Radiography Image Production
ohms law
V= IxR *draw triangle*
V= voltage ; I= current ; R= resistance
pixel size
field of view / matrix size = unit in mm
focal spot blur formula
FSS x (OID/SOD)
flux gain
output light photons / input x-ray photons
reciprocity law
mAs = mA x s *draw triangle*
name the 4 waveform factors and their unit
single phase = 1 ; three-phase six pulse = 1.35 ; three-phase twelve pulse = 1.41 ; high frequency = 1.45
spatial frequency (SF)
1/ 2 x pixel size = unit in lp/mm
***remember you need to find pixel size first...so remember that equation as well***
How do you find SOD
SID-OID
minification gain
d21 / d20
d1= input phosphor ; d0 = output phosphor
which one is NOT a common input phosphor diameters in fluoroscopy
A)25cm, B) 19cm, C)17cm, D)12cm
B
common = 25cm, 17cm, 12cm
turns ratio of a transformer equation
Vs = Vp x Ns/Np
bit depth chart
1-bit=(21) ; 2-bit=(22) ; 3-bit=(23) ; 8-bit=(28) ; 12-bit=(212) ; 16-bit=(216)
direct square law
mA2 = (mA1) x (D22 / D21)
brightness gain
flux gain x minification gain
Grid conversion formula & name all grid conversion factors
turns ratio
Ns/Np
SNR (signal to noise ratio)
image signal / image noise
heat unit (HU) formula
kVp x mAs x MF
**MF= modification factors....can you name all 4?**
magnification factor
full size input phosphor diameter / selected input phosphor diameter
equivalent dose & what unit is it in?
EqD = D x WR
unit= Sv
inverse square law
I2 = I1 x (D12/D22)
DQE
(SNR0)2 / (SNR1)2
P wave = electrical activity through atria ; QRS = electrical impulses through ventricles (systolic) ; ST segment = ventricles contracting but no electrical activity is flowing through ; T wave = ventricles are resetting electrically and preparing for next muscle contraction (diastole)
formula for exposure ; air kerma ; absorbed dose (D)
exposure= coulombs/kilogram (C/kg ; air kerma= Gy= 1 joule/ kilogram ; absorbed dose (D)= Gy= 1 joule/kilogram
effective dose & what unit is it in?
EfD = D x WR x WT
unit = Sv