Diagnostic Imaging

Question 1

what does CT stand for?

Answer 1

computed tomography

Question 2

how does a CT scanner work?

Answer 2

• uses an x-ray tube mounted opposite a detector which emits x-rays in a fan shape that pass through the patient to reach the detector
• x-ray tube moves around the patient

Question 3

what are the pros of a CT scan?

Answer 3

• detailed image quality
• automatically digitised
• tissue contrast greater and defined
• fluid and solid tissue can be distinguished
• internal structure of soft tissue is more detailed

Question 4

what is the hounsfied unit for water, bone and air?

Answer 4

Water - 0
bone - 3000
air - -1000

Question 5

what is the relation between a high housfied number and attenuation?

Answer 5

high number, white, increased attenuation

Question 6

what is the relation between a low housfied number and attenuation?

Answer 6

low number, black, decreased attenuation

Question 7

what is attenuation?

Answer 7

the reduction of the intensity of an x-ray beam as it transverses matter

Question 8

what is a consideration to a CT scan?

Answer 8

• patients will need to be anaesthetised or heavily sedated

Question 9

what can you use a CT scan for?

Answer 9

• images of the skull, lungs, brain, spine
• thoracic and abdominal masses
• can detect metastases
• useful for demonstrating size and position of tumours

Question 10

What is fluroscopy?

Answer 10

an imaging technique that uses x-rays to obtain real time moving images of the interior of an object

Question 11

what colours do soft tissue and bone appear during a fluroscopy?

Answer 11

• soft tissue - white
• bone - black

Question 12

what is a con of fluroscopy?

Answer 12

higher radiation due to continuous exposure

Question 13

how does an MRI scan work?

Answer 13

• magnets change alignment of the protons of hydrogen atoms in the body
• radio waves disorientate the protons so they move around
• protons give off signals when they return to original position

Question 13

what does MRI stand for?

Answer 13

Magnetic Resonance Imaging

Question 13

what is an MRI scanner used for?

Answer 13

• used to map location of protons in the body tissues
• soft tissue images
• moving areas such as heart and lungs

Question 13

what are some cons of an MRI scan?

Answer 13

• patient must be anaesthetised
• can be up to an hour
• danger with metal objects

Question 13

what is the unit of measurement used in MRI’s called?

Answer 13

TESLA

Question 14

what is a pro of an MRI scan?

Answer 14

does not use ionising radiation

Question 15

what is nuclear scintigraphy?

Answer 15

• involves the use of a radioactive isotope which are injected into the patient
• when these decay they release gamma radiation
• this can be scanned and forms a 2D image
• have to be isolated for at least 24hrs

Question 16

what can nuclear scintigraphy be used for?

Answer 16

• equine orthopaedics
• thyroid cats

Question 17

what law governs nuclear scintigraphy?

Answer 17

The Radioactive Substance Act 1993

Question 18

what is ultrasonography?

Answer 18

uses sound waves to provide an image

Question 19

what can ultrasonography be used for?

Answer 19

to complement radiography

Question 20

what is a pro of ultrasonography?

Answer 20

can be performed conscious

Question 21

what is a con of ultrasonography?

Answer 21

requires clipping of hair

Question 22

what does white image do in terms of ultrasonography?

Answer 22

• reflects all sound waves
• bone or gas

Question 23

what does black image do in terms of ultrasonography?

Answer 23

• lets sound pass through
• fluid

Question 24

what does grey image do in terms of ultrasonography?

Answer 24

• reflects some, lets some through
• soft tissue and fat

Question 25

why do we use ultrasound?

Answer 25

• highlight differences between fluid and soft tissue
• shows internal architecture of soft tissue
• real time moving picture

Question 26

what are some advantages of ultrasound?

Answer 26

• painless
• non invasive
• short notice
• conscious

Question 27

what are some disadvantages of ultrasound?

Answer 27

• doesn’t penetrate bone or air
• difficult to master

Question 28

what are the two types of tranducer?

Answer 28

• linear array transducer
• sector scanner transducer