Phantom Verification of AAA and Acuros Dose Calculations for Lung Cancer: Do Tumor Size and Regression Matter?
Autor: | Michael P. Grams, Satomi Shiraishi, Luis E. Fong de los Santos, Yolanda I. Garces, John A. Antolak, Sean S. Park, Kenneth R. Olivier |
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Rok vydání: | 2018 |
Předmět: |
Organs at Risk
Dose calculation medicine.medical_treatment Dose profile Imaging phantom 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine Neoplasms medicine Humans Radiology Nuclear Medicine and imaging Lung cancer Tumor size business.industry Phantoms Imaging Radiotherapy Planning Computer-Assisted Radiotherapy Dosage medicine.disease Regression Radiation therapy Oncology 030220 oncology & carcinogenesis Lung tumor Radiotherapy Intensity-Modulated Nuclear medicine business |
Zdroj: | Practical radiation oncology. 9(1) |
ISSN: | 1879-8519 |
Popis: | Purpose This study aimed to evaluate dose calculation accuracy for the Eclipse Analytical Anisotropic Algorithm (AAA) and Acuros XB algorithm for various lung tumor sizes and to investigate dosimetric changes associated with treatment of regressing tumors. Methods and materials A water phantom with cylindrical cork inserts (lung surrogates) was fabricated. Large (202 cm3), medium (54 cm3), and small (3 cm3) solid water tumors were implanted within cork inserts. A plain cork insert was used to simulate a lung without a tumor. The cork inserts and tumors were cut along the long axis, and Gafchromic film was placed between the sections to measure dose distributions. Three-dimensional conformal plans were created using 6 MV and 10 MV beams, and volumetric modulated arc therapy plans were created using 6 MV beams for each tumor size. Doses were calculated using Eclipse AAA and Acuros XB. The measured and calculated dose distributions were compared for each tumor size and treatment algorithm. To simulate a regressing tumor, the original plans created for the large tumor were separately delivered to the phantom that contained a small, medium, or no tumor. The dosimetric effects were evaluated using gamma passing rates with a 2%/2 mm criterion and dose profile comparisons. Results Agreement between the measurements and AAA calculations decreased as tumor size decreased, but Acuros XB showed better agreement for all tumor sizes. The largest difference was observed for a 6 MV volumetric modulated arc therapy plan created to treat the smallest tumor. The gamma passing rate was 89.7% but that of Acuros was 99.5%. For the tumor regression evaluation, the gamma passing rates ranged from 53% to 99% for AAA. For Acuros XB, the gamma passing rates were >98% for all scenarios. Conclusion Both AAA and Acuros XB calculated the dose accurately for the largest lung tumor. For the smallest and regressing tumors, Acuros XB more accurately modelled the dose distribution compared with AAA. |
Databáze: | OpenAIRE |
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