Step 1: Comparison of measured data

Comparison of data measured with & without IQM in plotting tank (6, 10 & 6FFF).


  • No significant differences in O/P factors was detected.
  • The beam attenuation is found to be a fixed amount for each energy.
  • IQM has little effect on PDD beyond Dmax or on profiles <20x20cm.
  • For 6 & 10 MV modelling at larger radial distances needed review.

Step2: Comparison with existing clinical models

Step3: Initial validation


  • The build up region is modified by the presence of the IQM, reducing ‘skin sparing’.
  • Smaller field PDDs & Profiles are not affected by IQM.
  • Larger fields have shoulders drop, more notably at shallower depths.
  • Adjustment of arbitrary fluence profile improved agreement – but not observable clinical benefit.
  • Clinical models acceptable at 6MV & 10MV.
  • Simple correction factor to change MUs was all that was required in Pinnacle 9.8.
  • Validation of your clinical models necessary when integrating the IQM into your planning system, but modifications are likely to be small.