Stage 8: Radiology and Ultrasound Imaging and Endoscopy

Radiology

The use of ionizing radiation (X-rays) for medical diagnosis.

Importance of Radiology in Vet Med

Major diagnostic tool; allows indirect visualization of internal structures to diagnose disease/injury.

Key Priorities in Radiology

1. Safety (for staff, patient).

2. Accuracy (for diagnosis and legal logs).

Veterinary Assistant's Role (12 Responsibilities)

Understand radiology, ensure safety/PPE, position patients, measure with caliper, read technique charts, adjust machine, label films, develop/process films, maintain darkroom, file films, refill cassettes, maintain log.

What is an X-ray?

A high-energy stream of electromagnetic radiation that can penetrate living tissues.

Risk of X-rays

Effects are always harmful. Can cause cell death or mutation, leading to cancer, burns, cataracts, or genetic effects.

Radiation Exposure Limits

Natural: ~3 mSv/year

· Occupational Limit: 50 mSv/year

· General Public: < 1/10th of occupational limit.

Cells Most Sensitive to Radiation

Cells that multiply rapidly: bone marrow, skin cells, intestinal epithelium, and the developing fetus.

Danger to Pregnant Women

The developing fetus is extremely vulnerable. Pregnant women must not be present during radiological procedures.

Radiation Dosimeter (Film Badge)

Measures and records a staff member's personal radiation exposure. Does not protect you, but monitors exposure levels.

Dosimeter DOs

Wear it when taking X-rays.

· Leave it at the facility.

· Turn it in on time.

· Report lost/damaged badges.

Dosimeter DON'Ts

Don't wear for personal medical X-rays.

· Don't wear it outside work.

· Don't wear under lead apron.

· Don't leave in sunlight.

· Don't share or tamper with it.

Limiting Exposure Time (ALARA)

· Minimize exposure time.

· Rotate staff.

· Plan carefully to avoid repeats.

· Measure properly.

· Use technique charts.

Protective Equipment (PPE)

Lead apron, lead gloves, lead thyroid shield, glasses with leaded lenses.

Keeping a Safe Distance

Stand at least 6 feet away.

· Unneeded staff leave room.

· Avoid primary beam.

· Look away during exposure.

· Use collimation.

ALARA Common Sense

Never put body parts in primary beam.

· No pregnant women or persons under 18 in room.

· Maintain 1" unexposed border on film.

Radiology Log Function

A legal document to record every radiographic procedure. Helps track techniques for future exams and reduces repeats.

Radiology Log Data

Date, patient/owner info, area imaged, view, thickness (cm), kVp, mA, time, staff name, comment

4 Principles of Patient Positioning

Ensure patient welfare, ensure effective restraint, get precise image, minimize radiation risk to staff.

3 Types of Restraint for Radiography

Physical, Psychological, Chemical (sedation/anesthesia).

V/D (Ventrodorsal)

Beam enters Ventral (belly) and exits Dorsal (back). Patient is on its back.

Lateral View

Patient lying on its side. Beam enters one side and exits the other.

Caliper Function

An instrument used to measure the thickness of a body part at its thickest point to determine the correct exposure settings.

Using a Caliper (Key Steps)

Measure at the thickest point. Read measurement in centimeters (cm) below the movable bar. Never estimate.

Primary Beam vs. Scatter Radiation

• Primary: The main, direct beam from the X-ray tube.

• Scatter (Secondary): Radiation that bounces off the patient/objects, creating a hazard for staff.

Causes of Scatter Radiation

• Long wavelength X-rays.

• Beam deflected by dense tissue/bone.

• Beam striking metal or the X-ray table.

Preventing Scatter Radiation

• Use lowest possible kVp.

• Use a collimator.

• Use rare-earth intensifying screens.

• Use a grid (for parts >10cm thick).

Technique Chart Function

A chart with pre-determined settings (kVp, mA, time) based on tissue thickness to ensure proper exposure without repeats.

3 Reasons to Use a Technique Chart

Saves time, decreases unnecessary radiation exposure (repeats), limits waste of film.

4 Dials/Factors on X-ray Machine

kVp (kilovoltage peak)

mA (milliamperage)

Time (seconds)

FFD (Focal Film Distance)

Parts of an X-ray Machine

X-ray tube (cathode [-], anode [+]), collimator, control panel, exposure button/pedal.

4 Reasons to Label Radiographs

• Legal document/evidence.

• Track patient recovery.

• Identify facility for consults.

• Prevent loss of film.

4 Methods of Labeling X-rays

Lead markers,

radio-opaque tape

light flasher system

film identification camera

4 Types of X-ray Markers

Left/Right markers, arrow/pointer markers, time markers, Mitchell markers (for standing animals).

5 Steps of Film Processing

Developing, Rinsing, Fixing, Washing, Drying.

Automatic vs. Manual Processing

• Automatic: Fast (90 sec), machine-controlled.

• Manual ("Wet Tank"): Slow, done by hand in chemical tanks.

3 Steps for Manual Developing

1. Develop (time/temp dependent).

2. Rinse in water.

3. Fix (twice as long as develop time).

Cassette Function

A light-tight holder that contains the X-ray film and intensifying screens, keeping film flat and protected.

3 Reasons for Film Filing

Radiographs are legal documents, are medical records (facility property), and must be kept for a required number of years by law.

4 Methods of Filing Films

Alphabetical (patient name), by patient ID number, by date and name/number, by date only.

Digital Radiography (CR/DR)

Transforms X-rays into digital data displayed on a computer. Stored in DICOM format on a PACS network.

Ultrasonography (Ultrasound)

Uses high-frequency sound waves to visualize internal organs. No radiation involved.

Transducer Function

A hand-held probe that emits sound waves and receives the returning echoes to create an image.

Veterinary Assistant's Role in Ultrasound

Prepare patient (clip, gel), restrain patient, prepare machine, clean up, file results.

Endoscopy

A minimally invasive procedure using a flexible tube with a camera (endoscope) to directly visualize hollow organs.

4 Primary Parts of an Endoscope

Fiberscope (tube), light source, camera lens system, extra channel for instruments.

Veterinary Assistant's Role in Endoscopy

Prepare patient (anesthesia/scrub), position patient, assist during procedure, care for/clean scope, send biopsies to lab.

20 Canine Bones

Scapula, Humerus, Radius, Ulna, Carpus, Metacarpus, Phalanges, Pelvis, Femur, Patella, Tibia, Fibula, Tarsus, Metatarsus, Skull, Ribs, Cervical/Thoracic/Lumbar/Sacral/Coccygeal vertebrae.

9 Major Organ Systems

1-Integumentary

2- Skeletal

3-Cardiovascular

4-Respiratory

5-Digestive

6-Urinary

7-Nervous,

8-Reproductive

9- Muscular

3 Layers of Skin

1-Epidermis

2-Dermis

3-Hypodermis.

Two Major Skeletal Groups

Axial skeleton (skull, spine, ribs) and Appendicular skeleton (limbs).

4 Functions of the Spinal Column

1-Structural support

2-protects spinal cord

3-base for muscle/ligament attachment

4-allows flexibility

4 Sections of Vertebrae

Cervical (neck, 7), Thoracic (chest, 13), Lumbar (lower back, 7), Sacral (pelvic, 3 fused).

7 Bones of Forelimb (Proximal to Distal)

Scapula → Humerus → Radius → Ulna → Carpus → Metacarpus → Phalanges.

8 Types of Bone Fractures

Simple, Compound, Comminuted, Transverse, Oblique, Spiral, Compacted, Greenstick.

Positional Terminology for Radiology

Lt

Left- The patient’s left side or left limb

Rt

Right-The patient’s right side or right limb

D

Dorsal- Toward the spine. The back or top side of an animal that walks on four legs—i.e., the upper parts of the body including the top of the head, neck, back and tail.

V

Ventral- Toward the sternum. The belly or underneath of an animal that walks on four legs—i.e., the underside of the head, neck, chest, abdomen and tail.

M

Medial- Toward the midline. The inner surface of a limb toward the center of the body.

L

Lateral- Away from the midline. The outer surface of a limb away from the center of the body

Cr

Cranial- Toward (or closer to) the head from the point of origin.*

Cd

Caudal-Toward (or closer to) the tail from the point of origin.**

Di

Distal- i Away from the body (trunk). Any point on the limb farther away from the trunk from the point of origin.**

P

Proximal- Toward (or closer to) the body (trunk). Any point on the limb closer to the trunk from the point of origin.

R

Rostral- Toward the nose in reference to parts of the head located closer to the nostrils or tip of the nose from the point of origin.

O

Oblique- At a 45° angle, between a horizontal and perpendicular angle