Free Limited Scope of Practice in Radiography Test
1. Which of the following types of radiation will NOT cause atoms in human tissue to lose electrons?
a. Gamma radiation
b. Ultraviolet light
c. X-rays from computed tomography (CT) scanning
d. Microwave radiation
2. Implications of the bremsstrahlung effect include which of the following?
a. Tungsten can be used to produce X-rays.
b. Shields consisting of large atoms, such as lead, can be used against beta radiation.
c. The intensity of radiation decreases in proportion to the square of the distance from the radiation source.
d. Positrons emitted by certain radionuclides produce gamma radiation through annihilation.
3. Ionizing radiation doses associated with flat film chest radiography (lateral or posterior-anterior) typically fall within which of the following ranges?
a. 5-10 microsieverts (?Sv)
b. 10-100 ?Sv
c. 0.1-1.0 millisieverts (mSv)
d. 5-100 mSv
4. Following nuclear accidents, such as the one that occurred at the Fukushima Daiichi power plant in Japan in 2011, which of the following is the greatest long-term health concern?
a. Lung cancer, due to the release of radon gas
b. Breast cancer, due to X-ray beam radiation
c. Thyroid cancer, due to high levels of iodine-131
d. Bone cancer, due to high levels of calcium-45
5. Regarding the Johnson method for imaging the hip, which of the following is MOST accurate?
a. The photographic plate is positioned anterior to the hip.
b. The X-ray beam is oriented at the level of the greater trochanter.
c. It is used for imaging the head and neck of the femur.
d. Both legs should be elevated at a 45 degree angle.
Answers & Explanations
1. D: Ionizing radiation is energetic enough so that when it interacts with matter, electrons become energized and are ejected from their atoms or molecules. After losing electrons, atoms or molecules become positive ions, meaning that they have an excess positive charge. X-rays and gamma rays are high-energy forms of electromagnetic radiation that are ionizing. Ultraviolet (UV) light is electromagnetic radiation that is slightly more energetic than visible light, but slightly less energetic than X-rays. Low UV, which is more energetic than visible light, is non-ionizing, while medium and high UV are ionizing. The rest of the radiation spectrum, including low UV, visible light, infrared, microwave, and radio waves, is non-ionizing.
2. A: Tungsten is often the material used inside an X-ray machine. When a beam of electrons strikes material consisting of atoms with a high atomic number, such as lead or tungsten, some of the energy is converted to X-rays through a phenomenon known as the bremsstrahlung effect. The rest of the energy is released as heat. A large atom material like lead is not an effective beta radiation shield, since lead will produce X-rays when bombarded by beta particles. The equation used to measure the decrease in radiation intensity of relative to the distance from the radiation source is known as the inverse square law. A positron emission tomography (PET) scan utilizes gamma radiation that results from positron-emitting radionuclides injected into the body to produce three-dimensional images of targeted tissue.
3. B: Flat film chest X-ray radiography (lateral and posterior-anterior) typically imparts ionizing radiation doses in the range of 10 to 100 microsieverts (?Sv), although this dose may be higher. Five to 10 ?Sv would be the range for typical dental X-rays, although certain dental X-rays could exceed it. Most medical imaging procedures do not impart exposures of more than a few millisieverts (mSv), the range that most people receive yearly from natural radiation sources. There are certain exceptions, notably computed tomography (CT) scanning, which exposes patients to radiation doses in the multiple mSv range, as high as 40 mSv for whole body scans.
4. C: After accidents involving nuclear reactors, long-term health concerns focus particularly on iodine-131 and cesium-137, both of which may be produced in significant quantities. Iodine-131 is absorbed by the thyroid, where it releases radiation in the form of beta particles, with some gamma rays. Beta particles can damage thyroid cells and cause cancer. Consequently, thyroid cancer always is a major concern following nuclear accidents. Radon gas has been implicated in lung cancer, but is released naturally from the ground, not from a nuclear accident. X-rays are typically produced by X-ray equipment used in diagnostic medicine. In nuclear accidents, X-rays may be produced through bremsstrahlung and K-shell effects, when beta particles from decaying radionuclides interact with materials made of large atoms. However, this effect is not significant enough to be a concern. Similarly, calcium-45, a radionuclide used in certain diagnostic applications, is not a particular concern in a nuclear accident.
5. C: The Johnson method is used for imaging the head and neck of the femur, with the photographic plate positioned laterally against the hip that needs to be imaged, not anterior to it. The Lilienfeld position is used to image the acetabulum and ileum from a posterolateral orientation. The beam is at the level of the greater trochanter, which is touching the photographic plate, with the patient prone and the opposite leg raised 75 degrees. The Judet view involves raising both legs at a 45 degree angle to provide an oblique projection of the acetabulum.
Last Updated: 04/17/2017