Radiation Monitoring

Question 1

Purpose of personnel radiation monitoring dosimeters

Answer 1

1. Provides an indication of the working habits and working conditions of diagnostic imaging personnel.
2. Determines occupational exposure by detecting and measuring the quantity of ionizing radiation to which the dosimeter has been exposed to.

Question 2

Dosimeters

Answer 2

Devices that detect and measure the amount of ionizing radiation to which it has been exposed to

Question 3

Placement of the dosimeter

Answer 3

• when aprons are not used, it should be attached to the clothing at the collar level on the anterior part of the body
• When aprons are used, the dosimeter should be worn outside the apron at collar level on the anterior surface of the body because of the unprotected head neck and lenses of the eye receive 10 to 20 times than the covered parts.

Question 4

Why should a dosimeter be placed at collar level

Answer 4

• to approximate the location of maximal radiation on the thyroid, neck and head
• It provides the reading of the approximate equivalent dose to thyroid glands and eyes of the exposed person.

Question 5

Characteristics of personal dosimeters

Answer 5

• should be light weight and easy to carry
• Should be made of materials durable enough to tolerate Norma daily use.
• Outside influences should not affect the performance of the dosimeter e.g humidity, temp, warm water

Question 6

Types of dosimeters

Answer 6

• Film badges
• Thermoluminescent dosimeters
• Optically stimulated luminescence dosimeters

Question 7

Film badges.

Answer 7

A type of dosimeter that record whole-body radiation exposure accumulated at a low rate over a long period of time.

Question 8

Parts of a film badge

Answer 8

1. A durable lightweight plastic film holder
2. An assortment of metal filters
3. A film packet which contains a radiographic film

Question 9

Properties of the film holder in film badges

Answer 9

1. Made of plastic material with low atomic number to filter low energy x-rays, gamma and beta particles

Question 10

What material is used to make the filters in film badges

Answer 10

1. Aluminum or copper
   Allow the measurement of the approximate energy of the radiation reaching the dosimeter.

Question 11

How can one know the direction from which the radiation has reached the film in film badges.

Answer 11

• the direction can be estimated from the appearance of the filter shadows imaged on the processed dosimetry film

Question 12

Functions of filter images in film badges.

Answer 12

• to determine the direction of radiation when it hit the badge
• To determine whether the exposure was as a result of excessive scattered radiation or a single exposure beam.

Question 13

How can a radiographer know that the exposure was from excessive scatter or single beam exposure.

Answer 13

• for excessive scattered radiation result in a relatively fuzzy image of the filters because the film badges was irradiated from many different angles.
• A single exposure beam results in a sharply defined image, because the ray came from a single direction.

Question 14

What is a densitometer

Answer 14

A device that measures optical density, the intensity of light transmitted through a given area of the dosimetry film and compares it with intensity of light incident on the anterior side of the film.

Question 15

How is the amount of radiation to which the film was exposed determined in film badges.

Answer 15

• Is determined by locating the exposure value of a control film of a similar optical density on a characteristic curve.