radiation units

Question 1

standardized quantities used to express and compare physical quantities.

Answer 1

units

Question 2

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

Answer 2

Exposure (X)

Question 3

conventional unit of exposure

Answer 3

roentgens (R)

Question 4

SI unit of exposure

Answer 4

couloumbs per kilogram (C/kg)

Question 5

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

Answer 5

coulomb per kilogram (roentgen) unit

Question 6

• 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

Answer 6

Absorbed Dose (D)

Question 7

conventional unit of absorbed dose

Answer 7

rad

Question 8

SI unit of absorbed dose

Answer 8

Gray (Gy)

Question 9

• 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

Answer 9

qualIty factor (Q)

Question 10

• measure of kinetic energy transferred from radiation to matter

Answer 10

kinetic energy released per unit mass

Question 11

kerma symbol and SI unit

Answer 11

K and gray (J/kg)

Question 12

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

Answer 12

Louis Harold Gray

Question 13

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

Answer 13

kerma

Question 14

1 milligray

Answer 14

1E-3 Gy

Question 15

1 microgray

Answer 15

1E-6 Gy

Question 16

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

Answer 16

absorbed dose

Question 17

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

Answer 17

kerma

Question 18

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

Answer 18

low energies

Question 19

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

Answer 19

higher energies

Question 20

• 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.

Answer 20

Equivalent Dose (H)

Question 21

Conventional Unit of Equivalent Dose

Answer 21

rem

Question 22

SI unit of Equivalent Dose

Answer 22

sievert (Sv)

Question 23

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

Answer 23

Radiation Weighing Factor (Wr)

Question 24

measure of how much u are exposed

Answer 24

roentgen

Question 25

how much u absorb

Answer 25

gray (rad)

Question 26

how much biological damage it does

Answer 26

sievert (rem)

Question 27

considers radiation type

Answer 27

equivalent dose (sv)

Question 28

considers the radiosensitivity of different organs

Answer 28

effective dose (Sv)

Question 29

- 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

Answer 29

CT Dose Index (CTDI)

Question 30

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

Answer 30

CTDI 100 (mGy)

Question 31

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

Answer 31

CTDIw (mGy)

Question 32

is obtained by dividing CTDIw by pitch factor.

Answer 32

CTDIvol (mGy)

Question 33

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

Answer 33

dose-length product (DLP)

Question 34

DLP is usually expressed in units of

Answer 34

mGy*cm

Question 35

- 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

Answer 35

Monte Carlo Simulation

Question 36

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

Answer 36

radioactivity

Question 37

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

Answer 37

activity

Question 38

Conventional Unit of Radioactivity

Answer 38

Curie (CI)

Question 39

SI unit of Radioactivity

Answer 39

Becquerel (Bq)

Question 40

1 Ci

Answer 40

3.7 × 10^10 decays per second

Question 41

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

Answer 41

Antoine Henri Becquerel, one decay per second 1dps

Question 42

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

Answer 42

226 Ra

Question 43

1 Bq

Answer 43

2.7 × 10 -11 Ci