SOME RADIATION CALCULATION FORMULAS AND EXAMPLES

SOME RADIATION CALCULATION FORMULAS AND EXAMPLES

SOURCE TO FILM DISTANCE CALCULATION

SFD (min)= t(1+d/ug)

t= thickness of job

d= source size

ug= 0.5 max

RADIATION SOURCE SIZE CALCULATION

source size= sq root of (dia of source x length)

if dia = 2.5mm and length = 0.6mm

then source size (d) = √2.5 x 0.6mm

                            d = 2.57

                  ug is max 0.5

               and if th of job is 12.5mm

              then SFD (min) = 12.5(1+2.57/0.5)

                                       = 76.75mm or 7.6cm

Exposure Time (min) = (FF x 2to the power (th/hvt) x SFD SQ X 60) / Ci x RHM x 100 SQ

FF = FILM FACTOR = 1.2

2TH/HVT = NO OF HVT IN TH OF JOB (MM)

SFD = 30CM

HVT= 12.5MM

TH= 16MM

CI= 39

FF = 1.2

RHM = 0.5 R/HR

EXPOSURE TIME (MIN)= 1.2 X 2 POW 16/12.5 X 30 SQ X 60/ 39X 0.5 X 100 SQ

                                           =  2.15MIN

DWDI TECH IS USED IF PIPE OD IS LESS THAN 90MM

DWSI TECH IS USED IF PIPE OD IS MORE THAN 90MM

Decay Table for iridium-192

Decay table for cobalt-60