Marginal misses after postoperative intensity-modulated radiotherapy for head and neck cancer.
ABSTRACT To describe the spatial distribution of local-regional recurrence (LRR) among patients treated postoperatively with intensity-modulated radiotherapy (IMRT) for head and neck cancer.
The medical records of 90 consecutive patients treated by gross total resection and postoperative IMRT for squamous cell carcinoma of the head and neck from January 2003 to July 2009 were reviewed. Sites of disease were the oral cavity (43 patients), oropharynx (20 patients), larynx (15 patients), and hypopharynx (12 patients). Fifty patients (56%) received concurrent chemotherapy.
Seventeen of 90 patients treated with postoperative IMRT experienced LRR, yielding a 2-year estimate of local regional control of 80%. Among the LRR patients, 11 patients were classified as in-field recurrences, occurring within the physician-designated clinical target volume, and 6 patients were categorized as marginal recurrences. There were no out-of-field geographical misses. Sites of marginal LRRs included the contralateral neck adjacent to the spared parotid gland (3 patients), the dermal/subcutaneous surface (2 patients), and the retropharyngeal/retrostyloid lymph node region (1 patient).
Although the incidence of geographical misses was relatively low, the possibility of this phenomenon should be considered in the design of target volumes among patients treated by postoperative IMRT for head and neck cancer.
- [Show abstract] [Hide abstract]
ABSTRACT: Patients with squamous cell carcinomas (SCCs) of the head and neck are increasingly treated nonsurgically. Imaging plays a critical role in helping define the targets for radiation therapy, especially intensity-modulated radiation therapy, in which the dose gradients are steep. Anatomic imaging with conventional modalities, particularly computed tomography (CT), has been used in patients with head and neck SCCs, but this approach has limitations. Functional imaging techniques, including positron emission tomography (PET) combined with CT or magnetic resonance (MR) imaging, offer complementary information and can be used noninvasively to assess a range of biomarkers in patients with head and neck SCCs, including hypoxia, cell proliferation and apoptosis, and epidermal growth factor receptor status. These biologic markers can be monitored before, during, and after treatment to improve patient selection for specific therapeutic strategies, guide adaptation of therapy, and potentially facilitate more accurate assessment of disease response. This article discusses the practical aspects of integrating functional imaging into head-and-neck radiation therapy planning and reviews the potential of molecular imaging biomarkers for response assessment and therapy adaptation. The uses of PET tracers for imaging cellular processes such as metabolism, proliferation, hypoxia, and cell membrane synthesis are explored, and applications for MR techniques such as dynamic contrast material-enhanced imaging, diffusion-weighted imaging, blood oxygenation level-dependent imaging, and MR spectroscopy are reviewed. The potential of integrated PET/CT perfusion imaging and hybrid PET/MR imaging also is highlighted. These developments may allow more individualized treatment planning in patients with head and neck SCCs in the emerging era of personalized medicine. © RSNA, 2013.Radiographics 11/2013; 33(7):1909-29. DOI:10.1148/rg.337125163 · 2.73 Impact Factor
Conference Paper: Performance of exhaustive cycle-gated access in high speed bus networks[Show abstract] [Hide abstract]
ABSTRACT: Fasnet and Expressnet, two proposed protocols for high-speed bus networks, have low maximum channel utilization for high values of end-to-end propagation delay, as is the case in high-speed local area networks (LANs) and metropolitan area networks (MANs). A service scheme called the exhaustive cycle-gated (ECG) scheme, in which stations are permitted to transmit in a cycle all the packets present in their buffer at the beginning of the cycle, is proposed instead. The maximum channel utilization of the scheme is one. The ECG scheme is analyzed under general conditions of asymmetric Poisson arrivals at stations. Extensive numerical results for the waiting time and number served per cycle are presented. Simulations are included to validate the analytic resultsGlobal Telecommunications Conference, 1992. Conference Record., GLOBECOM '92. Communication for Global Users., IEEE; 01/1993
- [Show abstract] [Hide abstract]
ABSTRACT: The oral cavity is the most common site of head and neck squamous cell carcinoma, a disease which results in significant morbidity and mortality worldwide. Though the primary modality of treatment for patients with oral cavity cancer remains surgical resection, many patients present with advanced disease and are thus treated using a multi-disciplinary approach. Patients with extracapsular spread of lymphatic metastasis and surgical margins that remain positive have been found to be at high risk for local-regional recurrence and death from disease, and are most often recommended to receive both post-operative radiation as well as systemic chemotherapy. The basis for this approach, as well as scientific developments that underly future trials of novels treatments for patients with high-risk oral cavity cancer are reviewed.Clinical and Experimental Otorhinolaryngology 03/2011; 4(1):1-10. DOI:10.3342/ceo.2011.4.1.1 · 0.84 Impact Factor