Harmony Search in Therapeutic Medical Physics - Music-Inspired Harmony Search Algorithm: Theory and Applications - page 190

2 2

f = 5 × ( 90 − D 100 ) + ( − V 125 )

prostate urethra

(2)

2 2

+ ( − V 75 ) + ( − V 75 )

bladder rectum

This modification takes into account both dose and volume constraints for the pros-
tate, urethra, bladder and rectum from RTOG Protocol 0321 shown in Table 1.

Table 1. DVH-based objective function constraints based on RTOG Protocol 0321

i Volume Constraint, D i,Vk Expected Value, d i ( V i,k )

1 Prostate D100 90%

2 Bladder V125 1 cc

3 Rectum V75 1 cc

4 Urethra V75 1 cc

All constraints were weighted equally, with exception of the prostate, which was
set to 5. The increased importance of the prostate reflects the fact that it is the target
volume. The prescription dose was set to 950 cGy, also from the RTOG protocol.

3.2 Optimization Parameters

The simulation environment was constructed using various open source software in-
cluding: Python, wxPython, NumPy, and Matplotlib. In the environment, the user is

Fig. 2. Default optimization settings for the simulation