Introduction To Medical Imaging Flashcards
Radiology
Branch of medicine concerned with use of radiant energy/ radioactive material in the diagnosis and treatment of disease.
Radiologist
Trained to interpret diagnostic images and perform some specialist tests
Radiographer
Trained to take/ perform X-ray, CT, MRI etc.
Sonographer
Trained to perform ultrasounds
Angioplasty
Insertion of a balloon into a vein/artery to widen it and improve circulation.
Stenting
Insertion of a tube to keep an artery or vein open
Biopsies
Lung, breast, renal, liver, bone etc.
Clinical Oncologist
Specialised physician who uses radiation in the treatment of cancer.
Order of e/m spectrum from lowest to highest frequency
R, M, I, V, U, X, G
X-ray
A form of e/m radiation which is able to pass through the human body and produce an image of internal structures.
Radiograph
X-ray / plain film
How is bone represented on an X-ray ?
Greyish, White colour
How is air represented on an X-ray ?
Black
Order of colours on an X-ray from darker to lighter
Air
Fat
Soft tissues / water
Bone
Contrast material / metal
Mammography
Uses a low-dose X-ray system
Designed for creating detailed images of the breast
Used as screening to detect early breast cancer without signs/symptoms or diagnose breast disease with symptoms
Fluoroscopy
Shows a continuous x-ray image on a monitor, used where real time examination is required.
e.g. positioning of implants during surgery
e.g. viewing the movement of contrast agents like barium
e.g. studying movement of body parts
Angiography
Used in the examination of the arteries/veins.
Angiograms usually carried out by IR.
Contrast agent injected to make blood vessels visible on the X-ray image.
CT scan
Computed Tomography
Uses of CT scan
Produces images of single tissue planes.
Provides cross-sectional imaging/slices of anatomy
Advantages of CT scan (3)
Fast
Readily Available
Good imaging of bony structures, abdomen and lungs
Disadvantages of CT scan (3)
High radiation Dose
Not so good at imaging soft tissue (brain, spinal cord, muscles)
High Resource use (staffing, time, space)
Scintigraphy Nuclear Medicine
Use of gamma radiation to form images following the injection of various radiopharmaceuticals
Metastable
Where the technetium actor has 2 basic energy states : high and low
Advantages of Scintigraphy
High Sensitivity
Provides functional information
PET scan
Coloured
Combination of CT and scintillation scanning
MRI
Magnetic Resonance Imaging
Disadvantages of Scintigraphy
High Radiation Dose
Cancer vs Infection looks same on scan
What is special about MRI ?
NO ionising radiation
What does MRI use ?
VERY powerful superconducting magnet that creates a static magnetic field.
What causes the tapping sound in an MRI machine ?
Radio signal being turned on and off
What is high signal intensity ?
White
What is intermediate signal intensity ?
Grey
What is low signal intensity ?
Black
T1 weighted MRI
Highlights fat tissue within the body
What does intensity mean in MRI ?
The shade of grey of tissues and fluid.
T2 weighted MRI
Highlights fat and water within the body
Advantages of MRI
Gold Standard of Imaging
No radiation
Good differentiation between pathologies
Excellent soft tissue imaging esp in brain & spinal cord
Disadvantages of MRI
Potentially dangerously strong magnet
Not good for bone
High cost
Long duration of scanning
Need for anaesthesia in younger/uncooperative patients
Ultrasound Imaging
Uses sound waves to create an image
Types of Imaging
X-ray
CT scan
Nuclear Medicine
MRI
Ultrasound
Advantages of Ultrasound
Safe
No ionising radiation
Portable equipment, compact and inexpensive
Disadvantages of Ultrasound
Highly operator dependent
Structures surrounded by bone e.g. brain/spinal cord don’t give clinically useful images
Causes of wasteful requests
Repeat investigations
Doing wrong investigation
Investigating too often
What 2 types of imaging use no ionising radiation ?
MRI and Ultrasound
