Radiation Protection/Physics/Image Production Numbers in Notes

Day Xrays were discovered

11/8/1895

how long was first exposure of roentgens wifes hand

15 min

1896

first medical xray taken and first biological damage indicators

becquerel discovers beta particles and gamma rays

1898

thomas edison invents flouroscope

1901

first noel prize in physics awarded to roentgen for xrays

1904

charles dally first radiation death

1920

skin erythema dose was first unit of radioactivity

1921

potter bucky grid

1928

unit of measurement roentgen for photons in air

1948

rad, and rem are used

1981

consumer radiation and safety act

speed of light

3 × 10^8 m/s or 186000 mi/s

quality factor alpha

20

charge of alpha

+2

quality factor beta

1

charge of beta

-1

quality factor fast neutron

10

quality factor gamma and xrays

1

leakage radiation max

100 mR/hr at 1 m or 1mGy/hr at 1m

times a scattered photon can scatter

2

xray wavelength

0.1-0.5 A

how many atoms an inch

125,000,000

k binding energy

69.5 kV

l binding energy

12 kV

m binding energy

3 kV

n binding energy

1 kV

max number of electrons in a shell

2n²

max number of electrons in valence

8

amt of photons that interact with body

95%

amt of photons that pass through w/o interacting

5%

coherent scatter happens how much

less than 5% of interactions

kvp range of coherent scatter

less than 30 kVp

compton equation

Ei=Es+(Eke+Eb)

photoelectric equation

Ei=Eke+Eb

pairproduction energy

1.022 mEv

photodisintegration energy

greater than 10 mEv

roentgen to C/kg

1R= 2.58 × 10^-4

curie to bequerel

1 ci= 3.7 × 10^10

1 rad is

100 ergs per gram

Rad to gy

1 Gy=100 rad

Rem to Sv

1 Sv=100 rem

Dose equivalent

Absorbed dose x quality factor

effective dose equation

Absorbed dose x quality factor x tissue weighting factor

ionization chamber detects

1 mR/hr to thousands R/hr

geiger muller counter detects

over 100 mR/hr

head/neck/thyroid recieve how much exposure

10-20x more

film badges detect

10mrem to 500rem, 0.1msv-5sv

OSL detects

1mrem to 1000 rem, 0.01 msv to 10 sv

how long OSL can be worn

1 yr

TLD detects

1.3 × 10^-6 c/kg or 5mR

poscket ionization chamber detects

0-200 mR

genetically significant dose

20 mrem/yr

gonadal shielding males

90% reduction

gonadal shielding females

50% reduction

use shielding when gonads within ___ of primary beam

2 in

extension cylinder length

10-12 in

manual collimation accurate within

2% of SID

PBL accurate within

1-2% of SID

source to skin distance collimator

6in (15cm)

inherent filtration

0.5 mm al

total filtration 50 kVp and less

0.5 mm al

total filtration 50-70 kvp

1.5 mm al

total filtration above 70 kvp

2.5 mm al

grid ranges

5:1-16:1 or 8:1-12:1 standard

bucky grids absorb

10-15% more scatter compared to stationary

grid frequency

number of lead strips

grids uses when parts

10-13cm

grid ratio formula

hight of lead strips/distance between them

airgap technique distance

10-15cm (4-6 in)

15% rule can reduce pt dose by

50-70%

amt of overexposure and under exposure that can produce fine image

500% over, 80% under

PA protects gonads by

90-95%

safest time to xray woman

within first 10 days of cycle

flouro timer

300s or 5 minutes

source to skin distance portable in OR

12 in, 30cm

source to skin distance fixed

15 in, 38cm

intensity of scattered photon

1/1000th the intensity of beam at 90degrees

barrier thickness primary

1/16th (0.16cm) in pb, 7 feet high

barrier thickness secondary

1/32in (0.08cm) pb floor to celing

barrier overlap

1/2in or 1.25cm

image intensifier lead

2mm pb

aprons, neck, thyroid sheilding

0.5 mm pb

gloves sheilding

0.25 mm pb

glasses shielding

0.35 mm pb

flouro drape/bucky cover sheilding

0.25 mm pb minimum, 0.5 mm pb reccomended

glass window thickness

1.5 mm pb

maternity shield

0.5 mm pb w/ 1mm pb panel on abdomen

portable cord length

6ft, 180cm, 2m

cord in fixed room length

18in, 45 cm

highest mA in flouro

5 mA

typical flouro mA

1-3 mA

maximum tabletop exposure rate

10 R/min (88mGy/min) or 5R/min at 1m

boost mode increases dose by

2-4x

LET xray

3 kEv/um

LET alpha

100 kEv/um

RBE

250 kEv of xray compared

percent of body water

80-85%

indirect effects account for how much of damage

95%

cell instant death

1000 gy in a period of seconds

cell reproductive death

1-10 Gy