Instruments Used for X-Ray Detection

DOE-HDBK-1109-97

Radiological Safety Training for Radiation-Producing (X-Ray) Devices

Student's Guide

Selection of the appropriate instrument based on type and energy of radiation and on

radiation intensity.

Correct operation of the instrument based on the instrument operating characteristics and

limitations.

Calibration of the instrument to a known radiation field similar in type, energy, and

intensity to the radiation field to be measured.

Instruments Used for X-Ray Detection

It is important to distinguish between detection and measurement of X-rays. Equipment

users often use a detector to detect the presence of X-rays, for example, to verify that the

device is off before entry into the area. The measurement of X-rays is normally the job of

a qualified Radiological Control Technician.

Measurement of radiation dose rates and surveys of record require an instrument that reads

roentgen or rem (R/hour, mR/hour, rem/hour, mrem/hour) rather than counts per minute

(cpm) or disintegrations per minute (dpm). Ion chambers measure energy deposited and

are good instruments for measuring X-ray radiation dose levels.

Instruments such as Geiger-Mueller (GM) counters are effective for detection of radiation

because of their good sensitivity. However, because both low-energy and high-energy

photons discharge the counter, GM counters do not quantify a dose well. A thin-window

GM counter is the instrument of choice for the detection of X-rays. However, this is not

the instrument of choice for measurement of X-ray dose.

ii. Facility-Specific Instrumentation.

(Insert facility-specific information on instrumentation, as appropriate.)