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Tucker WW, Mazur TR, Schmidt MC, Hilliard J, Badiyan S, Spraker MB, Kavanaugh JA. Script-based implementation of automatic grid placement for lattice stereotactic body radiation therapy. Phys Imaging Radiat Oncol 2024; 29:100549. [PMID: 38380154 PMCID: PMC10876586 DOI: 10.1016/j.phro.2024.100549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/26/2024] [Accepted: 02/05/2024] [Indexed: 02/22/2024] Open
Abstract
Background and purpose Spatially fractionated radiation therapy (SFRT) has demonstrated promising clinical response in treating large tumors with heterogeneous dose distributions. Lattice stereotactic body radiation therapy (SBRT) is an SFRT technique that leverages inverse optimization to precisely localize regions of high and lose dose within disease. The aim of this study was to evaluate an automated heuristic approach to sphere placement in lattice SBRT treatment planning. Materials and methods A script-based algorithm for sphere placement in lattice SBRT based on rules described by protocol was implemented within a treatment planning system. The script was applied to 22 treated cases and sphere distributions were compared with manually placed spheres in terms of number of spheres, number of protocol violations, and time required to place spheres. All cases were re-planned using script-generated spheres and plan quality was compared with clinical plans. Results The mean number of spheres placed excluding those that violate rules was greater using the script (13.8) than that obtained by either dosimetrist (10.8 and 12.0, p < 0.001 and p = 0.003) or physicist (12.7, p = 0.061). The mean time required to generate spheres was significantly less using the script (2.5 min) compared to manual placement by dosimetrists (25.0 and 29.9 min) and physicist (19.3 min). Plan quality indices were similar in all cases with no significant differences, and OAR constraints remained met on all plans except two. Conclusion A script placed spheres for lattice SBRT according to institutional protocol rules. The script-produced placement was superior to that of manually-specified spheres, as characterized by sphere number and rule violations.
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Affiliation(s)
- Wesley W. Tucker
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Thomas R. Mazur
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Matthew C. Schmidt
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Jessica Hilliard
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Shahed Badiyan
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
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Lin MH, Olsen L, Kavanaugh JA, Jacqmin D, Lobb E, Yoo S, Berry SL, Pichardo JC, Cardenas CE, Roper J, Kirk M, Cheung JP, Solberg TD, Moore KL, Kim M. Beyond Acceptable: The Vital Role of Medical Physicists in Ensuring High-Quality Treatment Plans. Pract Radiat Oncol 2024; 14:6-9. [PMID: 38182304 DOI: 10.1016/j.prro.2023.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/09/2023] [Accepted: 08/18/2023] [Indexed: 01/07/2024]
Affiliation(s)
- Mu-Han Lin
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas.
| | - Lindsey Olsen
- Department of Radiation Oncology, Memorial Hospital, Colorado Springs, Colorado
| | - James A Kavanaugh
- Department of Radiation Oncology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - Dustin Jacqmin
- Department of Human Oncology, University of Wisconsin, Madison, Wisconsin
| | - Eric Lobb
- Department of Radiation Oncology, Ascension NE Wisconsin-St. Elizabeth Hospital, Appleton, Wisconsin
| | - Sua Yoo
- Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Sean L Berry
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | | | - Carlos E Cardenas
- Department of Radiation Oncology, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Justin Roper
- Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia
| | - Maura Kirk
- Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Joey P Cheung
- Radiation Oncology, Sutter Health Mills-Peninsula Medical Center, San Mateo, California
| | - Timothy D Solberg
- Department of Radiation Oncology, University of Washington, Seattle, Washington
| | - Kevin L Moore
- Department of Radiation Oncology, UC San Diego, La Jolla, California
| | - Minsun Kim
- Department of Radiation Oncology, University of Washington, Seattle, Washington
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Lin M, Kavanaugh JA, Kim M, Cardenas CE, Rong Y. Physicists should perform reference planning for CBCT guided online adaptive radiotherapy. J Appl Clin Med Phys 2023; 24:e14163. [PMID: 37776261 PMCID: PMC10562033 DOI: 10.1002/acm2.14163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/05/2023] [Accepted: 09/09/2023] [Indexed: 10/02/2023] Open
Affiliation(s)
- Mu‐Han Lin
- Radiation OncologyUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | | | - Minsun Kim
- Radiation OncologyUniversity of WashingtonSeattleWashingtonUSA
| | - Carlos E. Cardenas
- Radiation OncologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Yi Rong
- RadiationOncologyMayo ClinicPhoenixArizonaUSA
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Grams MP, Deufel CL, Kavanaugh JA, Corbin KS, Ahmed SK, Haddock MG, Lester SC, Ma DJ, Petersen IA, Finley RR, Lang KG, Spreiter SS, Park SS, Owen D. Clinical aspects of spatially fractionated radiation therapy treatments. Phys Med 2023; 111:102616. [PMID: 37311338 DOI: 10.1016/j.ejmp.2023.102616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/06/2023] [Accepted: 05/30/2023] [Indexed: 06/15/2023] Open
Abstract
PURPOSE To provide clinical guidance for centers wishing to implement photon spatially fractionated radiation therapy (SFRT) treatments using either a brass grid or volumetric modulated arc therapy (VMAT) lattice approach. METHODS We describe in detail processes which have been developed over the course of a 3-year period during which our institution treated over 240 SFRT cases. The importance of patient selection, along with aspects of simulation, treatment planning, quality assurance, and treatment delivery are discussed. Illustrative examples involving clinical cases are shown, and we discuss safety implications relevant to the heterogeneous dose distributions. RESULTS SFRT can be an effective modality for tumors which are otherwise challenging to manage with conventional radiation therapy techniques or for patients who have limited treatment options. However, SFRT has several aspects which differ drastically from conventional radiation therapy treatments. Therefore, the successful implementation of an SFRT treatment program requires the multidisciplinary expertise and collaboration of physicians, physicists, dosimetrists, and radiation therapists. CONCLUSIONS We have described methods for patient selection, simulation, treatment planning, quality assurance and delivery of clinical SFRT treatments which were built upon our experience treating a large patient population with both a brass grid and VMAT lattice approach. Preclinical research and patient trials aimed at understanding the mechanism of action are needed to elucidate which patients may benefit most from SFRT, and ultimately expand its use.
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Affiliation(s)
- Michael P Grams
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
| | - Christopher L Deufel
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - James A Kavanaugh
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Kimberly S Corbin
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Safia K Ahmed
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Michael G Haddock
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Scott C Lester
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Daniel J Ma
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Ivy A Petersen
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Randi R Finley
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Karen G Lang
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Sheri S Spreiter
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Sean S Park
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Dawn Owen
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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Price AT, Schiff JP, Zhu T, Mazur T, Kavanaugh JA, Maraghechi B, Green O, Kim H, Spraker MB, Henke LE. First treatments for Lattice stereotactic body radiation therapy using magnetic resonance image guided radiation therapy. Clin Transl Radiat Oncol 2023; 39:100577. [PMID: 36718251 PMCID: PMC9883196 DOI: 10.1016/j.ctro.2023.100577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/29/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
Two abdominal patients were treated with Lattice stereotactic body radiation therapy (SBRT) using magnetic resonance guided radiation therapy (MRgRT). This is one of the first reported treatments of Lattice SBRT with the use of MRgRT. A description of the treatment approach and planning considerations were incorporated into this report. MRgRT Lattice SBRT delivered similar planning quality metrics to established dosimetric parameters for Lattice SBRT. Increased signal intensity were seen in the MRI treatments for one of the patients during the course of treatment.
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Affiliation(s)
- Alex T. Price
- Department of Radiation Oncology, University Hospitals, Cleveland, OH, USA
- Corresponding author.
| | - Joshua P. Schiff
- Department of Radiation Oncology, Washington University in St Louis School of Medicine, St. Louis, MO, USA
| | - Tong Zhu
- Department of Radiation Oncology, Washington University in St Louis School of Medicine, St. Louis, MO, USA
| | - Thomas Mazur
- Department of Radiation Oncology, Washington University in St Louis School of Medicine, St. Louis, MO, USA
| | | | - Borna Maraghechi
- Department of Radiation Oncology, Washington University in St Louis School of Medicine, St. Louis, MO, USA
| | - Olga Green
- Varian Medical Systems, Inc., Palo Alto, CA, USA
| | - Hyun Kim
- Department of Radiation Oncology, Washington University in St Louis School of Medicine, St. Louis, MO, USA
| | | | - Lauren E. Henke
- Department of Radiation Oncology, University Hospitals, Cleveland, OH, USA
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Duriseti S, Kavanaugh JA, Szymanski J, Huang Y, Basarabescu F, Chaudhuri A, Henke L, Samson P, Lin A, Robinson C, Spraker MB. LITE SABR M1: A phase I trial of Lattice stereotactic body radiotherapy for large tumors. Radiother Oncol 2022; 167:317-322. [PMID: 34875286 DOI: 10.1016/j.radonc.2021.11.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/09/2021] [Accepted: 11/22/2021] [Indexed: 12/31/2022]
Abstract
PURPOSE Stereotactic body radiotherapy (SBRT) is an attractive treatment option for patients with metastatic and/or unresectable tumors, however its use is limited to smaller tumors. Lattice is a form of spatially fractionated radiotherapy that may allow safe delivery of ablative doses to bulky tumors. We previously described Lattice SBRT, which delivers 20 Gy in 5 fractions with a simultaneous integrated boost to 66.7 Gy in a defined geometric arrangement (Lattice boost). The goal of this study was to prospectively evaluate the acute toxicity and quality of life (QoL) of patients with large tumors (>5 cm) treated with Lattice SBRT. METHODS This was a single-arm phase I trial conducted between October 2019 and August 2020. Patients with tumors > 4.5 cm were eligible. Lattice SBRT was delivered every other day. The primary outcome was the rate of 90-day treatment-associated (probably or definitely attributable) grade 3 + acute toxicity by Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 criteria. Other outcomes included changes in patient reported toxicity and QoL inventories, GTV, and peripheral blood cytokines. RESULTS Twenty patients (22 tumors) were enrolled. Median GTV was 579.2 cc (range: 54.2-3713.5 cc) in volume and 11.1 cm (range: 5.6-21.4 cm) in greatest axial diameter. Fifty percent of tumors were in the thorax, 45% abdomen/pelvis, and 5% extremity. There was no likely treatment-associated grade 3 + toxicity in the 90-day period (acute and sub-acute). There was one case of grade 4 toxicity possibly associated with Lattice SBRT. CONCLUSIONS This phase I study met its primary endpoint of physician reported short-term safety. An ongoing phase II clinical trial of Lattice SBRT will evaluate late safety and efficacy of this novel technique.
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Affiliation(s)
- Sai Duriseti
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Jeff Szymanski
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Yi Huang
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Franco Basarabescu
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Aadel Chaudhuri
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Lauren Henke
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Pamela Samson
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Alexander Lin
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Clifford Robinson
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Matthew B Spraker
- Department of Radiation Oncology, Washington University in St. Louis, United States.
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Hilliard EN, Carver RL, Chambers EL, Kavanaugh JA, Erhart KJ, McGuffey AS, Hogstrom KR. Planning and delivery of intensity modulated bolus electron conformal therapy. J Appl Clin Med Phys 2021; 22:8-21. [PMID: 34558774 PMCID: PMC8504596 DOI: 10.1002/acm2.13386] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/30/2020] [Accepted: 06/23/2021] [Indexed: 12/05/2022] Open
Abstract
PURPOSE Bolus electron conformal therapy (BECT) is a clinically useful, well-documented, and available technology. The addition of intensity modulation (IM) to BECT reduces volumes of high dose and dose spread in the planning target volume (PTV). This paper demonstrates new techniques for a process that should be suitable for planning and delivering IM-BECT using passive radiotherapy intensity modulation for electrons (PRIME) devices. METHODS The IM-BECT planning and delivery process is an addition to the BECT process that includes intensity modulator design, fabrication, and quality assurance. The intensity modulator (PRIME device) is a hexagonal matrix of small island blocks (tungsten pins of varying diameter) placed inside the patient beam-defining collimator (cutout). Its design process determines a desirable intensity-modulated electron beam during the planning process, then determines the island block configuration to deliver that intensity distribution (segmentation). The intensity modulator is fabricated and quality assurance performed at the factory (.decimal, LLC, Sanford, FL). Clinical quality assurance consists of measuring a fluence distribution in a plane perpendicular to the beam in a water or water-equivalent phantom. This IM-BECT process is described and demonstrated for two sites, postmastectomy chest wall and temple. Dose plans, intensity distributions, fabricated intensity modulators, and quality assurance results are presented. RESULTS IM-BECT plans showed improved D90-10 over BECT plans, 6.4% versus 7.3% and 8.4% versus 11.0% for the postmastectomy chest wall and temple, respectively. Their intensity modulators utilized 61 (single diameter) and 246 (five diameters) tungsten pins, respectively. Dose comparisons for clinical quality assurance showed that for doses greater than 10%, measured agreed with calculated dose within 3% or 0.3 cm distance-to-agreement (DTA) for 99.9% and 100% of points, respectively. CONCLUSION These results demonstrated the feasibility of translating IM-BECT to the clinic using the techniques presented for treatment planning, intensity modulator design and fabrication, and quality assurance processes.
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Affiliation(s)
- Elizabeth N. Hilliard
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - Robert L. Carver
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
- Mary Bird Perkins Cancer CenterBaton RougeLouisianaUSA
| | - Erin L. Chambers
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - James A. Kavanaugh
- Department of Radiation OncologyWashington University School of MedicineSaint LouisMissouriUSA
| | | | - Andrew S. McGuffey
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - Kenneth R. Hogstrom
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
- Mary Bird Perkins Cancer CenterBaton RougeLouisianaUSA
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Knutson NC, Kavanaugh JA, Li HH, Zoberi JE, Zhao T, Green O, Rodriguez V, Sun B, Reynoso FJ, Price AT, Prusator MT, Kim T, Cai B, Hugo GD. Radiation oncology physics coverage during the COVID-19 pandemic: Successes and lessons learned. J Appl Clin Med Phys 2021; 22:4-7. [PMID: 33742538 PMCID: PMC7984470 DOI: 10.1002/acm2.13225] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Nels C Knutson
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - H Harold Li
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jacqueline E Zoberi
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Tianyu Zhao
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Olga Green
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Vivian Rodriguez
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Baozhou Sun
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Francisco J Reynoso
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Alex T Price
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Michael T Prusator
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Taeho Kim
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Bin Cai
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Geoffrey D Hugo
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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Kennedy WR, DeWees TA, Acharya S, Mahmood M, Knutson NC, Goddu SM, Kavanaugh JA, Mitchell TJ, Rich KM, Kim AH, Leuthardt EC, Dowling JL, Dunn GP, Chicoine MR, Perkins SM, Huang J, Tsien CI, Robinson CG, Abraham CD. Internal dose escalation associated with increased local control for melanoma brain metastases treated with stereotactic radiosurgery. J Neurosurg 2020; 135:855-861. [PMID: 33307528 DOI: 10.3171/2020.7.jns192210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 07/09/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The internal high-dose volume varies widely for a given prescribed dose during stereotactic radiosurgery (SRS) to treat brain metastases (BMs). This may be altered during treatment planning, and the authors have previously shown that this improves local control (LC) for non-small cell lung cancer BMs without increasing toxicity. Here, they seek to identify potentially actionable dosimetric predictors of LC after SRS for melanoma BM. METHODS The records of patients with unresected melanoma BM treated with single-fraction Gamma Knife RS between 2006 and 2017 were reviewed. LC was assessed on a per-lesion basis, defined as stability or a decrease in lesion size. Outcome-oriented approaches were utilized to determine optimal dichotomization for dosimetric variables relative to LC. Univariable and multivariable Cox regression analysis was implemented to evaluate the impact of collected parameters on LC. RESULTS Two hundred eighty-seven melanoma BMs in 79 patients were identified. The median age was 56 years (range 31-86 years). The median follow-up was 7.6 months (range 0.5-81.6 months), and the median survival was 9.3 months (range 1.3-81.6 months). Lesions were optimally stratified by volume receiving at least 30 Gy (V30) greater than or equal to versus less than 25%. V30 was ≥ and < 25% in 147 and 140 lesions, respectively. For all patients, 1-year LC was 83% versus 66% for V30 ≥ and < 25%, respectively (p = 0.001). Stratifying by volume, lesions 2 cm or less (n = 215) had 1-year LC of 82% versus 70% (p = 0.013) for V30 ≥ and < 25%, respectively. Lesions > 2 to 3 cm (n = 32) had 1-year LC of 100% versus 43% (p = 0.214) for V30 ≥ and < 25%, respectively. V30 was still predictive of LC even after controlling for the use of immunotherapy and targeted therapy. Radionecrosis occurred in 2.8% of lesions and was not significantly associated with V30. CONCLUSIONS For a given prescription dose, an increased internal high-dose volume, as indicated by measures such as V30 ≥ 25%, is associated with improved LC but not increased toxicity in single-fraction SRS for melanoma BM. Internal dose escalation is an independent predictor of improved LC even in patients receiving immunotherapy and/or targeted therapy. This represents a dosimetric parameter that is actionable at the time of treatment planning and warrants further evaluation.
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Affiliation(s)
| | - Todd A DeWees
- 2Department of Biomedical Statistics and Informatics, Mayo Clinic, Scottsdale, Arizona; and
| | - Sahaja Acharya
- 3Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | | | | | | | | | | | - Keith M Rich
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
| | - Albert H Kim
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
| | - Eric C Leuthardt
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
| | - Joshua L Dowling
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
| | - Gavin P Dunn
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
| | - Michael R Chicoine
- 4Neurosurgery, Washington University School of Medicine, St. Louis, Missouri
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11
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Maraghechi B, Kim T, Mitchell TJ, Goddu SM, Dise J, Kavanaugh JA, Zoberi JE, Mutic S, Knutson NC. Filmless quality assurance of a Leksell Gamma Knife® Icon™. J Appl Clin Med Phys 2020; 22:59-67. [PMID: 33300664 PMCID: PMC7856498 DOI: 10.1002/acm2.13070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 08/18/2020] [Accepted: 09/20/2020] [Indexed: 11/05/2022] Open
Abstract
PURPOSE The annual quality assurance (QA) of Leksell Gamma Knife® (LGK) systems are typically performed using films. Film is a good candidate for small field dosimetry due to its high spatial resolution and availability. However, there are multiple challenges with using film; film does not provide real-time measurement and requires batch-specific calibration. Our findings show that active detector-based QA can simplify the procedure and save time without loss of accuracy. METHODS Annual QA tests for a LGK Icon™ system were performed using both film-based and filmless techniques. Output calibration, relative output factors (ROF), radiation profiles, sector uniformity/source counting, and verification of the unit center point (UCP) and radiation focal point (RFP) coincidence tests were performed. Radiochromic films, two ionization chambers, and a synthetic diamond detector were used for the measurements. Results were compared and verified with the treatment planning system (TPS). RESULTS The measured dose rate of the LGK Icon was within 0.4% of the TPS value set at the time of commissioning using an ionization chamber. ROF for the 8 and 4-mm collimators were found to be 0.3% and 1.8% different from TPS values using the MicroDiamond detector and 2.6% and 1.9% different for film, respectively. Excellent agreement was found between TPS and measured dose profiles using the MicroDiamond detector which was within 1%/1 mm vs 2%/1 mm for film. Sector uniformity was found to be within 1% for all eight sectors measured using an ionization chamber. Verification of UCP and RFP coincidence using the MicroDiamond detector and pinprick film test was within 0.3 mm at isocenter for both. CONCLUSION The annual QA of a LGK Icon was successfully performed by employing filmless techniques. Comparable results were obtained using radiochromic films. Utilizing active detectors instead of films simplifies the QA process and saves time without loss of accuracy.
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Affiliation(s)
- Borna Maraghechi
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Taeho Kim
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Timothy J Mitchell
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - S Murty Goddu
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Joe Dise
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - James A Kavanaugh
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Jacqueline E Zoberi
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Sasa Mutic
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Nels C Knutson
- Departments of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
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Prusator MT, Zhao T, Kavanaugh JA, Santanam L, Dise J, Goddu SM, Mitchell TJ, Zoberi JE, Kim T, Mutic S, Knutson NC. Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery. J Appl Clin Med Phys 2020; 21:95-102. [PMID: 31943756 PMCID: PMC6964756 DOI: 10.1002/acm2.12794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/15/2019] [Accepted: 11/20/2019] [Indexed: 11/16/2022] Open
Abstract
Current available secondary dose calculation software for Gamma Knife radiosurgery falls short in situations where the target is shallow in depth or when the patient is positioned with a gamma angle other than 90°. In this work, we evaluate a new secondary calculation software which utilizes an innovative method to handle nonstandard gamma angles and image thresholding to render the skull for dose calculation. 800 treatment targets previously treated with our GammaKnife Icon system were imported from our treatment planning system (GammaPlan 11.0.3) and a secondary dose calculation was conducted. The agreement between the new calculations and the TPS were recorded and compared to the original secondary dose calculation agreement with the TPS using a Wilcoxon Signed Rank Test. Further comparisons using a Mann‐Whitney test were made for targets treated at a 90° gamma angle against those treated with either a 70 or 110 gamma angle for both the new and commercial secondary dose calculation systems. Correlations between dose deviations from the treatment planning system against average target depth were evaluated using a Kendall’s Tau correlation test for both programs. The Wilcoxon Signed Rank Test indicated a significant difference in the agreement between the two secondary calculations and the TPS, with a P‐value < 0.0001. With respect to patients treated at nonstandard gamma angles, the new software was largely independent of patient setup, while the commercial software showed a significant dependence (P‐value < 0.0001). The new secondary dose calculation software showed a moderate correlation with calculation depth, while the commercial software showed a weak correlation (Tau = −.322 and Tau = −.217 respectively). Overall, the new secondary software has better agreement with the TPS than the commercially available secondary calculation software over a range of diverse treatment geometries.
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Affiliation(s)
- Michael T Prusator
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Tianyu Zhao
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Joe Dise
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - S Murty Goddu
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Timothy J Mitchell
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Jacqueline E Zoberi
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Taeho Kim
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Nels C Knutson
- Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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Knutson NC, Hawkins BJ, Bollinger D, Goddu SM, Kavanaugh JA, Santanam L, Mitchell TJ, Zoberi JE, Tsien C, Huang J, Robinson CG, Perkins SM, Dowling JL, Chicoine MR, Rich KM, Dunn GP, Mutic S. Characterization and validation of an intra-fraction motion management system for masked-based radiosurgery. J Appl Clin Med Phys 2019; 20:21-26. [PMID: 31055877 PMCID: PMC6522989 DOI: 10.1002/acm2.12573] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/28/2019] [Accepted: 03/07/2019] [Indexed: 11/29/2022] Open
Abstract
Purpose Characterize the intra‐fraction motion management (IFMM) system found on the Gamma Knife Icon (GKI), including spatial accuracy, latency, temporal performance, and overall effect on delivered dose. Methods A phantom was constructed, consisting of a three‐axis translation mount, a remote motorized flipper, and a thermoplastic sphere surrounding a radiation detector. An infrared marker was placed on the translation mount secured to the flipper. The spatial accuracy of the IFMM was measured via the translation mount in all Cartesian planes. The detector was centered at the radiation focal point. A remote signal was used to move the marker out of the IFMM tolerance and pause the beam. A two‐channel electrometer was used to record the signals from the detector and the flipper when motion was signaled. These signals determined the latency and temporal performance of the GKI. Results The spatial accuracy of the IFMM was found to be <0.1 mm. The measured latency was <200 ms. The dose difference with five interruptions was <0.5%. Conclusion This work provides a quantitative characterization of the GKI IFMM system as required by the Nuclear Regulatory Commission. This provides a methodology for GKI users to satisfy these requirements using common laboratory equipment in lieu of a commercial solution.
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Affiliation(s)
- Nels C Knutson
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Douglas Bollinger
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - S Murty Goddu
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Timothy J Mitchell
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jacqueline E Zoberi
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Christina Tsien
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jiayi Huang
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Clifford G Robinson
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Stephanie M Perkins
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Joshua L Dowling
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Michael R Chicoine
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Keith M Rich
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Gavin P Dunn
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
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Gay HA, Santiago R, Gil B, Remedios C, Montes PJ, López-Araujo J, Chévere CM, Imbert WS, White J, Arthur DW, Horton JK, Jagsi R, Rabinovich R, Beriwal S, Viswanathan A, Erickson BA, Rengan R, Palma D, Loo BW, Kavanaugh JA, Bradley J, Yom SS, Harari PM, Lee Burnett O. Lessons Learned From Hurricane Maria in Puerto Rico: Practical Measures to Mitigate the Impact of a Catastrophic Natural Disaster on Radiation Oncology Patients. Pract Radiat Oncol 2019; 9:305-321. [PMID: 30999000 DOI: 10.1016/j.prro.2019.03.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/24/2019] [Accepted: 03/13/2019] [Indexed: 12/25/2022]
Abstract
PURPOSE Although the wind, rain, and flooding of Hurricane Maria in Puerto Rico abated shortly after its landfall on September 20, 2017, the disruption of the electrical, communications, transportation, and medical infrastructure of the island was unprecedented in scope and caused lasting harm for many months afterward. A compilation of recommendations from radiation oncologists who were in Puerto Rico during the disaster, and from a panel of American Society for Radiation Oncology (ASTRO) cancer experts was created. METHODS AND MATERIALS Radiation oncologists throughout Puerto Rico collaborated and improvised to continue treating patients in the immediate aftermath of the storm and as routine clinical operations were restored gradually. Empirical lessons from the experience of radiation therapy administration in this profoundly altered context of limited resources, impaired communication, and inadequate transportation were organized into a recommended template, applicable to any radiation oncology practice. ASTRO disease-site experts provided evidence-guidelines for mitigating the impact of a 2- to 3-week interruption in radiation therapy. RESULTS Practical measures to mitigate the medical impact of a disaster are summarized within the framework of "Prepare, Communicate, Operate, Compensate." Specific measures include the development of an emergency operations plan tailored to specific circumstances, prospective coordination with other radiation oncology clinics before a disaster, ongoing communications with emergency management organizations, and routine practice of alternate methods to disseminate information among providers and patients. CONCLUSIONS These recommendations serve as a starting point to assist any radiation oncology practice in becoming more resiliently prepared for a local or regional disruption from any cause. Disease-site experts provide evidence-based guidelines on how to mitigate the impact of a 2- to 3-week interruption in radiation therapy for lung, head and neck, uterine cervix, breast, and prostate cancers through altered fractionation or dose escalation.
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Affiliation(s)
- Hiram A Gay
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
| | | | - Betty Gil
- Radiation Therapy and Cancer Institute, San Juan, Puerto Rico
| | | | - Pedro J Montes
- Northern Radiotherapy Cancer Center, Arecibo, Puerto Rico
| | | | - Carlos M Chévere
- Centro Comprensivo de Cáncer de la Universidad de Puerto Rico, San Juan, Puerto Rico
| | | | - Julia White
- Department of Radiation Oncology, Ohio State University, Columbus, Ohio
| | - Douglas W Arthur
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
| | - Janet K Horton
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Reshma Jagsi
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan
| | - Rachel Rabinovich
- Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado
| | | | - Akila Viswanathan
- Johns Hopkins Radiation Oncology and Molecular Radiation Sciences, Baltimore, Maryland
| | - Beth A Erickson
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Ramesh Rengan
- Department of Radiation Oncology, University of Washington, Seattle, Washington
| | - David Palma
- London Regional Cancer Program, London, Ontario, Canada
| | - Billy W Loo
- Department of Radiation Oncology & Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Jeff Bradley
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Sue S Yom
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, California
| | - Paul M Harari
- Department of Human Oncology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Omer Lee Burnett
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, Alabama
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Kavanaugh JA, Holler S, DeWees TA, Robinson CG, Bradley JD, Iyengar P, Higgins KA, Mutic S, Olsen LA. Multi-Institutional Validation of a Knowledge-Based Planning Model for Patients Enrolled in RTOG 0617: Implications for Plan Quality Controls in Cooperative Group Trials. Pract Radiat Oncol 2018; 9:e218-e227. [PMID: 30562615 DOI: 10.1016/j.prro.2018.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/30/2018] [Accepted: 11/19/2018] [Indexed: 12/13/2022]
Abstract
PURPOSE This study aimed to evaluate the feasibility of using a single-institution, knowledge-based planning (KBP) model as a dosimetric plan quality control (QC) for multi-institutional clinical trials. The efficacy of this QC tool was retrospectively evaluated using a subset of plans submitted to Radiation Therapy Oncology Group (RTOG) study 0617. METHODS AND MATERIALS A single KBP model was created using commercially available software (RapidPlan; Varian Medical Systems, Palo Alto, CA) and data from 106 patients with non-small cell lung cancer who were treated at a single institution. All plans had prescriptions that ranged from 60 Gy in 30 fractions to 74 Gy in 37 fractions and followed the planning guidelines from RTOG 0617. Two sets of optimization objectives were created to produce different trade-offs using the single KBP model predictions: one prioritizing target coverage and a second prioritizing lung sparing (LS) while allowing an acceptable variation in target coverage. Three institutions submitted a high volume of clinical plans to RTOG 0617 and provided data on 25 patients, which were replanned using both sets of optimization objectives. Model-generated, dose-volume histogram predictions were used to identify patients who exceeded the lung clinical target volume (CTV) V20Gy >37% and would benefit from the LS objectives. Overall plan quality differences between KBP-generated plans and clinical plans were evaluated at RTOG 0617-defined dosimetric endpoints. RESULTS Target coverage and organ at risk sparing was significantly improved for most KBP-generated plans compared with those from clinical trial data. The KBP model using prioritized target coverage objectives reduced heart Dmean and V40Gy by 2.1 Gy and 5.2%, respectively. Similarly, using LS objectives reduced the lung CTV Dmean and V20Gy by 2.0 Gy and 2.9%, respectively. The KBP predictions correctly identified all patients with lung CTV V20Gy > 37% (5 of 25 patients) and significantly reduced the dose to the lung CTV by applying the LS optimization objectives. CONCLUSIONS A single-institution KBP model can be applied as a QC tool for multi-institutional clinical trials to improve overall plan quality and provide decision-support to determine the need for anatomy-based dosimetric trade-offs.
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Affiliation(s)
- James A Kavanaugh
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri.
| | - Sarah Holler
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
| | - Todd A DeWees
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Scottsdale, Arizona
| | - Clifford G Robinson
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Jeffrey D Bradley
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Puneeth Iyengar
- Department of Radiation Oncology, University of Texas Southwestern, Dallas, Texas
| | - Kristin A Higgins
- Department of Radiation Oncology, Emory University, Atlanta, Georgia
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Lindsey A Olsen
- University of Colorado Health System, Colorado Springs, Colorado
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Altman MB, Kavanaugh JA, Wooten HO, Green OL, DeWees TA, Gay H, Thorstad WL, Li H, Mutic S. A framework for automated contour quality assurance in radiation therapy including adaptive techniques. Phys Med Biol 2015; 60:5199-209. [DOI: 10.1088/0031-9155/60/13/5199] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Kavanaugh JA, Hogstrom KR, Chu C, Carver RA, Fontenot JP, Henkelmann G. Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy. Med Phys 2013; 40:021724. [PMID: 23387747 DOI: 10.1118/1.4788657] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study was to demonstrate that a bolus electron conformal therapy (ECT) dose plan and a mixed beam plan, composed of an intensity modulated x-ray therapy (IMXT) dose plan optimized on top of the bolus ECT plan, can be accurately delivered. METHODS Calculated dose distributions were compared with measured dose distributions for parotid and chest wall (CW) bolus ECT and mixed beam plans, each simulated in a cylindrical polystyrene phantom that allowed film dose measurements. Bolus ECT plans were created for both parotid and CW PTVs (planning target volumes) using 20 and 16 MeV beams, respectively, whose 90% dose surface conformed to the PTV. Mixed beam plans consisted of an IMXT dose plan optimized on top of the bolus ECT dose plan. The bolus ECT, IMXT, and mixed beam dose distributions were measured using radiographic films in five transverse and one sagittal planes for a total of 36 measurement conditions. Corrections for film dose response, effects of edge-on photon irradiation, and effects of irregular phantom optical properties on the Cerenkov component of the film signal resulted in high precision measurements. Data set consistency was verified by agreement of depth dose at the intersections of the sagittal plane with the five measured transverse planes. For these same depth doses, results for the mixed beam plan agreed with the sum of the individual depth doses for the bolus ECT and IMXT plans. The six mean measured planar dose distributions were compared with those calculated by the treatment planning system for all modalities. Dose agreement was assessed using the 4% dose difference and 0.2 cm distance to agreement. RESULTS For the combined high-dose region and low-dose region, pass rates for the parotid and CW plans were 98.7% and 96.2%, respectively, for the bolus ECT plans and 97.9% and 97.4%, respectively, for the mixed beam plans. For the high-dose gradient region, pass rates for the parotid and CW plans were 93.1% and 94.62%, respectively, for the bolus ECT plans and 89.2% and 95.1%, respectively, for the mixed beam plans. For all regions, pass rates for the parotid and CW plans were 98.8% and 97.3%, respectively, for the bolus ECT plans and 97.5% and 95.9%, respectively, for the mixed beam plans. For the IMXT component of the mixed beam plans, pass rates for the parotid and CW plans were 93.7% and 95.8%. CONCLUSIONS Bolus ECT and mixed beam therapy dose delivery to the phantom were more accurate than IMXT delivery, adding confidence to the use of planning, fabrication, and delivery for bolus ECT tools either alone or as part of mixed beam therapy. The methodology reported in this work could serve as a basis for future standardization of the commissioning of bolus ECT or mixed beam therapy. When applying this technology to patients, it is recommended that an electron dose algorithm more accurate than the pencil beam algorithm, e.g., a Monte Carlo algorithm or analytical transport such as the pencil beam redefinition algorithm, be used for planning to ensure the desired accuracy.
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Affiliation(s)
- James A Kavanaugh
- Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, Baton Rouge, LA 70803, USA.
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