Aim: This
study aims to evaluate the difference between depth data from an intraoral cone
and a conventional irradiation tube calculated using a treatment planning
system (TPS), and that measured using an intraoral cone for electron
radiotherapy. Background: A TPS is only compatible with conventional
irradiation tubes. However, such systems are not suitable for determining dose
distributions when a special cone is employed. Materials and Methods: Dose distributions were calculated using the beam data for mounted intraoral
cones using a TPS. Then, the dose distribution by field size was calculated for
a low-melting-point lead alloy using the beam data for a mounted conventional
tube. The calculated data were evaluated against the measured intraoral-cone
depth data based on the dose and depth differences. Results: The
calculated data for the intraoral cone case did not match the measured data.
However, the depth data obtained considering the field size determined for the
lead alloy using the conventional tube were close to the measured values for
the intraoral cone case. The difference in the depth at which the absorbed dose
was 50% of the maximum value of the percentage depth dose was less than ±4 mm
for the generalized Gaussian pencil beam convolution algorithm and less than ±1
mm for the electron Monte Carlo algorithm. Conclusion: It was found that
the measured and calculated dose distributions were in agreement, especially
when then electron Monte Carlo algorithm was used. Thus, the TPS can be
employed to determine dose distributions for intraoral cone applications.
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