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radiation units Flashcards

1
Q

standardized quantities used to express and compare physical quantities.

A

units

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2
Q

amount of ionizing radiation that may strike an object such as the human body when in the vicinity of a radiation source

A

Exposure (X)

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3
Q

conventional unit of exposure

A

roentgens (R)

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4
Q

SI unit of exposure

A

couloumbs per kilogram (C/kg)

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5
Q
  • used for x-ray equipment calibration because xray output is measured directly with an ionization chamber.
  • also used to calibrate radiation survey instruments.
A

coulomb per kilogram (roentgen) unit

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6
Q
  • basic physical dose quantity, and it is used for all types of ionizing radiation and any irradiation geometry.
  • deposition of energy per unit mass by ionizing radiation in the patient’s body tissue
  • responsible for whatever biologic damage occurs as a result of tissues being exposed to x-radiation
A

Absorbed Dose (D)

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7
Q

conventional unit of absorbed dose

A

rad

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8
Q

SI unit of absorbed dose

A

Gray (Gy)

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9
Q
  • an adjustment multiplier that has been used in the calculation of dose equivalence to specify the ability of a dose of any kind of ionizing radiation to cause biological damage
  • used because some types of radiation, such as alpha particles, are more biologically damaging internally than other type
A

qualIty factor (Q)

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10
Q
  • measure of kinetic energy transferred from radiation to matter
A

kinetic energy released per unit mass

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11
Q

kerma symbol and SI unit

A

K and gray (J/kg)

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12
Q

This unit was named in honor of ____, who was one of the great pioneers in radiation biology

A

Louis Harold Gray

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13
Q
  • is measured in industry (except nuclear medicine).
    It often have usually lower doses than one gray, and the following
    multiples are often used:
A

kerma

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14
Q

1 milligray

A

1E-3 Gy

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15
Q

1 microgray

A

1E-6 Gy

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16
Q

defined as the amount of energy deposited by ionizing radiation in a substance

A

absorbed dose

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17
Q

defined as the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation in a substance

A

kerma

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18
Q

kerma approximately equals absorbed dose, since most initial kinetic energies of all the charged particles deposit their energy in sample

A

low energies

19
Q

kerma is larger than absorbed dose because some highly energetic secondary electrons and X-rays escape the region of interest before depositing their energy

A

higher energies

20
Q
  • measure of the biological effects of a particular type of radiation on organs or tissues.
  • considers the different radiation types
  • calculated value that represents the health effects of ionizing radiation. It takes into account the absorbed dose and the biological effectiveness of the radiation.
A

Equivalent Dose (H)

21
Q

Conventional Unit of Equivalent Dose

A

rem

22
Q

SI unit of Equivalent Dose

A

sievert (Sv)

23
Q

dimensionless constant that accounts for the relative biological effectiveness (RBE) of various types
of ionizing radiation

A

Radiation Weighing Factor (Wr)

24
Q

measure of how much u are exposed

A

roentgen

25
Q

how much u absorb

A

gray (rad)

26
Q

how much biological damage it does

A

sievert (rem)

27
Q

considers radiation type

A

equivalent dose (sv)

28
Q

considers the radiosensitivity of different organs

A

effective dose (Sv)

29
Q
  • standardized measure of radiation dose output of a CT scanner that allows the user to compare radiation output of different CT scanners
  • measure of the radiation output of a CT system, measured in a cylindrical acrylic phantom, that enables users to gauge the amount of radiation that a patient is exposed to during a CT scan
A

CT Dose Index (CTDI)

30
Q

linear measure of dose distribution over a pencil ionization chamber and hence does not take into consideration the topographical variation of a human body and is therefore not in clinical use

A

CTDI 100 (mGy)

31
Q

is closer to the human dose profile as compared with the CTDI100

A

CTDIw (mGy)

32
Q

is obtained by dividing CTDIw by pitch factor.

A

CTDIvol (mGy)

33
Q

Another commonly used index is the _____ which factors in
the length of the scan to show the overall dose output

A

dose-length product (DLP)

34
Q

DLP is usually expressed in units of

A

mGy*cm

35
Q
  • lets you see all possible outcomes of your decisions, including the actual probabilities each will occur, by running simulations with random variables thousands of times
  • helps in determining a more exact dose especially in CT
A

Monte Carlo Simulation

36
Q

defined as the emission of particles and electromagnetic rays from the nucleus of an unstable atom.

A

radioactivity

37
Q

rate of disintegration (transformation) or decay of radioactive material.

A

activity

38
Q

Conventional Unit of Radioactivity

A

Curie (CI)

39
Q

SI unit of Radioactivity

A

Becquerel (Bq)

40
Q

1 Ci

A

3.7 × 10^10 decays per second

41
Q

The SI unit of radioactivity is the Becquerel (Bq), named after ____, which equates to _______

A

Antoine Henri Becquerel, one decay per second 1dps

42
Q

One curie is roughly the activity of 1 gram of the radium isotope

A

226 Ra

43
Q

1 Bq

A

2.7 × 10 -11 Ci

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