Iranian journal of Pediatric Hematology and Oncology

en Feasibility and Dosimetric Evaluation of Beta-Emitting Sources in Surface Mold Brachytherapy for Oral Rhabdomyosarcoma: A Monte Carlo Study اطفال pediatrics پژوهشي Research Background: This study aimed to evaluate the feasibility and dosimetric characteristics of 90Sr/90Y and 188Re sources for treating superficial oral rhabdomyosarcoma (RMS) using a surface mold brachytherapy approach. Materials and Methods: In this Monte Carlo simulation study, TG-149 dosimetric parameters were calculated to validate the source models. A patient-specific surface mold was then simulated for a 2.0-cm superficial tongue RMS lesion in a 5-year-old child anatomical model based on International Commission on Radiological Protection Publication 156. The effects of radionuclide type, number of active sources per catheter, catheter arrangement, and total number of catheters on dose rate, treatment time, and dosimetric characteristics were evaluated. Also, cylindrical 188Re plaques with a 3.0-cm diameter and thicknesses of 0.1 and 0.2 cm were investigated. Results: Reference dose rates were 0.54 ± 0.00 Gy.min-1.mCi-1 for 90Sr/90Y and 7.24 ± 0.01 cGy.μCi-1.h-1 for 188Re. In the catheter-based design, increasing the number of loaded sources increased dose rate and reduced the flatness (F), while central catheter placement provided the highest dose rate together with lower symmetry (S) and penumbra (P). Increasing the number of catheters from 3 to 20 reduced the treatment time from 2307.4 to 413.7 min for 90Sr/90Y and from 268.5 to 52.4 min for 188Re. For 90Sr/90Y, F ranged from 16.0% to 19.5%, S reached 1.06, and P reached 1.09 cm; corresponding values for 188Re were 15.4%-18.3%, 1.10, and 1.13 cm, respectively. The 0.2-cm-thick 188Re plaque achieved a dose rate of 433.4 cGy.min-1 and reduced treatment time to less than 1 min, but showed F = 22.3% and S = 1.36. Conclusion: Catheter- and plaque-based beta-emitting brachytherapy geometries showed limitations for treating superficial oral RMS at a 0.5-cm prescription depth. These limitations were primarily related to restricted beta-particle penetration and nonuniform lateral dose distribution.   Beta Particles, Brachytherapy, Monte Carlo Method, Rhabdomyosarcoma 1031 1051 http://ijpho.ssu.ac.ir/browse.php?a_code=A-10-1049-4&slc_lang=en&sid=1 Shahriyar Seraj Shahriyar Seraj Shahriyar.Seraj@Gmail.Com 0009-0005-2090-7421 No Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Shiva Rahbar Yazdi Shiva Rahbar Yazdi rahbarshiva108@Gmail.Com 0000-0002-9146-5123 No Department of Medical Physics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Department of Medical Physics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Soroush Najafi Sarvestani Soroush Najafi Sarvestani S.Najafisarvestani@stu.ssu.ac.ir 0009-0000-5477-6240 No Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Mohammad Hosein Zare Mohammad Hosein Zare mhzare2009@Gmail.Com 0000-0002-7823-1146 Yes Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Saeedeh Hajihosseini Saeedeh Hajihosseini s.hosseini.ra@Gmail.com 0009-0008-8276-1538 No Assistant Professor, Medical Nanotechnology and Tissue Engineering Research Science Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Assistant Professor, Medical Nanotechnology and Tissue Engineering Research Science Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran