For use with MOSFET Dosimeters
MOSFETs are known to be highly accurate dosimeters that offer a wide range of measurement options, as one MOSFET can be used for all energies and modalities. MOSFET dosimeters have only 0.8mm inherent build-up, which allows for flexibility in measuring surface doses as well as doses at Dmax. In order to measure doses at Dmax, build-up is required. Measuring accurate doses at depth is of primary concern for the physics community when performing patient dosimetry. Precise dose measurement verifies that the target volume area has been treated with the appropriate dose, while sparing surrounding tissue and organs. Current tissue-equivalent build-up caps require a different size for each energy. Best Medical Canada offers a custom designed Build-up Cap for use with MOSFET Dosimeters, which allows for depth dose measurements over a wide range of energies.
Full Photon Range & 15 MeV - 18 MeV Electrons
Brass Build-up Caps – 0.635 cm Radius
In order to maintain the isotropic characteristics of the MOSFET dosimeter (±2% for 360°) and allow for one calibration factor for all energies and modalities, it is recommended that a hemispherical build-up cap be used. This small brass hemisphere is specially grooved for precise placement of the MOSFET and maintains the characteristics which distinguish these devices from other types of dosimeters.
The new brass build-up cap is very lightweight (only 4g) and small (radius: 0.635 cm), which makes it ideal for placement on patients.
This build-up cap may be affixed to the MOSFET for the duration of its life (i.e. 200 doses). Using just one build-up cap for all Photons and some Electron energies makes the dosimeters easier for therapists to use and saves on patient set-up time, as only one dosimeter is required for all energies. Additionally, this method saves time spent on switching between different sizes of build-up for each treatment, e.g. IMRT with multiple energies.