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Fogliata A, Burger H, Groenewald A, Punt L, Parkes J, Cozzi L. Intensity Modulated Therapy for Patients With Breast Cancer. Practical Guidelines and Tips for an Effective Treatment Planning Strategy. Adv Radiat Oncol 2024; 9:101535. [PMID: 38993192 PMCID: PMC11233865 DOI: 10.1016/j.adro.2024.101535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 03/16/2024] [Indexed: 07/13/2024] Open
Abstract
Purpose Practical guidelines and tips for effective and robust radiation therapy treatment planning for patients with breast cancer are addressed for fixed-field intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) techniques. The concepts described here are general and valid on all treatment planning systems. However, some details shown here have been applied to the Varian platforms used at the authors' institutions. Methods and Materials The specific aspects of using C-arm- or O-ring-mounted linear accelerators are covered in the document, as well as tips for dealing with certain resource constraints, target cropping, and skin flash aiming to reduce risks of skin toxicity and to manage (residual after breath control) respiration motion or edema. Results A decision tree is presented, and practical solutions for cases where a target volume is contoured or not and where volumetric modulated arc therapy or fixed-beam intensity modulation should be applied and details about the technical implementation (tangential IMRT, butterfly IMRT or VMAT, and large partial VMAT arcs) are discussed. Target cropping and skin flash implications are discussed in detail, and links to plan robustness are outlined. Conclusions Practical guidelines for breast planning are presented and summarized with a decision tree and technical summaries.
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Affiliation(s)
- Antonella Fogliata
- Department of Radiotherapy and Radiosurgery, Istituto di Ricovero e Cura a Carattere Scientifico Humanitas Research Hospital, Rozzano, Italy
| | - Hester Burger
- Department of Radiation Medicine, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
- Medical Affairs, Varian Medical Systems, a Siemens Healthineers Company, Palo Alto, California
| | - Annemari Groenewald
- Department of Radiation Medicine, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
| | - Lydia Punt
- Department of Radiation Medicine, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
| | - Jeannette Parkes
- Department of Radiation Medicine, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
| | - Luca Cozzi
- Department of Radiotherapy and Radiosurgery, Istituto di Ricovero e Cura a Carattere Scientifico Humanitas Research Hospital, Rozzano, Italy
- Medical Affairs, Varian Medical Systems, a Siemens Healthineers Company, Palo Alto, California
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Zhang X, Shi J, Wu X, Li L, Sun W, Zou Y, Chen G, Wu S, Duan S. Dosimetric Comparison of Commonly Used Volumetric Modulated Arc Therapy Field Arrangements Based on Flattening Filter-Free Beams for Synchronous Bilateral Breast Carcinoma Radiation Therapy. Pract Radiat Oncol 2024; 14:e190-e202. [PMID: 37967748 DOI: 10.1016/j.prro.2023.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/14/2023] [Accepted: 11/05/2023] [Indexed: 11/17/2023]
Abstract
PURPOSE Flattening filter-free (FFF)-based volumetric modulated arc therapy (VMAT) has been shown to be feasible and significantly improves treatment efficiency and lung protection for synchronous bilateral breast irradiation (SBBI). This research compared the commonly used VMAT field arrangements using FFF beams. METHODS Twenty-eight patients underwent SBBI were retrospectively enrolled to design irradiation plans using tangential arc VMAT (taVMAT), half arc VMAT (haVMAT), and large arc VMAT (laVMAT). Dosimetric and delivery parameters of all designed plans were recorded and compared. RESULTS Comparable target volume coverage was observed for all field arrangements. taVMAT significantly reduced the dose to spinal cord and the volume covered by 5 Gy (V5Gy) and V7Gy of the lungs while decreasing the conformity index of the target volume. It also increased the volume covered by 105% of the prescription dose (V105%) and V107% of the target volume. haVMAT considerably decreased V20 Gy and V30 Gy of the lungs, mean dose (Dmean) and V30 Gy of the heart and the liver. It also notably reduced Dmean and V40 Gy of the left anterior descending coronary artery while increasing the beam-on time. laVMAT significantly reduced the mean treatment time (range, 113-117 seconds) compared with the other field arrangements. CONCLUSIONS There were distinct differences in various dosimetric and delivery parameters for different field arrangements, highlighting the importance of selecting the appropriate field arrangement based on specific treatment goals and considerations. This study contributes valuable insights into the use of FFF-based VMAT techniques in SBBI.
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Affiliation(s)
- Xingxing Zhang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Juntian Shi
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Xiuxiu Wu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Liting Li
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Wei Sun
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yongmei Zou
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Guoquan Chen
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Shaokun Wu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Song Duan
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
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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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Alexander DA, Certa O, Haertter A, Li T, Taunk N, Zhu TC. Comparison of surface dose during whole breast radiation therapy on Halcyon and TrueBeam using Cherenkov imaging. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2023; 12371:1237108. [PMID: 37101538 PMCID: PMC10128868 DOI: 10.1117/12.2652588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
The emergence of the Halcyon linear accelerator has allowed for increased patient throughput and improved treatment times for common treatment sites in radiation oncology. However, it has been shown that this can lead to increased surface dose in sites like breast cancer compared with treatments on conventional machines with flattened radiation beams. Cherenkov imaging can be used to estimate surface dose by detection of Cherenkov photons emitted in proportion to energy deposition from high energy electrons in tissue. Phantom studies were performed with both square beams in reference conditions and with clinical treatments, and dosimeter readings and Cherenkov images report higher surface dose (25% for flat phantom entrance dose, 5.9% for breast phantom treatment) from Halcyon beam deliveries than for equivalent deliveries from a TrueBeam linac. Additionally, the first Cherenkov images of a patient treated with Halcyon were acquired, and superficial dose was estimated.
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Affiliation(s)
- Daniel A. Alexander
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Olivia Certa
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Allison Haertter
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Taoran Li
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Neil Taunk
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Timothy C. Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
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Price AT, Canfield C, Hugo GD, Kavanaugh JA, Henke LE, Laugeman E, Samson P, Reynolds-Kueny C, Cudney EA. Techno-Economic Feasibility Analysis of a Fully Mobile Radiation Oncology System Using Monte Carlo Simulation. JCO Glob Oncol 2022; 8:e2100284. [PMID: 35609229 PMCID: PMC9173580 DOI: 10.1200/go.21.00284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Disparities in radiation oncology (RO) can be attributed to geographic location, socioeconomic status, race, sex, and other societal factors. One potential solution is to implement a fully mobile (FM) RO system to bring radiotherapy to rural areas and reduce barriers to access. We use Monte Carlo simulation to quantify techno-economic feasibility with uncertainty, using two rural Missouri scenarios.
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Affiliation(s)
- Alex T Price
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO.,Department of Engineering Management and Systems Engineering, Missouri University of Science and Technology, Rolla, MO
| | - Casey Canfield
- Department of Engineering Management and Systems Engineering, Missouri University of Science and Technology, Rolla, MO
| | - Geoffrey D Hugo
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO
| | - Lauren E Henke
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO
| | - Eric Laugeman
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO
| | - Pamela Samson
- Department of Radiation Oncology, Washington University School of Medicine in St Louis, St Louis, MO
| | - Clair Reynolds-Kueny
- Department of Psychological Science, Missouri University of Science and Technology, Rolla, MO
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Synchronous bilateral breast carcinoma irradiation: A comparative investigation between flattened and unflattened beams. Appl Radiat Isot 2022; 181:110079. [DOI: 10.1016/j.apradiso.2021.110079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 12/24/2022]
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Intra-fraction motion monitoring during fast modulated radiotherapy delivery in a closed-bore gantry linac. Phys Imaging Radiat Oncol 2021; 20:51-55. [PMID: 34765749 PMCID: PMC8572954 DOI: 10.1016/j.phro.2021.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/25/2022] Open
Abstract
Surface scanning allows for continuous intra fraction monitoring in a closed-bore gantry. Patient baseline drift during fast cone-beam computed tomography imaging is non-negligible. Peak-to-peak breathing amplitude is smaller than baseline drift in 69% of fractions.
Background and purpose New closed-bore linacs allow for highly streamlined workflows and fast treatment delivery resulting in brief treatment sessions. Motion management technology has only recently been integrated inside the bore, yet is required in future online adaptive workflows. We measured patient motion during every step of the workflow: image acquisition, evaluation and treatment delivery using surface scanning. Materials and methods Nineteen patients treated for breast, lung or esophageal cancer were prospectively monitored from the end of setup to the end of treatment delivery in the Halcyon linac (Varian Medical Systems). Motion of the chest was tracked by way of 6 degrees-of-freedom surface tracking. Baseline drift and rate of drift were determined. The influence of fraction number, patient and fraction duration were analyzed with multi-way ANOVA. Results Median fraction duration was 4 min 48 s including the IGRT procedure (kV-CBCT acquisition and evaluation) (N = 221). Baseline drift at the end of the fraction was −1.8 ± 1.5 mm in the anterior-posterior, −0.0 ± 1.7 mm in the cranio-caudal direction and 0.1 ± 1.8 mm in the medio-lateral direction of which 75% occurred during the IGRT procedure. The highest rate of baseline drift was observed between 1 and 2 min after the end of patient setup (-0.62 mm/min). Baseline drift was patient and fraction duration dependent (p < 0.001), but fraction number was not significant (p = 0.33). Conclusion Even during short treatment sessions, patient baseline drift is not negligible. Drift is largest during the initial minutes after completion of patient setup, during verification imaging and evaluation. Patients will need to be monitored during extended contouring and re-planning procedures in online adaptive workflows.
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Comparison of sliding window and field-in-field techniques for tangential whole breast irradiation using the Halcyon and Synergy Agility systems. Radiat Oncol 2021; 16:213. [PMID: 34742291 PMCID: PMC8571882 DOI: 10.1186/s13014-021-01942-y] [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: 08/13/2021] [Accepted: 10/28/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To implement a tangential treatment technique for whole breast irradiation using the Varian Halcyon and to compare it with Elekta Synergy Agility plans. METHODS For 20 patients two comparable treatment plans with respect to dose coverage and normal tissue sparing were generated. Tangential field-in-field treatment plans (Pinnacle/Synergy) were replanned using the sliding window technique (Eclipse/Halcyon). Plan specific QA was performed using the portal Dosimetry and the ArcCHECK phantom. Imaging and treatment dose were evaluated for treatment delivery on both systems using a modified CIRS Phantom. RESULTS The mean number of monitor units for a fraction dose of 2.67 Gy was 515 MUs and 260 MUs for Halcyon and Synergy Agility plans, respectively. The homogeneity index and dose coverage were similar for both treatment units. The plan specific QA showed good agreement between measured and calculated plans. All Halcyon plans passed portal dosimetry QA (3%/2 mm) with 100% points passing and ArcCheck QA (3%/2 mm) with 99.5%. Measurement of the cumulated treatment and imaging dose with the CIRS phantom resulted in lower dose to the contralateral breast for the Halcyon plans. CONCLUSIONS For the Varian Halcyon a plan quality similar to the Elekta Synergy device was achieved. For the Halcyon plans the dose contribution from the treatment fields to the contralateral breast was even lower due to less interleaf transmission of the Halcyon MLC and a lower contribution of scattered dose from the collimator system.
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Costa E, Richir T, Robilliard M, Bragard C, Logerot C, Kirova Y, Fourquet A, De Marzi L. Assessment of a conventional volumetric-modulated arc therapy knowledge-based planning model applied to the new Halcyon© O-ring linac in locoregional breast cancer radiotherapy. Phys Med 2021; 86:32-43. [PMID: 34051551 DOI: 10.1016/j.ejmp.2021.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/31/2021] [Accepted: 05/13/2021] [Indexed: 10/21/2022] Open
Abstract
INTRODUCTION The aim of this study was to evaluate the performance of a knowledge-based planning (KBP) model for breast cancer trained on plans performed on a conventional linac with 6 MV FF (flattening filter) beams and volumetric-modulated arc therapy (VMAT) for plans performed on the new jawless Halcyon© system with 6 MV FFF (flattening filter-free) beams. MATERIALS AND METHODS Based on the RapidPlan© (RP) KBP optimization engine, a DVH Estimation Model was first trained using 56 VMAT left-sided breast cancer treatment plans performed on a conventional linac, and validated on another 20 similar cases (without manual intervention). To determine the capacity of the model for Halcyon©, an additional cohort of 20 left-sided breast cancer plans was generated with RP and analyzed for both TrueBeam© and Halcyon© machines. Plan qualities between manual vs RP (followed by manual intervention) Halcyon© plans set were compared qualitatively by blinded review by radiation oncologists for 10 new independent plans. RESULTS Halcyon© plans generated with the VMAT model trained with conventional linac plans showed comparable target dose distribution compared to TrueBeam© plans. Organ sparingwas comparable between the 2 devices with a slight decrease in heart dose for Halcyon© plans. Nine out of ten automatically generated Halcyon© plans were preferentially chosen by the radiation oncologists over the manually generated Halcyon© plans. CONCLUSION A VMAT KBP model driven by plans performed on a conventional linac with 6 MV FF beams provides high quality plans performed with 6 MV FFF beams on the new Halcyon© linac.
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Affiliation(s)
- Emilie Costa
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France.
| | - Thomas Richir
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Magalie Robilliard
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Christel Bragard
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Christelle Logerot
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Youlia Kirova
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Alain Fourquet
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France
| | - Ludovic De Marzi
- Institut Curie, Radiation Oncology Department, 26 rue d'Ulm, Paris 75005, France; Institut Curie, University Paris Saclay, PSL Research University, Inserm LITO, Orsay, France
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Sun T, Lin X, Zhang G, Qiu Q, Li C, Yin Y. Treatment planning comparison of volumetric modulated arc therapy with the trilogy and the Halcyon for bilateral breast cancer. Radiat Oncol 2021; 16:35. [PMID: 33602267 PMCID: PMC7890882 DOI: 10.1186/s13014-021-01763-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 02/11/2021] [Indexed: 12/12/2022] Open
Abstract
Background The Halcyon is a new machine from the Varian company. The purpose of this study was to evaluate the dosimetry of the Halcyon in treatment of bilateral breast cancer with volumetric modulated arc therapy. Methods On CT images of 10 patients with bilateral breast cancer, four Halcyon plans with different setup fields were generated, and dosimetric comparisons using Bonferroni’s multiple comparisons test were conducted among the four plans. Whole and partial arc plans on the Trilogy and the Halcyon, referred to as T-4arc, T-8arc, H-4arc and H-8arc, were designed. The prescription dose was 50 Gy in 2-Gy fractions. All plans were designed with the Eclipse version 15.5 treatment planning system. The dosimetric differences between whole and partial arc plans in the same accelerator were compared using the Mann–Whitney U test. The better Halcyon plan was selected for the further dosimetric comparison of the plan quality and delivery efficiency between the Trilogy and the Halcyon. Results Halcyon plans with high‐quality megavoltage cone beam CT setup fields increased the Dmean, D2 and V107 of the planning target volume (PTV) and the V5 and Dmean of the heart, left ventricle (LV) and lungs compared with other Halcyon setup plans. The mean dose and low dose volume of the heart, lungs and liver were significantly decreased in T-8arc plans compared to T-4arc plans. In terms of the V5, V20, V30, V40 and Dmean of the heart, the V20, V30, V40 and Dmean of the LV, the V30, V40, Dmax and Dmean of the left anterior descending artery (LAD), and the V5 and V40 of lungs, H-8arc was significantly higher than H-4arc (p < 0.05). Compared with the Trilogy’s plans, the Halcyon’s plans reduced the high-dose volume of the heart and LV but increased the mean dose of the heart. For the dose of the LAD and the V20 and V30 of lungs, there was no significant difference between the two accelerators. Compared with the Trilogy, plans on the Halcyon significantly increased the skin dose but also significantly reduced the delivery time. Conclusion For the Halcyon, the whole-arc plans have more dosimetric advantages than partial-arc plans in bilateral breast cancer radiotherapy. Although the mean dose of the heart and the skin dose are increased, the doses of the cardiac substructure and other OARs are comparable to the Trilogy, and the delivery time is significantly reduced.
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Affiliation(s)
- Tao Sun
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China
| | - Xiutong Lin
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China
| | - Guifang Zhang
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China
| | - Qingtao Qiu
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China
| | - Chengqiang Li
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China
| | - Yong Yin
- Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, 440 Jiyan Road, Jinan, 250117, Shandong, China.
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Delombaerde L, Petillion S, Weltens C, Depuydt T. Spirometer-guided breath-hold breast VMAT verified with portal images and surface tracking. Radiother Oncol 2021; 157:78-84. [PMID: 33515669 DOI: 10.1016/j.radonc.2021.01.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/07/2021] [Accepted: 01/07/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND PURPOSE Fast rotating closed-bore gantry linacs are ideally suited for breath-hold treatments due to reduced imaging and delivery times. We evaluated the reproducibility and stability of spirometer-guided breath-hold breast treatments, using intra-bore surface monitoring and portal imaging on Halcyon (Varian Medical Systems). MATERIALS AND METHODS Seven left-sided breast cancer patients were treated in breath-hold using the SDX spirometer (Dyn'R) with an integrated boost volumetric arc protocol on Halcyon. A dual depth-camera surface scanning system monitored the left breast. The interfraction, intrafraction and intrabreath-hold motion was determined in the anterior-posterior (AP) and superior-inferior (SI) direction. Portal images (PI), acquired at a tangential gantry angle were manually registered to the planning-CT to determine inter- and intrafraction breath-hold errors for the SI and tangential-anterior-posterior ("AP") axis. Correlations between PI and surface imaging deviations were investigated. To evaluate workflow efficiency, the total time and the number of breath-holds were recorded. RESULTS Systematic and random variability of breath-hold amplitude was below 0.7 mm for the AP and below 1.2 mm for the SI component as detected by surface monitoring (N = 130). Systematic and random errors retrieved from portal images (N = 140) were below 1.2 mm for the "AP" and 2.1 mm for SI axis. A limited correlation was found between PI and surface monitoring deviations for both the SI and "AP" axes (R2 = 0.27/0.38, p < 0.01). 75% of fractions were completed using four breath-holds and 82% within 10 min. CONCLUSION Surface imaging indicated spirometer-guided breath-hold VMAT breast radiotherapy can be accurately and quickly performed on a closed-bore gantry linac. Intra-bore surface scanning proved a valuable technique for monitoring breathing motion in closed-bore systems.
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Affiliation(s)
- Laurence Delombaerde
- Department of Oncology, KU Leuven, Herestraat 49, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
| | - Saskia Petillion
- Department of Radiation Oncology, University Hospitals Leuven, Belgium
| | - Caroline Weltens
- Department of Oncology, KU Leuven, Herestraat 49, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium
| | - Tom Depuydt
- Department of Oncology, KU Leuven, Herestraat 49, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
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12
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Yoon SW, Taunk NK, Freedman GM, Hubley E, O'Reilly S, Teo BKK, Anamalayil S, Dong L, Kennedy C, Zou W, Metz JM, Li T. Per-fraction positional and dosimetric performance of prone breast tangential radiotherapy on Halcyon™ linear accelerator assessed with daily rapid kilo-voltage cone beam computed tomography: a single-institution pilot study. Radiat Oncol 2020; 15:258. [PMID: 33160370 PMCID: PMC7648956 DOI: 10.1186/s13014-020-01700-6] [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: 06/26/2020] [Accepted: 10/29/2020] [Indexed: 11/10/2022] Open
Abstract
Background This study investigates daily breast geometry and delivered dose to prone-positioned patients undergoing tangential whole breast radiation therapy (WBRT) on an O-ring linear accelerator with 6X flattening filter free mode (6X-FFF), planned with electronic compensation (ECOMP) method. Most practices rely on skin marks or daily planar image matching for prone breast WBRT. This system provides low dose daily CBCT, which was used to study daily robustness of delivered dose parameters for prone-positioned WBRT. Methods Eight patients treated with 16-fraction prone-breast WBRT were retrospectively studied. Planning CTs were deformed to daily CBCT to generate daily synthetic CTs, on which delivered dose distributions were calculated. A total of 8 × 16 = 128 synthetic CTs were generated. Consensus ASTRO definition was used to contour Breast PTV Eval for each daily deformed CT. Breast PTV Eval coverage (V90%) and hotspot (V105% and Dmax) were monitored daily to compare prescription dose with daily delivered dose. Various predictors including patient weight, breast width diameter (BWD), and Dice similarity coefficient (DSC) were fit into an analysis of covariance model predicting V90% and V105% deviation from prescribed (ΔV90%, ΔV105%). Statistical significance is indicated with asterisks (* for p < 0.05; ** for p < 0.001). Results Daily delivered Breast PTV Eval V90% was moderately smaller than prescribed (median ΔV90% = − 0.1%*), while V105% was much larger (median ΔV105% = + 10.1%** or + 92.4 cc**). Patient’s weight loss correlated with significantly increased ΔV105% (+ 4.6%/ − 1% weight, R2 = 0.4**) and moderately decreased ΔV90% (− 0.071%/ − 1% wt., R2 = 0.2**). Comprehensive ANCOVA models indicated three factors affect ΔV90% and ΔV105% the most: (1) BWD decrease (− 0.09%* and + 10%**/ − 1 cm respectively), (2) PTV Eval volume decrease (− 0.4%** and + 9%**/ − 100 cc), and for ΔV105% only, (3) the extent of breast deformation (+ 10%**/ − 0.01 DSC). Breast PTV Eval volume also decreased with time (− 2.21*cc/fx), possibly indicating seroma resolution and increase in V105% over time. Conclusions Daily CBCT revealed key delivered dose parameters vary significantly for patients undergoing tangential prone breast WBRT planned with ECOMP using 6X-FFF. Patient weight, BWD, and breast shape deformation could be used to predict dosimetric variations from prescribed. Preliminary findings suggest an adaptive plan based on daily CBCT could reduce excessive dose to the breast.
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Affiliation(s)
- Suk W Yoon
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA.
| | - Neil K Taunk
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Gary M Freedman
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Emily Hubley
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Shannon O'Reilly
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Boon- Keng K Teo
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Shibu Anamalayil
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Lei Dong
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Christopher Kennedy
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Wei Zou
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - James M Metz
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
| | - Taoran Li
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Perelman Center for Advanced Medicine, 3400 Civic Center Blvd, Philadelphia, PA, USA
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13
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Barsky AR, Lin H, Mendes A, Dreyfuss A, Wright C, Anstadt EJ, Berman AT, Levin WP, Cengel KA, Anderson N, Dong L, Metz JM, Li T, Feigenberg S. Initial Clinical Experience Treating Patients With Lung Cancer on a 6MV-Flattening-Filter-Free O-Ring Linear Accelerator. Cureus 2020; 12:e10325. [PMID: 33052286 PMCID: PMC7546605 DOI: 10.7759/cureus.10325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 12/25/2022] Open
Abstract
Introduction Modern technologies, like intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), have improved the therapeutic ratio of thoracic radiotherapy (TRT) for lung cancer (LC). Halcyon™ (Varian Medical Systems, Palo Alto, CA, USA), a novel 6MV-flattening-filter-free O-ring linear accelerator (6X-FFF ORL), was designed to deliver IMRT and VMAT with greater speed than a C-arm linac. Herein, we report our initial clinical experience treating patients with LC on this linac. Methods All patients who received TRT for LC on the 6X-FFF ORL at our institution were retrospectively identified. Patients' clinicopathologic data, radiotherapy details, early disease-control and toxicity outcomes, dosimetric data, couch corrections, and treatment times are reported. Results Between 10/2018-12/2019, 30 consecutive patients (median age 66 years, range 54-94 years) received definitive or post-operative TRT for LC (median 66 Gy/33 fractions; range 5-70 Gy/2-37 fractions) following four-dimensional computed tomography (CT) simulation (97%) using daily kilovoltage KV cone-beam CT (CBCT) (100%) on a 6X-FFF ORL for non-small cell LC (84%) or small cell LC (16%), with 53% receiving VMAT, 43% receiving static-field IMRT, and 77% receiving concurrent systemic therapy. All plans were approved through institutional peer review. The average three-dimensional vector couch correction based on CBCT guidance was 0.90 ± 0.50 cm. The average beam-on and beam on plus CBCT times were 1.7 ± 1.1 min, and 5.0 ± 3.2 min, respectively. Grade 3 dyspnea and fatigue occurred in 3% and 3% of patients, respectively. There were no grade ≥4 toxicities. Conclusion In this first clinical report of TRT for LC on a 6X-FFF ORL, daily CBCT-guided treatment was fast and safe with respect to dosimetry and clinical outcomes. Thus, use of this linac for TRT may increase LC patient throughput without a detriment in radiotherapy quality.
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Affiliation(s)
- Andrew R Barsky
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Hui Lin
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Amberly Mendes
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Alexandra Dreyfuss
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Christopher Wright
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Emily J Anstadt
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Abigail T Berman
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - William P Levin
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Keith A Cengel
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Nathan Anderson
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Lei Dong
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - James M Metz
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Taoran Li
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Steven Feigenberg
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
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14
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Barsky AR, Kim MM, Dreyfuss A, Dong L, Metz JM, Anamalayil S, Li T, Taunk NK. Initial Clinical Experience Treating Patients With Gynecologic Cancers on a 6MV Flattening Filter Free O-Ring Linear Accelerator. Adv Radiat Oncol 2020; 5:920-928. [PMID: 33083654 PMCID: PMC7557142 DOI: 10.1016/j.adro.2020.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/26/2020] [Accepted: 01/26/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Radiation therapy (RT) is commonly used in the treatment of gynecologic cancers. Intensity-modulated RT (IMRT) has been shown to reduce gastrointestinal toxicity compared with 2-dimensional and 3-dimensional RT modalities. We report the initial clinical experience using IMRT for gynecologic cancers with a novel 6MV flattening filter free O-ring linear accelerator (6X-FFF ORL). METHODS AND MATERIALS We retrospectively identified consecutive women with uterine or cervical cancer who received pelvic RT on Halcyon (Varian Medical Systems, Palo Alto, CA), a novel 6X-FFF ORL. We report their clinicopathologic data, RT details, early disease-control outcomes, acute toxicities, dose-volume histogram data, couch corrections, and treatment times. RESULTS Seventeen women received RT on a 6X-FFF ORL for uterine cancer (76%) or cervical cancer (24%) between January 2017 and September 2019. RT was delivered postoperatively (82%) or to intact disease (18%), to a median dose of 50.4 Gy (range, 19.8-55.0 Gy) in 25 fractions (range, 11-28), with 12% receiving extended-field RT and 65% receiving chemotherapy. Target and organ-at-risk constraints were met in all plans. The 3-dimensional vector couch correction average was 0.90 ± 0.37 cm. The mean beam-on time was 2.9 ± 0.4 min and mean treatment time, from imaging start to beam-off, was 3.6 ± 0.4 min. Grade 2 fatigue, anorexia, diarrhea, bloating, and nausea occurred in 41%, 12%, 12%, 6%, and 6% of patients, respectively. There were no grade ≥3 toxicities. CONCLUSIONS In the initial clinical report of pelvic RT for gynecologic cancers using a 6X-FFF ORL, the linac showed versatility in treatment; comparability to flattening-filtered IMRT for early disease-control, toxicity, and dosimetry; and treatment speed that compared favorably to IMRT on a C-arm gantry. Accordingly, a 6X-FFF ORL may increase throughput or reduce day length in departments with high gynecologic cancer volumes, without compromising clinical outcomes.
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Affiliation(s)
- Andrew R Barsky
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Michele M Kim
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Alexandra Dreyfuss
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Lei Dong
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - James M Metz
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Shibu Anamalayil
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Taoran Li
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Neil K Taunk
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
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15
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Bollinger D, Laugeman E, Li T, Hilliard J, Heermann A, Kim H, Hugo G, Mutic S, Dong L, Cai B. Technical Note: Dosimetric characterization of the dynamic beam flattening MLC sequence on a ring shaped, Jawless Linear Accelerator with double stacked MLC. Med Phys 2019; 47:948-957. [PMID: 31885088 DOI: 10.1002/mp.14001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To characterize the dosimetric features and limitations of the dynamic beam flattening (DBF) on the Halcyon 2.0 linear accelerator (Varian Medical Systems). METHODS A predefined multi-leaf collimator (MLC) sequence was introduced and used to flatten the 6 MV flattening filter free (FFF) beam on the Halcyon 2.0. Dosimetric characterizations of the flattened beams, including beam flatness, symmetry, percent depth dose (PDD), output factor and MU linearity, were investigated. Flatness and symmetry were obtained from profile measurements with both radiographic films (EDR2) and a two dimensional ion-chamber array (IC Profiler, Sun Nuclear Corporation). MU linearity, output factors, and PDDs were measured in a water tank with a CC13 ion chamber (Scanditronix Wellhöfer, Nuremburg, Germany). In addition, the effect of the DBF sequence on 3D plan quality was evaluated by creating DBF plans for a 4-field box rectum and an AP/PA spine plan. Patient specific QA was performed on these plans. RESULTS At 100 cm SSD and 10 cm depth, a flatness of <3% was observed on both transversal and radial profiles for all square field sizes ≥10 cm with DBF. For both larger and smaller field sizes the flatness showed a tendency to increase as the fields got bigger or smaller, respectively. Similar trends in flatness were observed at all depths measured. All measured output factors for square field sizes ≥5 cm were within 1% of the TPS prediction. Linearity was ≤2.02% for all measurements. For both treatment sites, the MD judged the plans created for the Halcyon without the use of DBF not to be clinically acceptable, however considered both the TrueBeam plan and the Halcyon plan with the DBF sequence to be clinically acceptable. CONCLUSIONS The DBF sequence on the Halcyon and its characteristics were investigated. The analysis indicates that the DBF sequence can be used on the Halcyon to generate clinically acceptable 3D treatment plans.
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Affiliation(s)
- Douglas Bollinger
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Eric Laugeman
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Taoran Li
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jessica Hilliard
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Ana Heermann
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Hyun Kim
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Geoff Hugo
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Lei Dong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Bin Cai
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
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