1 Intro to Medical Imaging Techiques Flashcards
Q: What is CT scanning? How?
A: computed tomography
-using x rays to produce cross sectional images of body
x ray tube spins around patient and detector spins around patient opposite the tube
-> computer performs calculations to produce cross-sectional map of tissue density -> get 2D / 3D map
Q: What id radiology called today?
A: diagnostic imaging
Q: What is interventional radiology? (2)
A: branch on imagining
-minimally invasive surgery carried out under X ray imaging guidance
Q: What is radiotherapy?
A: use of high energy x rays to treat cancer
-therapeutic
Q: What is a radiologist?
A: doctor specialising in interpretation of medical imaging
Q: What is a radiographer?
A: non medical person/ technician that takes images
Q: What are the 2 types of diagnostic imaging? Give examples (3,2).
A: ionising
- X ray
- computed tomography CT
- nuclear medicine
non ionising
- ultrasound
- magnetic resonance imaging MRI
Q: What is the problem with ionising radiation? (2)
A: risk of inducing cancer years after exposure
-higher risk if exposed before 30years hence try and limit use on children and young adults
Q: How does an x ray passing through the human body create an image?
A: -because of inherent contrast between different body parts
-if lots of x rays pass through=appear black and if not =appear white
- air= black
- fat= dark grey
- soft tissue= grey
- bone, calcium= white
- metal= really white
Q: What does a chest radiograph look like? (4)
A: -healthy lungs are composed mainly of air= very black
- mediastinal structures are made of soft tissue = grey
- air around patient= black
- bone=white
Q: What do bones look like on a radiograph?
A: centre= marrow= fat= darker than outside
outside= dense cortical area (outer shell) = white
Q: On a chest radiograph, what can X rays not distinguish between?
A: heart muscle, pericardium and blood inside heart
Q: How can inherent tissue contrast be improved?
A: administration of contrast agent
-enhance differences between tissues of similar densities
Q: Give 2 examples of contrast agents. How can they be given? (3)
A: -barium (swallow, through rectum)
-iodine (into artery or vein)
Q: What are CT windows? What do they allow us to see?(3)
A: we can choose which parts we want to emphasise
- soft tissue (muscles in chest wall and structures in mediastinum)
- bone (cortex and medulla of bone)
- lung (can see presence of cancer/pneumonia)
Q: Name 3 CT reconstructions.
A: 1. sagittal= see shape of spine (CS from front to back)
- axial (transverse)= cut where belt is
- coronal= CS from side to side
Q: What is the contrast agent used in CT? Risks? (2) Advantages? (2)
A: iodine (in arm vein)
- allergic reaction
- kidney damage
- enhances blood vessels and makes them easier to see
- differentiates pathological from normal tissue
Q: What does a CT show when a patient has a right upper lobe pulmonary embolus? What is this?
A: black hole in pulmonary artery
-blood clot in legs that has travelled up to lungs= life threatening but we can now diagnose
Q: How does a CT show liver tumours? Why is using a contrast agent important?
A: shown as little black holes in liver
tumours have slightly different blood supply to the rest of liver so if we did it without contrast agent-> probably would have missed it
Q: Give an example of a 3D reconstruction.
A: pelvis
Q: What is an optical colonoscopy? Virtual? What can be seen?
A: medical test to inspect colon using very thin camera
small tube is inserted into rectum-> CO2 inserted-> distended up-> get 3D reconstruction = endoluminal view of colon
polyps
Q: How do ultrasounds produce images? Transducer? (2) Safety?
A: uses high frequency sounds to make 2D image
transducer
-speaker: sends sound into patient
-microphone: records sound coming back from patient
(use time difference to work out where structures are)
no radiation hazard, completely safe
Q: How have ultrasounds changed? (2)
A: -machines are much smaller
-used to be really hard to interpret but now even have 3D obstetric ones
Q: How are magnetic resonance images created? (4)
A: -strong magnet, supercooled with liquid helium
- transmit radio wave pulses into patient
- listen to return radio waves caused by interaction with protons (water) in the patient’s body
- different tissues give different intensities of returned radiowaves -> image
Q: What are the 2 types of MRI?
A: T1 and 2
Q: How do these structures appear on CT, MRI (T1) and MRI (T2):
(cortical) bone.
fluid.
fat.
A: white, black, black
dark grey, black, white
black, white, white
Q: What does nuclear imaging use? (2) How are images made? Name 2 uses.
A: -radioactive tracers that emit (ionising) radiation
-different tracers go to different organs/ parts of body
images are made by detecting the radiation coming out of the patient by gamma camera
- bone (see tumours)
- lungs: see blood flow and ventilation
Q: What is positron emission tomography? Uses? (3)
A: PET
- detects metabolic or functional changes in body rather than structural changes
- particularly effective in identifying whether cancer is present or not (diagnosis) -> if it has spread (staging), and if it is responding to treatment
Q: What are the benefits of PET/CT combined tests?
A: -better anatomical localisation of cancers
-faster and more specific than PET alone
Q: What’s the difference between lateral and medial?
A: talking about relationship to centre of body or structure/limb
- medial is closer to centre
- lateral is closer to edge of body
Q: How an you tell, looking at a cross sectional image, which is the left and right side?
A: imagine you are at the foot of the bed, looking at the patient= standard
right -eg brain image- left
