Best Medical Canada - Build-up Caps

By: Thomson & Nielsen Electronics  09-12-2011

Full Photon Range & 15MeV - 18MeV Electrons

MOSFET dosimeters have only 0.8mm inherent build-up, which allows for flexibility in measuring surface dose as well as dose at Dmax. In order to measure dose at Dmax, build-up is required. Measuring accurate dose 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.

  • Maintains isotropic characteristics of the MOSFET dosimeter (±2% for 360°)
  • Lightweight (only 4g) and small (radius: 0.635cm)
  • Ideal for placement on patients
  • Specially grooved for precise placement of the MOSFET
  • May be affixed to the MOSFET for the duration of its life, i.e. 200 doses
  • Easier for therapists to use
  • Saves on patient set-up time
  • Only one build-up cap is required for all energies

Brass is a metal alloy containing mainly copper and zinc compounds. Due to its high density (8.5g/cm3) and to its high Z number (Z ~ 30), it provides the minimal amount of metal needed to achieve full build-up at Dmax for a range of photon energies (4, 6, 10 and 18MV) and some electron energies (15-18MeV)* at a very practical size.

*Note: For low electron energies, it is suggested that no build-up is used. However, if desired, one can use the 1.5cm radius tissue equivalent build-up cap (model TN-RD-55-1.5).

Manufactured exclusively for Best Medical Canada by CIRS using their Plastic Water™, these build-up caps come in sizes of 1cm, 1.5cm, and 2cm (models TN-RD-55-1, TN-RD-55-1.5, TN-RD-55-2 respectively) for various beam energies.  The build-up caps have grooves specifically made for MOSFET dosimeters, allowing accurate measurements.

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