon platform and evaluate the accuracy of these metrics across multiple Halcyon linacs. Method The first energy metric is derived from the diagonal normalized flatness (FDN), which is defined as the ratio of the average measurements at a fixed off‐axis equal distance along the open profiles in two diagonals to the measurement at the central axis with an ionization chamber array (ICA). The second energy metric comes from the area ratio (AR) of the quad wedge (QW) profiles measured with the QW on the top of the ICA. Beam energy is changed by adjusting the magnetron current in a non‐clinical Halcyon. With D10cm measured in water at each beam energy, the relationships between FDN or AR energy metrics to D10cm in water is established with linear regression across six energy settings. The coefficients from these regressions allow D10cm(FDN) calculation from FDN using open profiles and D10cm(QW) calculation from AR using QW profiles. Results Five Halcyon linacs from five institutions were used to evaluate the accuracy of the D10cm(FDN) and the D10cm(QW) energy metrics by comparing to the D10cm values computed from the treatment planning system (TPS) and D10cm measured in water. For the five linacs, the D10cm(FDN) reported by the ICA based on FDN from open profiles agreed with that calculated by TPS within –0.29 ± 0.23% and 0.61% maximum discrepancy; the D10cm(QW) reported by the QW profiles agreed with that calculated by TPS within –0.82 ± 1.27% and –2.43% maximum discrepancy. Conclusion The FDN‐based energy metric D10cm(FDN) can be used for acceptance testing of beam energy, and also for the verification of energy in periodic quality assurance (QA) processes.
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Affiliation(s)
- Song Gao
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Bin Cai
- Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Abhishek Dwivedi
- Radiation Oncology, Rutgers CINJ/Robert Wood, Johnson University Hospital, New Brunswick, NJ, USA
| | | | - Xenia Ray
- Radiation Medicine and Applied Science, University of California San Diego, Moores Cancer Center, La Jolla, CA, USA
| | - Tucker Netherton
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Laurence E Court
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Peter A Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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13
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Hernandez V, Saez J, Angerud A, Cayez R, Khamphan C, Nguyen D, Vieillevigne L, Feygelman V. Dosimetric leaf gap and leaf trailing effect in a double-stacked multileaf collimator. Med Phys 2021; 48:3413-3424. [PMID: 33932237 DOI: 10.1002/mp.14914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE To investigate (i) the dosimetric leaf gap (DLG) and the effect of the "trailing distance" between leaves from different multileaf collimator (MLC) layers in Halcyon systems and (ii) the ability of the currently available treatment planning systems (TPSs) to approximate this effect. METHODS DICOM plans with transmission beams and sweeping gap tests were created in Python for measuring the DLG for each MLC layer independently and for both layers combined. In clinical Halcyon plans both MLC layers are interchangeably used and leaves from different layers are offset, thus forming a trailing pattern. To characterize the impact of such configuration, new tests called "trailing sweeping gaps" were designed and created where the leaves from one layer follow the leaves from the other layer at a fixed "trailing distance" t between the tips. Measurements were carried out on five Halcyons SX2 from different institutions and calculations from both the Eclipse and RayStation TPSs were compared with measurements. RESULTS The dose accumulated during a sweeping gap delivery progressively increased with the trailing distance t . We call this "the trailing effect." It is most pronounced for t between 0 and 5 mm, although some changes were obtained up to 20 mm. The dose variation was independent of the gap size. The measured DLG values also increased with t up to 20 mm, again with the steepest variation between 0 and 5 mm. Measured DLG values were negative at t = 0 (the leaves from both layers at the same position) but changed sign for t ≥ 1 mm, in line with the positive DLG sign usually observed with single-layer rounded-end MLCs. The Eclipse TPS does not explicitly model the leaf tip and, as a consequence, could not predict the dose reduction due to the trailing effect. This resulted in dose discrepancies up to +10% and -8% for the 5 mm sweeping gap and up to ±5% for the 10 mm one depending on the distance t . RayStation implements a simple model of the leaf tip that was able to approximate the trailing effect and improved the agreement with measured doses. In particular, with a prototype version of RayStation that assigned a higher transmission at the leaf tip the agreement with measured doses was within ±3% even for the 5 mm gap. The five Halcyon systems behaved very similarly but differences in the DLG around 0.2 mm were found across different treatment units and between MLC layers from the same system. The DLG for the proximal layer was consistently higher than for the distal layer, with differences ranging between 0.10 mm and 0.24 mm. CONCLUSIONS The trailing distance between the leaves from different layers substantially affected the doses delivered by sweeping gaps and the measured DLG values. Stacked MLCs introduce a new level of complexity in TPSs, which ideally need to implement an explicit model of the leaf tip in order to reproduce the trailing effect. Dynamic tests called "trailing sweeping gaps" were designed that are useful for characterizing and commissioning dual-layer MLC systems.
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Affiliation(s)
- Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, 43204, Tarragona, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, 08036, Barcelona, Spain
| | | | - Romain Cayez
- Department of Medical Physics, Oscar Lambret Center, 59000, Lille, France
| | - Catherine Khamphan
- Medical Physics Department, Institut Sainte-Catherine, 84000, Avignon, France
| | - Daniel Nguyen
- Centre de Radiothérapie de Mâcon, 71000, Mâcon, France
| | - Laure Vieillevigne
- Department of Medical Physics, Institut Claudius Regaud-Institut Universitaire du Cancer de Toulouse, 31059, Toulouse, France.,Centre de Recherche en Cancérologie de Toulouse UMR1037 INSERM, Université Toulouse 3-ERL5294 CNRS, Oncopole, 31037, Toulouse, France
| | - Vladimir Feygelman
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, 12902, Florida, USA
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14
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Hao Y, Cai B, Green O, Knutson N, Yaddanapudi S, Zhao T, Rodriguez V, Schmidt M, Mutic S, Sun B. Technical Note: An alternative approach to verify 6FFF beam dosimetry for Ethos and MR Linac without using a 3D water tank. Med Phys 2021; 48:1533-1539. [PMID: 33547684 DOI: 10.1002/mp.14757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/17/2020] [Accepted: 01/29/2021] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The current approach to Linac beam dosimetry verification is typically performed utilizing a three-dimensional (3D) water tank system. The 3D beam scanning process is cumbersome, labor intensive, error-prone, and costly. This is especially challenging for the new Ethos system and MR Linacs with a ring gantry. This work proposes an alternative approach to verify 6FFF beam dosimetry for Ethos, ViewRay MRIdian® Linac, and other Linacs with 6FFF beam quality using two-dimensional (2D) ion chamber arrays. METHODS Percentage depth dose (PDD) and profiles of an Ethos, an MRIdian® Linac, and several Linacs with 6FFF beams were measured at the nominal beam current. The beam energy was detuned by changing the bending magnet current on one TrueBeam. PDDs and profiles were measured for detuned beam energies. The peak shape of the 6FFF profile was defined by a "slope" parameter and unflatness. Correlations between peak slope and unflatness metrics vs PDDs were used to evaluate the sensitivity of beam energy to beam profile changes at different field sizes and depths. RESULTS Strong correlations were found between peak slope and PDDs for all Linacs with 6FFF beam. The R-squared values in the linear regression fitting between PDD and peak slope and unflatness were 0.99 and 0.84, respectively. Both profile slope and unflatness were proportional to PDD at the 10 cm depth and the peak slope was 4.3 times more sensitive than PDD. We have identified that measurements with a shallow depth are preferred to quantify the beam energy consistency. CONCLUSIONS Our work shows the feasibility of verifying 6FFF beam quality of Ethos, MR Linac, and other Linacs by defining a profile slope measured from 2D ionization chambers array devices. This new approach provides a simplified method for performing a routine beam quality check without using a 3D water tank system while maximizing cost effectiveness and efficiency.
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Affiliation(s)
- Yao Hao
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Bin Cai
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Olga Green
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Nels Knutson
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Sridhar Yaddanapudi
- Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, LL-W Pomerantz Family Pavilion, Iowa City, IA, 52242-1089, USA
| | - Tianyu Zhao
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Vivian Rodriguez
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Matthew Schmidt
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Baozhou Sun
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
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15
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Pokhrel D, Visak J, Critchfield LC, Stephen J, Bernard ME, Randall M, Kudrimoti M. Clinical validation of ring-mounted halcyon linac for lung SBRT: comparison to SBRT-dedicated C-arm linac treatments. J Appl Clin Med Phys 2020; 22:261-270. [PMID: 33342070 PMCID: PMC7856490 DOI: 10.1002/acm2.13146] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/19/2020] [Accepted: 12/04/2020] [Indexed: 12/31/2022] Open
Abstract
Stereotactic body radiotherapy (SBRT) of lung tumors via the ring‐mounted Halcyon Linac, a fast kilovoltage cone beam CT‐guided treatment with coplanar geometry, a single energy 6MV flattening filter free (FFF) beam and volumetric modulated arc therapy (VMAT) is a fast, safe, and feasible treatment modality for selected lung cancer patients. Four‐dimensional (4D) CT‐based treatment plans were generated using advanced AcurosXB algorithm with heterogeneity corrections using an SBRT board and Halcyon couch insert. Halcyon VMAT‐SBRT plans with stacked and staggered multileaf collimators produced highly conformal radiosurgical dose distribution to the target, lower intermediate dose spillage, and similar dose to adjacent organs at risks (OARs) compared to SBRT‐dedicated highly conformal clinical noncoplanar Truebeam VMAT plans following the RTOG‐0813 requirements. Due to low monitor units per fraction and less multileaf collimator (MLC) modulation, the Halcyon VMAT plan can deliver lung SBRT fractions with an overall treatment time of less than 15 min (for 50 Gy in five fractions), significantly improving patient comfort and clinic workflow. Higher pass rates of quality assurance results demonstrate a more accurate treatment delivery on Halcyon. We have implemented Halcyon for lung SBRT treatment in our clinic. We suggest others use Halcyon for lung SBRT treatments using abdominal compression or 4D CT‐based treatment planning, thus expanding the access of curative ultra‐hypofractionated treatments to other centers with only a Halcyon Linac. Clinical follow‐up results for patients treated on Halcyon Linac with lung SBRT is ongoing.
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Affiliation(s)
- Damodar Pokhrel
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Justin Visak
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Lana C Critchfield
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Joseph Stephen
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Mark E Bernard
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Marcus Randall
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Mahesh Kudrimoti
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
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16
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Pokhrel D, Tackett T, Stephen J, Visak J, Amin-Zimmerman F, McGregor A, Strup SE, St Clair W. Prostate SBRT using O-Ring Halcyon Linac - Plan quality, delivery efficiency, and accuracy. J Appl Clin Med Phys 2020; 22:68-75. [PMID: 33340388 PMCID: PMC7856496 DOI: 10.1002/acm2.13105] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/20/2020] [Accepted: 11/02/2020] [Indexed: 12/31/2022] Open
Abstract
Cone beam CT‐guided prostate stereotactic body radiotherapy (SBRT) treatment on the recently installed novel O‐ring coplanar geometry Halcyon Linac with a single energy 6MV‐flattening filter free (FFF) beam and volumetric modulated arc therapy (VMAT) is a fast, safe, and feasible treatment modality for early stage low‐ and intermediate‐risk prostate cancer patients. Following the RTOG‐0938 compliance criteria and utilizing two‐full arc geometry, VMAT prostate SBRT plans were generated for ten consecutive patients using advanced Acuros‐based algorithm for heterogeneity corrections with Halcyon couch insert. Halcyon VMAT plans with the stacked and staggered multileaf collimators (MLC) produced highly conformal SBRT dose distributions to the prostate, lower intermediate dose spillage and similar dose to adjacent organs‐at‐risks (OARs) compared to SBRT‐dedicated Truebeam VMAT plans. Due to lower monitor units per fraction and less MLC modulation through the target, the Halcyon VMAT plan can deliver prostate SBRT fractions in and overall treatment time of less than 10 minutes (for 36.25 Gy in five fractions), significantly improving patient compliance and clinic workflow. Pretreatment quality assurance results were similar to Truebeam VMAT plans. We have implemented Halcyon Linac for prostate SBRT treatment in our institution. We recommend that others use Halcyon for prostate SBRT treatments to expand the access of curative hypofractionated treatments to other clinics only equipped with a Halcyon Linac. Clinical follow‐up results for patients who underwent prostate SBRT treatment on our Halcyon Linac is underway.
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Affiliation(s)
- Damodar Pokhrel
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Tanner Tackett
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Joseph Stephen
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | - Justin Visak
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
| | | | - Andrew McGregor
- Lexington Clinic, University of Kentucky, Lexington, KY, USA
| | - Stephen E Strup
- Department of Urology, University of Kentucky, Lexington, KY, USA
| | - William St Clair
- Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA
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17
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Fogliata A, Cayez R, Garcia R, Khamphan C, Reggiori G, Scorsetti M, Cozzi L. Technical Note: Flattening filter free beam from Halcyon linac: Evaluation of the profile parameters for quality assurance. Med Phys 2020; 47:3669-3674. [PMID: 32367534 DOI: 10.1002/mp.14217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 01/15/2023] Open
Abstract
INTRODUCTION The use of flattening filter free (FFF) beams generated by standard linear accelerators is increasing in the clinical practice. The radiation intensity peaked toward the beam central axis is properly managed in the optimization process of treatment planning through intensity modulation. Specific FFF parameters for profile analysis, as unflatness and slope for FFF beams, based on the renormalization factor concept has been introduced for quality assurance purposes. Recently, Halcyon, an O-ring based linear accelerator equipped with a 6 MV FFF beam only has been introduced by Varian. METHODS Renormalization factors and related fit parameters according to Fogliata et al. ["Definition of parameters for quality assurance of FFF photon beams in radiation therapy," Med. Phys. 39, 6455-6464 (2012)] have been evaluated for the 6 MV FFF beam generated by Halcyon units. The Halcyon representative beam data provided by Varian were used. Dose fall-off at the field edges was matched with an unflattened beam generated by a 6 MV from a TrueBeam linac. Consistency of the results was evaluated against measurements on a clinical Halcyon unit, as well as a TrueBeam 6 MV FFF for comparison. RESULTS The five parameters in the analytical equation for estimating the renormalization factor were determined with an R2 of 0.997. The comparison of the unflatness parameters between the Halcyon representative and hospital beam data was consistent within a range of 0.6%. Consistently with the computed parameters, the Halcyon profiles resulted in a less pronounced peak than TrueBeam. CONCLUSION Renormalization factors and related fit parameters from the 6 MV FFF beam generated by the Varian Halcyon unit are provided.
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Affiliation(s)
- A Fogliata
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy
| | - R Cayez
- Oscar Lambret Center, rue Frédéric Combemale, Radiotherapy, 59000, Lille, France
| | - R Garcia
- Medical Physics Department, Institut Sainte-Catherine, 250 Chemin de Baigne Pieds, 84000, Avignon, France
| | - C Khamphan
- Medical Physics Department, Institut Sainte-Catherine, 250 Chemin de Baigne Pieds, 84000, Avignon, France
| | - G Reggiori
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy
| | - M Scorsetti
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy.,Department of Biomedical Science, Humanitas University, via Rita Levi Montalcini 4, 20090, Milan, Pieve Emanuele, Italy
| | - L Cozzi
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy.,Department of Biomedical Science, Humanitas University, via Rita Levi Montalcini 4, 20090, Milan, Pieve Emanuele, Italy
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