45 research outputs found
A procedure to mathematically amend possible thickness disuniformities in gel-layer dosimetry
No full textThe continuous development of conformal radiotherapies requires a corresponding improvement of dosimetric techniques. Fricke gel-layer dosimetry, coupled with a suitably developed software, has proven to be a reliable technique for 3D absorbed dose distribution verification. The method is based on the evaluation of the light transmitted by gel-layers due to the fact that th optical density difference between irradiated and non irraddiated dosimeters is proportional to the absorbed dose. Measurement are performed by means of a planar illumination source and a computer-controlled CCD camera. Recently, adoption of gel layers with increased superficial dimensions has evidenced a possible thickness disuniformity of layers, thus introducing a new source of measurement inaccuracy. In this work, a method to mathematically amend this possible source of error is proposed. Dose profiles along the central axis of phantoms irradiated with X-ray therapy and Boron Neutron Capture Therapy fields, obtained with and without the application of the proposed correction procedure, were compared with ionization chamber measurements and Monte Carlo simulations, respectively. The obtained results show a good reliability of the proposed procedure
supplementaryfig – Supplemental material for Prognostic role of primary tumor, nodal neck, and retropharyngeal GTVs for unresectable sinonasal cancers treated with IMRT and chemotherapy
No full textSupplemental material, supplementaryfig for Prognostic role of primary tumor, nodal neck, and retropharyngeal GTVs for unresectable sinonasal cancers treated with IMRT and chemotherapy by Letizia Ferella, Anna Cavallo, Rosalba Miceli, Nicola Alessandro Iacovelli, Tommaso Giandini, Emanuele Pignoli, Giuseppina Calareso, Paolo Bossi, Carlo Resteghini, Giovanni Luca Gravina, Piero Nicolai, Paolo Castelnuovo, Cesare Piazza, Lisa Licitra, Carlo Fallai and Ester Orlandi in Tumori Journal</p
Nonstandard Fractionation Schedules in Radiation Therapy of Head and Neck Cancer: A Review
No full text The authors present an updated review of the clinical trials on hyperfractionated and accelerated fractionation schedules in radiotherapy of head and neck cancer. The available results in terms of survival and local control, and acute and late toxicity data are summarized in order to show the current status of this research field. The new breed of fractionation schedules that are on study, designed on the ground of new rationales, are presented as well. Finally, an introductory overview of combination therapy including non standard fractionation radiotherapy associated with chemotherapy is reported70. </jats:p
Altered Fractionation Schedules in Radiotherapy of Head and Neck Cancer. A Review
No full text The authors review the main contributions of international literature to show the current status in clinical trials on unconventional fractionations of the dose in radiotherapy of head and neck cancers. Several clinical (but only a few randomized) trials have been conducted over the last 15 years using hyperfractionated (HF), accelerated (AF) or mixed (HF-AF) schedules. HF schedules have obtained promising results in terms of local control in comparison with conventional fractionation (CF) of the dose. Improvement in survival was also obtained by the random trials of Pinto and Sanchiz, whereas in EORTC trial no. 22791, the improvement in survival rate was only marginal. A significant increase in local control and, less frequently, in survival has been claimed in several studies using HF-AF. Such data still need to be confirmed by a random study, since EORTC trial 22811 showed superimposable results in comparison with CF. Selection of the most suitable cases for altered fractionation schemes is also being studied in ongoing trials of the EORTC (22851) and RTOG (90-03). As regards acute reactions during and after altered fractionation, they are more severe than after CF. Only pure HF with a dose intensity approximately comparable to CF seems to produce similar acute reactions. Several factors have been found to influence the severity of acute mucosal reactions: interfraction interval, overall treatment time, total dose, and field size. As regards late damage, genuine HF schemes seem to cause roughly equivalent late damage in comparison to CF, whereas high-dose intensity schedules have a higher rate of complications. Interfraction interval, overall treatment time, total dose, fraction size and field size can influence the risk of late sequelae. Before altered fractionations can be considered standard therapy, more data are needed, which should be provided by multicentric randomized trials, some of which are already in progress. </jats:p
Hyperfractionated and accelerated radiation therapy in central nervous system tumors (malignant gliomas, pediatric tumors, and brain metastases)
No full textRandomized Trials on Altered Fractionation in Head and Neck Cancer Radiotherapy with Conventional Fractionation as Control Arm: Another Lap to Go
No full text The Authors present a review of randomized trials on non conventional fractionation in head and neck cancer radiotherapy with conventional fractionation as control arm. Hyperfractionation was studied in 5 trials, accelerated hyperfractionation in 4 trials and accelerated fractionation in 3 trials. Furthermore, the reviews of eminent Authors dealing with the above mentioned trials are summarized. In spite of improved local control rate reported with hyperfractionation, non conventional radiotherapy schedules are not yet recommended as routine clinical practice, but all the radiation oncologists are invited to join trials on this subject. </jats:p
Impact of treatment expertise on the outcome of patients with head and neck cancer treated within 6 randomized trials
No full textBackground: We evaluated the impact of center expertise, in terms of number of patients treated, on the overall survival (OS) and progression-free survival (PFS) of patients with head and neck squamous cell carcinoma (SCC).
Methods: We performed a pooled analysis including data from 6 randomized trials in head and neck SCC conducted in Italy. We evaluated the association between OS or PFS and the number of patients recruited by the center.
Results: The outcome of 903 patients who had received radiotherapy (RT) was analyzed (median follow-up 76 months). The hazard ratio (HR) comparing the third and the first quartiles of the distribution of number of patients per center
showed an advantage in PFS (HR 0.59, range 0.53-0.65, P < .0001) and in OS (HR 0.70, 0.60-0.81, P < .0001) for centers with a higher number of patients recruited. A similar benefit was observed in PFS (HR 0.63, 0.60-0.66) and OS
(HR 0.74, 0.69-0.79) considering the mean number of patients per year.
Conclusions: The PFS and OS were longer for patients treated in high-casevolume centers
Predictors of Patient-Reported Dysphagia Following IMRT Plus Chemotherapy in Oropharyngeal Cancer
No full textThe aim of this cross-sectional study is to evaluate the factors associated with patient-reported dysphagia in patients affected by locally advanced oropharyngeal cancer (OPC) treated with definitive intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy (CHT), with or without induction CHT. We evaluated 148 OPC patients treated with IMRT and concurrent CHT, without evidence of disease and who had completed their treatment since at least 6 months. At their planned follow-up visit, patients underwent clinical evaluation and completed the M.D. Anderson dysphagia inventory (MDADI) questionnaire. The association between questionnaire composite score (MDADI-CS) and different patients’ and tumor’s characteristics and treatments (covariates) was investigated by univariable and multivariable analyses, the latter including only covariates significant at univariable analysis. With a median time from treatment end of 30 months [range 6–74 months, interquartile range (IQR) 16–50 months], the median (IQR) MDADI-CS was 72 (63–84). The majority of patients (82.4%) had a MDADI-CS ≥ 60. At multivariable analysis, female gender, human papilloma virus (HPV)-negative status, and moderate and severe clinician-rated xerostomia were significantly associated with lower MDADI-CS. Patient-perceived dysphagia was satisfactory or acceptable in the majority of patients. HPV status and xerostomia were confirmed as important predictive factors for swallowing dysfunction after radiochemotherapy. Data regarding female gender are new and deserve further investigation
Methodology and technology for the development of a prognostic MRI-based radiomic model for the outcome of head and neck cancer patients
No full textThe purpose of this study was to establish a methodology and technology for the development of an MRI-based radiomic signature for prognosis of overall survival (OS) in nasopharyngeal cancer from non-endemic areas. The signature was trained using 1072 features extracted from the main tumor in T1-weighted and T2-weighted images of 142 patients. A model with 2 radiomic features was obtained (RAD model). Tumor volume and a signature obtained by training the model on permuted survival data (RADperm model) were used as a reference. A 10-fold cross-validation was used to validate the signature. Harrel's C-index was used as performance metric. A statistical comparison of the RAD, RADperm and volume was performed using Wilcoxon signed rank tests. The C-index for the RAD model was higher compared to the one of the RADperm model (0.69±0.08 vs 0.47±0.05), which ensures absence of overfitting. Also, the signature obtained with the RAD model had an improved C-index compared to tumor volume alone (0.69±0.08 vs 0.65±0.06), suggesting that the radiomic signature provides additional prognostic information
