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Poster Display session (Friday) (ID 65)
- Event: ELCC 2018
- Type: Poster Display session
- Presentations: 1
- Coordinates: 4/13/2018, 12:30 - 13:00, Hall 1
116P - Comparison of conformity and homogeneity index values of VMAT and non-VMAT techniques used in lung cancer radiotherapy (ID 328)
12:30 - 13:00 | Author(s): I.S. Surenkok
The purpose of this study is to compare Conformity (CI) and Homogeneity (HI) Index values of different IMRT techniques (VMAT vs non-VMAT) in lung cancer patients who treated in our clinic.
We evaluated 37 locally advanced lung cancer patients who previously treated as curatively with IMRT (Volumetric and non-Volumetric (Forward or Inverse) planning techniques) in Eskisehir Osmangazi University Hospital between 2015 July and 2017 September. For each patient, CI and HI values were calculated retrospectively using different formulas according to literature.
Median prescribed dose was 64Gy (range: 57.5–66). When we compared CI values, there was a statistically different result in favor of VMAT only which is calculated according with Paddick's formula. When we compared HI values, there were no statistically different results between IMRT techniques (Table).Table:Calculated CI and HI values of VMAT and non-VMAT techniques
PIV = Prescribed isodose volume TV = Target volume TV~PIV~ = Intersection of Prescribed isodose volume and Target volumeaMann-Whitney TestbStudent T-Test
VMAT(n = 21) Non-VMAT(n = 16) p Dose (Gy) Min 57.50 57.50 NS Max 64.00 66.00 Mean 61.52 61.37 Median 64.00 61.00 CI (RTOG) PIV/TV Min 1.0706 1.2558 NS[a] Max 1.8617 3.9451 Mean 1.4787 1.9063 Median 1.4193 1.6721 CI (Knöös) TV~PIV~/TV Min 0.9421 0.9016 NS[b] Max 1.0000 1.0000 Mean 0.9902 0.9833 Median 0.9984 0.9881 CI (Paddick) TV~PIV~/(TV × PIV) Min 0.5372 0.2535 0.040[a] Max 0.8439 0.7895 Mean 0.6784 0.5656 Median 0.7046 0.5830 HI (Shaw et al.) D~max~/D~mean~ Min 1.0753 1.0931 NS[b] Max 1.3799 1.2472 Mean 1.1555 1.1620 Median 1.1350 1.1589 HI (Salt-Lomax) D~%98~/D~presc~ Min 0.9846 0.9814 NS[b] Max 1.0446 1.0424 Mean 1.0220 1.0157 Median 1.0263 1.0161 HI (Paddick) D~%2~/D~%98~ Min 1.0309 1.0484 [b] Max 1.1315 1.1092 Mean 1.0632 1.0769 Median 1.0563 1.0737 HI (ICRU 83) (D~%2~–D~%98~)/D~%50~ Min 0.0304 0.0472 NS[b] Max 0.1217 0.1015 Mean 0.0608 0.0731 Median 0.0547 0.0707
The VMAT technique is superior to the non-VMAT techniques in achieving the conformity index which is obtained by the Paddick's approach that a more complex and comprehensive formula is used to calculate the conformity index.
Clinical trial identification:
Legal entity responsible for the study:
Eskisehir Osmangazi University
Has not received any funding
All authors have declared no conflicts of interest.
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