Principle
Dosimetry, as a subspecialty of medical physics, deals with the
determination and calculation of dose rates, which is also of great
importance in view of the radiation protection directives. This
experiment demonstrates the principle of measurement and it
explains the various units of absorbed dose, equivalent dose, and
absorbed dose rate. Inside a plate capacitor, an air volume is
irradiated with X-rays. The resulting ion current is used to
determine the dosimetric data.
Tasks
- Using the two different diaphragm tubes and the fluorescent
screen, the given distance between the aperture and the
radiation source at maximum anode voltage and current is to be
determined.
- The ion current at maximum anode voltage is to be measured and
graphically recorded as a function of the capacitor voltage by
using two different beam limiting apertures. The ion dose rate and
the energy dose rate are to be determined from the saturation
current values.
- Using the d = 5 mm aperture, the ion current is to be
determined and graphically recorded at various anode currents but
with maximum anode and capacitor voltages.
- The ion current is to be measured and graphically recorded as a
function of the capacitor voltage at different anode voltages and
the corresponding saturation currents plotted graphically.
What you can learn about
- X-rays
- Absorption inverse square law
- Ionizing energy
- Energy dose
- Equivalent dose and ion dose and their rates
- Q factor
- Local ion dose rate
- Dosimeter