The diagram shows a radiographer preparing a patient for a diagnostic scan. A sealed gamma source is outside the body, and a detector is on the other side. ...

The diagram shows a radiographer preparing a patient for a diagnostic scan. A sealed gamma source is outside the body, and a detector is on the other side. Different tissues absorb different amounts of gamma radiation, allowing an image to be produced. The radiographer stands behind a movable lead-glass screen and uses a remote control. The radiation is ionising, so exposure time is kept as short as possible while enough counts are collected to give a clear image.

(a) What type of radiation is used in this scan? [1]
(b) Which property of gamma radiation allows some of it to reach the detector through the patient? [1]
(c) When planning the scan, state two ways the radiographer reduces the dose received by staff. [2]
(d) What damage can ionising radiation cause to body cells? [1]

A space agency tests a radiation badge worn by engineers who work near satellite components. Fig. 1 shows the badge before it is sent to a laboratory. The plastic holder contains a small photographic film and filters of different materials. Ionising radiation darkens the film. Comparing the darkness behind each filter helps the laboratory estimate the type and amount of radiation received. The badge does not protect the engineer, so it must be worn in the correct position and checked regularly.

(a) What is measured by the darkness of the film? [1]
(b) Which statement is correct: a badge prevents radiation reaching the body, or a badge records exposure? [1]
(c) When engineers receive a high badge reading, state two actions their employer should take. [2]
(d) What makes ionising radiation a health risk? [1]