chapter 3 and 6 radiology

What does ALARA stand for?

As Low As Reasonably Achievable

Which organs are most affected by radiation?

Skin, lymphatics, hemopoietic tissue, breast tissue, thyroid, bone growth centers, eyes, and gonads

What happens when intracellular water is ionized by radiation?

Toxic products are released that can damage DNA and other cell components

What are the possible effects of radiation on cells?

• No effect

• Damage repairable

• Damage not repairable

• Cell death

What is somatic radiation damage?

Damage that occurs only within the exposed individual during their lifetime

What is genetic radiation damage?

Damage that affects future generations through reproductive cells

During which trimester is the fetus most sensitive to radiation?

The first trimester

What are early signs of low-level radiation exposure?

Radiodermatitis (reddened, dry skin)

What unit measures radiation exposure in air?

Roentgen (R)

What unit measures the absorbed dose of radiation in tissue?

RAD

What unit accounts for radiation quality and biological effect?

REM

1 Sievert equals how many REMs

100 REM

What is the Maximum Permissible Dose (MPD) for occupational radiation exposure per year?

5 REMs

How is maximum accumulated dose calculated?

(Age – 18) × 5 REMs

Who should not assist in radiographs?

Pregnant women and anyone under 18 years old

What are the three ways to decrease radiation exposure?

Time, Distance, Shielding

What does the inverse square law state?

Doubling the distance from the beam reduces exposure to ¼ intensity

What is the best option for patient restraint during radiographs?

Non-manual restraint (sedation or positioning devices)

What thickness of lead is required in PPE?

0.5mm

How often should gloves be radiographed to check for holes?

Every 6 months

What conditions should dosimetry badges be protected from?

Heat, pressure, and fumes

What is the best practice when taking radiographs

Only essential staff present, never place body in beam, always collimate, check positioning twice, use technique chart

What are the three key image qualities to evaluate in radiographs?

Detail, density, and contrast

Who is responsible for ensuring radiation safety and quality assurance in a clinic?

The Radiation Safety Officer (RSO)

What information must be documented for each radiograph?

Animal name, date, anatomical location, measurement, settings, results

What does image detail refer to?

The degree of sharpness of the image

What factor most affects image detail?

Focal-film distance (FFD)

What is the typical focal-film distance used in veterinary radiography

36–48 inches

What is radiographic density?

The degree of blackness of the image

Which setting most affects image density?

mAs (quantity of x-rays)

How does increasing mAs affect film density?

Increases density (darker image)

How does increasing kVp affect film density?

Increases density (darker image)

What law explains the effect of distance on x-ray intensity?

Inverse square law

What is radiographic contrast?

The opacity or density difference between two areas or structures

What factor most affects contrast?

kVp

If a film is too dark/over-penetrated and you can’t see anatomical structures, what should be adjusted?

Decrease kVp by 10–15%

If a film is too light/under-penetrated and you can’t see the anatomical structures, what should be adjusted?

Increase kVp by 10–15%

If density is too dark but structures are still visible, what adjustment should be made?

Decrease mAs by 30–50%

If density is too light but structures are visible, what adjustment should be made?

Increase mAs by 30–50%

How is Sante’s rule used to estimate kVp?

kVp ≈ 40 + (2 × tissue thickness in cm)

At what anatomical measurement is the tabletop technique used instead of a grid?

Less than 10 cm

What is the primary goal when making a technique chart?

To use the shortest possible exposure time for a given mAs setting