CONTRIBUTING FACTORS FOR DENSITY, CONTRAST AND DETAIL

EVERYTHING YOU ALWAYS WANTED TO KNOW BUT WERE AFRAID TO ASK!!!!!!

DENSITY

GREATEST DENSITY

1) HIGH MAS

2) FASTEST SCREEN/FILM COMBO.

3) LOWEST GRID RATIO

4) SHORTEST DISTANCE

5) HIGHEST KV

CONTRAST

GREATEST CONTRAST (SHORT SCALE)

1) LOWEST KVP

2) HIGHEST GRID RATIO

DETAIL

GREATEST DETAIL

1) SMALLEST FOCAL SPOT

2) GREATEST FFD (SID)

3) SLOWEST FILM/SCREEN

 

IMPORTANT FORMULAS TO KNOW

15% RULE

FOR EVERY 10 KVP, MAS MUST BE MULTIPLED BY TWO OR DIVIDED BY TWO

FORMULAS CONT.

SCREEN CONVERSION

NEW MAS=OLD MAS X OLD SCREEN

                                  NEW SCREEN

FORMULAS CONT.

DISTANCE FORMULA

New MAS = Old MAS X NEW DIST.SQUARED

                                OLD DIST.SQUARED

GRID CALCULATION

Grid conversion

16:1      6

12:1      5

10:1      5

8:1        4

6:1        3

5:1        2

nongrid  1

 

You are exposing a patient using 10 mAs and a 12:1 grid. You repeat the exposure using a 6:1 grid. What is the new mAs?

 

1) Divide out the old grid -  10mAs / 5 = 2 mAs

2) Multiple in the new grid with the new mAs  =  2mAs x 3= 6 mAs   

 

One more formula

Photographic formula for greater density problems

MAS X KVSQUAREDX FILM SCREEN

SID SQUARED X GRID RATIO CONVERSION