Diagnostic Imaging For VT Exam 1 Material

Who discovered the X-ray?

Wilhelm Conrad Roentgen

What are X-rays?

A type of electromagnetic radiation

What is electromagnetic radiation?

A form of energy created by the movement of electrically charged particles such as electrons

Types of electromagnetic radiation

radio waves, microwaves, infrared, visible light, UV, x-rays, and gamma rays

How are the types of electromagnetic radiation determined?

By wavelength and frequency

Wavelength

The distance between two consecutive peaks

Frequency

The number of waves that form in a given length of time measured in wave cycles per second (Hertz, Hz)

Shorter wavelength

Higher frequency

Longer wavelength

Lower frequency

How is an x-ray characterized?

Shorter wavelength, higher frequency

What is the x-ray tube made of?

Two electrodes, the cathode and anode

Cathode

Negative electrode that contains electrons

Anode

Positively charged electrode that pull the electrons toward itself

When electrons are interact with the anode, what happens?

X-rays and heat are produced

Tungsten

Used in the cathode. Is heated by a low-energy circuit to produce free electrons. High melting point.

Focal spot

Area on the anode that electrons strike

What does the size of the focal spot determine?

The sharpness of the image; the smaller, the sharper.

Two types of anodes:

Stationary and rotating

Tube stand

Supports the x-ray tube

Collimator

Has lead shutters to control the size of the primary x-ray field and includes a visible light source to help with accurate patient positioning and personnel safety

Grid

Absorbs scatter radiation. Positioned between patient and image receptor.

Potter-Bucky Diaphragm

Contains a built in grid to absorb scatter, adjustable, located under the x-ray table or vertically

Control panel

On/off switch, voltage compensator/high voltage circuit, low voltage circuit

Kilo voltage peak selector, milliamperage and time selector, exposure pedal, and warning light

ALARA

As Low As Reasonably Achievable

What are 6 ways to accomplish ALARA in radiology?

Dosimetry badges

PPE and protective equipment

Patient positioning aides

Technique charts

Quality control measures

Emergency procedures

Three rules for radiology safety:

Time - shortest

Distance - greatest

Shielding/PPE - maximum

What does leaded PPE protect you from?

Scatter radiation only

How should aprons be stored?

Hanging vertically over a round surface, or laying flat

How should gloves be stored?

Vertically on holders in a way that air can circulate through them

4 Important factors in producing a diagnostic image:

1. Patient positioning and landmarks

2. Artifacts and technical errors

3. Radiographic density and contrast

4. Evidence of disease or other abnormal findings

Patient positioning

X-ray field must be directed perpendicular to patient and image receptor

SID should be 40 inches

Anatomy of interest must be parallel with the image receptor/tabletop and as close to the tabletop as possible

Proper anatomical landmarks

Centering

Collimation

Measurement

Centering

Center the x-ray field over the middle of the area of interest

Collimation

Include the entire area of interest when collimating so that the entire area can be properly evaluated

Measurement

Measure over the thickest area within the collimated field to set the machine for appropriate density and contrast

Artifacts may result from:

Errors in:

- patient positioning

- patient preparation

- patient measurement

Patient positioning artifacts:

Magnification, foreshadowing, elongation, artifactual changes in density and contrast

Patient preparation artifacts:

Food and feces, patient motion, leashes or collars, human anatomy

Patient measurement artifacts:

Using the wrong landmark, measuring the patient while sitting or standing, using the technique chart incorrectly

Intentional artifacts:

Gunshot/birdshot, splints, casts, pins, screws, plates, and microchips

Radiographic density

The degree of brightness or darkness on the X-ray (mAs)

Radiographic contrast

The difference in radiographic density between two areas on the x-ray (kVp)

Common abnormal findings

Fluid, air/gas, enlarged organs, displaced organs