Imaging

Question 1

barium examinations

Answer 1

not very commonly used today because there is better tech.
barium sulphate is swallowing, travels through the oesophagus, stomach, duodenum. Because it has higher atomic number, it can swallow more protons from the X-ray than the surrounding tissues and will appear on the radio graph.
- is not absorbed by the body.

Question 2

barium meal VS. enema

Answer 2

MEAL:

• 1.5 mSv
• goes to the stomach

ENEMA:

• 7.0 mSv (stronger radiation)
• goes to the large bowel. is no swallowed but inserted through the rectum and pushed forward by inflating the bowel with air.

Question 3

Types of cross sectional imaging

Answer 3

CT, MRI, PET

Question 4

the type of gas used in CT colonography?

Answer 4

CO2

- you drag the tool around the colon and image will be displayed on the screen.

Question 5

CT scan is useful for?

Answer 5

• initial diagnosis of disease (if nothing shows on CT, most likely not serious)
• monitoring response to treatment and post treatment.

Question 6

colors in CT scan

Answer 6

depends on how much photon of light passes through. Lighter means less got through, darker means lots got through:
bone - white
air - black
fat - dark grey, will be darker than water.

Question 7

contrast agents used in CT

Answer 7

dilute iodine based gastrografin - oral route, for GI tract

iondine based omnique - IV route, gets excreted by the kidneys

Question 8

organs you should no use PET on

Answer 8

brain and spinal cord , liver- PET targets highly metabolic organs, therefore, there will be bad effects on these
kidney - all the agents used for contrast will be excreted in the kidneys.
the reproductive organs

Question 9

organs you should not use MRI on

Answer 9

lungs - too little soft tissue, is made of mostly air

stomach, colon - MRI is not good with things that move

Question 10

organs you should not use CT on

Answer 10

spinal cord - the structure is too small, and is also made of soft tissue.

Question 11

what should pancreas, upper urinary tract, and testis be scanned by

Answer 11

CT

Question 12

what should spinal cord by scanned by

Answer 12

MRI

Question 13

MRI vs CT

Answer 13

MRI - 45-60 mins
unlike CT, it does not use rays but instead magnet and therefore completely harmless unless the patient has pacemakers or metal implants.
- MRIs can’t be turned off if there is a problem, but CT you can turn on and off whenever

Question 14

how MRI works

Answer 14

use of magnet to reorientate molecules in the body, and the different amount of time it takes for them to rotate back to their original orientation is what produces the images.
light weight molecules like water will take longer to return than fat.

Question 15

screening

Answer 15

done in population, not one person
- useful for diseases with a latent stage that does not manifest too quickly. 
- common condition
- must be treatment 
or else ppl won't be interested

Question 16

radionuclide imaging

Answer 16

use unstable radioactive molecule called radionuclide that will emit nuclear radiation.

Question 17

PET vs CT

Answer 17

PET uses gamma rays

• the rays are emitted in 2 180 degree directions
• the patient will be injected with gamma radiating radionuclide and they will emit radiations that are detected by the scan
• harmful
• ideally half life of 6 hrs. But if we use it for treatment, it can be weeks or months
• shows metabolic changes while CT or MRI don’t
• functional imaging
• sensitive

CT uses x-rays

• single photon emission, only in 1 direction
• anatomical imaging
• high resolution, specific location.
• both have rotating cameras
• both are 3D?

Question 18

radioactive element vs pharmaceutical element

Answer 18

RE are radionuclides that emit radiation while PE is the stuff attached to RE to lead it to the target organ.

Question 19

common pharmaceutical elements

Answer 19

Hydroxy diphosphonate: bone
Dimercaptosuccinic acid (DMSA): kidney
Hexamethyl propine amine oxime (HMPAO): brain, WBCs
Macroaggregated albumin: lung

Question 20

what is a SPECT collimator

Answer 20

sheet that restricts the number of oncoming rays detected by the screen to only perpendicular ones for high resolution image
- made of tungsten

Question 21

radiography vs radionuclide imgaing

Answer 21

RI uses gamma rays emission

radiography uses x-rays

Question 22

how does X- ray work

Answer 22

electrons emitted from a source and deflected so that it goes through the body
some of the rays will pass through, pass through or reduced, deflected back, or scattered. we will only focus on the rays that passed through.

Question 23

different types of particles

Answer 23

alpha: slow moving but easily stopped by paper, basically a moving electron
beta: fast moving, high energy, short wavelengths, basically a moving electron
gamma: high energy wave/particle. formed from radioactive decay of particle’s nuclei
x- ray: high energy photon

Question 24

ventilation vs perfusion

Answer 24

ventilation: radioactive isotopes inhaled
perfusion: injected
you can have normal perfusion of the lungs but abnormal ventilation and vice versa

Question 25

angiography define

Answer 25

imaging used to visualise the lumen of blood vessels especially in the heart chamber for obstruction

Question 26

radionuclide imaging pros and cons

Answer 26

PROS: useful in scans of structures that are disease specific - Ex. WBC scan for ulcerative colitis CONS: not specific, the elements can target a location, and that could be both and tumor or inflammation. - we know where, but not what.

Question 27

give one commonly used example of pharmaceutical element in radionuclide imaging

Answer 27

technetium 99

Question 28

what disease is 123 iondine dopamine transporter spect specifically used for

Answer 28

Parkinson's disease | - normal appearance should be like 2 commas.

Question 29

SPECT

Answer 29

like PET, it uses gamma emissions, but is different by the type of radionuclide used, which have different mechanisms of emission. - rays only in 1 direction

Question 30

PET

Answer 30

- very similar to SPECT, but uses positron (electron with + charge) emission. this will combine with e- and annihilate one another, which produces 2 photons that travel in opposite directions. - used in cancer mostly, but also in inflammation and infection. - reveals metabolism of the structure as well - often combined with CT so you get both anatomical and functional information. - not high resolution, not very specific, but very sensitive.

Question 31

ideal energy of gamma rays used in imaging

Answer 31

50-300 keV

Question 32

common PET radionuclides

Answer 32

18F - half life 110 mins (most ideal) 11C choline- 20 mins 13N - 10 mins 15O - 2 mins

Question 33

18F (fluorodeoxy glucose) - aka FDG

Answer 33

attached to pharma element glucose. - will go to any cell in the body where there is infection, inflammation, tumor - also go to brain and spinal cord due to high metabolism - shown in black

Question 34

cyclotron

Answer 34

11 MeV | particle accelerator that produces radioactive isotopes that is carried out under computer control

Question 35

radiation pros and cons

Answer 35

PRO: - good for diagnosis , management, treatment CON: - radiation --> cancer later in life - make sure benefits > damage

Question 36

ultrasound

Answer 36

effective for looking at soft tissues - pregnancy - gallstones