Common dosimeters

Calculate the exposure to a 0.6cc ionization chamber which collect 12nC of charge. Air density = 0.0013g/cc

• 55R

• 60R

• 67R

• 91R

What types of detectors rely on gas multiplication? (Select all that apply)

• Bubble detectors

• Proportional counters

• Geiger-Mueller counters

• Ionization chambers

Ion chamber charge is _____ the pressure of the gas in the chamber.

• • Not related to

• • Proportional to the inverse square of

• Directly proportional to

• • Proportional to the square of

A 0.6cc ion chamber records 21nC/Gy for a given beam. How many nC per Gy should a chamber with a sensitive volume of 27cc record?

• • 247nC/Gy

• • 827nC/Gy

• • 1017nC/Gy

• 945nC/Gy

Which of the following is not a property of an ideal scintillator?

• • Linear light production with energy deposition.

• High attenuation of its own scintillation wavelength

• High light yield

• Short decay time

A Geiger-Mueller detector can be used to determine what? (Select all that apply)

• Rate of incident ionizing radiation particles

• • Energy of incident radiation

• Presence of ionizing radiation

• • Radiation type (charged or uncharged)

Which of the following is not a desirable attribute of a standard inert gas filled Geiger Muller counter?

• • Rapid readout

• • Detects a wide range of exposure rates

• • Readily transported

• Able to detect neutron sources

What region of the gas amplification curve has sufficient voltage to prevent ion recombination but insufficient voltage to produce secondary ionizations?

• • Region V: Geiger-Muller

• • Region III: Proportional Region

• Region II: Ionization Region

• • Region VI: Continuous Discharge Region

A digitizer gives reads a transmittance value of 0.15 for a given film. What optical density would be measured through two such films?

• • 0.82

• • -0.82

• 1.65

• • -1.65

Which statement is not a benefit of film dosimeters?

• • Low energy dependence for MV fields

• • Low dose rate dependence

• • Very high spatial resolution

• Very accurate absolute dose measurement