Systems Of Dose Calculations

Question 1

Linacs are calibrated so that 1 MU delivers 1cGy for a standard reference __ at a standard reference __ at a standard source-to-calibration point

Answer 1

field size, depth

Question 2

MU reference depth used in most clinics followed by the alternative reference depth

Answer 2

Dmax is most common; 10cm depth is the alternative

Question 3

MU = __ at a point ÷ __ at that point

Answer 3

Dose, dose rate

Question 4

What things affect (impact) dose rate?

Answer 4

Output (distance specific)
Attenuation factors
Tissue attenuation (PDD, TAR, TMR, TPR)
Beam attenuation (tray factor, wedge factor)

Question 5

What special eqn to use to find dose to a point using PDD

Answer 5

Given Dose = Tumor Dose ÷ (PDDsubTD × 100)

Question 6

What is the ratio method eqn to find dose to a point uaing PDD?

Answer 6

DosesubA/PDDsubA = DosesubB/PDDsubB

Question 7

What is the eqn to calc MU setting using PDD?

Answer 7

MU = Rx / everything else (multiplied)

Question 8

PDD is used for SSD or SAD?

Answer 8

SSD

Question 9

FIXWhat eqn to use to find dose to a point with TAR, TMR, and TPR?

Answer 9

DosesubA = (DosesubB/TARsubB)(what is scpd??????

Question 10

TAR, TMR, TPR is used for SSD or SAD?

Answer 10

SAD

Question 11

Rx/PDD = ?

Answer 11

Dmax

Question 12

Define given dose

Answer 12

Dmax

Question 13

Define applied dose

Answer 13

Dmax

Question 14

Reference dose rate calibration parameter?

Answer 14

1 cGy to Dmax at 100cm SSD = 1.0 cGy per MU

Question 15

When do you use Mayneord Factor in calculations?

Answer 15

When you treat at extended distances. Must use Myaneord F to correct PDD (non inverse square)