Computed Tomography

Question 1

advantages of using CT?

Answer 1

uses the same principles of X-rays
- but longer exposure so more diagnostic

relatively quick and fast feedback

provides detailed images of bone, soft tissue and organs

creates an image of a cross-section of the body
- can be used to create 2D and 3D images
- you can break down an image into components

moderate movement/artefacts can be tolerated
- so suitable for critical patients that cant have sedation/GA

Question 2

how does CT work?

Answer 2

contains a 360° rotating x-ray bea, opposite a moving detector which collects information
- the patient lies inside the gantry on a moveable bed

a thin beam of X-ray is passed through the cross-section whilst rotating around the circumference of the gantry

the area of focus is slowly passed through the gantry
- creates the corkscrew effect of multiple slides/images

Question 3

regular vs high-resolution CT

Answer 3

regular = common use
- can use data to work out the average tissue volume for each slide
- can then fill in any gaps
- helps find tumours, nodules and lesions where location is unknown
- but will miss small features

high = often used for clinical trials
- better image quality
- produce exact representation and locations on each slice

Question 4

what would you use a CT scan for?

Answer 4

musculoskeletal injuries
bone remodelling/arthritis
internal bleeding
foreign body identification
scan masses
- know the size and vessels feeding it
CT guided biopsies

Question 5

considerations when using CT?

Answer 5

produces high doses of radiation

avoid staff staying in the room
- stand as far away as possible and to the side of the gantry
- wear PPE

control entrances
- lockable doors
- light box and x-ray light warning

room should have lead-lined walls
- consider rooms around - ceilings and floors
- close rooms around if not safe
- no throughway

have dosimeters checked regularly

RPA must be information
- have a plan for extra radiation
- protect staff, animals and area

Question 6

management of CT unit?

Answer 6

exposures produce a lot of heat
- prep early to warm up
- avoids overheating on first exposure

keep ambient temperature of room
- changes can cause pressure inside the machine damaging components

annually services

Question 7

how should you prepare a patient for CT?

Answer 7

sedation of GA is necessary
- so must be started and catheterised

have clean to reduce artefacts

consider pain scoring and effective positioning
- no natural reflexes when bones are overextended