Biomedical subjects

I M Hwang

Publications and source records attributed to I M Hwang.

3 recordsLinked to original sources

PubMed2001

Thresholding histogram equalization.

The drawbacks of adaptive histogram equalization techniques are the loss of definition on the edges of the object and overenhancement of noise in the images. These drawbacks can be avoided if the noise is excluded in the equalization transformation function computation. A method has been developed to separate the histogram into zones, each with its own equalization transformation. This method can be used to suppress the nonanatomic noise and enhance only certain parts of the object. This method can be combined with other adaptive histogram equalization techniques. Preliminary results indicate that this method can produce images with superior contrast.

Algorithms↗

PubMed2001

Simple empirical formula for predicting range variation of central-axis parameters in small electron fields.

The depth of central-axis percent dose Rx (except R100) and practical range, Rp, for small field electron beams can be calculated by the proposed empirical formula: Rx = Rxo x [1 - (1 - r/Rpo)m], where Rxo and Rpo are the broad beam percentage dose depth and practical range respectively; r is the small field cutout side when it is less than the maximum lateral scatter equivalent range, and m is the exponent term relative to the decreasing curvature. Five electron beams from a Varian CL-2100CD linear accelerator were used to verify this formula. The difference between measured and calculated depth dose range is within +/- 1 mm when cutout side reduced to 2 x 2 cm2. This formula offers a simple and time-saving method to quickly determine the useful treatment percentage dose depth of small field electron beams.

Electrons↗

PubMed1991

Enhancement of fracture healing by specific pulsed capacitively-coupled electric field stimulation.

The histologic procedure technique was used to evaluate the bone fracture healing rate of manually fractured fibulae after they were submitted to several different types of capacitively-coupled electric field stimulation, classified depending on the parameters of peak-to-peak voltage, frequency and duration. Using a completely randomized design, 30 New Zealand male rabbits were divided into six different groups: a control group, a 60 kHz and 220 mVp-p sine wave group as proposed by Brighton in 1985, and four special parameters of pulse wave groups. After comparing these different types of electrical stimulation, the group with the parameters of a pulse train repetition frequency of 15 Hz, a pulse frequency of 10 kHz and 5 V peak-to-peak intensity experienced the same enhancement of bone fracture healing as the group with the parameters suggested by Brighton in 1985.

Animals↗