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| Meiosis is a special type of cell division that reduces the number of chromosomes in each daughter cell to half the number of chromosomes in the parent cell |
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| prophase, metaphase, anaphase, and telophase. |
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| (TRACE) program was designed as a two phase approach to radiation dose awareness and overall patient dose reduction achieved through patient and community education, physician awareness, staff training, and technological enhancements. |
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| Time, Distance, Shielding |
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Term
| Nitrogenous organic bases in DNA |
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Definition
Adenine (A)
• Cytosine (C)
• Guanine (G)
• Thymine (T) |
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Term
Adenine (A)
• Cytosine (C)
• Guanine (G)
• Thymine (T) |
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Definition
| Adenine and guanine are compounds called purines, and the compounds cytosine and thymine are classified as pyrimidines. As can be seen in the figure, a primary difference between the two classes of compounds is the number of carbon–hydrogen rings, with purines always having two rings and pyrimidines only one. A unique characteristic of these organic bases in DNA is that purines link with pyrimidines only in certain specific combinations; more precisely, adenine always bonds only with thymine, and cytosine bonds only with guanine. This property is the reason the two strands of DNA are described as complementary. |
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Definition
| The OSL dosimeter shown in Fig. 5.3 contains an aluminum oxide (Al2O3) detector (thin layer). Filter made of AL, TiN( Sn) Copper (Cu) |
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Definition
| sensing material holder, preloaded packet incorporating an Al2O3 strip sandwiched within a three-element filter pack that is heat sealed within a light-tight black paper wrapper that has been laminated to the white paper label. The front of the white paper packet may also be color-coded to facilitate correct usage and placement of the dosimeter on the body of occupationally exposed personnel. (All components are sealed inside a tamperproof plastic blister pack.) |
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Term
| how does scatter radiation affect the radiographic image |
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Definition
| When an x-ray beam enters a patient's body, a large portion of the photons engage in Compton interactions and produce scattered radiation. Some of this scattered radiation leaves the body in the same general direction as the primary beam and exposes the image receptor. This scattered radiation reduces image contrast. |
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Definition
background equivalent radiation time
The BERT method compares the amount of radiation received, for example, from a patient's chest x-ray examination or from radiography of any other part of the anatomy, with natural background radiation received over a specified period such as days, weeks, months, or years |
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| ALARA is an acronym for “as low as reasonably achievable.” This term is synonymous with the term optimization for radiation protection (ORP) |
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At the beginning of the 20th century, leading scientists first realized that electromagnetic radiation appears to have a dual nature, referred to as wave–particle duality. This means that this form of radiation travels or propagates through space in the form of a wave but can interact with matter as a particle of energy called a photon. For this reason, x-rays may be described as both waves and particles
Due to a property known as wave-particle duality, x-rays and gamma rays, as we have seen in Chapter 3 and as discussed in Appendix E, can also be referred to as streams of particles called photons, each of which has no mass and no charge. |
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| Forms of electromagnetic radiation |
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Definition
Radio Waves. Radio waves have the longest wavelengths of all the electromagnetic waves. ...
Microwaves. Microwaves are shorter than radio waves with wavelengths measured in centimeters. ...
Infrared. Between microwaves and visible light are infrared waves. ...
Visible light. ...
Ultraviolet. ...
X-rays. ...
Gamma rays. ...
Activities. |
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| Radiation dose that changes blood |
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Definition
| 0.25 Gy and not exceed Gy |
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Definition
The full range of frequencies and wavelengths of electromagnetic waves is known as the electromagnetic spectrum. Each grouping on this scale represents a type or category of radiation generated by varying electric and magnetic fields. Table 2.1 shows the electromagnetic spectrum in terms of frequency (given in units of hertz [Hz] i.e., cycles per second), wavelength (in meters), and energy (specified in electron volts [eV],
1. Ionizing radiation
2. Nonionizing radiation
Of the entire span of types of radiation included in the electromagnetic spectrum, only the following radiations are classified as ionizing radiations1:
• X-rays
• Gamma rays
• Ultraviolet radiation with energy greater than 10 eV
Because they do not have sufficient kinetic energy to eject electrons from the atom, the following radiations are considered nonionizing:
• Ultraviolet radiation with energy less than 10 eV
• Visible light
• Infrared rays
• Microwaves
• Radio waves |
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| Unit that is used for occupational and non-occupational dose limits |
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Definition
effective dose (EfD)
Sievert (Sv). |
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Photoelectric absorption is an interaction between an x-ray photon and an inner-shell electron (usually in the K or L shells
Within the energy range of diagnostic radiology (23 to 150 kVp), which also includes mammography, photoelectric absorption is the most important mode of interaction between x-ray photons and the atoms of the patient's body for producing useful images
Photoelectric absorption is the most important mode of interaction between x-radiation and the atoms of the patient's body in the energy range used in diagnostic radiology because this interaction is responsible for both the patient's dose and contrast in the image. During the process of photoelectric absorption, the total energy of the incident photon is completely absorbed as it interacts with and ejects an inner-shell electron of biologic tissue from its orbit. The newly ejected photoelectron possesses kinetic energy and can ionize other atoms it encounters until its energy is spent. After losing an electron, the original ionized atom is unstable and attempts to restabilize. This occurs as an electron from a higher shell drops down and fills the vacancy in the inner shell by releasing energy as a characteristic photon. This cascading effect of electrons dropping down to fill existing shell vacancies continues until the original atom regains its stability |
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Definition
| Attenuation, then, refers to both absorption and scatter processes that prevent photons from reaching a predefined location. Fig. 3.3 shows that the path of photon 2 was bent, but not so much that the photon missed its target. Because photon 2 reaches the IR, it is part of the exit, or image-formation, radiation, but the bending of its path represents what is called small-angle scatter |
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Term
| how scatter affect contrast on an image |
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Definition
| When an x-ray beam enters a patient's body, a large portion of the photons engage in Compton interactions and produce scattered radiation. ... This scattered radiation reduces image contrast. The degree of contrast loss depends on the scatter content of the radiation emerging from the patient's body. |
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Term
| Review stochastic effects from radiation exposure |
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Definition
| Effects that occur by chance and which may occur without a threshold level of dose, whose probability is proportional to the dose and whose severity is independent of the dose. In the context of radiation protection, the main stochastic effect is cancer |
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