BLOCK 7: IONIZING RADIATION - Unit 8: Sources, Uses, and Production of X-Rays (complete)

Question 1

Typical x-ray sources, fixed and portable, found at an AF installation are _____________ and ____________ use sources.

Answer 1

MEDICAL and INDUSTRIAL use sources

Question 2

Medical uses can be broken into two groups: ___________ and ___________

Answer 2

DIAGNOSTIC and THERAPEUTIC

Question 3

_______________ machines are generally used for fixed, short-pulse duration procedures (conventional x-ray) and fluoroscopy, where the exposure duration is controlled real-time by an operator.

Answer 3

DIAGNOSTIC

Question 4

_______________ x-rays are used to treat patients with certain diseases, such as some forms of cancer.

Answer 4

THERAPEUTIC

Question 5

Outside of the medical treatment facility, x-ray machines used in ___________________________ are the most common type of x-ray machine in the AF.

Answer 5

NONDESTRUCTIVE INSPECTION (NDI)

Question 6

Converts electrical power to useful x-rays that expose film.

Answer 6

X-RAY TUBE

Question 7

An x-ray tube consists essentially of the following four components:

Answer 7

• Cathode
• Anode
• Sealed glass envelope
• Protective housing

Question 8

A filament that releases electrons when heated sufficiently.

Answer 8

CATHODE

A large electrical potential is created between the cathode and the anode. Electrons released from the cathode are strongly attracted to the anode target.

Question 9

An electrode through which electric current flows from an outside source.

Answer 9

ANODE

The anode attracts the electrons from the cathode. The anode is also connected to the metal target material, which has a high melting point and a high atomic number.

Question 10

Surrounding the cathode and anode is a ____________________ that is made of leaded glass (glass mixed with lead) to filter out some of the lower energy photons.

Answer 10

GLASS ENVELOPE

The interior is kept under a partial vacuum to prevent scattering and ionization interactions with air molecules that would result in loss of energy. The window is that portion of the envelope through which the more useful x-rays exit the tube.

Question 11

The __________________, along with its x-ray tube, oil bath, cooling fan, and filtration, make up what is called the tube head.

Answer 11

PROTECTIVE HOUSING

One of the main purposes of the housing, which is of interest to BE, is shielding. During this process, the x-rays produced emerge in all directions. The shielding in the housing is designed to limit the exit of x-rays to the window. Potential radiation leakage from a tube head may cause unnecessary exposures and is one major concern during x-ray scatter surveys.

Question 12

__________ is the major factor that limits the life of the x-ray tube.

Answer 12

HEAT

Question 13

The _______________ setting on an x-ray machine controls the number of electrons fired from the filament.

Answer 13

MILLIAMPERES (mA)

Increasing the mA setting causes the filament to heat up more and to send out more electrons. More electrons results in more x-rays and more exposure.

Question 14

The ____________________ setting controls the voltage applied between the cathode and anode and, thus, the speed (or energy) of the electrons.

Answer 14

KILOVOLT PEAK (kVp)

A high kVp gives the electrons more energy, so that they may produce more high-energy x-rays for greater penetration.

Question 15

Controls how long x-rays are being produced. In many modern medical xrays, this could be in the milliseconds (ms). When evaluating an industrial-use x-ray unit, such as in a non-destructive inspection (NDI), it could vary from a few seconds to several minutes.

Answer 15

EXPOSURE TIME (S)