Borders' Dictionary of Health Physics

Q
A unit used to express very large energy figures. One Q equals 10¹⁸ (1 billion billion) BTU (British thermal units).
(USAEC-1974)

Quadratic-dose model
A model which assumes that the excess risk is proportional to the square of the dose.
(BEIR IV)

Qualification
The characteristics or abilities gained through education, training, or experience, as measured against established requirements, such as standards or tests, that enable an individual to satisfactorily perform a required function.
(ANSI N15.54-1988)

Qualification
The characteristics or abilities gained through education, training, or experience, as measured against established requirements, such as standards or tests, that qualify an individual to perform a required function.
(ANSI N15.41-1984)

Qualification test
Tests performed on a representative sample of equipment to verify the adequacy of the design and that the equipment meets the specifications agreed upon between manufacturer and user under normal, operational conditions and anticipated operation occurrences.
(IEC 50-394-1993)

Qualification test
A test made on a product or equipment item when it is proposed as a candidate to meet certain service requirements, which will verify to the user or owner that the item can meet his requirements. (See production test).
(ERDA 76-21)

Qualified expert
A qualified expert, for radiation protection purposes, is a person having the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to advise regarding radiation protection needs (for example, persons certified in an appropriate field by the American Board of Radiology, of the American Board of Health Physics of thge American Board of Nuclear Medicine Science, or persons otherwise determined to have equivalent qualifications.
(NCRP 105)

Qualified expert
A person having the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to provide advice on radiation protection needs. This person shall have training and experience in the clinical applications of radiation physics to radiation therapy (for example, persons certified in Radiological Physics or Therapeutic Radiological Physics by the American Board of Radiology, or those having equivalent qualifications).
(NCRP 69)

Qualified expert
With reference to radiation protection, a person having the knowledge and training to advice regarding radiation protection needs, to measure ionizing radiation, and to evaluate radiation safety techniques (for example, persons having relevant certification from the American Board of Radiology, the American Board of Health Physics, the American Board of Industrial Hygiene, or those having equivalent qualifications).
(NCRP 59)

Qualified expert
A person having the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to provide advice on radiation protection needs. (Where guidance is needed as to the competence of an individual to discharge the responsibilities of a qualified expert, it may be obtained from the American Board of Health Physics, the American Board of Radiology, or the American Board of Industrial Hygiene.)
(ANSI N43.1-1978)

Qualified expert
A person having the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to provide advice on radiation protection needs. (Where guidance is needed as to the competence of an individual to discharge the responsibilities of a qualified expert, it may be obtained from the American Board of Health Physics, the American Board of Radiology, or the American Board of Industrial Hygiene.)
(ANSI N43.2-1977)

Qualified expert
With reference to radiation protection, a person having the knowledge and training to advice regarding radiation protection needs, to measure ionizing radiation, and to evaluate radiation safety techniques. (For example, persons having relevant certificates from the American Board of Radiology or the American Board of Health Physics, or those having equivalent qualifications.)
(NCRP 48)

Qualified expert
With reference to radiation protection, a person having the knowledge and training to advice regarding radiation protection needs, to measure ionizing radiation, and to evaluate radiation safety techniques (for example persons having relevant certification from the American Board of Radiology or the American Board of Health Physics, or those having equivalent qualifications.)
With reference to shielding design, a person having particular knowledge and training in the field of medical x-ray and gamma-ray shielding.
(NCRP 49)

Qualified expert
A person suited by training and experience to perform appropriate radiation surveys, to oversee radiation monitoring, to estimate the degree of radiation hazard, and to advise regarding radiation hazards.
(NCRP 38)

Qualified expert
A person having the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to provide advice on radiation protection needs. (Where guidance is needed as to the competence of an individual to discharge the responsibilities of a qualified expert, it may be obtained from the American Board of Health Physics, the American Board of Radiology, or the American Board of Industrial Hygiene.)
(USAS N13.2-1969)

Qualified expert
A person having the knowledge and training necessary to measure ionizing radiations and to advise regarding radiation protection.
(NBS 73)

Qualified expert
A person having the knowledge and training needed to measure radiations and to advise regarding radiation hazards.
(NBS 54)

Qualified expert
A person having the knowledge and training needed to measure radiations from an electron accelerator and to advise the safety officer regarding radiation hazards. The physician, safety officer, or plant superintendent employing him shall be responsible for seeing that he has the necessary qualifications. Certification by competent authority or by a board set up for the purpose is desirable.
(NBS 55)

Qualified expert on radiation shielding
A person having the knowledge and training to undertake the analysis and design of a radiation-shielding system.
(NCRP 51)

Qualified health physicist
A person professionally engaged in radiation protection, who is certified by the American Board of Health Physics or who has equivalent competence.
(NCRP 51)

Qualified individual
A person who, by possession of a recognized degree or certificate of professional standing, or by extensive knowledge, training, and experience, has demonstrated the ability to solve problems relating to the subject matter and work.
(ANSI N14.6-1986)

Qualified inspector
An individual who has passed the written examination sponsored by the National Board of Boiler and Pressure Vessel Inspectors, and holds a current certificate of competency, or other competent inspector designated by the cylinder owner's inspection authority.
(ANSI N14.1-1990)

Qualified life (of equipment)
Period of time that can be verified for which the equipment will meet all performance requirements for the specified operational conditions.
(IEC 50-393-1993)

Qualified opinion
A statement that (1) there are departures from generally accepted safeguards accounting practice that have a material (significant) effect on the status of nuclear material as stated in the nuclear material balance report or that (2) there are audit procedures that the auditor considers necessary but that have not been applied
(ANSI N15.11-1983)

Qualified procedure
An approved procedure which has been demonstrated to meet specified requirements for its intended purpose.
(ANSI N46.2-1978)

Qualified radiological physicist
A person professional engaged in the physics applied to radiology, who is certified in this field by the American Board of Radiology or who has equivalent competence.
(NCRP 51)

Quality
Degree of excellence. As related to a measurement process attempting to determine the true value of a physical or chemical property, the resulting uncertainty is a measure of the quality of the measurements, relative to acceptable limits imposed by their intended use.
(ANSI N15.54-1988)

Quality
For the purposes of this report, a term that characterizes the ability of photons to penetrate matter. This ability depends on the energy distribution of the photons that make up the beam. Many parameters have been used to describe radiation quality, but for general clinical use the following methods of quality specification are recommended. (a) For x rays up to 2 MV, the maximum photon energy or the maximum tube potential, and the half-value layer (HVL) are given. (b) For x rays above 2 MV, the maximum tube potential (or equivalent) is given. (c) For gamma rays, the nuclide (e.g., 60Co) is specified.
(NCRP 69)

Quality
A term referring to the ability of a radiation beam to penetrate into a patient. It is often expressed in terms of half value layer (q.v.).
(ICRU 24)

Quality (radiology)
The characteristic spectral-energy distribution of x radiation. It is usually expressed in terms of effective wave lengths or half-value layers of a suitable material; e.g., up to 20 kVp, cellophane; 20 to 120 kVp, aluminum; 120 to 400 kVp, copper; over 400 kVp, tin.
(RHH)

Quality Assurance
Planned and systematic actions necessary to provide adequate confidence that an analysis, measurement, or surveillance program will provide acceptable results or service.
(HPS N13.42-1997)

Quality Assurance
All those planned and systematic actions necessary to provide adequate confidence that an analysis, measurement, or surveillance program will perform satisfactorily in service.
(HPS N13.30-1996)

Quality assurance
The entire suite of procedures, practices, documentation, and records required to provide confirmation of the accuracy of a measurement or of the degree of compliance of an activity with regulations and/or specifications.
(HPJ 60)

Quality assurance
All those planned and systematic actions necessary to provide adequate confidence that an analysis, measurement, or surveillance program will perform satisfactorily in service.
(ANSI N13.30-1989D)

Quality assurance
Quality assurance (QA) is a comprehensive concept that comprises all of the management practices instituted by the imaging physician to ensure that
(1) Every imaging procedure is necessary and appropriate to the clinical problem at hand;
(2) the images generated contain information critical to the solution of the problem;
(3) the recorded information is correctly interpreted and made available in a timely fashion to the patient's physician; and
(4) the examination results in the lowest possible radiation exposure, cost and inconvenience to the patient consistent with the objective.
(NCRP 99)

Quality assurance
All those planned and systematic actions necessary to provide adequate confidence that an item or a facility will perform satisfactorily in service.
(NCRP 59)

Quality assurance
All those planned and systematic actions necessary to provide adequate confidence that a system or component will perform satisfactorily in service.
(ANSI N42.18-1974)

Quality assurance
All those planned and systematic actions necessary to provide adequate confidence that a system or component will perform satisfactorily in service.
(ANSI N13.10-1974)

Quality assurance (QA) program
The documentation and implementation of policies and procedures used to satisfy the requirements of 10 CFR 71.71.
(ANSI N14.19-1986)

Quality Assurance Program Approval
The document issued by the NRC to approve the quality assurance program submitted to the NRC as meeting the requirements of Sec. 71.101 of this chapter. Activities covered by the quality assurance program may be divided into two major groups: those activities including design, fabrication and use of packaging and those activities for use only of packaging.
(10CFR171.5)

Quality assurance record
Documents which furnish evidence of the required and/or obtained quality in items, and/or activities, affecting quality.
(ANSI N46.2-1978)

Quality Control
Those actions that control the attributes of the analytical process, standards, reagents, measurement equipment, components, system, or facility according to predetermined quality requirements.
(HPS N13.30-1996)

Quality control
The overall system of activities whose purpose is to control the quality of a product or service so that it meets the needs of users. The aim is to provide quality that is satisfactory, adequate, dependable, and economic.
(HPJ 60)

Quality control
Those actions that control the attributes of the analytical process, standards, reagents, measurement equipment, components, system or facility according to predetermined quality requirements.
(ANSI N13.30-1989D)

Quality control
Those quality assurance actions related to the control of the physical characteristics and quality of the material or component to predetermined requirements.
(ANSI N14.19-1986)

Quality Factor
The modifying factor used to calculate the dose equivalent from the absorbed dose; the absorbed dose (expressed in rad or gray) is multiplied by the appropriate quality factor.
(10CFR835.2-1998)

Quality factor
The principal modifying factor that represents the biological effectiveness of different radiation types with respect to induction of stochastic effects. It is used to calculate the dose equivalent from the absorbed dose. The absorbed dose, expressed in rad or Gy, is multiplied by the appropriate quality factor to obtain the dose equivalent.
(HPS N13.41-1997)

Quality factor
The principal modifying factor used to calculate the dose equivalent from the absorbed dose (the absorbed dose is multiplied by an appropriate quality factor). Quality factors for various types of radiation, set forth in 10 CFR Part 835, Occupational Radiation Protection § 835.2, Definitions, are also appropriate for evaluating doses to members of the public.
(10CFR834.2)

Quality factor
The principal modifying factor used to calculate the dose equivalent from the absorbed dose; the absorbed dose (expressed in rad or gray) is multiplied by the appropriate quality factor (Q).
(10CFR835.2-1993)

Quality factor
The linear-energy-transfer-dependent factor by which absorbed doses are multiplied to obtain (for radiation protection purposes) a quantity that expresses, on a common scale for all ionizing radiation, the effectiveness of the absorbed dose.
(HPJ 60)

Quality factor
Since the probability of stochastic effects is found to be dependent on the quality of radiation, a weighting factor has been traditionally introduced to modify the absorbed dose and to define the dose equivalent. This dimensionless factor, called the quality factor, Q, is given as a function of the unrestricted linear energy transfer.
(ICRP 60)

Quality factor
The principal modifying factor (which depends on the collision stopping power for charged particles) that is employed to derive dose equivalent from absorbed dose.
(ICRP 56)

Quality factor
A linear energy transfer dependent factor by which absorbed doses are multiplied to obtain (for radiation protection purposes) a quantity which corresponds more closely to the degree of biological effect produced by x or low energy gamma rays.
(BEIR IV)

Quality factor
A multiplying factor applied to absorbed dose to express the biological effectiveness of the radiation producing it. The numerical values of quality factor are given as a function of its linear energy transfer (LET) in water for the radiation producing the absorbed dose.
(NCRP 94)

Quality factor
The quality factor, which appears in the relation H = QD between dose equivalent and absorbed dose, weights the absorbed dose for the biological effectiveness of the type of radiation producing the absorbed dose. The quality factor is chosen after surveying measured values of the relative biological effectiveness (RBE) for low absorbed doses and/or low dose rates, including those on human material available. It is independent of the organ and tissue or of the biological endpoint under consideration. The quality factor represents a judgement for use in radiation protection, and it is not a direct result of radiobiological experimentation as is RBE.
(NCRP 93)

Quality factor
The quality factor, Q, is intended to allow for the effect on the detriment of the microscopic distribution of absorbed energy. It is defined as a function of the collision stopping power (L_¥) in water at the point of interest.
(ICRP 51)

Quality factor
A multiplying factor used with absorbed dose to express its effectiveness in causing detrimental biological effects.
(NCRP 81)

Quality factor
A multiplying factor used with absorbed dose to express its effectiveness in causing detrimental biological effects.
(NCRP 75)

Quality factor
The linear-energy-transfer-dependent factor by which absorbed doses are multiplied to give dose equivalent.
(NUREG/CR 3332)

Quality factor
The quality factor, Q, is intended to allow for the different types of ionizing radiation in producing deleterious effects. This effectiveness is linked to the differing microscopic distribution of absorbed energy and Q is therefore defined as a function of the collision stopping power (L_¥) in water at the point of interest.
(ICRP 33)

Quality factor
The principal modifying factor (which depends on the collision stopping power for charged particles) that is employed to derive dose equivalent from absorbed dose.
(ICRP 30)

Quality factor
A linear-energy-transfer-dependent factor which absorbed doses are multiplied to obtain the dose equivalent.
(ANSI N43.1-1978)

Quality factor
The ratio of the absorbed dose of 200-250 keV x rays to produce a given biological effect in human tissue to the absorbed dose of any other type of nuclear radiation required to produce the same effect, multiplied by a factor which expresses the biological difference in energy-absorption of the two types of radiation. Quality factors are the product of the relative biological effectiveness, (RBE's), averaged over several types of tissue, and certain other linear energy transfer (LET) factors expressing biological differences resulting from radiation absorption of the radiation type of interest and the reference radiation (200-250 kev x rays); they are assumed to be independent of type of organ exposed.
(ANSI N1.1-1976)

Quality factor
A linear-energy-transfer-dependent factor which absorbed doses are multiplied to obtain the dose equivalent.
(ANSI N319-1976)

Quality factor
A multiplying factor applied to absorbed dose to express its effectiveness. The numerical values of quality factor are given as a function of the stopping power in water for the radiation producing the absorbed dose.
(NCRP 45)

Quality factor
The factor by which absorbed dose is to be multiplied to obtain a quantity that expresses on a common scale, for all ionizing radiations, the irradiation incurred by exposed persons. (See dose equivalent, distribution factor, relative biological effectiveness.)
(USAEC-1974)

Quality factor
The modifying factor most frequent used is the quality factor (QF), which accounts for the difference in linear energy transfer of different directly ionizing radiations at the location of interest.
(ICRP 15)

Quality factor (for radiation protection purposes) (q)
Factor in the calculation of dose equivalent, by which the absorbed dose is to be weighted in order to account for different biological effectiveness of radiations.
(IEC 50-393-1993)

Quality factor (Q)
The modifying factor (listed in tables 1004(b).1 and 1004(b).2 of Sec. 20.1004) that is used to derived dose equivalent from absorbed dose.
(10CFR20.1003)

Quality factor (Q)
A factor used for radiation protection purposes that accounts for the differences in biological effectiveness between different radiations. It is the ratio of the slope of the curve of risk versus dose for a given radiation to that of a reference radiation in the range of dose where the curves are assumed to be linear.
(NCRP 91)

Quality factor (Q)
A multiplying factor used with absorbed dose to convert to dose equivalent and therefore to express the radiation's effectiveness in causing biological effects.
(NCRP 111)

Quality factor (Q)
The LET-dependent factor by which absorbed dose is multiplied to obtain (for radiation-protection purposes) the dose-equivalent, a quantity that expresses the effectiveness of an absorbed dose on a common scale for all kinds of ionizing radiation.
(NCRP 98)

Quality factor (Q)
The principal modifying factor that is employed in deriving dose equivalent, H, from absorbed dose, D; chose to account for the relative biological effectiveness (RBE) of the radiation in question, but to be independent of the tissue or organ under consideration, and of the biological endpoint. For radiation protection purposes, the quality factor is determined by the linear energy transfer (LET) of the radiation.
(FGR 11)

Quality factor (Q)
A factor chosen to encompass appropriate values of the relative biological effectiveness (RBE), but to be independent of the organ and tissue or of the biological endpoint under consideration. It is also chosen to be a smooth function of the collision stopping power of the charged particles.
(NCRP 84)

Quality factor (Q)
A multiplying factor used with absorbed dose to express its effectiveness in causing detrimental biological effects. The numerical values of the quality factor are given as a function of the stopping power in water for the radiation producing the absorbed dose. (See dose equivalent).
(NCRP 62)

Quality factor (Q)
A factor which is used in radiation protection to weight the absorbed dose with regard to its presumed biological effectiveness insofar as it depends on the LET of the charged particles. The quality factor is a function of LET of the charged particles that deliver the absorbed dose.
(NCRP 51)

Quality factor (QF)
A factor which is used in radiation protection to weight the absorbed dose with regard to its presumed biological effectiveness insofar as it depends on the LET of the charged particles. The quality factor is a function of LET of the charged particles that deliver the absorbed dose. The charged particles traversing irradiated matter usually have a range of values of LET and the term is then the average, or mean quality factor.
(NCRP 38)

Quantum
Smallest physically observable value of a quantity that changes in a discrete manner by multiples of the value.
(IEC 50-393-1993)

Quantum
Unit quantity of energy according to the quantum theory. It is equal to the product of the frequency of radiation of the energy and 6.6256 x 10^-27 erg-sec. The photon carries a quantum of electromagnetic energy. (See electromagnetic radiation, radiation.)
(USAEC-1974)

Quantum
An observable quantity is said to be "quantized" when its magnitude is, in some or all of its range, restricted to a discrete set of values. If the magnitude of the quantity is always a multiple of a definite unit, then that unit is called the quantum (of the quantity). For example, the quantum or unit of orbital angular momentum is h, and the quantum of energy of electromagnetic radiation of frequency is n is hn. In field theories, a field (or the field equations) is quantized by application of a proper quantum-mechanical procedure. This results in the existence of a fundamental field particle, which may be called the field quantum. Thus, the photon is a quantum of the electromagnetic field and in nuclear field theories the meson is considered the quantum of the nuclear field.
(RHH)

Quantum mottle
The variation of optical density, brightness, CT number, or other appropriate parameter in an image which results from the random spatial distribution of the x-ray or light quanta absorbed at the stage of the imaging chain containing the minimum information content. This stage is known as the quantum sink.
(NCRP 102)

Quantum mottle
The irregular density variation on a radiograph due to the random variation in x-ray intensity over the surface of the intensifying screen.
(NCRP 68)

Quantum theory
The statement according to Max Planck, German physicist, that energy is not emitted or absorbed continuously but in units or quanta. A corollary of this theory is that the energy of radiation is directly proportional to its frequency. (See quantum.)
(USAEC-1974)

Quantum theory
That concept that energy is radiated intermittently in units of definite magnitude called quanta, and absorbed in a like manner.
(RHH)

Quarter
A period of time equal to one-fourth of the year observed by the licensee (approximately 13 consecutive weeks), providing that the beginning of the first quarter in the year coincides with the starting date of the year and that no day is omitted or duplicated in consecutive quarters.
(10CFR20.1003)

Quasi-ideal observer
Model observers whose performance is lower than that of the ideal observer, e.g., Hotelling observer and the NPWMF, but whose performance may be measurable in circumstances where the use of the ideal observer is not appropriate.
(ICRU 54)

Quasistellar
Resembling radiation originating in the stars.
(NCRP 45)

Quench
To limit or stop the electrical discharge in an ionization detector.
(USAEC-1974)

Quenched sample
A popular expression which connotes a counting sample that contains adulterants which reduce the photon output.
(ANSI N42.15-1980)

Quenching
Process of terminating continuous or multiple discharges following a single ionizing event in a Geiger-Muller counter tube.
(IEC 50-394-1993)

Quenching
The process of inhibiting continuous or multiple discharge in a counter tube which uses gas amplification.
(RHH)

Quenching (counter tube)
The process of terminating a discharge in a radiation counter tube by inhibiting continuous or multiple discharges caused by a single ionizing event.
(ANSI N1.1-1976)

Quenching circuit
Circuit which achieves quenching by reducing, suppressing or reversing the potential applied to a Geiger-Muller counter tube.
(IEC 50-394-1993)

Quenching gas
Component of the gas mixture filling of a Geiger-Muller counter tube which is intended to ensure self-quenching of the discharge.
(IEC 50-394-1993)

Quenching vapor
Polyatomic gas used in Geiger-Mueller counters to quench or extinguish avalanche ionization.
(RHH)

Note: References shown in ()