International Journal of Radiation Research

en Evaluation of Monaco dose calculation errors for out-of-field regions in intensity modulated radiotherapy of nasopharyngeal cancer Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: The aim of this study is to assess the accuracy of dose calculations by Monaco Treatment Planning System (TPS) for critical organs positioned in out-of-field (OOF) regions during two intensity-modulated radiation therapy (IMRT) techniques in patients diagnosed with nasopharyngeal cancer (NPC). Materials and Methods: Computed tomography (CT) images from 10 NPC patients (aged 54-77 years) were used for treatment planning using 7 and 11 fields IMRT techniques with the Monaco TPS. Doses for organs at risk (OARs) in OOF regions, including the eyes, lenses, and optic nerves, were calculated using the TPS and compared with measurements obtained from the OCTAVIUS 4D phantom. Additionally, dose distributions derived from TPS calculations were compared with measurements using the gamma analysis method, with a threshold dose set at 10% of the maximum dose. Results: Although gamma pass rates exceeded 95% for all patients when OOF regions were excluded, measurements indicated that the Monaco TPS generally underestimated doses to OOF organs by approximately 25%. This underestimation tended to increase with lower dose values, and TPS errors varied across different tissues, including the eyes, lenses, and optic nerves. Conclusion: In conclusion, the Monaco TPS demonstrates significant underestimation errors in dose calculations, especially for organs located in OOF regions during IMRT for NPC patients. Considering the potential risk of secondary cancers, it is imperative to prioritize meticulous attention to ensure precise dose estimation in OOF regions by the TPS.</div> Dose, radiotherapy, nasopharyngeal carcinoma, phantom. 225 232 http://ijrr.com/browse.php?a_code=A-10-1-1314&slc_lang=en&sid=1 D. Sardari sardari@srbiau.ac.ir 7900319475328460030100 7900319475328460030100 Yes Department of Radiation Medical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran E. Saeedzadeh 7900319475328460030101 7900319475328460030101 No Department of Radiation Medical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran L. Karimkhani 7900319475328460030102 7900319475328460030102 No Department of Radiation Medical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran S.R. Mahdavi mahdavi.r@iums.ac.ir 7900319475328460030103 7900319475328460030103 No Radiation Biology Research Center, Medical Physics Department, Iran University of Medical Sciences, Tehran, Iran