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01.12.2017 | Research | Ausgabe 1/2017 Open Access

Radiation Oncology 1/2017

Radiation dose escalation based on FDG-PET driven dose painting by numbers in oropharyngeal squamous cell carcinoma: a dosimetric comparison between TomoTherapy-HA and RapidArc

Zeitschrift:
Radiation Oncology > Ausgabe 1/2017
Autoren:
Sarah Differding, Edmond Sterpin, Nicolas Hermand, Bianca Vanstraelen, Sandra Nuyts, Nathalie de Patoul, Jean-Marc Denis, John Aldo Lee, Vincent Grégoire
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​s13014-017-0793-0) contains supplementary material, which is available to authorized users.

Abstract

Purpose

Validation of dose escalation through FDG-PET dose painting (DP) for oropharyngeal squamous cell carcinoma (SCC) requires randomized clinical trials with large sample size, potentially involving different treatment planning and delivery systems. As a first step of a joint clinical study of DP, a planning comparison was performed between Tomotherapy HiArt® (HT) and Varian RapidArc® (RA).

Methods

The planning study was conducted on five patients with oropharyngeal SCC. Elective and therapeutic CTVs were delineated based on anatomic information, and the respective PTVs (CTVs + 4 mm) were prescribed a dose of 56 (PTV56) and 70 Gy (PTV70). A gradient-based method was used to delineate automatically the external contours of the FDG-PET volume (GTVPET). Variation of the FDG uptake within the GTVPET was linearly converted into a prescription between 70 and 86 Gy. A dilation of the voxel-by-voxel prescription of 2.5 mm was applied to account for geometric errors in dose delivery (PTVPET). The study was divided in two planning phases aiming at maximizing target coverage (phase I) and lowering doses to OAR (phase II). A Quality-Volume Histogram (QVH) assessed conformity with the DP prescription inside the PTVPET.

Results

In phase I, for both HT and RA, all plans achieved comparable target coverage for PTV56 and PTV70, respecting the planning objectives. A median value of 99.9 and 97.2% of all voxels in the PTVPET received at least 95% of the prescribed dose for RA and HT, respectively. A median value of 0.0% and 3.7% of the voxels in the PTVPET received 105% or more of prescribed dose for RA and HT, respectively. In phase II, no significant differences were found in OAR sparing. Median treatment times were 13.7 min for HT and 5 min for RA.

Conclusions

Both HT and RA can generate similar dose distributions for FDG-PET based dose escalation and dose painting in oropharyngeal SCC patients.
Zusatzmaterial
Additional file 1: illustration of individual contours of investigated patients. (DOCX 1173 kb)
13014_2017_793_MOESM1_ESM.docx
Additional file 2: images of individual dose volume histograms and dose distributions of patients. (DOCX 15022 kb)
13014_2017_793_MOESM2_ESM.docx
Additional file 3: Quality volume histograms of the five patients for planning phase I. (DOCX 116 kb)
13014_2017_793_MOESM3_ESM.docx
Additional file 4: Delivery quality assurance for patient # 3. (DOCX 20 kb)
13014_2017_793_MOESM4_ESM.docx
Literatur
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