Ch_2_ Radiation

absorbed dose

(D) The amount of energy per unit mass absorbed by an irradiated object (e.g., the patient's body tissue). This absorbed energy is responsible for any biologic damage resulting from the tissues being exposed to radiation. The gray (Gy) is the SI unit of this radiation quantity.

• List and describe three sources of natural background ionizing radiation and seven sources of manmade, or artificial, ionizing radiation.

*Natural Radiation* →terrestrail, cosmic, terrestrial and internal *Manmade Radiation* • Consumer products containing radioactive material • Air travel • Nuclear fuel for generation of power • Atmospheric fallout from nuclear weapons testing • Nuclear power plant accidents • Nuclear power plant accidents as a consequence of natural disasters • Medical radiation

• List the different forms of electromagnetic and particulate radiations, and identify those forms that are classified as ionizing radiation.

1) Electromagnetic radiation subdivided into Ionizing *(x-rays, gamma rays, ultraviolet > 10 eV)* and nonionizing *(ultraviolet < 10 eV, visible light, infrared, miro and radio waves)* 2) Particulate radiation is all ionizing when ejected from the atoms and includes Alpha, Beta, Neutrons, and Protons. At rest, no radiation is produced.

• Give some examples of different types of radiation.

1) mechanical vibrations of materials i.e. → ultrasound 2) Electromagnetic wave →radio waves, microwaves, visible light, & x-rays

radioactive decay

A naturally occurring process in which atoms with unstable nuclei relieve that instability by various types of nuclear spontaneous emissions, including charged particles, uncharged particles, and photons.

equivalent dose (EqD)

A radiation quantity used for radiation protection purposes when a person receives exposure from various types of ionizing radiation. This quantity attempts to numerically specify the differences in transferred energy and therefore potential biologic harm that are produced by different types of radiation. EqD is the product of the average absorbed dose in a tissue or organ in the human body and its associated radiation weighting factor chosen for the type of radiation in question. Equivalent dose enables the calculation of the effective dose (EfD).

milligray (mGy)

A subunit of a sievert equal to one one-thousandth of a gray (1/1000 Gy).

millisievert (mSv)

A subunit of a sievert equal to one one-thousandth of a sievert (1/1000 Sv).

2. Which of the following processes is the foundation of the interaction of x-rays with human tissue? A. Ionization B. Linear acceleration C. Particle emission D. Radioactive decay

A. Ionization

radionuclides

An unstable nucleus that emits one or more forms of ionizing radiation to achieve greater stability. The emissions may include alpha particles, beta particles, and gamma rays.

5. Which of the following are natural sources of ionizing radiation? A. Medical x-radiation and cosmic radiation B. Radioactive elements in the crust of the earth and in the human body C. Radioactive elements in the human body and a diagnostic x-ray machine D. Radioactive fallout and environs of atomic energy plants

B. Radioactive elements in the crust of the earth and in the human body

1. The amount of radiation actually received by a patient from a diagnostic x-ray procedure may be indicated in terms such as: 1. Entrance skin exposure (ESE) 2. Bone marrow dose 3. Gonadal dose A. 1 and 2 only B. 1 and 3 only C. 2 and 3 only D. 1, 2, and 3

D. 1, 2, and 3

biologic damage

Damage in living tissue.

radiation

Kinetic energy that passes from one location to another; a transfer of energy that results from either a change occurring naturally within an atom (see Radiation decay) or a process caused by the interaction of a particle with an atom.

electromagnetic radiation

Radiation composed of interacting, varying electric and magnetic fields that propagate through space at the speed of light. Examples include radio waves, microwaves, visible light, ultraviolet rays, x-rays, and gamma rays.

• Explain the concepts of equivalent dose and effective dose, and identify the unit of measure in which each of these radiation quantities is most commonly specified.

equivalent dose (EqD) takes into account the type of ionizing radiation that was absorbed within human tissue *(mSv)* where as the effective dose (EfD) take the organ and/or system also into effect when considering dose of radiation

effective dose (EfD)

measured in millisieverts (mSv), EfD attempts to quantify the harm in humans through the types of radiation exposure and organs/systems affected.

• Identify the unit of measure in which radiation absorbed dose is most commonly specified.

milligray (mGy)

manmade, or artificial, radiation

Ionizing radiation created by humans for various uses, including nuclear fuel for generation of power, consumer products containing radioactive material, air travel security, and medical radiation. Also called artificial radiation.

organic damage

changes in blood count

particulate radiation

As opposed to x-rays and gamma rays, which are electromagnetic radiations, particulate radiation is a form of radiation that includes alpha particles (nuclei of helium), beta particles (electrons), neutrons, and protons that are ejected from atoms at very high speeds.

isotopes

Atoms that have the same number of protons within the nucleus but have different numbers of neutrons (e.g., helium-3 and helium-4, whose nuclei contain one and two neutrons, respectively). Radioactive isotopes of atoms that make up biologic materials may be used in medical imaging nuclear medicine studies.

9. The Russian liquidators who worked during 1986 and 1987 at the Chernobyl power complex demonstrated a statistically significant rise in the number of: 1. Breast cancer cases 2. Leukemia cases 3. Prostate cancer cases A. 1 only B. 2 only C. 3 only D. 1, 2, and 3

B. 2 only

6. An equivalent dose as low as 250 mSv (.25 Sv) delivered to the whole body may cause which of the following within a few days? A. An increase in the number of lymphocytes in the circulating blood B. A substantial decrease within a few days in the number of lymphocytes or white blood cells that are the body's primary defense against disease C. A drop immediately to zero in the lymphocyte count D. A large increase in the number of platelets

B. A substantial decrease within a few days in the number of lymphocytes or white blood cells that are the body's primary defense against disease

3. Why are the long-term effects, such as an increased incidence of cancer in the exposed population living near Japan's Fukushima Daiichi Nuclear Plant, unable to be accurately determined? A. After the tsunami, winds carried all the radiation back out to sea. B. It was extremely difficult to measure the amounts of radiation people received. C. Radiation from the crippled reactors was negligible. D. Radiation levels exceeded the reading scales on the instruments used to measure population exposure.

B. It was extremely difficult to measure the amounts of radiation people received.

4. According to the most recent available data, what percentage of natural background radiation exposure comes from radon and thoron? A. 10 B. 29 C. 37 D. 48

C. 37

7. How is actual radiation dose to the global population from atmospheric fallout from nuclear weapons testing received? A. It is received all at once within a short period of time after such a test. B. It is received in large quantities within a period of 2 years after such a test. C. It is not received all at once but instead is delivered over a period of years at changing dose rates. D. No fallout from such testing is ever received.

C. It is not received all at once but instead is delivered over a period of years at changing dose rates.

8. Which of the following is the total average annual radiation equivalent dose from manmade and natural radiation? A. 1.8 mSv per year B. 3.0 mSv per year C. 3.2 mSv per year D. 6.3 mSv per year

D. 6.3 mSv per year

• Explain how ionizing radiation can cause biologic damage in body tissue.

Ejections of the electrons in the cell led to molecular changes within the cell leading to abnormal function or structure. These changes could possibly lead to further damage to the system including organic damage.

electromagnetic wave

Electric and magnetic fields that fluctuate rapidly as they travel through space, including radio waves, microwaves, visible light, and x-rays.

natural background radiation

Ionizing radiation created by humans for various uses, including nuclear fuel for generation of power, consumer products containing radioactive material, air travel security, and medical radiation. Also called artificial radiation.

radioisotope

Isotopes of a particular element that are unstable because of their neutron-proton configuration.

radiation dose

The amount of radiation received by an individual. The amount of energy transferred to electrons in biologic tissue by ionizing radiation is the basis of this concept.

ionization

The conversion of atoms to ions

radon

The first decay product of radium; a colorless, odorless, heavy radioactive gas that, along with its own decay products, polonium-218 and polonium-214 (solid form), is always present to some degree in the air. It comprises the largest component of natural background radiation

electromagnetic spectrum

The full range of frequencies and wavelengths of electromagnetic waves.

cellular damage

abnormal cell function or loss of cell function