VT120 Radiology Part 1

What transformer in an x-ray machine controls the temperature of the filament?

Step-down transformer

The target of an x-ray machine is a/an

Area of the anode struck by electrons during an exposure

Aluminum filters remove what part of the x-ray beam?

Low energy

A veterinary technician notes that a film is too dark, and there is minimal contrast (everything is gray). What is the most appropriate adjustment to be made to improve the quality of the repeat film?

decrease kVp

RAD stands for

radiation absorbed dose

Which of the following does not affect radiographic density?

object-film distance

The minimum lead equivalence for protective radiographic aprons and gloves is

0.25 mm

The minimum standard of lead equivalent for protective aprons and gloves is

0.5mm

The maximum permissible dose (MPD) for whole-body radiation per year in sieverts is

0.05

What device offers technicians the least protection from x-radiation?

Dosimeter badge

When must radiographs be labeled for certification organizations and for legal purposes?

During or after exposure but before processing

The kilovoltage electrical circuit controls the

Electrical potential between the cathode and the anode

The "target" in an x-ray tube is the area where the

Electrons impact the anode

Fog on the unexposed area of a processed radiographic film indicates

Exposure to extraneous light

What is the term used to describe the tube-to-film distance?

Focal-film distance

When taking radiographs, the veterinary technician should

Maximize distance between themself and x-ray sources

A radiation film badge worn at the collar level

Monitors exposure of the thyroid gland and lenses of the eyes

How often are radiation-monitoring film-badge reports usually submitted?

Monthly

The exposure factors from a standard technique chart should be modified by decreasing the mAs by 50% for which of the following patients?

Neonatal dog

Which of the following does not affect radiographic density?

Object-film distance

If a radiographic film appears overexposed, is it too light or too dark? Would you increase or decrease the exposure to improve the quality?

Too dark, decrease exposure

Information regarding the maximum safe exposure time that can be used without damaging the machine may be found on the

Tube rating chart

The filament of an x-ray tube is the

Tungsten coil that emits electrons when heated

In an x-ray tube, x-rays are formed on the

Tungsten target on the anode

Which of the following factors does not increase scatter radiation?

Type of cassette

A sievert (Sv) is the

Unit of radiation dose equivalent to the absorbed dose in tissue

In which of the following scenarios does the activity not increase the likelihood of personnel exposure to scatter radiation?

Use of a fast screen/fast film combination

A "rad" is a measure of the

Absorbed dose of x-ray energy/unit mass of tissue

The electron cloud is generated at the

Cathode

With the heel effect, the x-ray beam intensity is greater toward the

Cathode

During an exposure, electrons in the x-ray tube travel from the

Cathode to the anode

A universal format or standard for digital image storage, display, manipulation, and retrieval.

DICOM

A radiograph in front of you appears dark. You note that the bones are gray. You are best to do what for the next radiograph?

Decrease kVp

If a film is too dark and the image appears overpenetrated, you should

Decrease kVp 10% to 15%

If a radiograph is too dark, but the image shows adequate penetration, you should

Decrease mAs 30% to 50%

If a radiograph is too dark but has adequate penetration, you should

Decrease mAs 30-50%

When radiographing a distal extremity, a ___ scale of contrast is best.

Short

The cells that are most susceptible to the hazards of ionizing radiation are

The rapidly dividing cells of bone, lymphatics, and skin and leukocytes and hemopoietic cells

The workplace program that has been developed to ensure radiation exposures are kept as low as possible is

ALARA

A computerized system used to move, transmit, and store digital images.

PACS

What is the maximum recommended grid ratio for a 90-kVp x-ray machine for veterinary practice?

8:1

If mA = 100 and s = 1/10, what is the mAs of the x-ray exposure technique?

10

To produce x-rays, a great deal of energy in an x-ray tube is converted into heat. The ratio of heat generated to x-ray production is generally considered to be

99% : 1%

What is the maximum allowable whole-body occupational dose of x-ray beams in rems per calendar year?

5

The annual maximum permissible dose (MPD) standard of radiation for anyone working with radiation is

5 rem

The maximum permissible dose (MPD) is the dose of radiation a person is allowed to receive from occupational exposure over a certain time. The annual MPD is

5000 mrem

High kVp produces

A long scale of contrast

Low kVp produces

A short scale of contrast

The unit of absorbed ionizing radiation dose is

Gray (Gy)

Which of the following is a false statement regarding portable x-ray units?

Have a rotating anode tube and single focal spot

When depressing the "prep" switch on a rotating anode x-ray machine, you are effectively

Heating up the filament and spinning the rotating anode

Scatter radiation on a film is more noticeable if there is

Higher kVp, thicker patient, larger field size

If you suspect that your machine is not producing x-radiation, what would be the easiest and fastest test you could perform to confirm this?

Screen flourescence

If a radiograph is too light and is underpenetrated, you should

Increase kVp 10-15%

If a film is too light, but the image shows adequate penetration, you should

Increase mAs 30% to 50%

When evaluating a film, you note that the film is too light. You then determine that the film does not have adequate penetration, because you cannot discern the various forms in the abdomen. The best adjustment to make when repeating the film would be to

Increase the kVp

How does kVp affect the electrons and the x-ray beam?

Increasing it increases the speed at which electrons are pulled across to the anode and also increases the penetrating power of the x-ray beam.

What is the purpose of the collimator on an x-ray machine?

Limits the primary beam size

What is the primary source of scatter radiation?

Patient

What procedure must be followed to take advantage of the heel effect when obtaining a radiographic film?

Place the thick or dense part of the patient toward the cathode.

The kVp controls the

Quality of the X-ray beam. Higher kvp settings produce X-ray beams with greater penetrating power.

The kVp setting on an x-ray machine controls the

Quality of the x-ray beam

The milliampere-seconds (mAs) setting on an x-ray machine controls the

Quantity of x-rays emitted

The biologic effect of x-radiation is measured in

REMS

If the kilovoltage setting is increased, the

Radiographic density will increase, but the contrast will decrease

Which of the following substantially reduces the amount of radiation needed to produce diagnostic radiographic films?

Rare-earth screens

Which of the following increases the chance of exposure to ionizing radiation?

Retakes (repeated exposure)

Which of the following is a false statement regarding scatter radiation?

Scatter radiation is composed of high-energy x-ray photons that have undergone a change in direction after interacting with structures in the patient's body.

The acceleration of the electrons and their ultimate striking energy is determined by the

kVp

Which of the following controls radiographic contrast?

kVp

The machine setting that has the greatest influence on radiographic contrast is

kilovoltage (kVp)