AbstractID: 8210 Title: Comparison of Various Kodak Films and PinPoint Chamber for Dosimetry of
Radiosurgery Beams
In this study, we compare three different Kodak films, X-Omat V, X-Omat TL, and Extended Dose Range Film (EDR), to the PTW
PinPoint ion chamber (0.015 cm3 measuring volume) for dosimetry of the fields employed in stereotactic radiosurgery. Tissue
maximum ratios (TMR) were measured on a Varian 2100C linear accelerator for a 6 MV photon beam, and small circular cones
ranging from 5 mm to 40 mm in diameter. The measurements were performed in a solid water phantom for depths varying between 0
and 20 cm. Beam profiles were also measured using the three types of film, at the depth of 5 cm and SAD of 100 cm. The TMR
measurements showed a very good agreement (less than 1%) between the PinPoint ion chamber and the EDR and the X-Omat V films
for all depth of measurements, with the exception of the 20 cm depth where the deviation was found to be 2%. The X-Omat TL film
also agrees well with the data obtained with the PinPoint chamber for depths less than 15 cm. However, a 3% deviation was found for
depths between 15 and 20 cm. The results of beam profiles measurements illustrate differences between the three types of film, which
occur at 10-40% of the dose level.