ABSTRACT
The Monte Carlo (MC) method performs calculation of photon and electron tracks within the linear accelerator and patient tissues, and as such imitates how radiation is physically delivered to the patient. Decisions about the acceptable amount of statistical jitter in MC isodose distributions should be made with input from the clinical team and should include consideration of the uncertainty in the three-dimensional (3D) dose distribution in the target as well as surrounding normal organs. Detailed simulation of photon and electron interactions in the linac treatment head can provide a wealth of information about the spatial, energy, and angular fluence distributions of particles interacting in different components of the treatment head. Beamlet calculations for intensity-modulated radiotherapy (IMRT) optimization are often still computed using pencil-beam (PB) algorithms, primarily because of the large calculation time required to perform the many MC-based beamlet calculations required for inverse planning. MC simulations model radiation transport and energy deposition in realistic patient/treatment geometries.
