Ionising Radiation
Why is radiotherapy using high-energy x-rays an effective way of treating some cancer? Because:
If enough energy is deposited in tumour cells, they can be killed.
Most of the x-rays pass through the body without harming healthy tissue.
The dose to the skin surface is lower than with low-energy x-rays.
High-energy x-rays do not kill healthy cells.
If enough energy is deposited in tumour cells, they can be killed.
The ability of x-rays to be switched off and on and to deposit enough energy within a cell to kill it makes it suitable for treatment of cancer tumours.
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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 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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