PubMed · 8564765
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S J Seidel. 1994. Optivite as a nutritional supplement.. https://pubmed.ncbi.nlm.nih.gov/8564765/
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PURPOSE: To determine the effects of a lucite beam spoiler on the dose distribution to points inside and outside the primary beam for head and neck irradiation with a 10-MV photon beam. METHODS AND MATERIALS: Build-up and depth-dose measurements were performed with a parallel-plate ionization chamber for 5 x 5, 10 x 10, and 15 x 15-cm field sizes using lucite spoilers with two different thicknesses at two different lucite-to-skin distances (LSD) for a 10-MV x-ray beam. Corrections were applied to account for finite chamber size. Beam profiles and isodose curves were obtained at several depths using film dosimetry. Beam uniformity was determined from uniformity indices. Peripheral doses (PD) were measured at the surface and at 1.5- and 2.5-cm depths using film dosimetry and a parallel-plate ionization chamber. Measurement points were positioned at the edge of a 10 x 10-cm field and at distances extending to 5.0 cm away. The treatment planning data for the 10-MV x-ray beam were modified to account for the effects of the beam spoiler when treating head and neck patients. RESULTS: The spoiler increased the surface and build-up dose and shifted the depth of maximum dose toward the surface. With a 10-MV x-ray beam and a 1.2-cm-thick lucite at 15 cm LSD, a build-up dose similar to a 6-MV x-ray beam was achieved. The beam uniformity was altered at shallow depths. The peripheral dose was enhanced particularly at the surface and at the points close to the beam edge. The effects of the beam spoiler on beam profile and PD were reduced with increasing depths. CONCLUSION: The lucite spoiler allowed use of a 10-MV x-ray beam for head and neck treatment by yielding a build-up dose similar to that of a 6-MV x-ray beam while maintaining skin sparing. The increase in PD was at superficial depths and was reduced at points away from the edge; therefore, it is clinically nonsignificant. Spoiling the 10-MV x-ray beam resulted in treatment plans that maintained dose homogeneity without the consequence of increased skin reaction or treatment volume underdose for regions near the skin surface.
BACKGROUND: Despite extensive coverage in recent literature, controversy continues with regard to the relative sensitivities of computed tomography (CT) and physical examination (PE). OBJECTIVE: To identify a statistically significant consensus. DATA SOURCES: Initially, data were reviewed on 47 consecutive patients with head and neck cancer on whom a total of 53 neck dissections were performed. These data were combined with findings from a 15-year MEDLINE review of the English-language literature, including references. STUDY SELECTION: All publications that contained a direct comparison of CT with PE, with appropriate data availability, were included. DATA EXTRACTION: Multiple-observer independent extraction was used. A total of 647 neck dissections were included in the meta-analysis. The definition of metastasis varied minimally among studies as follows: (1) nodal size, greater than 10 to 15 mm; (2) multiplicity of 8- to 10-mm nodes; or (3) evidence of necrosis. Necks were compared for positivity or negativity rather than for the actual nodal staging. In all cases, a final determination was made by results of histopathologic examination of surgical specimens. DATA SYNTHESES: The results in this review favored CT over PE but were not statistically significant by use of the Fisher exact test. A combination of the present study's data with those of the literature review yielded the following meta-analysis results: sensitivity, 83% (CT) vs 74% (PE) (P = .002); specificity, 83% (CT) vs 81% (PE) (P = .7); and accuracy, 83% (CT) vs 77% (PE) (P = .006). Overall, PE identified 75% of pathologic cervical adenopathy; this detection rate increased to 91% with the addition of CT. The results of sensitivity analysis confirmed homogeneity across study designs. CONCLUSIONS: Computed tomography is a more sensitive indicator of cervical metastasis than PE. More importantly, these diagnostic modalities were additive, with CT significantly enhancing the detection rates of PE alone. All patients who are at risk for cervical metastasis should have CT or equivalent radiographic imaging performed prior to therapeutic intervention. Future studies correlating CT detection rates to the primary site and staging are needed before more specific conclusions can be drawn.
A review of the past 22 years of laser applications shows that a great deal of progress has been made. It allows one to see the evolution of laser therapy, compare it with other modalities used in surgical oncology, and identify certain program that merit clinical trial. Use of lasers in surgical oncology began with a laser knife. Tissues were divided and removed with the focused beam of the CO2 laser, which replaced the scalpel previously used to perform surgical procedures. Later, the Nd:YAG laser was used in hollow visci such as the trachea and esophagus to open obstructed passages and possibly to cure many cancers. The operating microscope was used in the larynx to remove benign and malignant lesions, and for obstructing lesions to provide time to treat medical complications by reopening airway passages, and to add irradiation and/or chemotherapy preoperatively. Many times the Nd:YAG laser was used gastroscopically to treat bleeding or obstruction. Cytoreduction by laser made surgery or chemotherapy, or both, plausible. Addition of the sapphire tip and, later, the bare of sculptured fiber increased the variety of procedures possible with the Nd:YAG laser. Photodynamic therapy (PDT) uses various drugs that are localized in cancer cells. The cancer is then destroyed by laser emissions of the proper wavelength. One of the problems with PDT is getting the light to the tumor. Preactivation is addressed in this report. The problems associated with anaerobic tumors are discussed and suggestions for clinical trials offered. Laser hyperthermia is compared with induced hyperthermia as well as in combination with irradiation. Protocols of local laser hyperthermia combined with irradiation need further exploration. This review addresses the use of lasers in the destruction of tumor cells for bone marrow transplant and several old and new experiments used to block the AIDS virus. Finally, ongoing research is discussed, including the present and future roles of lasers.