positioning x ray .pdf

radiology positing (x ray )

1. 155
Special Protection Measures for Women of Reproductive Capacity
radiographic techniques and appropriate protective devices – as the
effects are unpredictable and potentially far-reaching.
Heritable (also known as deterministic)
effects are de ned by two properties
1. Their severity will increase with increasing dose (i.e. the effect
is proportional to the dose).
2. There is usually a threshold below which the effect will not occur.
It is reasonable to say that heritable effects will always occur if a thresh-
old dose is achieved (unlike stochastic effects which may occur whatever
the dose received). Deterministic effects are associated with what we
would consider to be in diagnostic imaging terms, very large radiation
doses of an order of magnitude only experienced as a result of nuclear or
other radiation-related accidents. They may occur in radiotherapy.
Examples of deterministic effects might be:
◾fiRadiation burns (also called ‘erythema’ or skin reddening)
◾fiRadiation-induced cataracts and sterility.
Erythema will occur from 1 to 24 hours after a radiation dose of 2
Sieverts and cataracts will occur after 2–10 Sieverts have been received,
but may take many years to develop. To apply some perspective for
diagnostic radiographers, 1 Sievert is equivalent to around 50  000
chest X-rays or 100 whole-body CT scans.
In very basic terms, the aim of the radiographer when undertaking
a radiographic investigation is, first and foremost, to secure an opti-
mum diagnostic image while at the same time, minimising the risk of
a cancer event and subjecting the patient to no risk at all of a heritable
event occurring.
SPECIAL PROTECTION
MEASURES FOR WOMEN OF
REPRODUCTIVE CAPACITY
The fetus, as has been mentioned previously, is a structure which is rel-
atively sensitive to ionising radiation, largely due to the rate of cellular

4. 165
MCQs
MCQs
1. Discussions with patients should always include:
a. The risks
b. The benefits
c. Risk-benefit
d. Statistical analysis of the risk.
2. Risk of X-rays include:
a. Saving the person’s life.
b. Giving the patient the correct treatment as a result of the
correct diagnosis
c. Making a diagnosis with an examination which has less
morbidity and mortality than an alternative test
d. Hair loss.
3. The risk of developing a carcinoma in the general population is:
a. 1 in 2
b. 1 in 3
c. 1 in 4
d. 1 in 5.
4. The everyday risk associated with a chest X-ray is approximately
−ying for:
a. 1 hour
b. 2 hours
c. 3 hours
d. 4 hours.
5. An X-ray described as minimal risk is:
a. Less than 1 in 1,000,000
b. 1,000,000 to 100,000
c. 100,000 to 10,000
d. 10,000 to 1,000.
6. The following are ways to minimise the risk from X-rays:
a. Justification
b. Optimisation
c. DR L’s
d. All of the above.

6. 174
Chapter formulas
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