RAD BIO review 1 Flashcards by Donovan Tompkins

what are some of the ways we can measure radiation?

primary radiation
secondary radiation (as leakage radiation)
patient absorption
healthcare absorption

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what are the common radiation measurements?

exposure (air)
air kerma (air)
absorbed dose (tissue)
equivalent dose (tissue)
effective dose (tissue)

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What are the measurements of air?
what are some of the measurements of tissue?

exposure & air kerma (air)
absorbed dose, equivalent dose, & effective dose

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the intensity of the x-ray beam is measured by?
what does this measure?

exposure or air kerma
amount of radiation exiting the x-ray tube directed at patient

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what measures the leakage radiation escaping the tube housing?

exposure & air kerma

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what is the order of measurement for patient/occupational dose?

absorbed dose
converted to equivalent dose
converted to effective dose

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what does absorbed dose tell us?
what does it not?

absorbed energy & short-term effects (skin erythema or hair loss)
long-term effects (cancer)

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if we increase the kVp or mAs and don’t change anything else what happens to intensity, exposure, air kerma, absorbed, equivalent, & effective dose?
what if we increased distance?

intensity increases
exposure & air kerma increase
absorbed, equivalent, & effective dose increase
all of these decrease
(all of these factors are directly related)

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what does effective dose tell us?
what does it not?
what is it the opposite of?

long-term effects
absorbed energy & short-term effects (best for measuring cancer)
absorbed dose

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(t/f) All radiation measurements in diagnostic imaging fall into two categories
what are they?

true
radiation in air & radiation in tissue

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radiation that escapes the protective housing of the x-ray tube is known as?

leakage

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which of the following radiation measurements are used to quantify the risk of the long-term radiation injuries, such as cancer?

effective dose

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Exposure and air Kerma are important for?

occupational & patient safety

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exposure measures?

the number of ionizations in the air

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increase in beam intensity, ______ ionizations & _________

increases
exposure

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what are the units of measurement for exposure?

coulombs/kilograms (per kg)

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one coulomb is equal to?

1C= 6.242x10^18 ionizations

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how are we able to measure exposure in micro-coulombs?

increase MA/KVP increases photons, ionizations, & exposure

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Air Kerma measures?

the energy of ionizations in the air

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how does Air Kerma & exposure differ?

Exposure measures the number of ionizations
air Kerma measures the energy of ionizations

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what does KERMA stand for?

kinetic
energy
released per unit
MAss

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the primary by-product of x-ray interactions in air is?

free electrons

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KERMA is measured by?

gray (=1 joule per kg)

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what are the measurements for AIR KERMA & GRAY?

joules (energy) per kg (mass) (gray)
coulombs per kg

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what is the process through which x-rays create charged particles such as free electrons?

ionization

exposure is a radiation measurement used to quantify which of the following?

absolute number of ionization events in air

Air KERMA is a radiation measurement that describes the:

kinetic energy absorbed by ions in air

what units are used to measure exposure?

coulombs per kg (C/kg)

Air Kerma & exposure:

only measure radiation and error directed towards the patient/occupational

what best describes radiation exposure?

quantity of radiation directed at the patient

what does absorbed dose tell us?

how much radiation is absorbed in patient/occupational

absorbed dose comes from?

photoelectric absorption & Compton scattering

what is absorbed dose?

energy absorbed in the body (per unit mass)

absorbed dose calculation:

1 gray= 1 Joule per kg (J/kg) (ex 0.009J/ 1.5kg=0.006 Gy)

what negative effects can be caused by absorbed dose?

sperm depression (100 mGY) skin erythema (2,000 mGy) epilation (3,000 mGy)

what other variables affect the absorbed dose?

tissue thickness tissue density tissue with high atomic number

units of measurement for absorbed dose is?

Gy or mGy

absorbed dose is commonly used to describe which of the following?

quantity of radiation absorbed in the patient

How is absorbed dose calculated? how is exposure measure? how is Air Kerma measured?

(J/kg) (C/kg) (J/kg)

what dose LET stand for? what is it?

linear energy transfer the rate at which radiation energy is deposited in matter

what is the equivalent dose (EqD) formula?

D x Wr dose x radiation weighting factor

x-rays have a _____ LET alpha particles have a ____ LET

low high (concentrated)

higher LET =

more biological harm

what are these? LET? RBE? WR? EqD?

linear energy transfer relative biological effectiveness radiation weighting factor equivalent dose

what is the main reason for equivalent dose?

compare biological damage from different radiation types

equivalent dose is affected by?

radiation type (Wr) absorbed dose (D) kVp/ mAs exposure time distance

what is the effective dose calculation (EfD)?

D x Wr x Wt ( absorbed dose x radiation weighting factor x tissue weighting factor)

what variable must be known to calculate the effective dose (EfD)?

absorbed dose exposed tissue types radiation type

equipment survey devices ensure proper?

radiation output of x-ray machines

who use the equipment survey devices?

medical physists

Survey devices also ensure that mA and kVp assigned are:

the actual kVp & mAs output during exposure

what do environmental survey devices monitor? they are for? what is an example of one?

radioactive contamination & x-ray transmission occupational & public safety Geiger counter (GM counter)

personal dosimetry device track radiation dose to:

occupational workers

how do we measure radiation?

interacts with detector of the device convert anergy into a unit of measure (mGy)

radiation equipment survey devices evaluate? environmental radiation survey instruments evaluate? personal dosimetry devices evaluate?

radiation output of x-ray machine radioactive contamination occupational radiation dose

what type of radiation detection instrument is used to check MA and KVP? what type of radiation detection instrument is used to detect dose to radiographer?

equipment survey device personal dosimetry device

who is qualified to operate equipment survey devices?

medical physicists

in order to be measured, radiation must interact with the:

detector

what is an ionization chamber?

metal chamber filled with air or gas

what is an ionization chamber that serves as an occupational dosimeter?

pocket ionization chamber

the radiation-sensitive portion of an ionization chamber is composed of: A radiation measurement is acquired by ionization chamber when radiation:

air ionizes the air in the chamber

an ionization chamber calibrated to measure air kerma will display units of: exposure? equivalent dose?

Gray (Gy) C/kg (coulombs per kg) sieverts per hour (Sv/hr)

scintillation devices are effective for measuring ________ surveys who uses these?

environmental nuc med techs & medical physicists

scintillation device is comprised of ___ parts what are these?

3 scintillation crystal (absorbs alot of radiation) photocathode (create electrons, light to electrons) photomultiplier tube (multiply's the weak photocathode signal)

Scintillation is a process that creates?

visible light

what is measured during the process of gamma spectroscopy?

photon energies (keV)

what is the radiation-sensitive portion of scintillation detector composed of?

light-emissive crystal

the function of scintillation crystal is to convert? photocathode layer? photomultiplier?

x-rays into light light into electrons electrons into more electrons

what are types of semiconductor dectectors?

hand-held detector x-ray testing detector AEC cells DR receptor

units for semiconductor detectors: are used to evaluate ____ energy

radioactivity, bequerel, CPM (counts per min), CPS (counts per sec) photon (keV or mEv)

one difference between scintillation detectors and semicondictors?

semiconductors do not produce visible light

what is the function of the semiconductor crystal?

convert x-rays into electrons

the radiation-sensitive portion of a semiconductor detector is composed of?

electron-emissive crystal

what is the annual effective dose limit to the whole body? purpose? limit to the eyes? purpose? skin/extremity? purpose?

50 mSv & to limit stochastic effects like cancer 150 mSv & prevent radiation induced cataracts 500 mSv & limit deterministic effects

for members of the public the dose limits are all _____ of the occupational dose limit what are these for whole body, eyes, & skin?

10% 5 mSv, 15 mSv, 50 mSv

What are TLD & OSL? do they have the same fnction?

thermoluminescent dosimeter & optically stimulable luminescent yes

what are the type of radiation detector devices?

film badge pocket ionization TLD (most common) OSL (most common)

OSL & TLD track ___ over time this is read ____ and tracks the ___ ___ ___ limits

dose quarterly skin, lens, & whole body

_______ ______ _______ absorb all forms of ionizing radiation in TLD

lithium fluoride crystal

the loss of stored radiation dose energy is called:

fading

disadvantages of TLD?

fades in high heat or light can only be read once

OSL is comprised of:

aluminum oxide crystal

what is an advantage of OSL? disadvantage?

more sensitive to radiation, can be read multiple times, & not fade in heat or light more expensive than TLDs