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Cui G, Duan J, Yang Y, Yin F. Technical Note: Investigation of the dosimetric impact of stray radiation on the Common Control Unit of the IBA Blue Phantom 2. J Appl Clin Med Phys 2020; 21:191-196. [PMID: 31729812 PMCID: PMC6964763 DOI: 10.1002/acm2.12769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/03/2019] [Accepted: 10/11/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE This technical note aims to investigate the dosimetric impact of stray radiation on the Common Control Unit (CCU) of the IBA Blue Phantom2 and the measured beam data. METHODS Three CCUs of the same model were used for the study. The primary test CCU was placed at five distances from the radiation beam central axis. At each distance, a set of depth dose and beam profiles for two open and two wedge fields were measured. The field sizes were 10 × 10 cm2 and 30 × 30 cm2 for the open fields, and 30 × 30 cm2 and 15 × 15 cm2 for the 30° and 60° wedges, respectively. The other two CCUs were used to cross check the data of the primary CCU. Assuming the effect of stray radiation on the data measured at the farthest reachable distance 4.5 m is negligible, the dosimetric impact of stray radiation on the CCU and consequently on the measured data can be extracted for analysis by comparing it with those measured at shorter distances. RESULTS The results of three CCUs were consistent. The dosimetric impact of stray radiation was greater for lower energies at larger field sizes. For open fields, the data variation was up to 4.5% for depth dose curves and 7.1% for beam profiles. For wedge fields, the data variation was up to 9.3% for depth dose curves and 10.6% for beam profiles. Moreover, for wedge field profiles in the wedge direction, they became flatter as the CCU was placed closer to the primary radiation beam, manifesting smaller wedge angles. CONCLUSION The stray radiation added a uniform background noise on all measured data. The magnitude of the noise is inversely proportional to the square of the distance of the CCU to the primary radiation beam, approximately following the inverse square law.
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Affiliation(s)
- Guoqiang Cui
- Department of Radiation OncologyDuke University Medical CenterDurhamNCUSA
| | - Jun Duan
- Department of Radiation OncologyDuke University Medical CenterDurhamNCUSA
| | - Yun Yang
- Department of Radiation OncologyDuke University Medical CenterDurhamNCUSA
| | - Fang‐Fang Yin
- Department of Radiation OncologyDuke University Medical CenterDurhamNCUSA
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Knutson NC, Schmidt MC, Belley MD, Nguyen N, Price M, Mutic S, Sajo E, Li HH. Equivalency of beam scan data collection using a 1D tank and automated couch movements to traditional 3D tank measurements. J Appl Clin Med Phys 2018; 19:60-67. [PMID: 30188009 PMCID: PMC6236829 DOI: 10.1002/acm2.12444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 07/16/2018] [Accepted: 08/04/2018] [Indexed: 12/18/2022] Open
Abstract
This work shows the feasibility of collecting linear accelerator beam data using just a 1‐D water tank and automated couch movements with the goal to maximize the cost effectiveness in resource‐limited clinical settings. Two commissioning datasets were acquired: (a) using a standard of practice 3D water tank scanning system (3DS) and (b) using a novel technique to translate a commercial TG‐51 complaint 1D water tank via automated couch movements (1DS). The Extensible Markup Language (XML) was used to dynamically move the linear accelerator couch position (and thus the 1D tank) during radiation delivery for the acquisition of inline, crossline, and diagonal profiles. Both the 1DS and 3DS datasets were used to generate beam models (BM1DS and BM3DS) in a commercial treatment planning system (TPS). 98.7% of 1DS measured points had a gamma value (2%/2 mm) < 1 when compared with the 3DS. Static jaw defined field and dynamic MLC field dose distribution comparisons for the TPS beam models BM1DS and BM3DS had 3D gamma values (2%/2 mm) < 1 for all 24,900,000 data points tested and >99.5% pass rate with gamma value (1%/1 mm) < 1. In conclusion, automated couch motions and a 1D scanning tank were used to collect commissioning beam data with accuracy comparable to traditionally acquired data using a 3D scanning system. TPS beam models generated directly from 1DS measured data were clinically equivalent to a model derived from 3DS data.
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Affiliation(s)
- Nels C Knutson
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, 01852, USA.,Department of Radiation Oncology, Rhode Island Hospital, The Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Matthew C Schmidt
- Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, 01852, USA.,Department of Radiation Oncology, Rhode Island Hospital, The Alpert Medical School of Brown University, Providence, RI, 02903, USA.,Education Department, Varian Medical Systems, Las Vegas, NV, 89119, USA
| | - Matthew D Belley
- Department of Radiation Oncology, Rhode Island Hospital, The Alpert Medical School of Brown University, Providence, RI, 02903, USA.,Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Ngoc Nguyen
- Department of Radiation Oncology, Rhode Island Hospital, The Alpert Medical School of Brown University, Providence, RI, 02903, USA.,Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Michael Price
- Department of Radiation Oncology, Rhode Island Hospital, The Alpert Medical School of Brown University, Providence, RI, 02903, USA.,Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Erno Sajo
- Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, 01852, USA
| | - H Harold Li
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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