Chapter 4: Radiation Quantities and Units Flashcards
1
Q
who discovered xrays
A
wilhelm conrad roentgen
2
Q
when was xrays discovered
A
November 8, 1895
3
Q
how was xrays discovered
A
with crookes tube
4
Q
First xray image
A
roentgens wifes hand
5
Q
who was the first fatality
A
Clarence Dally
6
Q
what was the crookes tube then updated to
A
Coolidge tube
7
Q
who discontinued his xray research because of clarence dallys injuries and death
A
Thomas edison
8
Q
when did clarence dally die
A
October 1904
9
Q
Result of excessive occupational radiation exposure for early pioneers and excessive exposure of patients
Radiodermatitis
Cancer
Blood disorders
A
Radiodermatitis
Cancer
Blood disorders
10
Q
somatic
A
to yourself
11
Q
genetic
A
future generations
12
Q
when were committees being started
A
1910
first death was 1904
13
Q
best overall dose
A
effective dose
14
Q
Early tissue reactions
A
nausea
fatigue
diffuse redness of the skin
loss of hair
intestinal disorders
fever
blood disorders
shedding of the outer layer of skin
15
Q
Late Tissue Reactions
A
Cataract formation
Fibrosis
Organ Atrophy
Loss of parenchymal cells
Reduced Fertility
Sterility
16
Q
Stochastic Effects
A
Cancer
Genetic (hereditary) effects
17
Q
stochastic
A
random
18
Q
meaning nothing is safe
A
nonthreshold
19
Q
meaning up to a certain point, your fine after that you start seeing reactions
A
Threshold
20
Q
Unit used from 1900 to 1930 to measure radiation exposure Problems encountered in using the skin erythema dose as a way to measure radiation exposureNeed to find a more reliable unitNew unit selected to be based on some exactly measurable effect produced by radiation, such as ionization of atoms or energy absorbed in the irradiated objec
A
Skin Erythema Dose
21
Q
Concept of tolerance dose
A
Threshold dose
22
Q
is recommended as a tolerance daily dose limit in 1934
A
0.2 R
23
Q
is recommended as a tolerance daily dose limit in 1936
A
0.1 R
24
Q
is a radiation dose to which occupationally exposed persons could be subjected without any apparent harmful acute effects, such as erythema of the skin.
A
Tolerance dose
25
radiation exposure received in the course of exercising professional responsibilities, many radiologists and dentists using the new penetrating rays developed a reddening of the skin called radiodermatitis.
occupational exposure
26
From 1900 to 1930, the unit in use for measuring radiation exposure was called
skin erythema dose
27
defined as the received quantity of radiation that causes diffuse redness over an area of skin after irradiation.
skin erythema dose
28
which appeared within minutes, hours, days, or weeks of the time of radiation exposure, were believed to be preventable if doses to radiation workers were limited.
early tissue reaction
29
that is, a dose of radiation lower than which an individual has a negligible chance of sustaining specific biologic damage.
threshold dose
30
A radiation dosimetry quantity that was defined by the NRC to monitor and control human exposure to ionizing radiation
Total Effective Dose Equivalent (TEDE)
31
Described by NRC regulations as “the sum of effective dose equivalent from external radiation exposure and a quantity called committed effective dose equivalent (CEDE) from internal radiation exposures.
36Total Effective Dose Equivalent (TEDE)
32
If 200 people receive an average effective dose of 0.25 Sv, the collective effective dose is
(200)(0.25)= 50 person - sieverts
33
Used in radiation protection to describe internal and external dose measurement
collective EfD
34
Quantity used to describe radiation exposure of a population or group from low doses of different sources of ionizing radiation
collective EfD
35
Determined as the product of the average EfD for an individual belonging to the exposed population or group and the number of persons exposed
Collective EfD
36
Person-sievert is the radiation unit for this quantity.
Collective EfD
37
Units for exposure
Coulombs per kilogram
38
units for air kerma
Gray
39
Units for absorbed dose
Gray
40
Units for equivalent dose and effective dose
Sievert
41
In the early 1950s, what replaces tolerance dose
Early 1950s: maximum permissible dose (MPD) replaces tolerance dose for radiation protection purposes
42
is the total electric charge of one sign, either all plus or all minus, per unit mass that x-ray and gamma ray photons with energies up to 3 million electron volts (MeV) generated in dry (i.e., nonhumid) air at standard temperature (22° C) and pressure (760 mm Hg or 1 atmosphere at sea level).
exposure
43
44
It is a radiation quantity “that expresses the concentration of radiation delivered to a specific area, such as the surface of the human body.
exposure
45
The basic unit of electric chargeIt is equal to the “amount” of electrical charge moving past a point in a conductor in 1 second when an electric current amounting to 1 ampere is used
Coulomb
46
The SI unit of electric current
Ampere
47
SI unit of measure for the radiation quantity, exposure, is equal to an electric charge of 1 C produced in a kilogram of dry air by ionizing radiation.
Coulomb per kg
48
Acronym forKinetic energy released in airKinetic energy released in materialKinetic energy released per unit mass
Air Kerma
49
Gradually replacing the traditional quantity, exposure
Denotes a calculation of radiation intensity in air
Quantity that can be used to express x-ray tube output and inputs to image receptors
Air Kerma
50
SI quantity used to express how energy is transferred from a beam of radiation to a material such as the patient’s skin
Air Kerma
51
Total amount of ionization (charge) an x-ray beam produces in a known mass of air must be obtained.
This type of direct measurement is accomplished in an accredited dosimetry calibration laboratory by using a standard, or free-air, ionization chamber.
Away from the laboratory much smaller and less complicated instruments are used.
Units used away from the laboratory must be periodically recalibrated in a standardization laboratory against a free-air chamber.
19Precise Measurement of Radiation Exposure in Radiography
52
Expressed in metric units of joule per kilogram (J/kg)
May be stated in Gy
When the Gy is used to indicate kinetic radiation energy deposited or absorbed in a mass of air, it is written as Gya.
When the Gy is used to indicate kinetic radiation energy deposited or absorbed in a mass of tissue, it is written as Gyt.
air kerma
53
Is the sum total of air kerma over the exposed area of the patient’s surface, or a measure of the amount of radiant energy that has been thrust into a portion of the patients body surfaceIs usually specified in units of mGy-cm2
Dose area product
54
A collected electrical charge of 2.58 × 10–4 C/kg of irradiated air constitutes an exposure of 1 roentgen (R
55
This quantity is the amount of energy per unit mass absorbed by an irradiated object
Absorbed Dose
56
It is responsible for any biologic damage resulting from exposure of the tissues to radiation.
Some structures in the body can absorb more radiant energy than others
Absorbed Dose
57
The amount of energy absorbed by a structure depends on the
Atomic number (Z) of the tissue comprising the structure
Mass density of the tissue
Energy of the incident photon
58
The Si unit of absorbed dose is :
Gy
59
Units for the following :
- in the air
- hit tissue
- scatter
- in the air - coulombs
- hit tissue - mGy
- scatter - sieverts
60
-field of view
- how much tissue are you radiating
Dose area product
61
Quality Factor of xray
1
62
quality factor of beta
1
63
quality factor of gamma
1
64
quality factor of alpha
20
65
Is the product of the average absorbed dose in a tissue or organ in the human body and its associated WR chosen for the type and energy of the radiation in question.
EqD
66
Used for radiation protection purposes when a person received exposure from various types of ionizing radiation
For measuring biologic effects may be determined and expressed in Sv or in a subunit of the Sv
EqD
67
D x WR and Sv = Gy x WR
EqD
68
tissue is only used with which dose
effective
69
Must be used when determining EqD Is a dimensionless factor (a multiplier) used for radiation protection purposes to account for differences in biologic impact among various types of ionizing radiationPlaces risks associated with biologic effects on a common scale
Radiation Weighting Factor (WR)
70
Provides a measure of the overall risk of exposure to humans from ionizing radiation
EfD
71
“The sum of the weighted equivalent doses for all irradiated tissues or organs” (NCRP Report No. 116)Incorporates both the effect of the type of radiation used and the variability in radiosensitivity of the organ or body part irradiated through the use of appropriate weighting factorsThese factors quantify the overall potential harm to those biologic components and the risk of developing a radiation-induced cancer or, for the reproductive organs, the risk of genetic damage.
EfD
72
D × WR × WT
EfD
73
Takes into account the relative detriment to each specific organ and tissueUsed in the calculation of EfDA value that denotes the percentage of the summed stochastic (cancer plus genetic) risk stemming from irradiation of tissue (T) to the all-inclusive risk, when the entire body is irradiated in a uniform fashionAccounts for the risk to the entire organism brought on by irradiation of individual tissues and organs
Tissue Weighting Factor (WT)
74
Used in radiation protection to describe internal and external dose measurements
Collective EfD
75
Person-sievert is the radiation unit for this quantity
Collective EfD
76
Quantity used to describe radiation exposure of a population or group from low doses of different sources of ionizing radiation
Collective EfD
77
Determined as the product of the average EfD for an individual belonging to the exposed population or group and the number of persons exposed
Collective EfD
78
is another SI quantity that is used to express how energy is transferred from a beam of radiation to air. It is mostly replacing the traditional quantity, exposure.
Air Kerma
79
is defined as the amount of energy per unit mass absorbed by an irradiated object
Absorbed Dose
80
