Different treatment planning protocols can lead to large differences in organ at risk sparing

作者：Tol Jim P^*; Dahele Max; Doornaert Patricia; Slotman Ben J; Verbakel Wilko F A R

来源：Radiotherapy and Oncology, 2014, 113(2): 267-271.

DOI：10.1016/j.radonc.2014.10.008

• Planning protocols
• PTV dose homogeneity
• OAR sparing

Background and purpose: Different planning protocols may define varying planning target volume (PTV) dose criteria. We investigated the hypothesis that this could result in differences in organ-at-risk (OAR) sparing. %26lt;br%26gt;Material and methods: Volumetric modulated arc therapy plans were created for ten locally advanced head and neck cancer patients following PTV criteria specified by the RTOG, EORTC and institutional (VUmc) protocols. Resulting plans were evaluated on the basis of the homogeneity index, calculated for the boost/elective PTVs as HIB/HIE = 100% * (D2% - D98%)/D50% and mean dose to individual and composite salivary (comp(sal)) and swallowing (comp(swal)) OARs. %26lt;br%26gt;Results: RTOG plans were the most homogeneous, with mean HIB of 8.2 +/- 0.9%, compared to 9.5 +/- 1.0%/ 11.6 +/- 1.5% for the VUmc/EORTC plans. EORTC plans provided most OAR sparing, with comp(sal)/comp(swal) doses of 24.6 +/- 7.7/22.9 +/- 4.2 Gy, compared to 32.2 +/- 9.7/29.9 +/- 4.2 Gy and 28.4 +/- 8.1/24.7 +/- 5.3 Gy for RTOG and VUmc, respectively. EORTC provided 7.2/7.7 Gy mean dose reductions to the contra/ipsilateral parotid glands compared to RTOG. %26lt;br%26gt;Conclusions: Different planning protocols resulted in different levels of PTV dose homogeneity. We observed differences of up to 27 Gy in composite and individual mean OAR doses. This could influence rates of toxicity and should be taken into account when comparing clinical studies. A consensus should be reached between major trial groups on appropriate PTV parameters.

• 出版日期2014-11