477 / 1542
6/3/2017
Conformity Index
NOTE:
Conformity index is defined differently in different texts:
RTOG /ICRU:
CI=
V
treated to specific Iso-dose
/
V
target
The “
specific Iso-dose” is often prescription dose, 95% dose or 50% dose
Both definitions CI close to 1 is ideal, provided ALL of PTV is covered.
BE careful not to only look at CI, as lack of PTV coverage may lead to CI
near 1.
5
0
1
2
3
4
5
6
7
8
0
2
4
6
8
Conformity Index
Volume of Isodose/Volume of PTV
CI (Knoss et al.)
CI (ICRU)
Beam shaping and modulating techniques
Conventional RT
Only Jaws to limit the beam
apertures, wedges to modulate
the intensity
ESTRO physics course 2017
6
7.3
3. 626
76.
2315
%95
CI
Bladder
Rectum