Ionising Radiation
Which of the following absorbed radiation dose equivalents would cause the most harm to your body?
0.05 sievert per year to the whole body for the human lifespan (75 years) = 3.75 Sv
1 sievert (acutely) to the gonads only
40 sievert (acutely) to the heart only
7 sievert (acutely) to the whole body
7 sievert (acutely) to the whole body
This dose given acutely to the entire body will probably be lethal. Higher doses can be withstood if only a limited part of the body is exposed or if the dose is accumulated over a long time.
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Which anatomical plane is usually displayed in a CT scan?A. Transverse
B. Sagittal
C. Coronal
D. Longitudinal section
What are isotopes? Atoms of the one element whose nuclei:
A. Contain the same number of protons and neutrons
B. Have different numbers of protons
C. Have different numbers of neutrons
D. Do not have the optimum neutron to proton ratio
What does the “maximum permissible dose” of radiation (100 mSv/5 year period) refer to?
A. The average dose for the general population as a whole
B. The dose for an individual not exposed to radiation through their work
C. The dose allowed to people exposed to radiation through their work
D. The dose above which radiation is likely to cause harm to humans
Why are radionuclides that emit low-energy gamma radiation preferred than other radionuclides for in vivo diagnosis using a nuclear medicine technique? Because:
A. Other forms of radiation are emitted with too much energy.
B. High-energy gamma radiation is not penetrating enough.
C. Most of the radiation will emerge from the patient’s body.
D. Sources of x-rays require more extensive technical support than gamma sources.
The advantage of computed tomography (CT) over conventional radiography is:
A. CT delivers lower doses than conventional radiography.
B. CT images are faster to acquire than conventional radiographs.
C. CT produces a cross-sectional image that is not obscured by overlying anatomical structures.
D. CT projects a 3D structure onto a 2D image.
Which one of the statements about the penetrating ability of radiation is true?
A. 750 keV gamma rays are more penetrating than 750 keV x-rays.
B. 140 keV gamma rays are more penetrating than 60 keV x-rays.
C. 2 MeV beta rays (electrons) are more penetrating than 1 MeV gamma rays.
D. 1 MeV gamma rays are more penetrating than 2 MeV x-rays.
Exposing a foetus or young baby to x-rays should be avoided. What is most likely the cause of the danger?
A. Denaturing of cells due to the increase in temperature in cells absorbing radiation
B. Damage to a cell’s DNA
C. The baby becoming radioactive
D. The formation of a blood clot
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