14. RADIATION HEALTH EFFECTS: HUMAN RADIATION RISKS Flashcards
- What are 2 types of Human Radiation Risks?
- Stochastic Effects
- Deterministic Effects
- What are 2 types of Stochastic Effect?
- Somatic
- Heritable
- What are 5 examples of Stochastic Somatic Disorders?
- Adult Leukaemia
- Carcinomas
- Sarcomas
- Foetal Leukaemia
- Malformations
- What are 3 examples of Deterministic Effects?
- Early (Acute) Erythema
- Late (Chronic) Skin Ulcerations
- Tissue Fibrosis
- What is the likelihood of an event occurring governed by?
- the laws of Probability
NB:
- this means that the chance of an event occurring is
directly related to the dose of ionising Radiation
received
- What is the 2 fold guiding Principle of this Probability Related effect?
- There is no threshold limit below which a Stochastic
effect cannot occur - While the chance of a cancer effect occurring may be
probability related, the severity of any resultant effect
will not be
- What can be said about the phrase: “There is no threshold limit below which a Stochastic effect cannot occur.”
- if the received dose is greater it will increase the risk of
the effect occurring - we can use Dose Equivalent Limits to calculate the
Statistical Risks
NB:
- Stochastic effects are Probabilistic
- the severity of these effects is not related to the dose
received
- What can be said about the phrase: “While the chance of a cancer effect occurring may be probability related, the severity of any resultant effect will not be.”
- Populations that are exposed to ionising radiations
have a greater risk of developing cancer
IF THE DISEASE IS CONTRACTED:
- the severity will not be related to the radiation dose
received
THERE IS A SIGNIFICANTLY REDUCED RISK OF DEVELOPING CANCER
- when the patient follows a low-dose examination
- compared to a high dose examination
- Please give an example of a Stochastic effect.
A PERSON HAS A DENTAL PANORAMIC X-RAY EXAMINATION:
- this is 0.1 mSv of Dose
- 0.015% x 0.1
= 0.0015%
ANOTHER PERSON HAS A CT ANGIOGRAPHY:
- this is 12 mSv of Dose
- 0.015% x 12
= 0.18%
THEREFORE:
- the risk of developing cancer from a CT Angiography is
directly related to the dose
- there will be an increased risk of getting cancer
- the resultant severity of the cancer is not related to the
dose
- What can be said if cancer did not result from either radiological examination?
- the rate and the extent of progression of the cancer
would not be relayed to the dose of radiation that may
have caused it
- What is the main kind of Somatic Effect?
- cancer itself
- the risk of developing a cancer from Medical Irradiation
is related to the dose of radiation received
HOWEVER:
- the general risk of developing cancer is very small
across all examinations
- Which kinds of human tissues are more at risk of developing a Malignancy than others?
- more sensitive tissues
- Name the 7 parts of the Human Body that have High Radio Sensitivity.
- Bone Marrow
- Spleen
- Thymus
- Lymphatic Nodes
- Gonads
- Eye Lenses
- Lympochytes
- Name the 5 parts of the Human Body that have Medium Radio Sensitivity.
- Skin
- Mesoderm Organs
MESODERM ORGANS SUCH AS:
3. Liver
4. Heart
5. Lungs
- Name the 3 parts of the Human Body that have Low Radio Sensitivity.
- Muscle
- Bones
- Nervous System
- Which develops more quickly, cancer or the surrounding human body tissue?
- cancer
- it may respond to the use of ionising radiation as a
treatment - this treatment could destroy or shrink the tumour
- What is the down side of using Ionising Radiation as treatment?
- it can harm some naturally developing tissues
- these tissues will start to develop extremely rapidly
- these tissues are at a greater risk now
NB:
- it is for reasons such as these that we have Radiation
Protection Regulations
- these protect vulnerable groups of people
(such as pregnant women)
- What principle do we apply to aim to minimise the risk of cancer?
- THE ALARA PRINCIPLE
- “As low as reasonably achievable”
- What happens to the effects on the genetic material of an individual that are caused by radiation-induced damage?
- these effects are carried in the individual’s gene cells
- ionising radiation can cause biological damage to these
genes - this may cause combinations of chromosomes to occur
- such damage will only show itself in future generations
(especially for women) - it can even become a part of the broader human gene
pool depending on whether the resulting individuals
reproduce
- What is the aim when it comes to Radiation dose?
- to ensure that the radiation dose received by the
gonads is kept to an absolute minimum - this is why lead is used to cover the Gonads during X-
Rays
- Why are sound radiographic techniques and appropriate protective devices essential?
- they help to manage the unpredictable and potentially
far reaching effects of radiation
- Which two properties define the Deterministic (Heritable) Effects of Radiation?
- THEIR SEVERITY
- will increase with increasing dose
- the effect is proportional to the dose
- A THRESHOLD EXISTS
- below which the effect of the radiation will not occur
- When will Deterministic Effects always occur?
- if the threshold is achieved
- What are Deterministic Effects associated with?
- they are associated with very large radiation doses
- these doses have a magnitude that would only be
experienced as a result of nuclear or other radiation-
related accidents - deterministic effects might also occur due to
Radiotherapy
- List some examples of Deterministic effects.
- Does this table make sense?
- yes
- Who is Alexander Litvinenko?
- he is a former KGB/FSB Personnel
- he is the first known victim of Radioactive Polonium
210-induced Acute Radiation Syndrome - he was poisoned by the Polonium
- he had received a very high dose over a short period of
time
- What is 1 Sievert (Sv) equivalent to?
- 50 000 chest rays
- 100 whole - body CT scans
- Does this graph make sense?
- yes
