Rachael Curry Flashcards
(22 cards)
radiology =
A branch of Medicine concerned with the use of radiant energy or radioactive material in the diagnosis and treatment of disease.
radiologic anatomy =
study of structure and function of the body using MI techniques, ie- anatomic basis of radiology
radiologist vs. radiographer
A Radiologist is a doctor who is specially trained to INTERPRET diagnostic images such as X-rays, MRI and CT scans and perform ultrasonography
A Radiographer is a healthcare professional who has been trained to take your X-ray or PERFORM your MRI or CT scan.
advantages of conventional X-ray imaging =
fast
painless and non-invasive
don’t require any special preparation (except when contrast media is used)
require no recovery time
disadvantages of conventional X-ray imaging =
Very small increased risk of cancer in future from exposure to ionising radiation (X-rays)
Risk is greater for children
advantages of CT =
Fast.
Readily available.
Good imaging of bony structures, abdomen and lungs.
disadvantages of CT =
High radiation Dose.
Not so good at imaging soft tissue such as brain / spinal cord
Magnetic Resonance Imaging (MRI) =
MRI systems use a powerful magnetic field and radiofrequency pulses to produce detailed images of the body’s internal structures as cross-sectional images or slices.
provides high quality images with excellent contrast detail of soft tissue and anatomic structures such as grey and white matter in the brain.
MRI does not emit any ionizing radiation.
X-RAY AP vs. PA projection
AP (anterior –> posterior direction of beam) produces an image that enlarges the apparent size of an organ.
PA (posterior –> anterior direction of beam) does the same to a LESSER extent
advantages of MRI =
Gold standard of imaging No Radiation Good localization of pathology. Good differentiation between pathologies Excellent soft tissue imaging such as brain / spinal cord
disadvantages of MRI =
Potentially dangerously strong magnet Not so good for showing bony anatomy Cost Long duration of scanning. Need for anaesthesia in younger children / uncooperative patients.study
Scintigraphy =
Scintigraphy refers to the use of gamma radiation to form images following the injection of various radiopharmaceuticals
The gamma rays emitted by the radionuclides are detected by a gamma camera that converts the absorbed energy of the radiation to an electric signal.
This signal is analysed by a computer and displayed as an image.
interventional radiology =
encompasses any procedure that is invasive,
eg- insertion of a needle, cannula (tube), catheter, or wire into the patient for diagnosis and /or treatment.
Procedures include:
angioplasty (insertion of a balloon into a vein or artery to widen it and improve circulation)
stenting (insertion of a tube to keep an artery or a vein open)
biopsies e.g. lung
Disadvantages of scintigraphy
High radiation Dose
Not so good at differentiating between different pathologies
MRI sequences
An MRI sequence is a number of radiofrequency pulses and gradients that result in a set of images with particular appearance.
When describing most MRI sequences we refer to the shade of grey of tissues or fluid with the word intensity, leading to the following absolute terms:
high signal intensity = white
intermediate signal intensity = grey
low signal intensity = black
T1 vs. T2 MRI images
timing of radiofrequency pulse sequences used to make T1 images results in images which highlight FAT tissue within the body
timing of radiofrequency pulse sequences used to make T2 images results in images which highlight FAT AND WATER within the body.
T1 vs. T2 MRI images
timing of radiofrequency pulse sequences used to make T1 images results in images which highlight FAT tissue within the body
timing of radiofrequency pulse sequences used to make T2 images results in images which highlight FAT AND WATER within the body.
Ultrasound imaging =
visualises superficial or deep structures by recording pulse of US waves REFLECTING off tissues
Appears as a cross-sectional video / still
advantages of ultrasounds
safe
No ionizing radiation
The equipment required is portable, compact and relatively inexpensive
disadvantages of ultrasounds
Highly operator dependent
Structures surrounded by bone, such as the brain and spinal cord, do not give clinically useful images
The reduction of the ultrasound signal at air/tissue boundaries means that the technique is not suitable for imaging structures in the lung or abdominal organs obscured by gas in the overlying bowel.
6 wasteful uses of MI =
Repeating investigations which have already been done.
Investigation when results are unlikely to affect patient management.
Investigating too often.
Doing the wrong investigation.
Failing to provide appropriate clinical information and questions that the imaging investigation should answer.
Over-investigating.
ALARA =
“As Low As Reasonably Achievable.”
making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical.
