4.4a Dosimetry Codes of Practice Flashcards
What is the primary standard dosimeter for kV photons (low energy)?
Free air ionisation chamber
What is the Secondary Standard dosimeter for kV photons (low energy)?
Thimble/ sueprficial parallel plate
What is the field instrument for kV photons (low energy)?
Farmer/ superfiical parallel plate chamber
What quantity is kV dose measured in?
Air KERMA
What is the beam/energy quality index of kV photons (low energy)?
Half Value Layer
What is the Primary Standard (at NPL) for mV photons (high energy)?
e.g. from a Linac
Calorimeter - graphit
What is the Secondary Standard (at NPL) for mV photons (high energy)?
e.g. from a Linac
Thimble chamber
What is the Field Instrument for mV photons (high energy)?
e.g. from a Linac
Farmer chamber
How is the quantity (dose) measured for mV photons?
Absorbed dose to water
What is the beam/energy quality index for mV photons?
Tissue Phantom Ratios
TPR20/10
What is the Primary Standard (at NPL) for MeV electrons (high energy)?
Calorimeter (graphite)
What is the Secondary Standard for MeV electrons (high energy)?
Parallel plate chamber
What is the Field instrument for MeV electrons (high energy)?
Parallel plate chamber
How is the quantity dose of MeV electrons measured?
Absorbed dose to water
How is the beam/energy of MeV electron beam quality measured?
R50,D (Z Ref)
Depth, in water, along the beam’s central axis at which the dose is 50% of the max
aka the depth at which the depth dose curve has dropped to 50%
