Biomedical subjects

L M Luo

Publications and source records attributed to L M Luo.

5 recordsLinked to original sources

PubMed2004

Gestational diabetes mellitus in Chinese women.

OBJECTIVE: To determine whether foreign diagnostic criteria for the diagnosis of gestational diabetes mellitus (GDM) are suitable for Chinese pregnant women. METHODS: The study participants were 340 pregnant women receiving obstetric care at the Shanghai Jiaotong University-Affiliated Sixth People's Hospital in Shanghai, China. The normal-pregnancy group comprised 190 women with no risk factor for GDM and the high-risk pregnancy group comprised 150 women who had at least one high-risk factor for GDM. All women took the diagnostic 100-g, 3-h oral glucose tolerance test (100-g 3-h OGTT) between 24 and 28 weeks of pregnancy. The results of the 100-g 3-h OGTT were classified according to three different sets of diagnostic criteria: (1) new, "Chinese" diagnostic criteria based on the results from the 100-g 3-h OGTT performed in the 190 healthy participating women; (2) the Carpenter and Coustan criteria; and (3) the National Diabetes Data Group (NDDG) criteria. Venous plasma glucose (VPG) was measured by the glucose oxidase method. A consistency check was used for analysis. Obstetric and neonatal outcomes were recorded. RESULTS: With 97.5% as the statistical cutoff value for the 100-g 3-h OGTT, the new diagnostic criteria for this study, based on data obtained from the 100-g 3-h OGTT performed on the 190 participating healthy pregnant women, were 5.2, 10.3, 8.9, and 7.7 mmol/L at 0, 60, 120, and 180 min. The e value was 0.83 for the new criteria vs. the Carpenter and Coustan criteria (P<0.001) and 0.70 for the new criteria vs. the NDDG criteria (P<0.001). In women with GDM and gestational-impaired glucose tolerance (GIGT), the incidence rates of macrosomia by the new criteria and the Carpenter and Coustan criteria were similar, but higher than the rates calculated with the NDDG criteria (P<0.05). CONCLUSION: With venous plasma glucose level measured by the glucose oxidase method, the Carpenter and Coustan criteria are applicable to Chinese pregnant women for diagnosis of GDM.

Adult↗

PubMed2000

An orthogonal moment-based method for automatic verification of radiation field shape.

The purpose of this paper is to develop a new method for automated on-line verification of the treatment field shape during radiotherapy. The treatment field boundary is extracted from the digital portal image and is then approximated by a polygon. The proposed procedure used one of the approved field shapes as the reference boundary for automated comparison with subsequent portal field boundaries. The orthogonal moment-based method was applied to align treatment field boundaries that include the translational shifts, scaling factor and rotation angle. Firstly, the moments of order up to one were used to adjust the magnification and translation of the test field boundary related to the reference one; this step created a common coordinate system for the two images. Then a quadratic least-square objective function based on the orthogonal moments (e.g. Legendre moments) of the two field shapes was employed to perform rotational correction. Since moment computation by a straightforward method required a large number of multiplication and addition operations, a fast method for computing Legendre moments was also developed to decrease the calculation time. Application of the method to some simulated cases showed that our alignment procedure has an accuracy of 0.5 mm in detecting translational shift, 0.004 in detecting magnification and less than 0.3 degrees in detecting rotation angle between the test shape and the reference shape. The alignment procedure using the proposed method can be done within 2 s on a Pentium II personal computer. Therefore, our method is potentially useful for automated real-time treatment field shape verification.

Algorithms↗

PubMed1999

[Study on adsorption of atrazine by soil leaching column chromatography].

A recently developed soil leaching column chromatography was applied to study the adsorption of pesticide in water-soil system. Soil was filled directly into a liquid chromatographic column and pesticide solution was applied as an eluant, and the adsorption equilibrium was monitored by a UV detector. The herbicide atrazine, i. e. 2-chloro-4-ethylamino-6-isopropylamino-s-triazine, was chosen as an example. Its mass concentration ranged from 19.73 mg/L to 29.60 g/L. After the soil phase was rinsed with methanol, the amount of atrazine adsorbed was calculated from the difference between the atrazine totally rinsed and that in solution in the column. The low content atrazine sample was determined by enrichment on an ODS column and step-gradient method. It shows that the adsorption of atrazine on a sandy loam soil is in accordance with Freundlich isotherm. The adsorption coefficient Kf is 842.6 mL/kg and the normalized organic carbon adsorption coefficient log Koc is 1.832.

Adsorption↗

PubMed1998

Treatment planning optimization by quasi-Newton and simulated annealing methods for gamma unit treatment system.

The gamma unit is used to irradiate a target within the brain. During such a treatment many parameters, including the number of shots, the coordinates, the collimator size and the weight associated with each shot, affect the amount of dose delivered to the target volume and to the surrounding normal tissues. Hence it is not easy to determine an appropriate set of these parameters by a trial and error method. For this reason, we present here an optimization method to determine mathematically those parameters. This method is composed of two steps: firstly, a quasi-Newton method is used to deal with the continuous variables such as position and weight of shots; the result obtained at the end of this step then serves as the initial configuration for the next step, in which a simulated annealing method is applied to optimize all the aforementioned parameters. Application of the proposed methods to two examples shows that our optimization algorithm runs in a satisfactory way.

Algorithms↗

PubMed1993

A moment-based three-dimensional edge operator.

This paper presents a three-dimensional edge operator aimed at the detection of anatomical structures in medical imaging. It uses the spatial moments of gray level surface, and operates in three dimensions with any window size. It allows us to estimate the location and the contrast surface, as well as the surface orientation. The computation of the discrete version is reported. Bias and errors due to the spatial sampling and noise are analyzed both at a theoretical and experimental level. The moment-based operator is compared with other well-known edge operators on simple shaped primitives for which the analytical solution is known. The 3D rendering of real data is then provided by merging the operator in a ray-tracing framework.

Artifacts↗