Unit 3 - Xrays and Ultrasound Flashcards
What type of wave lengths do X-rays have and what type of waves are they?
X-rays are high frequecny, short wavelenghth elevtromagnetic waves
What size are X-rays
Similar size to atoms (10-10M)
With what do X-rays classification overlap with?>
Gamma rays
How to X-rays affect photographic film?
The same way as light (create fog)
What do x-rays pass through and what are they absorbed by?
X-rays pass through healthy tissues and are absorbed by denser materials like bone and metal
How are X-rays formed electronically?
By using charge-coupled devices (CCD’s)
Give an advantage of using CCD
You can review it straight away (as apose to photographs which takes time to develop and they’re not always developed properly)
How do CT scans work?C
CT scans use X-rays (from different angles) to produce high resulution images (with lots of detail) of soft and hard tissue
Why do CT scans use lots more X-rays than a normal X-ray scan?
Soft tissue can absorb a small amount of X-ray radiation. Ct scans use lots of X-rays to distinguish between tiny variations in tissue density
What is the disadvantage of CT scans?
High radiation dose, highly ionising - this can cause DNA mutations (which can lead to a risk of cancer)
Why can X-rays be used to treat cancer?
X-rays can cause ionisation, meaning a high dose of x-rays will kill living cells.
How do X-rays treat cancer (process)
- The x-rays are focussed on the tumor using a wide beam
- The beam is rotated round the patient with the tumor at the centre
- This minimises exposure of normal healthy cells to radiation, and reduces the chance of damaging the rest of the body
Give 3 ways that radiographers can minimise their dose of radiation
- Wear lead aprons
- Stand behind a lead screen
- Leave the room whilst the scan is bieng done
Definition of Ultrasound
Ultrasound is the name given to sounds waves that hae frequencies greater tha 20,000Hz
What is the human hearing range?
20-20,000Hz
Give 5 uses of ultasound
- Scanning foetuses during pregnancy
- Investigating liver/heart problems
- Breaking down kidney stones and stones elsewhere
- Measuring the speed of blood flow in the body
- Cleaning jewellery
How does ultasound imaging work?
- The ultrasound is sent into the patients body
- At each boundry between tissues/organs, some of the ultrasound is relected
- The depth of each layer is calculated using the time taken for each reflected wave to return
- The reflected waves (echoes) are usually processed to produce a picture of the inside of the body on a screen
Why is jel used during an ultrasound?
To allow everything to be in contact, if there was air gaps over 90% of the waves wouldn’t be reflected and a very weak image produced
Why do high frequencies give you more detail?
They have a short wavelength
What are kidney stones?
A build up of salts, that resonate
Kidney stones can be removed by operation, but what are the disadvantages of this?
- Costs
- Risk to the patient
- Risk of infection
How is ultrasound used to break down kidney stones?
A high powered ultrasound wave is used to break down the kidney stones (as well as other stones) as the stones vibrate until the shake themselves apart
Comparing Ultrasound, X-ray and CT scans: Are they safe?
- Ultrasound is non-ionising (safe)
- X-rays are ionising.
They can cause cancer when exposed to a high dose, not safe to use on developing babies
- CT Scans are highly ionising and are only used when they’re really needed because of the increased radiation dose
Comparing Ultrasound, X-ray and CT scans: Image quality?
- CT Scans produce detailed images and can be used to diagnose complicated illnesses (the high resolution can make them easier to diagnose)
High quality 3D images can also be used to plan complicated surgery
- X-ray’s produce clear images of bones and metal, however not a lot else
- Ultrasound images are typically fuzzy and can therefore make it harder to diagnose some conidtions using these images
