Diagnostic Imaging

What helps dissipate heat and allow for higher exposure setting?

the rotating anode

Heel Effect

describes the variation in x-ray beam intensity due to anode angle

Cathode

emits electrons when heats

What is the relationship between wavelength and frequency?

It is inverse

high wavelength means low frequency

X-rays are produced when high-speed electrons strike what?

the anode

mA

controls the quantity of electron produced during x-ray exposure

The higher the ____, the more x-rays that are produced

what will increasing the mA do

it will darken the image

kVp

• The energy of the electrons as they reach the anode.

• This controls the quality of the x-ray beams.

• The higher the _____, the more penetrating power the beam will have.

will 100 mA and 1/10 second and 200 mA and 1/20 seconds result in 10mAs

yes they both do

how to reduce blur in radiographs

use high mA and the lowest exposure time

Exposure light

notifies the technician that x-rays can be released

Intensifying screens

can be used to reduce the amount of radiation needed to produce an image

Cassette

hold the film and intensifying screens in place during exposure

Types of intensifying screen

• rare earth(green)

• calcium tungstate(blue)

• blue sensitive

• green sensitive

Speed of intensifying screen

affects image detail and exposure time

Disadvantage of fast screens

lower image detail

How often should proper cleaning of intensifying screens be done

weekly

Label should include what?

• name of veterinary practice

• date of exposure

• patient name

• owner first and last name

Methods to label

• lead marker

• graphite tape

• light flasher

Latent image

invisible image created on the film after exposure

Film storage

Dark, cool, dry place

Should be upright

emulsion layer contains what?

silver halide crystals

Developer solution

converts the latent image into a visible image

Part of the film development process

• developing

• fixing

• washing

Safelight

should be in the dark room to help prevent film fogging

Fixer solution

hardens the film emulsion

DR

Direct Digital Radiography

• after exposure the detector plate automatically sends the digital image to the computer for viewing

CR

Computed Radiography

• Uses photostimulable plate to capture the image

• After exposure the PSP is places into a reader that scans the interior screen and produces a digital image

DICOM

Digital Imaging and Communications in Medicine
This is the universal format for storing and sending medical images.
Includes:
● Patient name and ID
● Study date and time
● Modality and description
● Series and image metadata

PACS

Picture archiving and communication system

Digital artifacts

ghosting

dust

fogging

What are intensifying screens used for

they are used to reduce the amount of radiation needed to produce an image

What is part of the film development process

• Developing

• fixing

• washing

• drying

What are some benefit of digital imaging

• Immediate image preview

• reduced radiation dose

• easy image storage

Does patient signalment need to be included on radiographic labels

NO they don’t

What does need included is:

• Name of vet practice

• date of exposure

• owner first and last name

• patient name

Radiographic density

The degree of blackness on the image

• Air(gas) --> Fat --> Soft tissue --> Fluid --> bone --> contrast media --> metals

What affects the contrast of a radiographic image

kVp

(Higher kVp the higher the scale of contrast so, more greys)

Increasing mAs

this will result in a darker, denser radiographic image

Sante’s rule

kVp = 40 + (2 x thickness in cm)

What absorbs the least x-rays

air (gas)

what absorbs the the most x-rays

metal

Recommended exposure time for thoracic radiographs to minimize motion blur

1/30 - 1/120 second

Caliper

tool used to measure the widest portion of the body that will be within the radiograph

If the radiograph is too dark but not over-penetrated, what adjustment should be made

decrease mAs by 30-50%

What does the technique chart do?

helps determine ideal settings for kVp, mAs, and exposure time for different anatomical regions

Inverse-square law

states that the intensity of the x-ray beam is inversely proportional to the square of the distance from the source

What are X-rays

x-rays are ionizing form of electromagnetic radiation

Stationary X-ray machine

Tube head, control center, table, bucky tray, transformer, generator

Portable X-ray Machine

Control panel, Exposure switch, Battery, Various stand and table options

Film-Screen Radiography

The image is produced by exposing film contained within a cassette that must then be developed using wet-processing

Grid

• Made of alternating strips of radiodense and rediolucent material

• Used to reduce radiation scatter and increase image contrast

Advantages to DICOM

it has tools that can be used to enhance images by reducing noise, changing brightness or contrast, and enhancing sharpness

Focus Film Distance (FFD)

• The distance between the x-ray source and the cassette(plate)

• As the distance increases, the intensity of the x-ray beam decreases

mAs

Controls the total quantity of x-rays produced per exposure.

• As mA is increased, the exposure time will be decreased

• Affect image density

Radiographic Detail

the sharpness of the image

Contrast

the degree of visual difference in densities between structures

Underexposure

the image appears too bright and/or grainy as a result of not enough beam reaching the detector

Overexposure

Image appears too dark as a result of too much radiation reaching the detector

3 categories of artifacts

Pre-exposure, Exposure, Post-exposure

Developing a Technique Chart

Exposure Latitude

Each setting correlates to a range rather than one specific measurement, becuase digital systems, because digital systems have contrast optimization software that allows a wider range of techniques to result in a diagnostic quality image

How x-rays are produced

an electrical current is applied to the cathode, which allows negatively charged electrons to enter the tube where they are attracted to the positively charged anode. Once they hit the anode this created heat and x-rays

ALARA

As Low As Reasonably Achievable

Minimum lead equivalence required for protective equipment

0.5mm

MPD

Maximum permissible dose

Maximum permissible dose for occupational personnel

5 REM per year

4 types of dosimeter Badges

1) Film Badges

2) Thermoluminescent Dosimeter (TLD)

3) Optical Stimulated Luminescence (OSL) dosimeter

4) Ion Chamber dosimeter

How often should you check lead aprons and thyroid collars for cracks?

every 12 months

How often should lead gloved be checked?

Every 6 months

First Trimester of Pregnancy

The most sensitive period for fetal radiation exposure

Sources of Scatter radiation 

Table, Patient, floor

Where should your dosimeter be worn?

At thyroid level, OUTSIDE the lead

4 possible effects of radiation on living tissue

1) Can pass through with no effect

2) Repairable cell damage

3) Irreparable cell damage

4) Cell death

Somatic

Radiation effect within the individuals during their life time

Genetic

Radiation effects that affect future generations through damage of reproductive cells

What is the primary source of radiation exposure to personnel

Scatter radiation

4 ways to minimize radiation exposure

time, distance, shielding, and technique

Which of the following is NOT a required PPE in radiology

safety goggles