Stereotactic radiosurgery-radiotherapy: Should Monte Carlo treatment planning be used for all sites?

Purpose: To evaluate a Monte Carlo (MC) treatment planning system for CyberKnife treatments of cranial and extracranial lesions and determine whether it is necessary for all treatment sites. Dose distributions are compared to those calculated with a ray-tracing algorithm. Maximum doses and dose-volume histograms for the target and selected critical structures are analyzed.

Comparison of planned dose distributions calculated by Monte Carlo and Ray-Trace algorithms for the treatment of lung tumors with cyberknife: a preliminary study in 33 patients.

Purpose: To compare dose distributions calculated using the Monte Carlo algorithm (MC) and Ray-Trace algorithm (effective path length method, EPL) for CyberKnife treatments of lung tumors.

Materials And Methods: An acceptable treatment plan is created using Multiplan 2.1 and MC dose calculation.

Dosimetric verification of intensity modulated radiation therapy of 172 patients treated for various disease sites: comparison of EBT film dosimetry, ion chamber measurements, and independent MU calculations.

Three independent dose verification methods for intensity modulated radiation therapy (IMRT) were evaluated. Planar IMRT dose distributions were delivered to EBT film and scanned with the Epson Expression 1680 flatbed scanner. The measured dose distributions were then compared to those calculated with a Pinnacle treatment planning system.

Accuracy of dose measurements and calculations within and beyond heterogeneous tissues for 6 MV photon fields smaller than 4 cm produced by Cyberknife.

For the small radiation field sizes used in stereotactic radiosurgery, lateral electronic disequilibrium and steep dose gradients exist in a large portion of these fields, requiring the use of high-resolution measurement techniques. These relatively large areas of electronic disequilibrium make accurate dosimetry as well as dose calculation more difficult, and this is exacerbated in regions of tissue heterogeneity. Tissue heterogeneity was considered insignificant in the brain where stereotactic radiosurgery was first used.

Evaluation of GAFCHROMIC EBT film for Cyberknife dosimetry.

External beam therapy (EBT) GAFCHROMIC film is evaluated for dosimetry and characterization of the CyberKnife radiation beams. Percentage depth doses, lateral beam profiles, and output factors are measured in solid water using EBT GAFCHROMIC film (International Specialty Products, Wayne, NJ) for the 6 MV radiation beams of diameter 5 to 60 mm produced by the CyberKnife (Accuray, Sunnyvale, CA). The data are compared to those measured with the PTW 60008 diode and the Wellhofer CC01 ion chamber in water.

Comparison of the epson expression 1680 flatbed and the vidar VXR-16 dosimetry PRO film scanners for use in IMRT dosimetry using gafchromic and radiographic film.

Intensity-modulated radiotherapy (IMRT) treatment plan verification is often done using Kodak EDR2 film and a Vidar Dosimetry PRO film digitizer. However, since many hospitals are moving towards a filmless environment, access to a film processor may not be available. Therefore, we have investigated a newly available Gafchromic EBT film for IMRT dosimetry.

Multigroup discrete ordinates modeling of 125I 6702 seed dose distributions using a broad energy-group cross section representation.

Our purpose in this work is to demonstrate that the efficiency of dose-rate computations in 125I brachytherapy, using multigroup discrete ordinates radiation transport simulations, can be significantly enhanced using broad energy group cross sections without a loss of accuracy. To this end, the DANTSYS multigroup discrete ordinates neutral particle transport code was used to estimate the absorbed dose-rate distributions around an 125I-model 6702 seed in two-dimensional (2-D) cylindrical R-Z geometry for four different problems spanning the geometries found in clinical practice. First, simulations with a high resolution 210 energy groups library were used to analyze the photon flux spectral distribution throughout this set of problems.