• Involves the measurement of radiation based on the changes in thermal energy per unit mass of the medium • Based on the fact that almost all the energy deposited in the medium by the radiation beam eventually appears as heat within the medium

calorimetry

• Is based on chemical changes caused by radiation

frickle dosimetry

• When the x-ray film is exposed to ionizing radiation, the exposed silver bromide crystal form a latent image • In the film development process, the affected crystals causes darkening of the film and the unaffected crystal leave the film clear

film dosimetry

• Measurement of radiation energy based on ion pairs produced in a given mass of medium

ionization method

• When a crystal is irradiated, a very minute fraction of the absorbed energy is stored in the crystal lattice • Some of this energy can be recovered later as visible light if the material is heated • This phenomenon of the release of visible photons by thermal means is known as Thermoluminiscence

thermoluminescence dosimetry

heating of TLD crystal to remove unwanted residual signal (400 ° C FOR 3 hours)

annealing

• a small cylindrical detector used in radiotherapy

thrimble chamber

• Defined as the ratio of the dose rate at the depth of maximum dose for the given field size to that for the reference field size (10 x10 cm 2) at its dmax

output factor

• It represents points of equal dose • A set of these curves, normally given in 10% increments normalizes to the dose at the reference depth, can be plotted on a chart • Dose profiles are particularly well suited to the description of field flatness and penumbra

isodose curve

• It is the absorbed dose at a given depth expressed as a percentage of the absorbed dose at a reference depth on the central axis of the field

percent depth dose PDD

• A general term used to refer to the effect on a material which is exposed to radiation

dose

• The radiation dose delivered per unit time

dose rate

• Defined generally as any device that is capable of providing a reading that is measured of the absorbed dose deposited in its sensitive volume by ionizing radiation

dosimeter

• Unit used in linear accelerator to determine the dose • Linear accelerator is calibrated to 1 MU = 1 cGy

monitor unit

• Is tissue equivalent materials that have electron density, physical density, and atomic number similar to that of tissue or water • Is placed directly on the skin surface to even out the irregular patient contour and thereby provide a flat surface for normal beam incidence

bolus

• Are used to produce the same effect as the bolus yet preserve the skin sparing effect of megavoltage photon beams

compensators

• May be used to even out the isodose surfaces for photon beams striking relatively flat patient surface under an oblique beam incidence

wedge filter

• Are used to shield organs at risk, made of lead or Lipowitz's med 10 Which consists of 13.3 % Tin, 50 % Bismuth, 26.7 % Lead and 10 % Cadmium.

blocks