Radiation protection Flashcards
What risk is there for non-pregnant females?
The ovaries are radiosensitivity
Stochastic and deterministic effects can result in risks to any future offspring
What risk is there for pregnant females?
The foetus is considered to be the ‘critical structure’
Radiation dose, foetal age and tissue radiosensitivity are important
The Ionising Radiation (Medical Exposure) Regulations affect female patients by?
IR(ME)R state that, where appropriate, the pregnancy and breast feeding status of a female patient must be established
Why do we check breastfeeding status?
Radionuclides are excreted from the body In breast milk, as well as by the more traditional physiological pathways.
This means the infant gets a dose of radiation.
To reduce the risk the mother should not breastfeed for 48 hours (or have a test to assess the activity in the breast milk)
For radiographic purposes, the abdominal region is designated as?
Diaphragm down
Knees up
What’s the 28 day rule?
If within 28 days of last menstrual period (LMP) then proceed with the examination or
Patient is asked if her menstrual period is overdue – if the answer is NO then proceed with the examination
What’s the biological basis for 28 day rule?
Normal cycle is considered as being 28 days
Ovulation occurs at 14 days
14 days is the earliest time that pregnancy can occur
At 28 days the pregnancy is two weeks old
During this time the radiation risk is extremely small due to the undeveloped state of the embryo
When is organogenesis and what is it?
How does the 28-day rule affect this?
3 weeks post fertilisation
When organs start to develop (radiosensitivity high)
The 28-day rule means the most the foetus has developed is 2 weeks, avoiding this.
What is the 10 days rule?
High dose examinations may carry significant risk to a foetus e.g. CT of the abdomen
If within 10 days of LMP then proceed with the examination
If longer than 10 days from LMP then do not proceed
What is the biological basis for 10-day rule?
At 10 days from the onset of menstrual bleeding:-
Ovulation has not occurred therefore cannot be pregnant.
The endometrium has not repaired enough to support implantation
Hormonal levels have not high enough to support pregnancy
What are the principles of radiation protection?
JUSTIFICATION (of radiation procedure)
OPTIMISATION (ALARP) (of radiation dose)
As Low As Reasonably Practicable
LIMITATION (of radiation dose)
What are the risks associated with radiation?
Radiation-induced cancers in the individual
Tissue morbidity
Serious hereditary effects in offspring (first 2 generations)
What is justification?
No diagnostic exposure is justifiable without a valid clinical indication
Risk vs benefit
Benefit- is successful diagnosis and treatment – without unnecessary damage
Why are the risks twice as much as the average for children
Children are more radiosensitive as they are still growing, meaning cells are developing more rapidly.
Why are the risks half as much as the average for over 60?
The rate of growth of tissues is slower, less changing/new cells
