25

Question 1

what kind of radiation is in an X-ray

Answer 1

heterogenous ionising radioation, gamma radiation at diff wavelengths.

Question 2

in an xray, what densities are black? white? grey?

Answer 2

Air = black 
Fat = light grey  
Soft tissue/fluid = shades of grey 
Calcium = most dense naturally occurring tissue 
Metal = white

Question 3

what is the main use of x rays

Answer 3

skeletal system and some diseases in soft tissue

Question 4

advantage of x rays

Answer 4

Quick
Cheap
Most common readily available –> First call you request

Question 5

disadvantages of x rays

Answer 5

2D representation of a 3D object
things in front can hide things that are behind and you cant see into the bone itself.
Don’t get good view of muscle tissue and other soft tissues bc of density pb
Limited range of densities that can be seen in x ray
Only calcified tissue shows up clearly
Soft tissues do not show up very well
Not very sensitive
You have to loose 30% of bone mass before it shows up on an X-ray
Processes taking place inside the bone can not be seen (avascular necrosis, osteomyelitis etc)
You sometimes have to do lateral view to see other structures

Question 6

what view are CHEST x rays taken in

Answer 6

PA view.

Question 7

why is the dome of the diaphragm higher on the right side

Answer 7

bc liver is dense organ so pushes diaphragm further up, even when stomach fills w food its not that dense

Question 8

what view is most commonly used for the APPENDICULAR SKELETON

Answer 8

AP and lateral view, bc doesn’t matter if things are distorted

Question 9

what color is radioopaque

Answer 9

white (v dense)

Question 10

what coloraturas is radio Lucent

Answer 10

black (less dense)

Question 11

what’s situs inverses totals

Answer 11

all the organs are the other way around, BUT be careful maybe it hasn’t been labelled properly

Question 12

what’s dextrocardia

Answer 12

when only the heart is flipped

Question 13

what are epiphyseal growth plates

Answer 13

Bones need to grow so plate of cartilage at either ends of bone which become bones after to allow bones to lengthen

Question 14

what’s a pneumothorax

Answer 14

(air in intrapleural space between parietal and visceral pleura causing right lung to collapse)

Question 15

what’s a DEXA scan

Answer 15

Two different low energy X-ray sources (heterogenous)
The denser the bone the fewer X-rays that get to the detector
Using 2 different X-ray rather than massive amount of sources improves accuracy
Used to detect ostoeporosis and body fat compositin
Lower levels of xray comparired to normal radiograph
X ray of arm of legs give you 1.5milisivers vs dexoscan 0.001 milisivers so much lower x ray exposure

Question 16

why would you use a contrast medium

Answer 16

Large difference in the densities of two organs show up
e.g solid muscle of the heart and the air in the lungs
If two organs have similar densities then do not show up
e.g. the small and large intestines
Reduce the density of a hollow organ by filling it with gas or air, provides negative contrast
Increase average atomic number of hollow structure (ie making it denser) by filling cavity with a liquid with a much higher average atomic number
Contrast media are solutions or suspensions of non-toxic substances that contain elements of high atomic number
Barium
Iodine
Gadolinium
No longer used bc it caused discomfort and air that had to be expelled so not pleasant

Question 17

what 3 contrast mediums exist and what are they used for

Answer 17

barium sulfate for GI
iodine for vascular system
gavalinium used for MRI

Question 18

what’s a CT scan

Answer 18

Here multiple x ray beans at diff angles passing through body to diff detectors, builds up picture of inside of body w more accuracy

Question 19

CT scan advantage

Answer 19

Cross-sectional images and other planes can be reconstructed afterwards or 3D reconstructions
Good high contrast bone detail so good for calcified tuissue
Well tolerated (not claustrophobic noisy)
Readily available

Question 20

CT scan disadvantage

Answer 20

Ionising radiation dose is higher bc multiple x ray sources so NOT FOR PREGGOS
Metallic artefacts cause loss of detail
Soft tissue surrounded closely by bone difficult to image
Respiratory movement artefact cause loss of details that’s why they tell you not to breath and hold your breath
Sturcutures that are close to ech other can lead to loss of details

Question 21

Whats an MRI

Answer 21

uses magnets instead of ionising radiation

Question 22

MRI advantage

Answer 22

Very high soft tissue contrast bc soft tissue has lots of water which has hydrogen ions
Images acquired in transverse plane (patient passes through the MRI lying down)
Can be reconstructed in any plane
Can get both structural and functional information

Question 23

disadvantage

Answer 23

Does not image bone directly (bones only 5% water)

Question 24

what’s an ultrasound

Answer 24

non ionising radiation based on density how d¡sound waves are absorbed by tissue and bounce back to receiver.

Question 25

advantages of ultrasound

Answer 25

Safe during fetal development as no radiation
Cheap
Readily available
Becoming more common for both diagnosis and therapeutic imaging
But difficult to interpret what is going on
Gives you real time imaging
Not as clautrophobic and noisy as MRI

Question 26

what’s the difference between T1 and T2 wighted MRI imaging o

Answer 26

The timing of radiofrequency pulse sequences used to make T1 images results in images which highlight fat tissue within the body.
The timing of radiofrequency pulse sequences used to make T2 images results in images which highlight fat AND water within the body.