Module 2 Flashcards
Who discovered X-rays in 1895?
Wilhelm Rontgen
Who is Wilhem Rontgen?
Discovered Xrays on 8th november 1895 and in 1896 the first xray was taken in the UK at the Glasgow Royal infirmary.
In 1896 medical xray diagnosis began.
When was the first dental xray taken and who by?
The first dental xray was taken by otto walkhoff a german dentist in january 1896 less than two weeks after wilhem roentgen announced discovery of xrays and it used a 25 minute exposure.
RADIOGRAPHY -
uses xrays to produce images of areas inside objects
RADIOLOGY -
uses images to diagnose and treat disease
Electromagnetic spectrum -
- Electromagnetic Radiation is made up from both electric and magnetic fields
- Waves are energy and momentum from one point to another known as wave packet called a photon
- One photon is equivelent to one quantum of energy
- Photons have no mass and travel at the speed of light, they behave as both a wave and a particale
- there are millions of photons of diffrent energies which move at 90 degrees to each other.
- if the frequency is doubled then the energy of the photon is doubled.
- energy of photons is measured in electrons volts (eV)
- electromagnetic waves travel through a vacuum without changing speed
- vibrations transfer energy from one place to another without matter being transferred
- electromanetic raidation travels through empty space and the electic and magnetic fields vibrate as they travel
- all electromagnetic radiation act in this way.
Frequency -
- Number of repetitions in a given time period
- Greek letters nu, v
- more repetitions = higher frequency = shorter wave length
- measured hertz ‘Hz’
- measured from one point to another
- Greek letter lambda (λ)
EMR waves -
- energy and momentum
- electric and magnetic
- travel at 90 degrees to each other
- wave packets - photo/quantum
- no mass
- measured in electron volts (eV)
- travel through a vacuum
- the shorter the wavelength the more dangerous they are
- any waves shorter than visible light can cause cancer
- gamma rays are the shortest, then Xrays!
Natural background radiation
Radioactive substances can be found around us, in the ground, granite releases randon a decay product of uranium, the air, building materials and food as well as cosmic rays from space. it is estimated that an individuals dose from background radiation will be approximatley 2.7mSv per year.
How many xrays are approx. taken in the uk per year?
In the uk approximately 20-25 million dental xrays are taken a year and it is estimated that the overall risk in the UK us apporximatley 10 fatal malignancies per year therfore we must keep all exposures As Low As Reasonable Practicable -ALARP
What xray equipment is in the dental surgery?
- tube head
- positioning arm
- control panel
- wall mounted
- part of chair
- on wheels
- hand held
Equipment and requirements
- Safe and robust
- accurae and simple to operate
- capable of generating Xrays for film and digital
- small
- easy to position, move and store
- stable and balanced once positioned
what are the components of the tubehead?
- the outer casing is made of lead - this must be checked regurlarly to ensure no cracks or damage
- xray tube is in a glass envelope which is filled with oil to remove the heat
- step up transofrmer - increases the voltage from 240v to 60-90kv
- step down transformer - decreases the 240v to 7-10v required to heat the filament
- aluminum filtration - removes harmful low energy x-rays (soft xrays less than 30kv)
- focal spot
production of x-rays
- glass tube which is where the x-rays are produced
- found at the back of the tubehead surrounded by lead which absorbs any excess x-rays which are travelling in all directions, it also creates a vacuum
Cathode
- a tungsten filament centred in a focusing cup
- electrons are produced by the filament and are focused at the target on the anode(the xrays are produced at the anode)
- the focusing cup has a negative charge - the same as the electrons - this helps direct the electrons to the target