ORTHOVOLTAGE RADIATION-THERAPY TREATMENT PLANNING USING MONTE-CARLO SIMULATION - TREATMENT OF NEUROENDOCRINE CARCINOMA OF THE MAXILLARY SINUS

Dose distributions that result from treating a patient with orthovolta ge beams are best determined with a treatment planning system that use s the Monte Carlo method, and such systems are not readily available. In the present work, the Monte Carlo method was used to develop a comp uter code for determining absorbed dose distributions in orthovoltage radiation therapy. The code was used in planning treatment of a patien t with a neuroendocrine carcinoma of the maxillary sinus. Two lateral high-energy photon beams supplemented by an anterior orthovoltage phot on beam were utilized in the treatment plan. For the clinical case and radiation beams considered, a reasonably uniform dose distribution (/-10%) is achieved within the target volume, while the dose to the len s of each eye is 4-8% of the prescribed dose. Therefore, an orthovolta ge photon beam, when properly filtered and optimally combined with meg avoltage beams, can be effective in the treatment of cancers below the skin, providing that accurate treatment planning is carried out to es tablish with accuracy and precision the doses to critical structures.