ESTRO 36 Abstract Book

S578 ESTRO 36 2017 _______________________________________________________________________________________________

distant relapse. Eight patients (21.1%) died of tumour progression. The TLG ATA was predictive of local recurrence (p = 0.04). ROC curves analysis revealed a cut-off value of 19.6 for SUVmax, and 13.7 for SUVmean ATA (AUC 0.72, p=0.03 and AUC 0.72 p=0.03, respectively). The 2-year DFS rate was significantly lower in patients with a SUVmax >19.6 (p= 0.001) and with a SUVmean ATA >13.7 (p= 0.02). ROC curves analysis revealed a cut-off value of 19.6 for SUVmax, 8.6 for SUVmean ATA and 49.1 for TLG ATA (AUC 0.8, p=0.03; AUC 0.9 p=0.007, and AUC 0.8 p= 0.01 respectively). The 2-year OS rate was significantly lower in patients with a SUVmax >19.6 (p= 0.004), with a SUVmean ATA >8.6 (p= 0.03) and TLG ATA >49.1 (p= 0.004). Table 1. [18F] FDG-PET paramenters based on multiple threshold levels.

had T4a and 14 had T4b tumors. All 21 patients enrolled in this study did not have cervical node metastases. The median total dose and number of fractions were 60.8 Gy (RBE) and 16 fractions, respectively. Four patients received neo-adjuvant chemotherapy. The median follow- up period was 39 months (range, 5–111 months). The 3 year overall survival and local control rates were 88.4% and 83.0%, respectively. Grade 4 late toxicity was observed in 3 patients . Of the three patients, 2 developed ipsilateral optic nerve disorder and 1ipsilateral retinopathy. With respect to these patients whose adverse events could not be avoided, the GTV was over 34cc and the tumors were in close proximity to the orbit. Except eye disorder, grade ≧ 4 late toxicities did not occurred. Conclusion C-ion RT is an effective treatment modality for locally advanced ONB. EP-1059 A [18F] FDG-PET adaptive thresholding algorithm for delineation of RT volumes of head&neck cancer. M. Paolini 1 , L. Deantonio 1 , L. Vigna 2 , R. Matheoud 2 , G. Loi 2 , G. Sacchetti 3 , M. Brambilla 2 , M. Krengli 1 1 University Hospital Maggiore della Carità, Radiotherapy, Novara, Italy 2 University Hospital Maggiore della Carità, Medical Physics, Novara, Italy 3 University Hospital Maggiore della Carità, Nuclear Medicine, Novara, Italy Purpose or Objective A standardized way of converting PET signals into target volume is not yet available. The aim of this study was to evaluate a [18F] FDG-PET adaptive thresholding algorithm for the delineation of the biological tumour volume for the radiotherapy (RT) treatment planning of head and neck cancer patients. Material and Methods Thirty-eight patients, who underwent exclusive intensity modulated RT with simultaneous integrated boost (IMRT- SIB) for head-and-neck squamous cell carcinoma (3 oral cavity, 9 nasopharynx, 19 oropharynx, 6 hypopharynx, and 1 larynx cancer) were included in the present study. Thirty-five/38 patients presented a locally advanced disease (92.1%), and 30/38 patients (78.9%) received a concomitant chemoradiotherapy. For all patients, [18F] FDG-PET/CT was performed in treatment position with the customized thermoplastic mask. Two radiation oncologists defined the primary biologic tumour volumes (BTV) using the adaptive thresholding algorithm implemented on the iTaRT workstation (Tecnologie Avanzate, Italy). The algorithm used specific calibration curves that depended on the lesion-to-background ratio (LB ratio) and on the amplitude of reconstruction smoothing filter (FWH). The evaluation of reproducibility of adaptive thresholding algorithm for volume estimation was determined by the volume overlap of multiple segmentation of the same lesion by two radiation oncologists. Each primary tumour volume was segmented by the adaptive thresholding algorithm (BTV ATA ). The target volumes for the primary tumours previously delineated on the planning computed tomography (CT) scan using anatomic imaging (CT and MRI) (gross tumour volume standard GTV ST ) and a fixed image intensity threshold method (40% of maximum intensity) of [18F] FDG-PET standardized uptake value (GTV 40%SUV) were used to perform a volumetric comparison. Results The algorithm generated a tumour volume in all but two patients. The mean values with standard deviation (SD) of volumes based on the three different methods were reported in Table 1. The BTV ATA was significantly smaller than the GTV ST (17 vs. 21 cc, p= 0.04); the conformity index (CI) was 0.46, and the similarity coefficient (DICE) was 0.7 (Sensibility 66%, specificity 85%). BTV ATA is a part of the GTV ST .

Parameters

MTV (cc)

SUVmax SUVmean

TLG

Adaptive threshold algorithm (ATA)

16.37 (4.41 – 34.53) 16.37 (4.41 – 34.53) 16.37 (4.41 – 34.53)

17.21 (1.5 – 61.53) 10.30 (1.02 – 58) 7.79 (0.45 – 47.11)

149.89 (5.3 – 877.85) 130.90 (3 850.86) 107.77 (2.10 – 736.33) –

9.15 (2.8 – 19.71)

10.50 (2.94 21.78) 11.45 (3.33 23.73)

SUV41%

–

SUV50%

–

Conclusion Adaptive threshold-based SUVmean, MTV, and TLG and SUVmax could have a role in predicting local control and survival in head and neck cancer patients treated with chemoradiotherapy. EP-1058 A multicenter study of carbon-io n RT for locally advanced olfactory neuroblastomas (J- CROS1402HN) H. Suefuji 1 , M. Koto 2 , Y. Demizu 3 , J. Saitoh 4 , Y. Shioyama 1 , H. Tsuji 2 , T. Okimoto 3 , T. Ohno 4 , K. Nemoto 5 , T. Nakano 4 , T. Kamada 2 1 Ion Beam Therapy Center- SAGA-HIMAT Foundation, radiation oncology, tosu, Japan 2 National Institute of Radiological Science Hospital- National Institutes for Quantum and Radiological Sciences and Technology, radiation oncology, chiba, Japan 3 Hyogo Ion Beam Medical Center, radiology, tatsuno, Japan 4 Gunma University Heavy Ion Medical Center, radiology, maebashi, Japan 5 Yamagata University Faculty of Medicine, radiation oncology, yamagata, Japan Purpose or Objective The combination with surgery and postoperative radiotherapy is the most common therapy for locally advanced olfactory neuroblastomas (ONB), but has a high incidence of local recurrence.We analyzed the ONB patients treated by carbon-ion radiotherapy (C-ion RT) in the Japan Carbon Ion Radiotherapy Study Group study. In this study, we evaluated the efficacy and safety of C-ion RT for locally advanced ONBs in Japan. Material and Methods Patients with T4N0-1M0 ONBs who were treated with C-ion RT at 4 institutions in Japan between November 2003 and December 2014 were analyzed retrospectively. A total of twenty-one patients (16 male and 5 female; median age, 53 years) with locally advanced ONBs were enrolled in this study. Results Main tumor sites included the nasal cavity in 11 patients and sphenoid sinuses in 10, respectively. Seven patients