Radiation Physicist Interview Questions & Answers

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Detector is a device that is sensitive to radiation and can produce a response signal suitable for measurement or analysis. A radiation detection instrument.

Collective dose (Animation) The sum of the individual doses received in a given time period by a specified population from exposure to a specified source of radiation

Biodosimetry The use of physiological, chemical or biological markers of exposure of human tissues to ionizing radiation for the purpose of reconstructing doses to individuals or populations.

Electron volt (eV) is a unit of energy equivalent to the amount of energy gained by an electron when it passes from a point of low potential to a point one volt higher in potential

Decay constant is the fraction of a number of atoms of a radionuclide that disintegrates in a unit of time. The decay constant is inversely proportional to the radioactive half-life.

Assigned Protection Factor Assigned Protection Factor (APF) means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees enrolled in a continuing, effective respiratory protection program.

Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations; and the application of this study to the control of health problems.

Background radiation ionizing radiation from natural sources, such as terrestrial radiation due to radionuclides in the soil or cosmic radiation originating in outer space.

Committed dose a dose that accounts for continuing exposures expected to be received over a long period of time (such as 30, 50, or 70 years) from radioactive materials that were deposited inside the body. For more information

Exposure pathway a route by which a radionuclide or other toxic material can enter the body. The main exposure routes are inhalation, ingestion, absorption through the skin, and entry through a cut or wound in the skin.

Deuterium a non-radioactive isotope of the hydrogen atom that contains a neutron in its nucleus in addition to the one proton normally seen in hydrogen. A deuterium atom is twice as heavy as normal hydrogen.

Americium (Am) a silvery metal; it is a man-made element whose isotopes Am-237 through Am-246 are radioactive. Am-241 is formed spontaneously by the beta decay of plutonium-241. Trace quantities of americium are widely used in smoke detectors and as neutron sources in neutron moisture gauges.

Biological half-life the time required for one half of the amount of a substance, such as a radionuclide, to be expelled from the body by natural metabolic processes, not counting radioactive decay, once it has been taken in through inhalation, ingestion, or absorption.

Kerma is the initial kinetic energy of the primary ionizing particles (photoelectrons, Compton electrons, positron/negatron pairs from photon radiation, and scattered nuclei from fast neutrons) produced by the interaction of the incident uncharged radiation, per unit mass of interacting medium. Unit of measure is gray.

Combined injury physical, thermal, and/or chemical trauma combined with radiation exposure at a dose sufficient to diminish the likelihood of overall survival or functional recovery.

Activity (radioactivity) the property of certain nuclides of emitting radiation by spontaneous transformation of their nuclei. Various units of (radio)activity have been used including curie (1 Ci = 3.7 x 1010 disintegrations per second) and becquerel

Cutaneous Radiation Syndrome (CRS) the complex syndrome resulting from radiation exposure of more than 200 rads to the skin. The immediate effects can be reddening and swelling of the exposed area (like a severe burn), blisters, ulcers on the skin, hair loss, and severe pain. Very large doses can result in permanent hair loss, scarring, altered skin color, deterioration of the affected body part, and death of the affected tissue (requiring surgery).

Health physics a scientific field that focuses on protection of humans and the environment from radiation. Health physics uses physics, biology, chemistry, statistics, and electronic instrumentation to help protect individuals from any damaging effects of radiation.

Biological Effects of Ionizing Radiation (BEIR) Reports of the National Research Council's committee on the Biological Effects of Ionizing Radiation. For more information

Actinides elements in the periodic table with atomic numbers from 90 to 103 (thorium to lawrencium); i.e., elements with a higher atomic number than actinium, which has an atomic number of 89. These are also called "rare earth metals." They include most of the well-known elements found in nuclear reactions. Actinides with atomic numbers higher than 92 do not occur naturally but are produced artificially by bombarding other elements with particles. Some of the actinides include plutonium, curium, and californium.

High-Efficiency Particulate Air Filter (HEPA) a filter that is at least 99.97% efficient in removing monodisperse particles of 0.3 micrometers in diameter. The equivalent NIOSH 42 CFR 84 particulate filters are the N100, R100, and P100 filters.

Leukocyte reduction a process used to filter and remove white blood cells from whole blood before transfusion. Leukocytes are removed from blood because they provide no benefit to the recipient but may carry bacteria and viruses to the recipient. Patients who receive blood that has not been leuko-reduced may have adverse effects, including fever with chills; alloimmunization, an immune system reaction that can compromise a later transfusion; and the transmission of viruses, including cytomegalovirus, which can be dangerous for low-birth weight infants and to immunosuppressed patients.

Effective half-life the time required for the amount of a radionuclide deposited in a living organism to be diminished by 50% as a result of the combined action of radioactive decay and biological elimination.

Beta burns Energetic beta particles with high enough specific-activity, if left on the skin surface for a sufficient length of time, may cause erythema and dry (or even wet) desquamation. These are often called "beta burns." "Beta burns" have been described after a nuclear weapon detonation as a consequence of fallout on the skin.

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