CLINICAL TUMOR DIMENSIONS MAY BE USEFUL TO PREVENT GEOGRAPHIC MISS IN CONVENTIONAL RADIOTHERAPY OF UTERINE CERVIX CANCER-A MAGNETIC RESONANCE IMAGING-BASED STUDY

Purpose: To evaluate the risk of geographic miss associated with the classic four-field ""box"" irradiation technique and to define the variables that predict this risk. Materials and Methods: The study population consisted of 80 patients with uterine cervix cancer seen between 2001 and 2006. Median age was 55 years (23-82 years), and 72 (90%) presented with squamous cell carcinoma. Most patients (68.7%) presented with locally advanced disease (IIb or more). Magnetic resonance imaging findings from before treatment were compared with findings from simulation of the conventional four-field ""box"" technique done with rectal contrast. Study variables included tumor volume; involvement of vagina, parametrium, bladder, or rectum; posterior displacement of the anterior rectal wall; and tumor anteroposterior diameter (APD). Margins were considered adequate when the target volume (primary tumor extension, whole uterine body, and parametrium) was included within the field limits and were at least 1 cm in width. Results: Field limits were inadequate in 45 (56%) patients: 29 (36%) patients at the anterior and 28 (35%) at the posterior border of the lateral fields. Of these, 12 patients had both anterior and posterior miss, and this risk was observed in all stages of the disease (p = 0.076). Posterior displacement of the anterior rectal wall beyond S2-S3 was significantly correlated with the risk of geographic miss (p = 0.043). Larger tumors (APD 6 cm or above and volume above 50 cm(3)) were also significantly correlated with this risk (p = 0.004 and p = 0.046, respectively). Conclusions: Posterior displacement of the anterior rectal wall, tumor APD, and volume can be used as guidance in evaluating the risk of geographic miss. (C) 2009 Elsevier Inc.

Endoscopic Anatomy of the Pterygopalatine Fossa and the Transpterygoid Approach: Development of a Surgical Instruction Model

Introduction: The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach. Methods: We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF. Results: We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel`s cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA. Conclusion: Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.

Deposition of Lead and Cadmium Released by Cigarette Smoke in Dental Structures and Resin Composite

Cigarette smoke is a significant source of cadmium, lead, and toxic elements, which are absorbed into the human organism. In this context, the aim of this study was to investigate in vitro the presence of toxic elements, cadmium, and lead deriving from cigarette smoke in the resin composite, dentine, and dental enamel. Eight cylindrical specimens were fabricated from resin composite, bovine enamel, and root dentin fragments that were wet ground and polished with abrasive paper to obtain sections with 6-mm diameter and 2-mm thickness. All specimens were exposed to the smoke of 10 cigarettes/day during 8 days. After the simulation of the cigarette smoke, the specimens were examined with scanning electron microscopy (SEM) and the energy-dispersive X-ray analysis. In the photomicrographic analysis in SEM, no morphological alterations were found; however, the microanalysis identified the presence of cadmium, arsenic, and lead in the different specimens. These findings suggest that the deposition of these elements derived from cigarette smoke could be favored by dental structures and resin composite. Microsc. Res. Tech. 74:287-291, 2011. (C) 2010 Wiley-Liss, Inc.