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Ohira S, Ueda Y, Nishiyama K, Miyazaki M, Isono M, Tsujii K, Takashina M, Koizumi M, Kawanabe K, Teshima T. Couch height-based patient setup for abdominal radiation therapy. Med Dosim 2015; 41:59-63. [PMID: 26553471 DOI: 10.1016/j.meddos.2015.08.003] [Citation(s) in RCA: 3] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/03/2015] [Indexed: 10/22/2022]
Abstract
There are 2 methods commonly used for patient positioning in the anterior-posterior (A-P) direction: one is the skin mark patient setup method (SMPS) and the other is the couch height-based patient setup method (CHPS). This study compared the setup accuracy of these 2 methods for abdominal radiation therapy. The enrollment for this study comprised 23 patients with pancreatic cancer. For treatments (539 sessions), patients were set up by using isocenter skin marks and thereafter treatment couch was shifted so that the distance between the isocenter and the upper side of the treatment couch was equal to that indicated on the computed tomographic (CT) image. Setup deviation in the A-P direction for CHPS was measured by matching the spine of the digitally reconstructed radiograph (DRR) of a lateral beam at simulation with that of the corresponding time-integrated electronic portal image. For SMPS with no correction (SMPS/NC), setup deviation was calculated based on the couch-level difference between SMPS and CHPS. SMPS/NC was corrected using 2 off-line correction protocols: no action level (SMPS/NAL) and extended NAL (SMPS/eNAL) protocols. Margins to compensate for deviations were calculated using the Stroom formula. A-P deviation > 5mm was observed in 17% of SMPS/NC, 4% of SMPS/NAL, and 4% of SMPS/eNAL sessions but only in one CHPS session. For SMPS/NC, 7 patients (30%) showed deviations at an increasing rate of > 0.1mm/fraction, but for CHPS, no such trend was observed. The standard deviations (SDs) of systematic error (Σ) were 2.6, 1.4, 0.6, and 0.8mm and the root mean squares of random error (σ) were 2.1, 2.6, 2.7, and 0.9mm for SMPS/NC, SMPS/NAL, SMPS/eNAL, and CHPS, respectively. Margins to compensate for the deviations were wide for SMPS/NC (6.7mm), smaller for SMPS/NAL (4.6mm) and SMPS/eNAL (3.1mm), and smallest for CHPS (2.2mm). Achieving better setup with smaller margins, CHPS appears to be a reproducible method for abdominal patient setup.
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Affiliation(s)
- Shingo Ohira
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan; Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yoshihiro Ueda
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan; Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kinji Nishiyama
- Department of Radiation Oncology, Yao Municipal Hospital, Yao, Japan
| | - Masayoshi Miyazaki
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Masaru Isono
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Katsutomo Tsujii
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Masaaki Takashina
- Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan
| | - Masahiko Koizumi
- Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kiyoto Kawanabe
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
| | - Teruki Teshima
- Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
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