Principles of Anatomy and Imaging Flashcards
What are the 2 main specialities of radiology / medical imaging?
- Diagnostic imaging - imaging of the body and interpreting it to help find the pathology
- Interventional Radiology - surgical speciality, where interventions and treatments are done under imaging control, usually with the patient awake
Radiologist Vs Radiotherapist Vs Radiographer? Define the terms.
Radiologist - doctor specialising in interpretation of medical imaging
Radiotherapist - doctor specialising in providing radiotherapy to e.g. cancer patients
Radiographer - highly skilled technician, not medically trained, but takes the imaging
What are the different diagnostic imaging methods and group them into ionising and non-ionising radiation?
Ionising Radiation: X-rays and CTs (computer tomography), Nuclear medicine
Non-ionising Radiation: Ultrasound, MRI (magnetic resonance imaging)
What is the issue with ionising radiation?
Do the risks associated with ionising radiation impact the young and elderly equally?
Risk of inducing cancer after years of exposure
No, more significant impact in developing cancer later on if exposed to ionising radiaton young, that if exposed to ionising radiation when older (as shown on the graph)
How does an X-ray passing through the body produce an image?
The more X-rays that pass through, the blacker the image, the fewer the X-rays that pass through, the whiter the image
Different body tissues attentuate (block) X-rays differently i.e. most x-rays pass through air and fat = black image, 50% of x-rays pass through soft tissue = grey image, almost no x-rays pass through bone = white image
Often, on x-ray images, soft tissue looks very similar, and different tissues are difficult to differentiate.
What can be given to improve tissue contrast?
What are some risks associated with this method?
A contrast agent - enhances differences between tissues of similar densities e.g. blood vessels, can differentiate between pathological and normal tissue etc.
e.g. IV iodine, swallowed / injested barium
Some people are allergic to the contrast agents, and they may cause kidney damage
What is a CT scan and how does it work?
Why is the imaging produced from a CT scan better than a regular X-ray?
Uses X-rays to produce a cross-sectional image
X-ray tube spins around the patient, detector spins around the patient in an opposite tube, computer does the calculations to produce cross-sectional map of tissue densities
CT scan also shows where there is water present in the body and differentiates between different soft tissues
CT scans are also digital images that can be post-processed to emphasise different things e.g. bone, soft tissue, lung etc.
What are 3D reconstructions on the CT scans?
Where the cross-sectional images produced by the CT scanner are compiles to form a 3D image
What are ultrasounds and how do they work?
Imaging technique using high frequency sounds to make images - by measuring how quickly it takes for the sound to bounce back from the inside of the body to the outside
Uses a device called the transducer - it produces and detects the high frequency sound
What is an MRI and how does it work?
On who would it be unsafe to use an MRI?
Strong magnet, supercooled with helium that produces a strong magnetic field that causes the protons within a person’s body to align with it. Radiowave pulses are transmitted to the patient, which interacts with protons, and different tissues give different intensities of returned radiowaves (sounds), which produces the image
If a person has any metal in their bodies
How to differentiate between CT and MRI imaging of body parts?
Bone = white on CT, black on MRI
Fluid = dark grey on CT, black on T1 MRI, white on T2 MRI
Fat = black on CT, white on MRI
Hint: There is fat around the skull
Label on the diagram, which images are MRI (T1), MRI (T2) and CT:
What is nuclear medicine?
Involves nuclear medicine isotopes - uses radioactive tracers that emit radiation (radiation dose to patient)
Different tracers go to different organs / different parts of the body e.g. bone tracers, lung tracers, glucose tracers etc.
Images are made by using a gamma camera that picks up on the radiation coming out of the body
Why are nuclear medicines used?
Usually has a low resolution so not for fine details / anatomical details, but overall functioning e.g. looking to see if cancer has spread to the bone (metastatic cancer)
e.g. in this image: hotspots = metastatic cancer
Also known as a VQ scan (ventilation-perfusion scan)
Why are lung scans using nuclear medicine also a common practice in medicine? i.e. what does it look at?
To look at the ventilation and blood perfusion to the lungs - used to diagnose pulmonary embolisms (blood clot to the lung)
e.g. the top image shows normal blood flow and ventilation, the bottom image shows abnormal blood flow due to clots, but normal ventilation
What does PET scan stand for?
How do PET scans work? (i.e. what do they look for in their imaging?)
What disease is it used for particularly?
Positron Emission Tomography
PET scans detect metabolic or ‘functional’ changes rather than structural changes
Effective in identifying the presence of cancer (diagnosis) and effectiveness of the treatment of cancer, i.e. if it is responding to treatment
Looking at the feet and hands, why are posterior and anterior not used?
What terminology is used instead?
Because it depends on the way one looks at the feet and hands, although anaotmically, hand palms facing up is the default
Feet - dorsal and plantar
Hands - palmar / volar, dorsal, distal, and proximal
What are the three anatomical planes?
Axial - tranverse cut through the body
Coronal - cut through the body from left to right
Saggital - cut thorugh the body from the front to back
