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Nichols EM, Bentzen SM, Milburn M, Kesmodel SB, Bellavance E, Becker SJ, Mutaf Y, Tkaczuk K, Rosenblatt P, Feigenberg SJ. A Prospective Trial of Single-Fraction Radiation to the Tumor Bed with a Novel Breast-Specific Stereotactic Radiation Therapy Device: The GammaPod. Adv Radiat Oncol 2024; 9:101398. [PMID: 38778822 PMCID: PMC11110030 DOI: 10.1016/j.adro.2023.101398] [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: 01/27/2023] [Accepted: 09/24/2023] [Indexed: 05/25/2024] Open
Abstract
Purpose Radiation therapy for early-stage breast cancer is typically delivered in a hypofractionated regimen to the whole breast followed by a tumor bed boost. This results in a treatment course of approximately 4 weeks. In this study, the tumor bed boost was delivered in a single fraction as part of a safety and feasibility study for FDA clearance of the device. Methods and Materials Eligible women with early-stage breast cancer underwent lumpectomy followed by radiation therapy. Patients underwent breast immobilization using a system specific to the GammaPod followed by CT simulation, boost treatment planning, and boost treatment delivery all in a single treatment day. Patients then started whole-breast radiation therapy within 1 week of the boost treatment. Patients and treatments were assessed for safety and feasibility. Acute toxicities were recorded. Results A single-fraction boost of 8 Gy was delivered to the tumor bed before a course of whole-breast radiation. The GammaPod treatment was successfully delivered to 14 of 17 enrolled patients. Acute toxicities from all radiation therapy, inclusive of the boost and whole-breast radiation, were limited to grade 1 events. Conclusions The GammaPod device successfully delivered a single-fraction boost treatment to the tumor bed with no change in expected acute toxicities. The results of this study led to FDA clearance of the device through the Investigational Device Exemption process at the FDA. The GammaPod is in clinical use at 4e institutions nationally and internationally, with additional sites pending in 2023.
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Affiliation(s)
- Elizabeth M. Nichols
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Søren M. Bentzen
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | | | | | | | | | | | | | | | - Steven J. Feigenberg
- Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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Zhang-Velten E, Zhang Y, Radpour S, Gu X, Kim DN, Alluri P, Nwachukwu C, Chiu T, Lu W, Parsons D, Tan J, Gillespie J, Stevenson S, Choy H, Timmerman R, Rahimi A. A How-To Compendium for GammaPod Treatments, Clinical Workflow, and Clinical Program at an Early Adopting Institution. Pract Radiat Oncol 2022; 12:e177-e182. [PMID: 35150897 DOI: 10.1016/j.prro.2022.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/18/2021] [Accepted: 01/18/2022] [Indexed: 11/29/2022]
Abstract
Breast irradiation following breast-conserving surgery is an integral part of breast conserving therapy for curative treatment of early-stage breast cancer1-7. With the recognition that the majority of ipsilateral local relapses following breast-conserving therapy occur at the site of the tumor bed, several trials have since investigated the efficacy of accelerated partial-breast irradiation (APBI)8-10 as an alternative to the established but less convenient option of daily whole breast irradiation over several weeks. However, the setup uncertainty and inter-fraction movement expected with 3-dimensional conformal radiation therapy (3D-CRT) APBI has generally required the use of larger planning target volume margin expansions, which ultimately results in a larger dose to normal tissues, as well as an association with worsened cosmesis11-13. A stereotactic partial breast irradiation (S-PBI) approach is needed to allow more precise radiation therapy to the region of the primary tumor. As the GammaPod uses a vacuum assisted breast cup and pump, it allows for smaller CTV margins than 3D-CRT. Here, we describe our methods and workflow for efficient GammaPod S-PBI, as the second institution in the world to go live with GammaPod.
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Affiliation(s)
- Elizabeth Zhang-Velten
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - You Zhang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sepeadeh Radpour
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xuejun Gu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - D Nathan Kim
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Prasanna Alluri
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chika Nwachukwu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tsuicheng Chiu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Weiguo Lu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jun Tan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jennifer Gillespie
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Stella Stevenson
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hak Choy
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Robert Timmerman
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Asal Rahimi
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Chen L, Becker SJ, McAvoy SA, Nichols EM, Guerrero M. Correlation of treatment time to target volume for GammaPod treatments: A simple second calculation. J Appl Clin Med Phys 2022; 23:e13524. [PMID: 35132771 PMCID: PMC8992953 DOI: 10.1002/acm2.13524] [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: 09/04/2021] [Revised: 12/07/2021] [Accepted: 12/20/2021] [Indexed: 11/29/2022] Open
Abstract
Purpose The GammaPod is a novel device for stereotactic breast treatments that employs 25 rotating Co‐60 sources while the patient is continuously translated in three axes to deliver a highly conformal dose to the target. There is no commercial software available for independent second calculations. The purpose of this study is to determine an efficient way to estimate GammaPod treatment times based on target volume and use it as a second calculation for patient‐specific quality assurance. Methods Fifty‐nine GammaPod (Xcision Medical Systems, LLC.) breast cancer patient treatments were used as the fitting dataset for this study. Similar to the Curie‐seconds concept in brachytherapy, we considered dose‐rate × time/(prescribed dose) as a function of target volumes. Using a MATLAB (Mathworks, Natick, MA, USA) script, we generated linear (with 95% confidence interval (CI)) and quadratic fits and tested the resulting equations on an additional set of 30 patients. Results We found a strong correlation between the dose‐rate × time/(prescribed dose) and patients’ target volumes for both the linear and quadratic models. The linear fit was selected for use and using the polyval function in MATLAB, a 95% CI graph was created to depict the accuracy of the prediction for treatment times. Testing the model on 30 additional patients with target volumes ranging from 20 to 188 cc yielded treatment times from 10 to 25 min that in all cases were within the predicted CI. The average absolute difference between the predicted and actual treatment times was 1.0 min (range 0–3.3 min). The average percent difference was 5.8% (range 0%–18.4%). Conclusion This work has resulted in a viable independent calculation for GammaPod treatment times. This method has been implemented as a spreadsheet that is ready for clinical use to predict and verify the accuracy of breast cancer treatment times.
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Affiliation(s)
- Leah Chen
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
| | - Stewart J Becker
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
| | - Sarah Anne McAvoy
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
| | - Elizabeth M Nichols
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
| | - Mariana Guerrero
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
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Yi B, Becker SJ. Simplified method for determining dose to a non-water phantom through the use of N D,w and IAEA TRS 483 for the GammaPod. Phys Med 2021; 88:138-141. [PMID: 34242885 DOI: 10.1016/j.ejmp.2021.05.024] [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: 11/25/2020] [Revised: 05/12/2021] [Accepted: 05/16/2021] [Indexed: 11/26/2022] Open
Abstract
PURPOSE GammaPod, a breast stereotactic radiosurgery device, utilizes 25 rotating Co-60 sources to deliver highly conformal dose distributions. The GammaPod system requires that reference dosimetry be performed in a specific vendor-supplied poly-methylmethacrylate (PMMA) phantom. The nonstandard nature of GammaPod dosimetry, in both the phantom material and machine-specific reference (msr), prohibits use of the American Association of Physicists in Medicine Task Group 51 (TG-51) protocol. This study proposes a practical method using TRS 483 to make the reference dosimetry procedure simpler and to reduce overall uncertainties. METHODS The dose to PMMA (DPMMA) is determined under msr conditions using TRS 483 with an Exradin A1SL chamber placed in a PMMA phantom. The conversion factor, which converts from the dose-to-water (Dw) in broad-beam Co-60 reference geometry to DPMMA in the msr small field Co-60 (Qmsr) geometry, is derived using the Monte Carlo simulations and procedure described in TRS 483. RESULTS The new conversion factor value for an Exradin A1SL chamber is 0.974. When combined with ND,w, DPMMA differs by 0.5% from the TG-21/Nx method and 0.2% from the IROC values. Uncertainty decreased from 2.2% to 1.6%. CONCLUSION We successfully implemented TRS 483 reference dosimetry protocols utilizing ND,w for the GammaPod in the PMMA phantom. These results show not only agreement between measurements performed with the previously published method and independent thermoluminescent dosimetry measurements but also reductions in uncertainty. This also provides readers with a pathway to develop their own IAEA TRS 483 factor for any new small field machine that may be developed.
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Affiliation(s)
- ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Stewart J Becker
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Snider JW, Nichols EM, Mutaf YD, Chen S, Molitoris J, Diwanji T, Becker SJ, Feigenberg SJ. Reproducibility of a novel, vacuum-assisted immobilization for breast stereotactic radiotherapy. J Appl Clin Med Phys 2021; 22:8-15. [PMID: 33656237 PMCID: PMC7984473 DOI: 10.1002/acm2.13127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 10/12/2020] [Accepted: 10/18/2020] [Indexed: 11/13/2022] Open
Abstract
A novel, breast‐specific stereotactic radiotherapy device has been developed for delivery of highly conformal, accelerated partial breast irradiation. This device employs a unique, vacuum‐assisted, breast cup immobilization system that applies a gentle, negative pressure to the target breast with the patient in the prone position. A device‐specific patient loader is utilized for simulation scanning and device docking. Prior to clinical activation, a prospective protocol enrolled 25 patients who had been or were to be treated with breast conservation surgery and adjuvant radiotherapy for localized breast cancer. The patients underwent breast cup placement and two separate CT simulation scans. Surgical clips within the breast were mapped and positions measured against the device’s integrated stereotactic fiducial/coordinate system to confirm reproducible and durable immobilization during the simulation, treatment planning, and delivery process for the device. Of the enrolled 25 patients, 16 were deemed eligible for analysis. Seventy‐three clips (median, 4; mean, 4.6; range, 1–8 per patient) were mapped in these selected patients on both the first and second CT scans. X, Y, and Z coordinates were determined for the center point of each clip. Length of vector change in position was determined for each clip between the two scans. The mean displacement of implanted clips was 1.90 mm (median, 1.47 mm; range, 0.44–6.52 mm) (95% CI, 1.6–2.20 mm). Additional analyses stratified clips by position within the breast and depth into the immobilization cup. Overall, this effort validated the clinically utilized 3‐mm planning target volume margin for accurate, reliable, and precise employment of the device.
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Affiliation(s)
- James W Snider
- Department of Radiation Oncology, University of Alabama at Birmingham Alabama, Birmingham, AL, USA
| | - Elizabeth M Nichols
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Yildirim D Mutaf
- Department of Radiation Oncology, Kaiser Permanente, Dublin, CA, USA
| | - Shifeng Chen
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jason Molitoris
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tejan Diwanji
- Department of Radiation Oncology, University of Miami, Coral Gables, FL, USA
| | - Stewart J Becker
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Steven J Feigenberg
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
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Nichols EM, Guerrero M, McAvoy S, Biggins T, Yi B, Becker SJ. Workflow guide to delivering a safe breast treatment using a novel stereotactic radiation delivery system. JOURNAL OF RADIOSURGERY AND SBRT 2021; 7:249-252. [PMID: 33898089 PMCID: PMC8055237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Affiliation(s)
- Elizabeth M Nichols
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Mariana Guerrero
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Sarah McAvoy
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Terri Biggins
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Stewart J Becker
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Parsons D, Zhang Y, Gu X, Lu W. POD‐DOSI: A dedicated dosimetry system for GammaPod commissioning and quality assurance. Med Phys 2020; 47:3647-3657. [DOI: 10.1002/mp.14221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 11/05/2022] Open
Affiliation(s)
- David Parsons
- Department of Radiation Oncology University of Texas Southwestern Medical Center 2280 Inwood Rd. Dallas TX 75390 USA
| | - You Zhang
- Department of Radiation Oncology University of Texas Southwestern Medical Center 2280 Inwood Rd. Dallas TX 75390 USA
| | - Xuejun Gu
- Department of Radiation Oncology University of Texas Southwestern Medical Center 2280 Inwood Rd. Dallas TX 75390 USA
| | - Weiguo Lu
- Department of Radiation Oncology University of Texas Southwestern Medical Center 2280 Inwood Rd. Dallas TX 75390 USA
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Kopchick B, Xu H, Niu Y, Becker S, Qiu X, Yu C. Technical Note: Dosimetric feasibility of lattice radiotherapy for breast cancer using GammaPod. Med Phys 2020; 47:3928-3934. [PMID: 32640039 DOI: 10.1002/mp.14379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/06/2020] [Accepted: 06/10/2020] [Indexed: 01/16/2023] Open
Abstract
PURPOSE Studies on Lattice radiotherapy (LRT) for breast cancer have been largely lacking. This study investigates the dosimetric feasibility of using Gamma Pod, a stereotactic radiotherapy apparatus originally designed for breast SBRT, to deliver LRT to large, bulky breast tumor as a noninvasive treatment option. METHODS The GammaPod-based LRT was simulated using Geant4 Gate Monte Carlo software. The simulated GammaPod was equipped with 5 mm diameter non-coplanar circular beams that span 28° latitudinally from 18° to 43° off the horizontal plane. Two degrees longitudinal intervals were used to simulate rotating sources. To simulate the treatments to different breast sizes, three water-equivalent hemisphere volumes with diameters of 10, 15, and 20 cm were analyzed. The lattice was planned by spacing focal points 2 cm apart in the transverse and sagittal planes and 2.5 cm in the coronal plane. This resulted in 22-172 shots for full breast treatment. The maximum dose for each individual shot was 20 Gy. The peak-to-valley dose differences and skin dose were analyzed. To verify the feasibility of delivering LRT, a test plan was created and delivered to a commercial diode array dose verification device using a clinical GammaPod system with 15 mm collimators. RESULTS The dose profiles showed the average peak-to-valley dose percent differences of 94.10% in the 10 cm hemispherical volume, 88.95% in the 15 cm hemispherical volume, and 83.60% in the 20 cm hemispherical volume. Average skin dose was 1.27, 1.72, and 2.13 Gy for the 10, 15, and 20 cm irradiation volumes, respectively. The LRT plan delivered using a clinical GammaPod system with larger collimators verified the feasibility of LRT plan delivery. CONCLUSION GammaPod-based lattice radiotherapy is a viable treatment option and its application can be extended to treating large bulky breast tumors.
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Affiliation(s)
| | - Huijun Xu
- University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Ying Niu
- Xcision Medical Systems, Columbia, MD, 21045, USA
| | - Stewart Becker
- University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Xiangyun Qiu
- The George Washington University, Washington, DC, 20052, USA
| | - Cedric Yu
- University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Xcision Medical Systems, Columbia, MD, 21045, USA
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Becker SJ, Culberson WS, Poirier Y, Mutaf Y, Niu Y, Nichols EM, Yi B. Dosimetry evaluation of the GammaPod stereotactic radiosurgery device based on established AAPM and IAEA protocols. Med Phys 2020; 47:3614-3620. [DOI: 10.1002/mp.14197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/23/2020] [Accepted: 04/08/2020] [Indexed: 11/06/2022] Open
Affiliation(s)
- Stewart J. Becker
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Wesley S. Culberson
- Department of Medical Physics University of Wisconsin–Madison Madison Wisconsin 53705 USA
| | - Yannick Poirier
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Yildirim Mutaf
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Ying Niu
- MedStar Georgetown University Hospital Washington DC 20007 USA
| | - Elizabeth M. Nichols
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Byongyong Yi
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
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Becker SJ, Niu Y, Mutaf Y, Chen S, Poirier Y, Nichols EM, Yi B. Development and validation of a comprehensive patient-specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions. J Appl Clin Med Phys 2019; 20:138-148. [PMID: 31833640 PMCID: PMC6909122 DOI: 10.1002/acm2.12778] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 10/18/2019] [Accepted: 10/20/2019] [Indexed: 11/22/2022] Open
Abstract
PURPOSE The GammaPod is a dedicated prone breast stereotactic radiosurgery (SRS) machine composed of 25 cobalt-60 sources which rotate around the breast to create highly conformal dose distributions for boosts, partial-breast irradiation, or neo-adjuvant SRS. We describe the development and validation of a patient-specific quality assurance (PSQA) system for the GammaPod. METHODS We present two PSQA methods: measurement based and calculation based PSQA. The measurements are performed with a combination of absolute and relative dose measurements. Absolute dosimetry is performed in a single point using a 0.053-cc pinpoint ionization chamber in the center of a polymethylmethacrylate (PMMA) breast phantom and a water-filled breast cup. Relative dose distributions are verified with EBT3 film in the PMMA phantom. The calculation-based method verifies point doses with a novel semi-empirical independent-calculation software. RESULTS The average (± standard deviation) breast and target sizes were 1263 ± 335.3 cc and 66.9 ± 29.9 cc, respectively. All ion chamber measurements performed in water and the PMMA phantom agreed with the treatment planning system (TPS) within 2.7%, with average (max) difference of -1.3% (-1.9%) and -1.3% (-2.7%), respectively. Relative dose distributions measured by film showed an average gamma pass rate of 97.0 ± 3.2 when using a 3%/1 mm criteria. The lowest gamma analysis pass rate was 90.0%. The independent calculation software had average agreements (max) with the patient and QA plan calculation of 0.2% (2.2%) and -0.1% (2.0%), respectively. CONCLUSION We successfully implemented the first GammaPod PSQA program. These results show that the GammaPod can be used to calculate and deliver the predicted dose precisely and accurately. For routine PSQA performed prior to treatments, the independent calculation is recommended as it verifies the accuracy of the planned dose without increasing the risk of losing vacuum due to prolonged waiting times.
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Affiliation(s)
- Stewart J. Becker
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Ying Niu
- MedStar Georgetown University HospitalWashingtonDCUSA
| | - Yildirim Mutaf
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Shifeng Chen
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Yannick Poirier
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Elizabeth M. Nichols
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - ByongYong Yi
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
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