ABSTRACT
OBJECTIVE: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. MATERIALS AND METHODS: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an X-ray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. RESULTS: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-micrometer thickness. With a thicker molybdenum filter (100 micrometer thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-micrometer thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. CONCLUSION: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue.
Subject(s)
Humans , Equipment Design , Mammography/instrumentation , Molybdenum , Optics and Photonics/instrumentation , Phantoms, Imaging , Radiographic Image Enhancement/instrumentation , RhodiumABSTRACT
A prescriçäo de auxílios visuais ópticos, sua interferência na qualidade de vida dos pacientes portadores de um estado de visäo subnormal, além do grau de adaptaçäo a estes auxílios, säo analisados através de um estudo retrospectivo de uma amostra aleatória de 100 pacientes referendados. A análise de variância é utilizada como tratamento estatístico e conclui-se, com fortes evidências que, säo válidos os esforços multidisciplinares na reabilitaçäo visual, pois em 52 p/cento dos casos, recuperou-se a razäo de viver de muitos seres humanos, por vezes tidos como cegos