Rad-103 Ch 1 Radiation and It's Discovery

when were x-ray discovered

november 8, 1895

who discovered x-ray

wilhelm conrad roentgen

when did roentgen receive nobel prize in physics

1901

when was it discovered x-rays cause biological damage

1898

what material was used to discover x-ray

crooke’s tube (cold cathode)

x-ray was an ___ discovery

accidental

how did roentgen discover x-ray

studying conduction of high voltage electricity through a low vacuum tube → piece of paper few feet away began to glow → placed hand between tube and barium paper and noticed bone of hand

what was the glowing paper covered in

barium platinocyanide

how long did the first x-ray take to expose

15 minutes

what type of radiation is x-ray a form of

electromagnetic radiation

x-ray behaves like

waves and particles

x-ray behaving as waves moves like

wavelengths and frequency

how are wavelength and frequency related

inversely

x-ray behaving as particles moves like

as a photon or quanta (plural)

what is a photon

small bundle of energy

how is photon energy measured

units of electron volts (eV)

what is the range of eV for diagnostic x-ray

between 10⁴ and 10⁵ eV

what does wavelengths represent

distance between two successive crests or troughs

what does x-ray used in radiography range from in wavelength

aprox. 0.1 to 1.0 Å

what does 1 Å equal

.1 nm aka 10^-9 m

what does frequency represent

number of waves (cycles) passing a given point per given unit of time (se)

x-rays used in radiography range in frequency from

aprox. 3×10¹⁹ Hz to 3×10¹⁸ Hz

what level of frequency and wavelengths do higher EMR have

high frequency

low wavelengths

what is equation for electromagnetic radiation (EMR)

c= λ v

what does each value of EMR represent

C = speed of light

λ = wavelength

v (f) = frequency

what are the two systems for quantifying radiation

standard British system

international system (SI)

what system for quantifying radiation is widely used

international system (SI)

units measures radiation for exposure in air (a)

standard: roentgen (R)

SI: coulomb/kilogram & air kerma (Gy_a)

what does roentgen (R) measure

amount of ionizations or electrical change in specified amount of air

aka intensity of radiation exposure

what is coulomb/kilogram a measure of

number of electron liberated by ionizations per kilogram of air

what does air kerma express

exposure or intensity

how is air kerma expressed

gray (Gy)

how much Gy_a is 1 R of exposure in air equal to

aprox. 0.01 (Gy_a) air kerma

radiation exposure is typically expressed in

smaller units by adding milli

1 R = 1000 mR

1 Gy = 1000 mGy

radiation units of measure for absorbed dose in tissue (t)

standard: radiation and absorbed dose (rad)

SI: gray (Gy_t)

what does absorbed dose measure

transfer of radiation energy into matter

what does one rad of (t) equals a transfer of

100 ergs per gram of any absorbing matter

how is one gray (Gy) defined as for (t)

1 joule of energy absorbed in each kilogram of absorbing material

1 rad / 0.01 Gy equal

1 rem / 0.01 Sv

a conversion factor of ___ is used to convert rads into grays

0.01

what does absorbed dose depend on

energy of ionizing radiation and tissue type

radiation unit of measurement for dose equivalent aka occupational radiation

standard: radiation equivalent in man (rem)

SI: sievert (Sv)

dose equivalent units are derived by

multiplying quality factor and units of absorbed exposure, rads, or gray

x-ray and gamma rays have a factor of

1 meaning they are equal in biologic effect on tissue

what is 1 rad/ 0.01 gray equal to

1 rem

0.01 Sv

radiation units of measurement for radioactivity

standard: curie (Ci)

SI: becquerel (Bq)

what do unstable atoms do and why

spontaneously emit particles and energy from nucleus

in an attempt to reach stability called radioactive disintegration or decay

what does curie and becquerel measure

rate of nuclear disintegration or decay of a material

what is half-life

time it takes for radiation activity to reduce to 50% of original activity

what are radioisotopes

radioactive elements used in nmt and radiation therapy

what is typical range of half life of radioisotopes

hours or days

what is effective dose

expression of relative risk to humans of exposure to ionizing radiation

what does effective dose not consider

patient variability like age, gender, weight

effective dose is used for

population instead of individual

what are properties of x-ray

invisible

electrically neutral

no mass

travel at speed of light in a vacuum

can’t be optically focused

forms a polyenergentic or heterogenous beam

produced in range of 30-150 KeV

travel in straight lines in all direction

cause some substance to fluoresce

penetrate human body

can be absorbed or scattered by tissue

produce secondary radiation

can cause chemical and biologic damage to living tissue

fundamental of radiation protection

minimize dose to patient and technologist using ALARA

limit amount of time exposed

maintain a distance of at least 6 feet from source

maximize use of shielding

collimate only what is needed

use combination of kVp and mAs to to minimize patient exposure

avoid unnecessary duplicate exams

screen for pregnancy

develop mental checklist for procedures and perform consistently