Dosimetry characteristics of metallic cones for intraoperative radiotherapy

Dosimetry data were obtained on the first dedicated linear accelerator of its type designed for electron intraoperative radiotherapy (IORT) within an operating room. The linear accelerator uses a high dose rate, 9 Gy.min-1, to reduce the treatment time. Its chrome-plated brass treatment cones, designed with straight ends and 22.5 degrees beveled ends, are not mechanically attached to the collimator head, but are aligned using a laser projection system. Dosimetry measurements were made for each combination of energy (6, 9, 12, 15, and 16 MeV), cone size (diameters range from 5 to 12 cm), and cone type (22.5 degrees beveled or straight). From these data, depth-dose curves, cone output, and air-gap correction factors were generated that allow the calculation of the monitor setting for delivering a prescribed dose at any depth for any irradiation condition (energy, cone, air gap). Isodose data were measured for every cone using film in a solid water phantom. Scatter off the inside wall of the cone resulted in peripheral dose horns near the surface that were energy and cone dependent, being as large as 120%.     

Spontaneous perinephric and subcapsular renal hemorrhage: evaluation with CT, US, and angiography

Eighteen consecutive patients with acute spontaneous perinephric hemorrhage were examined with computed tomography (CT) (n = 18), ultrasonography (US) (n = 15), and angiography (n = 9). Renal cell carcinoma was found in 10 patients; angiomyolipoma, three; and segmental renal infarction, arteriovenous malformation (AVM), hemorrhagic cyst, abscess, and idiopathic hemorrhage, one each. Initial CT examinations demonstrated the extent of hemorrhage in all cases and a distinct mass in 12 (67%), with CT characteristics suggestive of the correct diagnosis in 11. In the other six patients (33%), a discrete mass was not seen at initial CT, and in five cause of hemorrhage was not clear. Two of the five underwent follow-up CT, which correctly demonstrated carcinoma in both. Overall, CT findings suggested the correct diagnosis in 14 patients (78%). US was sensitive for detection of an abnormality but nonspecific as to its nature. Angiography demonstrated unsuspected AVM in one patient, segmental renal infarction seen at CT in one, but only one of five carcinomas suspected at CT. Data from this study suggest that CT is the most valuable examination for patients with spontaneous renal hemorrhage.     

Multiphasic MR imaging: a new method for direct imaging of pulsatile CSF flow

A new technique is described that allows for the creation of pure pulsatile flow magnetic resonance (MR) images in a single acquisition. Five to 16 electrocardiographically gated images spanning the entire cardiac cycle are obtained with use of a gradient-echo pulse sequence. The section can be varied from 4 mm thick to full thickness projection. Taken singly, each image provides direct assessment of flow direction and velocity. Subtraction of image pairs eliminates signal detected from stationary protons, producing images of pulsatile flow. In this study the technique was used to image the flow of cerebrospinal fluid (CSF) in healthy subjects and in one patient with syringohydromyelia. The data suggest that multiphasic MR imaging provides a powerful means for the noninvasive assessment of CSF pulsatile flow dynamics and may have potential clinical application for the investigation of a variety of abnormalities such as normal pressure hydrocephalus, syrinx, and spinal block.     

Fluid collections in the intraperitoneal and extraperitoneal spaces: comparison of MR and CT

Fourteen patients with abnormal subdiaphragmatic fluid collections (eight intraperitoneal, two extraperitoneal, and four intra- and extraperitoneal) were examined with computed tomography (CT) and magnetic resonance (MR) imaging. MR and CT provided equivalent information concerning the presence and extent of fluid collections in 13 of the 14 cases. Image acquisitions with two different repetition times (TRs) and two echo times (TEs) were necessary, in most cases, to detect and discriminate between different types of pathologic fluids. Transudative ascites demonstrated long T1 and T2 relaxation times, whereas abscesses, phlegmon, pancreatic pseudocyst, exudative pancreatitis, and chronic hematoma demonstrated an intermediate or short T1 and a long T2.     

Evaluating community health worker performance in India

In 1977 the Government of India launched a health care experimentin which volunteers were used to provide a basic health careservice. Community health workers have also been used in manysmall, non-governmental programmes. Although much has been saidabout the selection and training of such workers, there havebeen very few attempts to evaluate their actual work performance.This paper makes the plea for more, regular evaluations of theiractivities by those involved in the programmes: communities,supervisors and health workers themselves. Such evaluationsare useful even if they are only done on a small scale. Whatis described here is a small study of the performance of part-timecommunity health workers (PTCHWs) in a programmme initiatedin 1977 by the Community Health Department of the ChristianMedical College in Vellore, South India. It concludes that thePTCHWs with the highest performance scores have, on the whole,less education, more experience, less population to cover andmore intense supervision.     

Developmental biology of the dendritic cell system

Aim : To determine whether an imbalance of dendritic cell subsets might contribute to diminished adaptive host responses observed in newborn infants. It was hypothesized that the proportion of lymphoid dendritic cells would be greater than that of myeloid dendritic cells in cord blood. Methods : To investigate this, dendritic cell subsets were evaluated in whole cord blood by flow cytometry. Circulating dendritic cells were also isolated from cord blood based on CD1c and BDCA-2 expression. Myeloid dendritic cells were also obtained by culturing cord and adult blood monocytes. Surface phenotypes of these cells were determined by flow cytometry using monoclonal antibodies directed against lineage, major histocompatibility, adhesion, co-stimulation and cytokine receptor molecules. Antigen-presenting functions of dendritic cell subsets were determined by mixed leukocyte reactions. Results : Circulating myeloid dendritic cells were higher in cord blood than previously reported in adult blood, whereas lymphoid dendritic cell numbers were similar between cord and adult blood. Expression of CD11c, CD45RA and CD45RO did not accurately differentiate between dendritic cell subsets circulating in cord blood. Fresh and culture-derived cord blood myeloid dendritic cells stimulated adult allogeneic leukocyte proliferation, while lymphoid dendritic cells were less effective inducers of an adult allogeneic leukocyte response. Culture-derived dendritic cells induced modest autologous cord blood leukocyte proliferation, but freshly isolated myeloid and lymphoid dendritic cells did not stimulated autologous leukocytes.
Conclusion : Contrary to the hypothesis, an imbalance in the ratio of circulating myeloid to lymphoid dendritic cell subsets does not exist and, therefore, does not contribute to diminished adaptive immune responses in newborn infants.