Math formulas Flashcards
what is the inverse square formula? I1-D2 - 2
(I1/I2) = (D2/D1)^2
what’s the formula to see if its underused or overdosed? ( 2 slices )
(ssd1/ssd2)^2
what the direct proportions formula? ( F shelly)
(FS1/FS2) = (SSD1/SSd2)
what’s the central axis formula? (find doses besides PDD) no cross dressing for A and B
DoseA/ DepthA = Dose B/ Depth B
What is the formula for PDD? ( max is under 100 ft below the the deck
PDD = (Absorbed dose at depth/Aboserbed dose at dmax) x 100
what is the Maynor F formula? no max on deck
Maynor F = ( ssd(new) + dmax)/(Ssd(old)+dmax) x (Ssd(old) + depth / Ssd(new) + depth ) x 2
What is the formula for new PDD
New PDD = Maynor F x old PDD
what is the magnification factor? I then O
Image Size/ Object size or SID/SOD
SID - Source to image distance
SOD - source to object distance
what is the formula for Dose at DMax(applied dose)
Total dose / PDD
what is the formula for dose at a depth?
Applied dose x pDD of depth
what is the Gap formula?
gap call = d/2 (L1/ssd1. + l2/ssd2)
what is the collimator rotation for CSI? (Spine) broke in half by the sun
Arc tan x 1/2 (L1/ssd1)
L1 = length of spine
Ssd = Spine
what is the couch rotation for CSI? (Brain) - brain broke in half cause he fell from the couch
Arc tan x 1/2(L2/SAdD)
L2 = length of brain field
SAD = BrAin
what is the equivalent square?
ES = 2(AxB)/ (A+B)
B - perimeter
what is blocked area Formula?
BS = square root (area of open field) - (area of blocked field)
what is the field weighing/ Mu weighing formula?
Field weighing/MU = total dose/mu x Weight of field/sum of field
what is the gantry speed formulas?
gantry speed = degrees of arc / MU
what is the therapeutic ratio formula
Therapeutic ratio = normal tissue tolerance/ tumor metal dose
if answer is less than 1 then no its not favorable therapeutic ratio
what is the tissue weighting formula? ME U weight of F / Sum of F
MU x (weight of field/ sum of field)
What is the wedge angle?
Wedge angle = 90 - Hinge angle/2
wedge angle - angle of the actual wedge angle
what is the hinge angle ?
Hinge angle = 180 - (Wedge angle x2)
- angle between gantry angles
What is the HVL formula?
.693/M. - ??
m - coefficient
what is the temperature correct formula ?
(f + 273)/295 x (760/p)
temperature change F to celcius
TC = (Tf -32) x (5/9)
what are the MU calculations? SSD
Dose/ PDD x everything else
what is the wedge factor formula? beam shaping
dose With wedge factor / dose with out wedge factor
what is the Oxygen formula?
OER = Oxgen with O / Oxygen with o
What are the MU cal for SAD
SAD = dose/ TAR x everything else
What is the Extende distance (Inver square formula?
ISF = (Calibrated Ssd + depth / Extended SSD + depth) ^2
what is the Work load factor formula?
Work load = number of patients x dose at 1m per week
What is the electrons line 80% inside line formula?
80% inside line = Mev/3
what is the electron line at 90% Line formula?
90% isode line = Mev/4
what is the useful range formula ?
Useful range = Mev/2
Electron cutout thickness in mm
(MeV/2 ) + 1
what is the activity formula
AF = Ao(.5) ^ t/ T1/2
what is the half life formula
.693/l
what is the mean life formula?
1.44 x (T 1/2)
