Medical physics Flashcards
How are sound waves transmitted?
By particles. They must travel through a medium such as air in order to be transmitted from one place to another. Any solid, liquid or gas will do but sound waves cannot travel through a vacuum where there are no particles.
What is Ultrasound?
Human hearing ranges from 20-20000Hz, any sound above 20000Hz is called Ultrasound.
How is ultra sound used in medicine?
Ultrasound can be used in medicine to produce scans of the inside of the body. Since they do not cause any damage they are often used for looking at Babies in the womb of the mother.
High intensity ultrasounds can also be used to break up kidney stones- in the past these would have been surgically removed.
How do Ultrasound scanners work?
Ultrasonic waves are produced by a hand held device called a transducer. This is pressed against the skin of the patient it send out high frequency ultrasounds ( over 1 million hertz, 1 MHz) in a narrow beam which is scanned across the body. Some of the ultrasounds are reflected back to the transducer whenever they pass from one type of tissue to another. A computer is used to analyse the reflected ultrasounds and produce an image of the inside of the body.
What speed do all the waves in the electromagnetic spectrum travel at?
3x10*8m/s (to the power of)
What is infrared radiation used for in Medicine?
Infrared radiation is produced by any hot object.
The pattern of infrared radiation given off by the human body can be used to indicate how healthy a person is- if blood circulation is poor then the affected parts of their body are colder than normal and give off less infrared radiation.
Infrared radiation is also used to treat muscle injuries. By warming the area with infrared radiation.
Infrared can be used to create a heat picture this is called a thermogram.
How are optical fibres used in medicine, optical fibres are visible light.
Light can be transmitted down optical fibres. These fibres can be used to transmit light into a patient without transmitting any heat from the lamp producing the light i.e. the light is cold.
How are endoscopes used in medicine?
Endoscopes are medical devices which use optical fibres to transmit light into a patient’s body. Other optical fibres are used to carry the light out of the patient where it is either viewed through an eyepiece or can be connected to a camera for viewing on a television.
How are lasers used in medicine?
A laser produces a beam of very intense light, so intense that it can be used in various surgical techniques such as:
Destroying tumours by vaporising them- this can be done for tumours within the body by directing the laser beam into the body through an endoscope.
Sealing damaged blood vessels
Removing birth marks and tattoos.
What are pros and cons to Ultra violet radiation?
Ultraviolet radiation can be a hazard. It is found in sunlight and too great an exposure to it can cause skin cancers. At lower doses, though it can be used to help certain skin conditions like severe acne. It is also used for the treatment of jaundice babies. UV also helps our bodies produce vitamin D which can help our bones stay strong and healthy.
What are the 2 different types of UV radiation sun block and sunscreen protects us from?
UVA: this type of UV radiation can travel through glass, clothing. It is UVA which causes ageing of the skin.
UVB: this type of UV radiation cause burning to the skin if exposed too long. UVB can go through clouds so even if it is cloudy you can burn.
How are X-rays used?
X-rays have been used in medicine for many years as a means of seeing inside the body. X-rays pass through soft tissue but are absorbed by harder tissue like bone. They will pass through the body and can then be detected using a photographic plate or film where an image is produced.
Apart from detecting things like broken bones, X-rays can be used to treat different types of cancers, this is called Radiotherapy.
X-rays can also be used for CAT scans.
What’s re computerised tomography ( CAT scans )
An X- ray tube and detector rotate around the body. The intensity of the X-rays after they have passed through the body is analysed by a computer and an image of a slice through the body is displayed on the television.
CAT scans are able to produce a much clearer picture for the doctor to look at and since there are a number of slices through the body the doctor can determine the extent of the diseases or injury.
What does an atom consist of?
All nuclear radiation comes from inside the atom. An atom consists of protons( positivity charged) and neutrons on charge, surrounded by orbiting electrons( negativity charged)
What is an alpha particle?
What can it be stopped by?
What is the amount of ionisation it produces?
An alpha particle is a helium nucleus- 2protons and 2 neutrons.
It can be stopped by a thin sheet of palate or a few cm of air.
It strongly ionises
Alpha radiation produces most ionisation which makes alpha radiation the most dangerous if a source of alpha radiation is swallowed or breathed in.
