Formulas Flashcards
PDD is ____/____.
absolute dose at depth/absolute dose at dmax
dose along central axis formula/dose at another point when given 2 PDDs and 1 dose:
doseA/PDDA = doseB/PDDB
New PDD formula:
Old PPD * MFactor
Maynard Factor formula:
(SSD1 + d/SSD1 + dmax)^2 X (SSD2 + dmax/SSD2 + d)^2
Mag Factor equations: (3)
SID/SOD
Image size/object size
FFD/FOD
Gap formula:
1/2d (L1/SSD1 + L2/SSD2)
Equivalent Square formula:
2(l*w)/l+w
Blocked Equivalent Square formula:
square root of (area open) - (area blocked)
If there is a change in SSD when calculating dose or output, use ____.
- Multiply by this or divide?
(what you know/where you wanna go)^2
- Multiply
Field weighting - dose per field formula:
total dose * (field weight/total fields)
Wedge Factor formula:
dose with wedge/dose without
Tray Factor formula:
dose with tray/dose without
Gantry Rotation Speed formula:
degress/MUs
Radioactivity formulas: (2)
1.
- n =?
- Afinal = Ainitial (1/2)^n
- n = t/half life - Afinal = Ainitiale^-lamdat
Mean Life Formula:
1.44 *T1/2
Wedge Angle formula:
90 - (hinge angle/2)
Hinge Angle formula:
180 - (wedge angle * 2)
Patient Separation is also called: (3)
Pt thickness
Intrafield Distance (IFD)
Innerfield Distance (IFD)
Collimator Rotation formula:
tan-1 * 1/2(L1/SSD1)
tan-1 * 1/2(L1/SSD1)
- L1 is length of ___ field
- SSD is SSD of ___ field
- Spinal
- Spinal
Couch Rotation formula:
tan-1 * 1/2(L2/SAD)
tan-1 * 1/2(L2/SAD)
- L2 is length of ___ field
- SAD is SAD of ___ field
- Brain
- Brain
Add image..
Use __ (PDD or TMR) for SAD?
TMR
Use __ (PDD or TMR) for SSD?
PDD
