Radiation Quantities and Units

Question 1

Discovery of Rays

• Need to develop standards for ___ and ___ radiation exposure
• ___ ___, 1___ Wilhelm Roentgen discovered x-rays.
• Within the following months many pioneers began their experiments using this new beam.
• As early as 1896 reports of ___ ___ to the body caused by exposure to ___ ___ were reported in Europe.

Answer 1

Discovery of Rays

• Need to develop standards for measuring and limiting radiation exposure
• November 8, 1895 Wilhelm Roentgen discovered x-rays.
• Within the following months many pioneers began their experiments using this new beam.
• As early as 1896 reports of biologic damage to the body caused by exposure to ionizing radiations were reported in Europe.

Question 2

Clarence Madison Dally

• First American died from radiation-induced ___ in October 1904 at the age of 39.
• Other physicians reported ___ ___ ___ and ___ resulted in:
• occupational exposure from early radiation workers which reported:
• ___ – ___ of the skin
• ___ ___ – blood disorders
• ___ – abnormal overproduction of ___ ___ cells

Answer 2

Clarence Madison Dally

• First American died from radiation-induced cancer in October 1904 at the age of 39.
• Other physicians reported biological tissue damages and deaths resulted in:
• occupational exposure from early radiation workers which reported:
• Radiodermatitis – reddening of the skin
• Aplastic anemia – blood disorders
• Leukemia – abnormal overproduction of white blood cells

Question 3

Somatic Damage

• Result of excessive ___ radiation exposure for early ___ and excessive exposure of ___
• ___itis
• ___
• ___ disorders

Answer 3

Somatic Damage

• Result of excessive occupational radiation exposure for early pioneers and excessive exposure of patients
• Radiodermatitis
• Cancer
• Blood disorders

Question 4

Need to Develop Standards for Measuring and Limiting Radiation Exposure

• 1st standard was the ___ ___ ___
• Developed from 19__ to 19__
• Defined as the received ___ of radiation that causes diffuse ___ over an area of skin after ___
• Not ___ as depended on the ___ and ___ of radiation exposure
• The ___ ____ on ___ ___ and ___ (ICRU) was formed in 1925 to develop new units of measure.

Answer 4

Need to Develop Standards for Measuring and Limiting Radiation Exposure

• 1st standard was the Skin Erythema Dose
• Developed from 1900 to 1930
• Defined as the received quantity of radiation that causes diffuse redness over an area of skin after irradiation
• Not reliable as depended on the equipment and type of radiation exposure
• The International Commission on Radiation Units and Measurements (ICRU) was formed in 1925 to develop new units of measure.

Question 5

Early Deterministic Somatic Effects

• Deterministic – you know ___ ___ will occur
• Somatic – the effects will occur on the ___ ___
• Tolerance dose is a radiation dose to which ___ exposed person could be ___ subjected without any apparent ___ ___ effects.
• *today no radiation exposure is considered to be ___ (___ Principle)

Answer 5

Early Deterministic Somatic Effects

• Deterministic – you know radiation effects will occur
• Somatic – the effects will occur on the exposed individual
• Tolerance dose is a radiation dose to which occupationally exposed person could be continuously subjected without any apparent harmful acute effects.
• *today no radiation exposure is considered to be safe (ALARA Principle)

Question 6

Effects of Radiation

Answer 6

​Effects of Radiation

Question 7

Roentgen Unit was Developed

• In 1930 – first unit was ___ — Tolerance dose was ___ per day
• In 1936 – Tolerance dose was ___ per day
• In 1948 – The ___ ___ of ___ (___ units) were developed
• In 1950 – ___ ___ dose replaced the tolerance dose for ___ workers

Answer 7

Roentgen Unit was Developed

• In 1930 – first unit was Roentgen — Tolerance dose was 0.2 R per day
• In 1936 – Tolerance dose was 0.1R per day
• In 1948 – The international Systems of Units (SI units) were developed
• In 1950 – maximum permissible dose replaced the tolerance dose for occupational workers

Question 8

1970 – Dosimetry and Risk Analysis

• Become quite sophisticated by just the means to measure the amount of ___ and comparing to the ___ ___
• Radiation units were developed for the ___ of different types of radiation:
• ___
• ___
• ___
• ___
• ___

Answer 8

1970 – Dosimetry and Risk Analysis

• Become quite sophisticated by just the means to measure the amount of exposure and comparing to the risks factors
• Radiation units were developed for the bioeffects of different types of radiation:
• *- Alpha
• Beta
• Gamma
• X-radiation
• Neutrons**

Question 9

1991 the ICRP Revisions

• Findings based on data from ___ ___ survivors
• Adopted the term: ___ (___) on the ___ deposited in the tissue by ___ radiation which includes:
• • Type of radiation
• Variable sensitivity of the ___ exposed to radiation (___ vs. ___ ___ vs. ___)
• Exposure to the ___ body vs ___ area of the body
• EfD is expressed in ___ (___) or ___ (___)

Answer 9

1991 the ICRP Revisions

• Findings based on data from atomic bomb survivors
• Adopted the term: Effected dose (EfD) on the energy deposited in the tissue by ionizing radiation which includes:
• • Type of radiation
• Variable sensitivity of the tissues exposed to radiation (skin vs. blood cells vs. gonads)
• Exposure to the whole body vs smaller area of the body
• EfD is expressed in sieverts (Sv) or millisieverts (mSv)

Question 10

Units Today

• ___ units have replaced the traditional units in the US on the ARRT beginning in January 2017.

Name changes:

• • ___ (___) = ___ - Radiation measured in ___
• • ___ = ___ - Radiation ___ to ___
• • ___ = ___ - Radiation ___ dose

Answer 10

Units Today

• SI units have replaced the traditional units in the US on the ARRT beginning in January 2017.

Name changes:

• • Roentgen (R) = Coulomb - Radiation measured in air
• • Rem = Sievert - Radiation equivalent to man
• • Rad = Gray - Radiation absorbed dose

Question 11

Radiation Quantities and their units of measure

These are the 5 ways to describe the measurements of radiation exposure:

1. ​
2. 3. 4. 5.

Answer 11

Radiation Quantities and their units of measure

These are the 5 ways to describe the measurements of radiation exposure:

1. Exposure (X)
2. Air Kerma
3. Absorbed dose (D)
4. Equivalent dose (EqD)
5. Effective dose (EfD)

Question 12

Exposure (X)

Described as the ___ of ___ charge of ___ radiation that may ___ an object when the vicinity of a radiation course.

Answer 12

Exposure (X)

Described as the amount of electrical charge of ionizing radiation that may strike an object when the vicinity of a radiation course.

Question 13

Air Kerma

• SI quantity that can be used to express radiation ___ transferred to a ___, which may be at the ___ of a patient’s or radiographer’s ___
• Gradually replacing the traditional quantity, ___
• Denotes a calculation of radiation ___ in ___
• Quantity that can be used to express x-ray tube ___ and ___ to ___ ___

Acronym for:

• • Kinetic energy released in ___
• • Kinetic energy released in ___
• • Kinetic energy released per ___ ___
• Expressed in metric units of ___ per ___ (__/__)
• May be stated in ___
• When the Gy is used to indicate ___ radiation energy deposited or absorbed in a mass of ___, it is written as ___
• When the Gy is used to indicate ___ radiation energy deposited or absorbed in a mass of ___, it is written as ___

Answer 13

Air Kerma

• SI quantity that can be used to express radiation concentration transferred to a point, which may be at the surface of a patient’s or radiographer’s body
• 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

Acronym for:

• • Kinetic energy released in matter
• • Kinetic energy released in material
• • Kinetic energy released per unit mass
• 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

Question 14

Dose Area Product (DAP)

• Is the sum total of ___ ___ over the ___ area of the patient’s surface or, a measure of the amount of radiant ___ that has been thrust into a portion of the patients body surface
• Is usually specified in units of ___-cm²

Answer 14

Dose Area Product (DAP)

• 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 surface
• Is usually specified in units of mGy-cm²

Question 15

Absorbed Dose

• Is the deposition of ___ per unit ___ in the patient’s body to ___ radiation
• This quantity is the amount of ___ per unit mass absorbed by an ___ object
• It is responsible for any ___ ___ resulting from exposure of the ___ to radiation
• Some structures in the body can ___ more radiant energy than others.

Answer 15

Absorbed Dose

• Is the deposition of energy per unit mass in the patient’s body to ionizing radiation
• This quantity is the amount of energy per unit mass absorbed by an irradiated object
• 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.

Question 16

Equivalent dose (EqD)

• Is the product of the average ___ dose in a ___ or ___ in the human body and its associated WR (weight exposed in radiation) chosen for the ___ and ___ of the radiation in question.
• Is used for radiation ___ purposes when a person received exposure from various types of ___ radiation
• For measuring ___ effects may be determined and expressed in ___ or in a subunit of the ___
• The Sv replaces the ___ for accounting for differences in biologic effectiveness of various types of ionizing radiation.
• Used to summarize the potential for ___ ___ to a human from exposure to ___ radiation.

Answer 16

Equivalent dose (EqD)

• Is the product of the average absorbed dose in a tissue or organ in the human body and its associated WR (weight exposed in radiation) chosen for the type and energy of the radiation in question.
• Is 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 mSv
• The Sv replaces the rem for accounting for differences in biologic effectiveness of various types of ionizing radiation.
• Used summarize the potential for biological damage to a human from exposure to ionizing radiation.

Question 17

Effective dose (EfD)

• Provides a measure of the overall ___ of exposure to ___ radiation
• “The sum of the weighted equivalent doses for all ___ tissues or organs” (NCRP Report No. 116)
• Incorporates both the ___ of the type of radiation used and the variability in ___ of the organ or body part irradiated through the use of appropriate weighting factors
• These factors determine the overall ___ to those biologic components for risk of developing a radiation-induced ___ or, for the ___ organs, the risk of ___ damage.

Answer 17

Effective dose (EfD)

• Provides a measure of the overall risk of exposure to ionizing radiation
• “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 factors
• These factors determine the overall harm to those biologic components for risk of developing a radiation-induced cancer or, for the reproductive organs, the risk of genetic damage.

Question 18

Linear Energy Transfer (LET)

• The concept of linear energy transfer helps explain the need for a ___, or ___, factor.
• It is the amount of energy transferred on average by ___ radiation to an object per unit ___ of track through the object
• It is expressed in units of ___/μm
• Radiation with a high LET transfers a ___ amount of energy into a ___ area and can therefore do more biologic damage than radiation with a ___ LET.

Answer 18

Linear Energy Transfer (LET)

• The concept of linear energy transfer helps explain the need for a quality, or modifying, factor.
• It is the amount of energy transferred on average by incident radiation to an object per unit length of track through the object
• It is expressed in units of keV/μm
• Radiation with a high LET transfers a large amount of energy into a small area and can therefore do more biologic damage than radiation with a low LET.

Question 19

Radiation Weighting Factor (WR)

• Must be used when determining ___
• Is a ___ factor (a multiplier) used for radiation ___ purposes to account for ___ in biologic impact among various types of ___ radiation
• Places ___ associated with ___ effects on a common scale

Answer 19

Radiation Weighting Factor (WR)

• 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 radiation
• Places risks associated with biologic effects on a common scale

Question 20

Answer 20

Question 21

Effective Dose EfD

• Takes into account the ___ of the tissue
• EfD = radiation dose x Wr x Wt
• Organ/Tissue and their Wt
• *is measured in ___ (___ or ___)

Answer 21

Effective Dose EfD

• Takes into account the radiosensitivity of the tissue
• EfD = radiation dose x Wr x Wt
• Organ/Tissue and their Wt
• *is measured in Sieverts (Sv or mSv)

Question 22

Answer 22

Question 23

Answer 23

Question 24

Roentgens to Coulombs

• 1 R = 2.58 x 10-4 C/kg
• Know the value but an easier unit to work with is gray
• (Gya) measured in air:
• Gya states for ___ measured in ___ ___
• ___ R = 1 Gya (___ ___ ___)

Answer 24

Roentgens to Coulombs

• 1 R = 2.58 x 10-4 C/kg
• Know the value but an easier unit to work with is gray
• (Gya) measured in air:
• Gya states for gray measured in air kerma
• 100 R = 1 Gya (gray in air)

Question 25

Answer 25

Question 26

Answer 26

Question 27

Answer 27

Question 28

Subunit Conversions

Because many x-ray examinations require small radiation doses, ___ may frequently be used to indicate ___ dose values. These subunits are only a ___ of a specific unit.

Answer 28

Subunit Conversions

Because many x-ray examinations require small radiation doses, subunits may frequently be used to indicate absorbed dose values. These subunits are only a fraction of a specific unit.

Question 29

Answer 29

Question 30

Radiation Weighting Factor (WR)

• WR has a different value depending on the type of radiation the person is exposed to:
• Radiation and WR listing:
• *X-rays and gamma is ___
• *Neutrons, energy < 10 is ___
• 10 keV – 100 keV is ___
• >100 keV – 2 Mev is ___
• > 20 mEv is ___
• *Protons is ___
• *Alpha particles is ___
• (NCPR #60)

Answer 30

Radiation Weighting Factor (WR)

• WR has a different value depending on the type of radiation the person is exposed to:
• Radiation and WR listing:
• *X-rays and gamma is 1
• *Neutrons, energy < 10 is 5
• 10 keV – 100 keV is 10
• >100 keV – 2 Mev is 20
• > 20 mEv is 2
• *Protons is 2
• *Alpha particles is 20
• (NCPR #60)

Question 31

Equivalent dose (EqD)

• is a product of the average ___ dose in a ___ or ___ (___ is the absorbed dose in the tissue)
• Will depend on the type of radiation you were exposed to:
• EqD = ___ X ___
• An individual received 0.25 Gyt of x-radiation of alpha. What is the total equivalent dose (EqD)?
• EqD = D X WR
• EqD = 0.25 X 20 = 5 Sv (change units due to knowing the type of radiation the person was exposed to)

Answer 31

Equivalent dose (EqD)

• is a product of the average absorbed dose in a tissue or organ (Gyt is the absorbed dose in the tissue)
• Will depend on the type of radiation you were exposed to:
• EqD = D X WR
• An individual received 0.25 Gyt of x-radiation of alpha. What is the total equivalent dose (EqD)?
• EqD = D X WR
• EqD = 0.25 X 20 = 5 Sv (change units due to knowing the type of radiation the person was exposed to)

Question 32

Effective Dose (EfD)

• Provides a measure of the overall ___ of exposure to the ___ radiation
• “The sum of the ___ equivalent doses for all ___ tissues or organs” NCPR Report #116
• EfD = ___ X ___ X ___
• D = ___ value
• WR = type of radiation ___ by a set ___ (___, ___)
• WT = ___ Weighting Factor (ie., ___, ___, ___)

Answer 32

Effective Dose (EfD)

• Provides a measure of the overall risk of exposure to the ionizing radiation
• “The sum of the weighted equivalent doses for all irradiated tissues or organs” NCPR Report #116
• EfD = D X WR X WT
• D = exposure value
• WR = type of radiation weighted by a set number (x-rays, alpha)
• WT = Tissue Weighting Factor (ie., thyroid, gonads, skin)

Question 33

Answer 33