1. Measurement of Radiation: Instrumentation&Techniques Part Three
The Physics of Radiology
Measurement of Radiation: Instrumentation&Techniques
Part Three
BME College
Sherman Sheen(辛学刚)

2. solid state detectors—the diode
Short response time
High sensitivity
Enormous dynamic range
Flexible forms

3. Thermoluminescent Dosimetry (TLD)
PRECISION OF TLD AND DOSE RANGE
MATERIALS FOR TLD
USES OF TLD-CLINICAL DOSIMETRY
PERSONNEL MONITORING
DOSE CALIBRATION SERVICES

4. Chemical Dosimetry
△Aλ is the change in absorbance at λ following a dose
D to the ferrous sulphate
∈λ is the molar extinction coefficient of the ferrous ion
The energy absorbed from radiation may produce a chemical change in the absorbing medium, and the amount of this may be used to measure dose. One of the most useful chemical radiation dosimeters is the Fricke dosimeter
ρ is the density of the solution in kg/m3
G is the yield in number per 100 eV

5. Example. It is required to determine the average dose to a
sample of water in a complexly shaped radiation container
near a cobalt source. This is most easily done using the
Fricke dosimeter. The container is filled with Fricke solution
and exposed. A sample of the well-mixed irradiated solution
is then placed in a quartz cuvette of 2 cm path length and
its absorbance measured against the stock solution at
304 nm. Suppose the measured absorbance is
Calculate the dose.

6. Film as a Dosimeter radiant energy crystals of silver bromide
latent image
File developed
film fixed
X rays have the property of affecting a film in much the same way as light. The film contains very small crystals of silver bromide. When radiant energy strikes these crystals, they become more susceptible to chemical change and form what is referred to as a latent image. When the film is developed, the crystals that have been altered by the radiation are reduced to small grains of metallic silver. The film is then fixed; this dissolves the unaffected silver bromide, leaving a clear film, but does not affect the metallic silver. Thus areas that have been exposed to x rays appear dark and a negative film results
negative film results
areas that have been exposed to x rays appear dark