L. Olteanu

Three-phase adaptive dose-painting-by-numbers for head-and-neck cancer: initial results of the phase I clinical trial

PURPOSE To evaluate feasibility of using deformable image co-registration in three-phase adaptive dose-painting-by-numbers (DPBN) for head-and-neck cancer and to report dosimetrical data and preliminary clinical results. MATERIAL AND METHODS Between November 2010 and October 2011, 10 patients with non-metastatic head-and-neck cancer enrolled in this phase I clinical trial where treatment was adapted every ten fractions. Each patient was treated with three DPBN plans based on: a pretreatment 18[F]-FDG-PET scan (phase I: fractions 1-10), a per-treatment 18[F]-FDG-PET/CT scan acquired after 8 fractions (phase II: fractions 11-20) and a per-treatment 18[F]-FDG-PET/CT scan acquired after 18 fractions (phase III: fractions 21-30). A median prescription dose to the dose-painted target was 70.2 Gy (fractions 1-30) and to elective neck was 40 Gy (fractions 1-20). Deformable image co-registration was used for automatic region-of-interest propagation and dose summation of the three treatment plans. RESULTS All patients (all men, median age 68, range 48-74 years) completed treatment without any break or acute G≥4 toxicity. Target volume reductions (mean (range)) between pre-treatment CT and CT on the last day of treatment were 72.3% (57.9-98.4) and 46.3% (11.0-73.1) for GTV and PTV(high_dose), respectively. Acute G3 toxicity was limited to dysphagia in 3/10 patients and mucositis in 2/10 patients; none of the patients lost ≥20% weight. At median follow-up of 13, range 7-22 months, 9 patients did not have evidence of disease. CONCLUSIONS Three-phase adaptive 18[F]-FDG-PET-guided dose painting by numbers using currently available tools is feasible. Irradiation of smaller target volumes might have contributed to mild acute toxicity with no measurable decrease in tumor response.

Evaluation of Deformable Image Coregistration in Adaptive Dose Painting by Numbers for Head-and-Neck Cancer

PURPOSE To assess the accuracy of contour deformation and feasibility of dose summation applying deformable image coregistration in adaptive dose painting by numbers (DPBN) for head and neck cancer. METHODS AND MATERIALS Data of 12 head-and-neck-cancer patients treated within a Phase I trial on adaptive (18)F-FDG positron emission tomography (PET)-guided DPBN were used. Each patient had two DPBN treatment plans: the initial plan was based on a pretreatment PET/CT scan; the second adapted plan was based on a PET/CT scan acquired after 8 fractions. The median prescription dose to the dose-painted volume was 30 Gy for both DPBN plans. To obtain deformed contours and dose distributions, pretreatment CT was deformed to per-treatment CT using deformable image coregistration. Deformed contours of regions of interest (ROI(def)) were visually inspected and, if necessary, adjusted (ROI(def_ad)) and both compared with manually redrawn ROIs (ROI(m)) using Jaccard (JI) and overlap indices (OI). Dose summation was done on the ROI(m), ROI(def_ad), or their unions with the ROI(def). RESULTS Almost all deformed ROIs were adjusted. The largest adjustment was made in patients with substantially regressing tumors: ROI(def) = 11.8 ± 10.9 cm(3) vs. ROI(def_ad) = 5.9 ± 7.8 cm(3) vs. ROI(m) = 7.7 ± 7.2 cm(3) (p = 0.57). The swallowing structures were the most frequently adjusted ROIs with the lowest indices for the upper esophageal sphincter: JI = 0.3 (ROI(def)) and 0.4 (ROI(def_ad)); OI = 0.5 (both ROIs). The mandible needed the least adjustment with the highest indices: JI = 0.8 (both ROIs), OI = 0.9 (ROI(def)), and 1.0 (ROI(def_ad)). Summed doses differed non-significantly. There was a trend of higher doses in the targets and lower doses in the spinal cord when doses were summed on unions. CONCLUSION Visual inspection and adjustment were necessary for most ROIs. Fast automatic ROI propagation followed by user-driven adjustment appears to be more efficient than labor-intensive de novo drawing. Dose summation using deformable image coregistration was feasible. Biological uncertainties of dose summation strategies warrant further investigation.

Deformation field validation and inversion applied to adaptive radiation therapy.

Development and implementation of chronological and anti-chronological adaptive dose accumulation strategies in adaptive intensity-modulated radiation therapy (IMRT) for head-and-neck cancer. An algorithm based on Newton iterations was implemented to efficiently compute inverse deformation fields (DFs). Four verification steps were performed to ensure a valid dose propagation: intra-cell folding detection finds zero or negative Jacobian determinants in the input DF; inter-cell folding detection is implemented on the resolution of the output DF; a region growing algorithm detects undefined values in the output DF; DF domains can be composed and displayed on the CT data. In 2011, one patient with nonmetastatic head and neck cancer selected from a three phase adaptive DPBN study was used to illustrate the algorithms implemented for adaptive chronological and anti-chronological dose accumulation. The patient received three (18)F-FDG-PET/CTs prior to each treatment phase and one CT after finalizing treatment. Contour propagation and DF generation between two consecutive CTs was performed in Atlas-based autosegmentation (ABAS). Deformable image registration based dose accumulations were performed on CT1 and CT4. Dose propagation was done using combinations of DFs or their inversions. We have implemented a chronological and anti-chronological dose accumulation algorithm based on DF inversion. Algorithms were designed and implemented to detect cell folding.

Biological 18[F]-FDG-PET image-guided dose painting by numbers for painful uncomplicated bone metastases: A 3-arm randomized phase II trial

BACKGROUND Antalgic radiotherapy for bone metastases might be improved by implementing biological information in the radiotherapy planning using (18)F-FDG-PET-CT based dose painting by numbers (DPBN). MATERIALS AND METHODS Patients with uncomplicated painful bone metastases were randomized (1:1:1) and blinded to receive either 8Gy in a single fraction with conventionally planned radiotherapy (arm A) or 8Gy in a single fraction with DPBN (dose range between 610Gy and 10Gy) (arm B) or 16Gy in a single fraction with DPBN (dose range between 1410Gy and 18Gy) (arm C). The primary endpoint was overall pain response at 1month. The phase II trial was designed to select the experimental arm with sufficient promise of efficacy to continue to a phase III trial. RESULTS Forty-five patients were randomized. Eight (53%), 12 (80%) and 9 patients (60%) had an overall response to treatment in arm A, B and C, respectively. The estimated odds ratio of overall response for arm B vs. A is 3.5 (95% CI: 0.44-17.71, p=0.12). The estimated odds ratio of arm C vs. A is 1.31 (95% CI: 0.31-5.58, p=0.71). CONCLUSION A single fraction of 8Gy with DPBN will be further evaluated in a phase III-trial.

Late mucosal ulcers in dose-escalated adaptive dose-painting treatments for head-and-neck cancer

Abstract Background: To identify predictive factors for the development of late grade 4 mucosal ulcers in adaptive dose-escalated treatments for head-and-neck cancer. Material and methods: Patient data of four dose-escalated three-phase adaptive dose-painting by numbers (DPBN) clinical trials were analyzed in this study. Correlations between the development of late grade 4 ulcers and factors related with the treatment, disease characteristics and the patient were investigated. Dosimetrical thresholds were searched among the highest doses received by 1.75 cm3 (D1.75cc) of the primary gross tumor volume (GTVT) and the corresponding normalized isoeffective dose (NID21.75cc, with a reference dose of 2Gy/fraction and α/β of 3 Gy). Results: From 39 studied patients, nine developed late grade 4 mucosal ulcers. The continuation to either smoke or drink alcohol after therapy was the factor that showed a strong (eight out of nine patients) association with the occurrence of grade 4 ulcers. Six of the patients who continued to smoke or/and drink had D1.75cc and NID21.75cc above 84 Gy and 95.5 Gy, respectively. Seven of the patients with grade 4 had the dose levels above these thresholds, but even if the D1.75cc threshold was significant in the prediction of late grade 4 ulcers, it could not be considered as the only contributing factor. Conclusions: The search for patterns provided strong reasons to apply a dosimetrical threshold for the peak-dose volume of 1.75 cm3 as a preventive measure for late grade 4 mucosal ulcers. Also, patients that continue to smoke or drink alcohol after therapy have increased risk to develop late mucosal ulcers.

OC-0452: Prospective randomized adaptive dose-de-escalation in the elective neck: late toxicity and control

German Cancer Research Center DKFZ, Heidelberg and German Cancer Consortium DKTK partner site Dresden, Dresden, Germany , F. Lohaus, S. Löck, V. Gudziol, A. Nowak, C. Von Neubeck, I. Tinhofer, V. Budach, A. Sak, M. Stuschke, P. Balermpas, C. Rödel, M. Avlar, A.L. Grosu, A. Abdollahi, J. Debus, C. Belka, S. Pigorsch, S.E. Combs, D. Mönnich, D. Zips, G.B. Baretton, F. Buchholz, M. Baumann, M. Krause

EP-1190: Prone breast irradiation: from indirect to direct tumor bed localization

Purpose/Objective: Adjuvant RT after quadrantectomy or lumpectomy plays an essential role in breast conserving therapy for early stage carcinoma and 60 Gy delivered in 30 fractions in 6 weeks is generally considered the standard dose. The present study aims to evaluate acute, sub-acute and short term late side effects in patients with early stage breast cancer treated with adjuvant radiotherapy (RT) using concomitant boost. Materials and Methods: Between June 2010 and October 2013, 586 patients (median age 60 years, range 27-96 years) with early-stage breast cancer were treated with a hypofractionated schedule of external beam RT after conserving surgery; 143 patients underwent post-operative chemotherapy before starting RT. RT was delivered as follow: 45 Gy in 20 fractions (225 cGy/fr) in 4 weeks to the whole breast and a daily concomitant boost dose (5Gy) to the lumpectomy cavity (25 cGy/fr). The cumulative nominal dose was 50 Gy. The technique used was 3D-conformational RT with 2 tangential fields for the whole breast and 2 oblique fields for the boost. The surgical bed was primarily defined with clips. Toxicity was scored according to LENT-SOMA scale. Results: Twenty-five patients experienced grade 3 skin toxicity within one week from the end of the RT course (eight after adjuvant chemotherapy administered before breast RT). After 19-month median follow-up (range 12-52 months), no grade 4 toxicity were detected; only 5 patients experienced grade 3 skin toxicity and thirty-nine patients reported grade 2 breast pain. Concerning cosmetic results, one patients developed scar retraction; the others 585 patients showed excellent or good cosmetic results. Disease recurrences were recorded in 4 patients: one of them with local relapse, the others three with systemic spread. Conclusions: The explored regimen seems to be feasible providing consistent clinical results with excellent toxicity profile.