Ionising Radiation
The lead aprons that are used for protection of staff in diagnostic radiography procedures do not provide protection against the ionising radiation used in nuclear medicine or radiotherapy. Why is this? Because:
Charged particles are much easier to stop (are less penetrating) than photons are.
Gamma rays are more penetrating than x-rays even if both have the same energy.
Such aprons do not cover the arms, feet, head and neck.
The shielding provided by aprons is not sufficient to stop photons with energies above 100 keV.
The shielding provided by aprons is not sufficient to stop photons with energies above 100 keV.
Diagnostic radiography uses x-rays with an average energy of 70 keV or less, which can be stopped by relatively thin amounts of lead (or lead-like) material. In order to stop the gamma rays used in nuclear medicine imaging, the thickness of the “aprons” would make them prohibitively heavy to wear.
The shielding provided by aprons is not sufficient to stop photons with energies above 100 keV. Diagnostic radiography uses x-rays with an average energy of 70 keV or less, which can be stopped by relatively thin amounts of lead (or lead-like) material. In order to stop the gamma rays used in nuclear medicine imaging, the thickness of the “aprons” would make them prohibitively heavy to wear.
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C. Coronal
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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 of the following absorbed radiation dose equivalents would cause the most harm to your body?
A. 0.05 sievert per year to the whole body for the human lifespan (75 years) = 3.75 Sv
B. 1 sievert (acutely) to the gonads only
C. 40 sievert (acutely) to the heart only
D. 7 sievert (acutely) to the whole body
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.
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