Diagnostic imaging Exam (Lectures 1, 4-5)

As Low As Reasonably Achievable

What does the acronym ALARA stand for?

shielding, distance, and time

Which combination represents the major strategies used to follow ALARA principles?

it will decrease by a factor of 4

A technician normally stands 1 foot from the radiation source but moves to 2 feet away. Approximately how will their radiation exposure change?

scatter radiation

Lead aprons, thyroid shields, and lead gloves are primarily intended to protect personnel from:

This is unsafe because the primary beam can penetrate lead PPE and expose underlying tissues.

A veterinary technician wearing lead gloves places their hands directly within the primary x-ray beam. Which statement is most accurate?

skin cancer

What is the major concern associated with chronic low-dose radiation exposure identified in this lecture?

Using a plate extender and maximizing the distance of handlers from the beam

Which practice would BEST decrease occupational radiation exposure during equine radiography?

rotating which technicians take radiographs

Which is an example of using the time component of ALARA?

narrow the primary bean to the area of interest

What is the primary purpose of collimation?

it should be worn outside the lead apron while in the workplace

Which statement regarding a dosimeter badge is correct?

measure occupational radiation exposure

What is the primary purpose of a dosimeter badge?

They can be deflected by magnetic fields

Which of the following is NOT a property of x-rays?

They can ionize atoms

Which statement regarding x-rays is correct?

high-speed electrons strike metal

X-rays are produced when:

Cathode → positively charged anode

Which correctly describes electron movement during x-ray production?

To prevent electrons from interacting with air

Why is a vacuum maintained within the x-ray tube?

Quantity of x-rays produced

Increasing mAs primarily increases:

higher-energy x-rays

Increasing kVp primarily results in:

kVp

A radiograph requires x-rays with greater energy. Which machine setting should primarily be increased?

mAs

A radiograph requires a greater quantity of x-rays without primarily changing their energy. Which setting should be increased?

travel at a higher velocity toward the anode

Increasing kVp causes electrons to:

They are based on patient size and the body region being radiographed.

How are appropriate kVp and mAs settings selected for an individual patient?

Air, fat, soft tissue/water, mineral/bone, metal

Which correctly orders the five basic radiographic opacities listed in the lecture?

Filter scatter radiation to improve the recorded image

What is the purpose of a grid during radiography?

Using chemical restraint or positioning aids when possible to avoid manual restraint

A veterinary technician is manually restraining a dog for radiographs. Which situation represents the BEST radiation-safety practice?

the filament is charged sending electrons to the positively charged anode to produce x-rays

What is the correct chain of events?

kVp

In regards to radiation physics, which setting on the machine can increase the speed the electrons travel from the cathode to anode?

Cranial to the left and dorsal at the top

When viewing a properly oriented lateral abdominal radiograph, how should the image be displayed?

Cranial at the top; patients right on the readers left

You are viewing a VD abdominal radiograph. How should it be oriented?

cranial or dorsal toward the readers left

A mediolateral radiograph of an extremity should generally be oriented with:

use the same systematic approach every time

What is the BEST approach to interpreting radiographs?

Gas → fat → soft tissue/fluid → mineral/bone → metal

Which sequence correctly orders the five basic radiographic opacities from MOST radiolucent to MOST radiopaque?

gas

Which radiographic opacity appears the DARKEST?

Metal

Which material would appear the WHITEST on a radiograph?

fat

Which opacity lies between gas and soft tissue/fluid?

It absorbs/attenuates more x-rays and appears relatively white

Which statement BEST describes a radiopaque structure?

Size, shape, number, location, margination, opacity

You identify a suspected lesion on a radiograph. Which combination represents the six Roentgen signs used to describe it?

number

A radiograph shows three round mineral-opaque structures within the urinary bladder. Which Roentgen sign describes the fact that there are three structures?

margination

A lesion is described as having poorly defined, irregular edges. Which Roentgen sign is primarily being described?

opacity

A lesion is described as being mineral opaque. Which Roentgen sign is being reported?

size and shape

A mass is described as "round and approximately 3 cm in diameter." Which TWO Roentgen signs are being described?

Distance between the structure and image receiver

What is the primary cause of radiographic magnification described in the lecture?

the object and receiver are not parallel

Radiographic distortion occurs primarily when:

using standardized positioning

Which technique helps minimize the effects of magnification and distortion?

summation

Two normal structures overlap on a radiograph, creating an apparent opacity that could be mistaken for a mass. What phenomenon is occurring?

right and left kidneys

Which is a classic location for summation described in the lecture?

border effacement

Two structures of the same opacity are directly contacting each other, causing their individual margins to become indistinguishable. What is this called?

Summation creates an apparent opacity from overlapping structures, while border effacement causes loss of a visible margin

What is the key difference between summation and border effacement?

too bright

An underexposed radiograph will generally appear:

Increase mAs or kVp

An underexposed radiograph is noisy and lacks sufficient detail. Which adjustment may help?

too dark

An overexposed radiograph will generally appear:

Lower contrast

Assuming mAs remains stable, increasing kVp will generally produce:

Lower kVp or mAs

An overexposed radiograph is too dark. What can we change?

less

A higher kVp gives more/less contrast because more x-rays are transmitted through the patient to the plate.

DICOM

What is the standard file format for all radiographs?

literally anything!

What structures can you ultrasound?

anatomy

What do you need to know when operating ultrasound?

high-frequency sound waves penetrate tissue and bounce back to the transducer

How does ultrasound work?

crystals in transducers

What converts sound waves into an electric current while performing ultrasound?

no waves back

What does it mean in ultrasound if the image is black?

all waves back

What does it mean in ultrasound if the image is white?

some waves back

What does it mean in ultrasound if the image is grey?

goes through the tissue or bounces back

What is the fate of the ultrasound wave?

the wave travels back in a while line

What do you expect to see on ultrasound when the structure is solid?

tissue water content

What is important to think about when ultra sounding?

air

What do ultrasound waves hate?

lungs

Which organ is particularly difficult to ultrasound in its normal state?

anechoic

Which term is used for a black structure?

hypoechoic

Which term is used for when a few waves go back to the transducer?

isoechoic

Which term is used when an equal number of waves go back and go through the tissue?

hyperechoic

Which term is used when more waves go back to the transducer than go through the tissue?

reflective

Which term is used when you are ultrasounding bone and the image comes back as a bright white line?

acoustic shadow

Which ultrasound artifact is when you cannot see below a structure that reflects back all waves Ex: ribs?

acoustic enhancement

Which ultrasound artifact is where there is brightness deep to an anechoic structure?

reverberation artifact

Which ultrasound artifact occurs when sound waves are reflecting multiple times between 2 strong reflectors Ex:lung?

mirror image artifact

Which ultrasound artifact is the duplication of an image of the opposite side of a strong reflector and is most common in the thorax/abdomen interface?

the diaphragm

What medium would be the strong reflector at the thorax/abdomen interface?

slice thickness artifact

Which ultrasound artifact is from imaging a 3D structure with anechoic fluid and is most common in bladder and gall bladder?

edge-shadowing artifact

Which ultrasound artifact is when sound waves bend as they hit a curved surface tangentially?

linear probe/transducer

Which ultrasound probe (transducer) is most commonly used for equine tendons?

curvilinear probe/transducer

Which ultrasound probe is most commonly used for LA thorax & abdomen?

increase/higher frequency

What frequency has greater resolution but less depth?

decrease/lower frequency

What frequency has greater depth but less resolution?

abdomen

3-5 mHz= 20-25cm of depth, low resolution

Would we want to image equine tendon or abdomen with this?

tendon

10-12 mHz= 8cm of depth, high resolution

Would we want to image equine tendon or abdomen with this?

loss of collagen fibers and inflammatory edema present

When ultrasounding an equine leg, what do you expect would appear as a "core lesion"?

measuring movement (heart beat) or assessing direction of flow (ex: regurgitation of blood through a leaky valve)

When would you want to use real-time imaging (doppler mode) on ultrasound?

Computed tomography

What does CT stand for?

computed tomography (CT)

Which type of imaging is an X-ray tube in a circle that rotates at a predetermined speed and software programs can reconstruct slices into a 3D image?

carpus/tarsus, digit, and the head

Which structures are you able to image in a horse using CT?

animal is anesthetized or very heavily sedated

How do you need to prep patients getting a CT?

detailed evaluation of bone (fracture repair planning)

image the head

image the spine

image the abdomen

What are the indications with CT?

injection of a contrast solution

What needs to be done when imaging soft tissues with CT?

hydrogen protons

What do tissues have a lot of due to them being made of H2O?

MRI

Which imaging modality uses a strong magnet which excites protons by radiofrequency pulse?

magnetic resonance imaging

What does MRI stand for?

must remove horseshoes

use non-magnetic anesthesia equipment

What is important to remember when using MRI?

white

On an MRI, if the signal is emitted, what color is that signal on the image?

MRI

Which imaging modality has better contrast resolution and is superior for imaging soft tissues?

CT

Which imaging modality is superior for imaging bone due to not much water content and is superior for fracture planning?