| ORIGINAL ARTICLE |
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| Year : 2012 | Volume
: 37
| Issue : 2 | Page : 72-80 |
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Evaluation of PTW Seven29 for tomotherapy patient-specific quality assurance and comparison with ScandiDos Delta 4
Pamela Myers1, Sotirios Stathakis1, Alonso N Gutiérrez1, Carlos Esquivel1, Panayiotis Mavroidis2, Niko Papanikolaou1
1 Department of Radiology and Radiation Oncology, Cancer Therapy and Research Center at University of Texas Health Science Center at San Antonio, 7979 Wurzbach Rd, San Antonio, USA
2 Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, Stockholm, Sweden
Correspondence Address:
Sotirios Stathakis
Department of Radiation Oncology, Cancer Therapy and Research Center at University of Texas Health Science Center at San Antonio, 7979 Wurzbach Rd, San Antonio, TX
USA
DOI: 10.4103/0971-6203.94741
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For routine quality assurance of helical tomotherapy plans, an alternative method, as opposed to the TomoTherapy suggested cylindrical solid water phantom with film and ionization chamber, is proposed using the PTW Seven29 2D-ARRAY inserted in a dedicated octagonal phantom, called Octavius. First, the sensitivity of the array to pitch was studied by varying the pitch during planning to 0.287, 0.433, 1.0, and 2.0. For each pitch selected, the dependence on field size was investigated by generating plans with field widths (FWs) of 1.06 cm, 2.49 cm, and 5.02 cm, for a total of 12 plans. Secondly, a total of 15 patient QA plans were delivered using helical tomotherapy with the Delta 4 and Seven29/Octavius for comparison. Using the clinical gamma criteria, 3% and 3 mm, all FW and pitch plans had a passing percentage of >90%. For patient QA plans, the average gamma pass percentage was 97.0% (94.4-99.8%) for the Delta 4 and 97.6% (92.5-100.0%) for the Seven29/Octavius. Both the Seven29/Octavius and Delta 4 performed to a high standard of measurement accuracy and had a 90% or greater gamma percent for all plans and were considered clinically acceptable. |
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