Testing of a treatment planning system with beam data from IAEA TECDOC 1540

Abstract

Quality assurance of external-beam treatment-planning systems is recommended, and this can be partly achieved with predefined type tests. The beam data and test geometries of IAEA TECDOC 1540 have been used to test the analytical anisotropic algorithm (AAA) and pencil-beam convolution (PBC) algorithm of the Varian Eclipse treatment planning system. Beam models were created in Eclipse for 6 MV, 10 MV and 18 MV from the available beam data. Twelve test geometries were re-created in Eclipse, and the differences between Eclipse dose calculations and dose measurements were recorded. The AAA algorithm generally performed better than the PBC algorithm for the 12 tests, but both algorithms did not meet predefined tolerances for asymmetric wedge fields. An in-house monitor unit check program based on collimator and phantom scatter factors with tissue-phantom ratios was also tested and its calculations were found to agree with measurements to within 3.2% for on-axis points.

An institutional experience of quality assurance of a treatment planning system on photon beam

“…In the study by Healy and Murry, 25 it was reported that the Eclipse TM analytical anisotropic algorithm (AAA) generally perform better than the PBC algorithm of Eclipse TM , but both algorithms did not meet tolerances for asymmetric wedge fields.…”

“…These authors have reported that the most critical difference occurred for oblique incidence, oblique incidence-off axis, shaped fields and off axis-wedged. Some reports [24][25][26] have demonstrated differences of algorithms for various special regions.…”

Validation of the geometric equivalent field concept in total scatter factor calculations, for half‐, quarter‐ and off‐isocenter asymmetric square fields

“…The S cp (EFC) was calculated from Equation (), which is similar to the head scatter (symbolized as H s or S c ) Equations, defined in previous studies 12,13,14 $$$$\begin{equation} {S_{cp}} \left( {{\mathrm{EFC}}} \right) = \frac{{{R_{EFC}} ({{y_1},{y_2},\ {x_1},\ {x_2},\ r})}}{{{R_{IC}} ({10 \times 10c{m^2}}) \times OAR\left( r \right)}} \end{equation}$$$$where R EFC (y 1 , y 2 , x 1 , x 2 , r) and R IC (10 × 10 cm 2 ) are the charges measured at the location of EFC and IC, respectively, and OAR(r) is the OAR measured in a water phantom for a point at a perpendicular distance r cm from the central axis for the maximum field size (40 × 40 cm 2 ), 27–30 as defined in Equation (). $$$$\begin{equation} OAR \left( r \right) = \frac{{{R_r} ( {40 \times 40\ c{m^2}})}}{{{R_{IC}} ({40 \times 40\ c{m^2}})}} \end{equation}$$$$where R r (40 × 40 cm 2 ) is the measured charge at a distance r from the IC and R IC (40×40 cm 2 ) is the measured charge at the IC for 40 × 40 cm 2 field size.…”

“…where R EFC (y 1 , y 2 , x 1 , x 2 , r) and R IC (10 × 10 cm 2 ) are the charges measured at the location of EFC and IC, respectively, and OAR(r) is the OAR measured in a water phantom for a point at a perpendicular distance r cm from the central axis for the maximum field size (40 × 40 cm 2 ), [27][28][29][30] as defined in…”

A Novel Algorithm in Radiation Dosimetry of Regular and Irregular Treatment Fields

“…For irregularly-shaped fields, the parameter r d is the equivalent field size determined by Clarkson's technique or geometric approximation. [789]…”