RAD03-2001 What is an X-Ray? Flashcards
What is an X-ray?
A wave-packet of energy called a photon that can penetrate human tissues
What occurs to x ray beams that have high energy?
They pass through patients
What occurs to x ray beams that have low energy?
Stop inside the patient
Where do x-rays originate from inside an x-ray machine?
From a tungsten target
What type of wave from the EM spectrum have has the lowest photon energy?
Radio waves
What type of wave from the EM spectrum has the highest photon energy
X-rays and gamma rays
What forms of radiation are ionising?
X-rays and gamma rays
What are gamma rays?
Gamma rays are one of the radioactive emissions, these include: alpha particles, beta (+ve) and beta (-ve) particles and gamma rays
What is the difference between X-rays and gamma rays?
There is no difference
X-rays used in clinical practice are man-made and are produced and emitted by X-ray machines, however gamma rays are naturally occuring and emitted by radioisotopes that come from rocks and soils
What occurs when the X-ray photons hit the patient?
Transmitted unchanged: Highest energy photons will pass straight through the patient unchanged
Absorbed: Lowest energy photons will be absorbed by the patient and disappear
Deflected: some photons lose some energy
Scattered: Some photons are just scattered with no loss of energy
What are the 3 categories of damaging effects of X-rays on human tissue?
Somatic Deterministic/ Certainty effects
Somatic stochastic effects
Genetic stochastic effects
What does somatic refer to?
The body of a person being irradiated and hence effects therefore develop in patients who have been x-rayed
What does deterministic mean?
They will definitely happen (certainty)
What is included in acute somatic deterministic effects?
Short-term including radiation sickness, coma and death
What is included in chronic long-term somatic deterministic effects?
Hair loss, damage to blood vessels and cataract formation in the eye
Can dentistry cause somatic deterministic effects?
No, large enough doses are not used
What does stochastic mean?
By chance
What is an example of a stochastic effect?
Cancer induction, as there is no known threshold dose for these effects
How does the size of the exposure affect the somatic stochastic effects?
It does not effect the severity of the damage, only the probability of it happening
Can dentistry cause somatic stochastic effects?
Yes, just because little films and small amounts of radiation are used, it may cause little cancers
What do genetic effects involve?
The future offspring of the person being irradiated
The genetic material of the patient being irradiated, but the resultant damage only becomes apparent in their children
Are genetic effects due to chance?
yes
How can genetic stochastic effects occur?
reproductive organs need to be irradiated for genetic material to be damaged
Can dentistry cause genetic stochastic effects?
Highly unlikely as, X-ray bean is aimed at the patient’s teeth and jaw
