An assessment of GafChromic film for measuring 50 kV and 100 kV percentage depth dose curves.

Percentage depth dose (PDD) curves were obtained for 50 kV and 100 kV x-rays on a Gulmay Medical D3000 DXR unit. Different dosimetry systems were compared including a Scanditronix Wellhofer small volume cylindrical ion chamber, a Wellhofer photon PFD diode, a PTW soft x-ray parallel plate chamber (N23342) and two types of radiochromic film: GafChromic EBT and GafChromic MD55. The PDD curves were also compared to BEAMnrc Monte Carlo predictions. GafChromic film was found to be a valid choice of dosimeter for measuring percentage depth dose curves at 100 kV and 50 kV. All the dosimeters showed agreement with predictions at depths greater than 10 mm, while near the surface GafChromic film and PFD diodes give the best agreement to Monte Carlo values.