Week 1 - Radiography & Ultrasound Intro

Why do we use imaging?

Identify disease, identify lack of disease, allow planning of treatment/further investigation, monitor progress, determine prognosis, screening

X-Ray definition

Photon of ionizing electromagnetic radiation

Radiograph definition

Image of an object produced by exposing to radiation (Made by X-Ray)

What happens when more X-rays reach the film?

There is an increase in film blackening

Tissue Radio-Opacity gradient

White → Black

Metal>Bone>Soft Tissue/Fluid>Fat>Gas

Types of image detections for X-Rays

Film, film//screen, digital radiography

Cons of Radiograph

2-dimensional shadow of 3-dimensional structure, need multiple pictures to get 3D

What areas cannot be seen with Radiographs?

Spinal cord, kidney, bladder

How are projections named?

Direction x-ray beam travels through patient, side patient is lying on (ex: cranio-caudal, right lateral recumbency)

What is the proper orientation when looking at radiographs?

Patient's head on our left or their right on our left

Pros of Ultrasounds

Good for soft tissues, safe, non-invasive, cheap, rapid, real-time imaging

Cons of Ultrasounds

Poor for viewing bone and gas, need to clip hair, takes practice to understand what is being seen

What is an ultrasound?

Sound waves from a machine that bounce off of bone or tissues or fat (etc) and get registered on a machine

What is the velocity of sound in objects that you might scan?

• Air = 331m/s

• Fat = 1450m/s

• Fluid & soft tissue = 1540m/s

• Bone = 4080m/s

What can happen when the ultrasound beam hits a tissue?

Reflected, refracted/scattered, or transmitted

What is the relationship between Frequency, Resolution, and Depth in Ultrasounds?

Higher frequency = higher resolution = shallower depth

Lower frequency = lower resolution = deeper depth

Name some transducer types

Sector/phased Array, Linear Array, Curvilinear Array

What is B Mode Ultrasound?

It is a brightness mode ultrasound, it shows the strength of the echo and can do cross-section of anatomy

What are the planes that ultrasound is done on?

Long Axis and Short Axis

What types of reflection can you get with ultrasound?

Hyperechoic, hypoechoic, anechoic

Hyperechoic definition

Reflect all

Hypoechoic definition

Reflect half

Anechoic definition

Reflect none

Gradient of Ultrasound

White → Black

Gas>Bone>Tissue>Fluid