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排序方式: 共有562条查询结果,搜索用时 15 毫秒
21.
MC Chau SF Leung KM Kam KY Cheung WH Kwan KH Yu KW Chiu TC Chan 《Journal of Medical Imaging and Radiation Oncology》2007,51(5):480-484
To assess the dosimetric effect of using interpolated contours in planning intensity‐modulated radiation therapy (IMRT) for advanced T‐stage nasopharyngeal carcinoma. The present study focused on T3–T4 tumours where the proximity of targets to neurological organs poses a stringent test on the feasibility of such an approach. Contours of targets and organs were delineated on CT images of 2.5‐mm interval and a reference IMRT plan was generated. An investigative (INV) IMRT plan was then generated with the same planning protocol, but based on interpolated contours that replaced deleted contours on alternate slices. The reference and INV plans were compared. Regarding target coverage, all targets in the INV plans met the acceptance criteria except for the PTV in one case. Regarding organs, the mean dose to 1% volume of the brainstem and spinal cord in the INV plans were kept below their dose limits. No significant differences in the mean doses to others organs were found. Satisfactory target coverage and protection of critical organs to a degree similar to full‐scale contouring could be achieved with use of interpolated contours. The saving in manpower time for contouring is expected to significantly improve the throughput of the IMRT planning process. 相似文献
22.
AM Cotterill WH Majrowski S Hearn S Jenkins MA Preece MO Savage 《Archives of disease in childhood》1996,74(5):452-454
The UK 1990 height charts are derived from an up to date dataset and introduce a change in the centile lines, particularly the addition of the 0.4th centile. This study examined the likely impact of these changes. Height data from London school children (1990-1993) were examined using Tanner and Whitehouse (TW) and UK 1990 charts. Numbers of children with height below TW 3rd centile were compared with numbers below the UK 1990 3rd and 0.4th centiles. The TW charts identified only 1% of children below the TW 3rd centile, while the UK 1990 charts identified 3% below the 3rd and 0.4% below the 0.4th centiles. If the 3rd centile remains as the referral 'cut off' for short stature, the introduction of the UK 1990 charts would increase current workload two- to three-fold, while a change to the 0.4th centile would reduce it by 50%. A significant number of children with abnormalities may be excluded from further assessment as a result of this latter change. In this small scale community study it is not possible to assess the consequences of this change. The heights at diagnosis of children with growth hormone (GH) deficiency (peak GH < 20 mU/l during a standard provocation test) were therefore compared to the 0.4th centile (UK 1990 charts). Sixty eight children with heights < 2nd centile (UK 1990 charts) currently receiving GH replacement (17 female, 51 male, aged 9.7, SD 3.5, years) were assessed, and of these, 28 (41%) had heights at diagnosis between 0.4th and 2nd centile, with a mean height standard deviation score of -2.32 (SD 0.21). This suggests that if the 0.4th centile were to be used as the sole criterion for referral for slow growth, a significant proportion of children with abnormality would not be referred for further assessment. The UK 1990 2nd centile should replace the TW 3rd centile. Children below this should undergo an intermediary medical assessment to confirm height measurement, to exclude from referral children with mild familial short stature and to identify concerns regarding the child. 相似文献
23.
Forty one (1%) of 4000 children referred for respiratory disease had chronic suppurative lung disease not due to cystic fibrosis. Further investigations showed congenital malformations in six (15%), primary ciliary dyskinesia syndrome in seven (17%), 11 had immunological abnormalities (27%), and two bronchiectasis due to aspiration (5%). Therefore the underlying cause for the disease was found in 63%. Identification of predisposing causes may facilitate prevention of further bronchial damage. 相似文献
24.
BACKGROUND: Because mitochondria are abundant in white cells and are also present in platelets, polymorphic sequences in mitochondrial DNA (mtDNA) represent a unique target for polymerase chain reaction (PCR)- based detection of donor material. STUDY DESIGN AND METHODS: A PCR assay was developed that uses sequence-specific primers (SSP) focused on two continent-specific mtDNA polymorphisms. Results were validated by the use of informative restriction endonucleases. Three commercially available methods to extract mtDNA from white cell-reduced human platelets was compared. In preparation for in vivo studies, in vitro mixing studies designed to mimic transfusion were conducted to investigate the performance of the SSP-PCR assay. RESULTS: The gene sequences of two representative examples of amplicons obtained with the new SSP-PCR matched the sequence expected from the published genetic code. Fifteen individuals were classified as either positive (n = 6) or negative (n = 9) for the Asian polymorphism by the use of published primers known to flank the polymorphic site followed by digestion with appropriate restriction enzymes. Results with SSP-PCR were nearly perfectly concordant with those of restriction enzyme analysis. Although the use of three DNA extraction methods allowed the preparation of mtDNA that was suitable for PCR, large and consistent differences (ranging from 10- to 1000-fold) in endpoint sensitivity were found. In vitro mixing studies reproducibly documented that the SSP-PCR assay could detect as little as 1 percent of donor platelets mixed with recipient blood. CONCLUSION: PCR-SSP can be reliably used to identify human mtDNA polymorphisms. By optimization of the method of mtDNA extraction, the sensitivity of PCR-SSP assay was greatly increased. This assay should prove useful in investigations of allogeneic platelet transfusions without cell labeling. It may also be applied to studies of the donor cell microchimerism that follows transfusion or transplantation. 相似文献
25.
Templeton AW; Johnson JA; Anderson WH; Cook LT; Dwyer SJ d; Preston DF; Lee KR; Rosenthal SJ; Batnitzky S; Levine E 《Radiology》1984,151(2):527-528
The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use. 相似文献
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28.
麦冬多糖对正常和实验性糖尿病小鼠血糖的影响 总被引:25,自引:0,他引:25
目的:研究麦冬多糖对正常和实验性糖尿病小鼠血糖的影响。方法:昆明种小鼠40只,分成4组,分别用麦冬多糖(100和300mg/kg)、优降糖(2.5mg/kg)和等体积生理盐水(2ml/只)灌胃,测定各组正常小鼠的血糖水平及以葡萄糖(2g/kg)、四氧嘧啶(70mg/kg)、肾上腺素(0.02mg/kg)所致小鼠高血糖模型的血糖水平。结果:剂量为100和300mg/kg的麦冬多糖灌胃对葡萄糖、四嘧啶 相似文献
29.
A radiographic study of the ligamentous anatomy of the ankle 总被引:1,自引:0,他引:1