Outcome and patterns of failure after postoperative intensity modulated radiotherapy for locally advanced or high-risk oral cavity squamous cell carcinoma

Background To determine the outcome and patterns of failure in oral cavity cancer (OCC) patients after postoperative intensity modulated radiotherapy (IMRT) with concomitant systemic therapy. Methods All patients with locally advanced (AJCC stage III/IV) or high-risk OCC (AJCC stage II) who underwent postoperative IMRT at our institution between December 2006 and July 2010 were retrospectively analyzed. The primary endpoint was locoregional recurrence-free survival (LRRFS). Secondary endpoints included distant metastasis-free survival (DMFS), overall survival (OS), acute and late toxicities. Results Overall 53 patients were analyzed. Twenty-three patients (43%) underwent concomitant chemotherapy with cisplatin, two patients with carboplatin (4%) and four patients were treated with the monoclonal antibody cetuximab (8%). At a median follow-up of 2.3 (range, 1.1–4.6) years the 3-year LRRFS, DMFS and OS estimates were 79%, 90%, and 73% respectively. Twelve patients experienced a locoregional recurrence. Eight patients, 5 of which had both a flap reconstruction and extracapsular extension (ECE), showed an unusual multifocal pattern of recurrence. Ten locoregional recurrences occurred marginally or outside of the high-risk target volumes. Acute toxicity grades of 2 (27%) and 3 (66%) and late toxicity grades of 2 (34%) and 3 (11%) were observed. Conclusion LRRFS after postoperative IMRT is satisfying and toxicity is acceptable. The majority of locoregional recurrences occurred marginally or outside of the high-risk target volumes. Improvement of high-risk target volume definition especially in patients with flap reconstruction and ECE might transfer into better locoregional control

Taxane-containing induction chemotherapy followed by definitive chemoradiotherapy: Outcome in patients with locally advanced head and neck cancer

Background: Induction chemotherapy followed by definitive chemoradiotherapy is an intensified treatment approach for locally advanced squamous cell carcinoma of the head and neck (HNSCC) that might be associated with high rates of toxicity. Materials and methods: The data of 40consecutive patients who underwent induction chemotherapy with docetaxel-containing regimens followed by intensity-modulated radiotherapy (IMRT) and concomitant systemic therapy for unresectable locally advanced HNSCC were retrospectively analyzed. Primary objectives were RT-related acute and late toxicity. Secondary objectives were response to induction chemotherapy, locoregional recurrence-free survival (LRRFS), overall survival (OS), and influencing factors for LRRFS and OS. Results: The median follow-up for surviving patients was 21months (range, 2-53months). Patients received a median of three cycles of induction chemotherapy followed by IMRT to 72Gy. Three patients died during induction chemotherapy and one during chemoradiotherapy. Acute RT-related toxicity was of grade 3 and 4 in 72 and 3 % of patients, respectively, mainly dysphagia and dermatitis. Late RT-related toxicity was mainly xerostomia and bone/cartilage necrosis and was of grade 3 and 4 in 15 % of patients. One- and 2-year LRRFS and OS were 72 and 49 % and 77 and 71 %, respectively. Conclusion: Induction chemotherapy followed by chemoradiotherapy using IMRT was associated with a high rate of severe acute and late RT-related toxicities in this selected patient cohort. Four patients were lost because of fatal complications. Induction chemotherapy did not compromise the delivery of full-dose RT; however, the use of three cycles of concomitant cisplatin was impaire

Charge-state dependence of K

Article discussing research on the charge-state dependence of K-shell x-ray production in aluminum by 2-12-MeV carbon ions

MONTE CARLO SIMULATION OF THE RESPONSE OF Si(Li) X-RAY DETECTORS TO PROTON INDUCED K X-RAYS OF LIGHT ELEMENTS

A new detector model is deduced from measured ratios of low energy background counts to photopeak counts. This detector model assumes both the existence of a surface layer with reduced charge carrier collection efficiency and the existence of a low concentration of small regions of detector defects which have enhanced charge carrier recombination probability within the volume of the Si(Li) detector. Monte Carlo simulations of the response of two different Si(Li) detectors to K X-rays have been performed in order to quantify possible contributions of detector front contact and dead layer, respectively, to the measured X-ray spectra. Upper limits of those contributions and upper limits of dead layer thickness are given. The consequence of these results for detector efficiency calibration measurements are discussed

THE EFFECT OF MO FORMATION IN LIGHT ION INDUCED K-SHELL IONIZATION

In a recent experiment Ti K-shell ionization cross sections were measured for low energy 0-ion impact. Large deviations were found when the experimental results were compared with the ECPSSR theory. A modification of the ECPSSR theory is now proposed, which considers the effect of M0 formation. The modified MECPSSR theory is then in much better agreement with the experimental data

Energy resolution of silicon detectors approaching the physical limit

This work gives a review about the response of silicon detectors to electrons, protons, deuterons and alpha particles. The detector nonlinearity pulse height as a function of particle energy and the shape of the response function pulse height distribution for monoenergetic particles are discussed in detail. For electrons, the measured nonlinearity is found to be negligible within the experimental uncertainties. The response function of a particle implanted and passivated silicon detector PIPS for electrons 200 to 1000 keV is measured with thin radionuclide sources of conversion electrons. From these measurements an accurate value of the Fano factor is derived. For light ions protons, deuterons and helium ions , measurements are compared to calculations using a detector model, which assumes a thin dead layer at the front contact, followed by a fully sensitive region. This model takes into account electronic energy loss straggling in the dead layer, thickness variations of the dead layer, multiple scattering and nonelectronic losses in the sensitive region, electron hole pair statistics, a particle dependence of the energy per electron hole pair and electronic resolution. For H and He ions, at low energies 40 to 700 keV the nonlinearity is mainly due to the finite thickness of the dead layer, and in the MeV range the particle dependence of the energy per electron hole pair contributes considerably, in accordance with the model of Lennard. Measurements of the response function for monoenergetic He ions yield a detector resolution of 8 keV FWHM in the energy range 3 to 6 MeV. The well known asymmetric shape of the response function is found for both, H and He ions, at all energies. Using our detector model, calculated spectra agree quantitatively with the corresponding measurements both in the width and in the shape, without any adjustable parameter in the calculations. Based on this detector model, the ultimate resolution which can be obtained with silicon detectors is discusse