This paper was reviewed in recent progress of medical ultrasonic technology. Obviously in 21 century we face to the second generation of ultrasonic technology in medicine. First of all, B-mode imaging and Doppler color flow mapping have been improved by the digital beam forming technology. This technology leads to high research activity in the field of image processing such as automated tumor segmentation. Harmonic imaging is also newly developed technology. This technique uses harmonic component of echoes while the ultrasound waves are traveling through the nonlinear media such as biological tissues so that high quality images are obtained. Contrast echo method is expected to detect small echo signals from slow and small blood flow. Harmonic power Doppler imaging using micro bubbles is expected to detect early stage of cancer. Three dimensional real time imaging is next generation of ultrasonic image diagnosis system. Two dimensional array is a key technology to realize this imaging. Finally, ultrasonic therapy is described.

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Three-dimensional (3-D) imaging has recently been utilized for medical diagnosis alongside of the use of cross-sectional imaging. In X-ray CT and MRI equipment, a computer installed inside executes 3-D image reconstruction with the raw data obtained from the patient. However, in ultrasound equipment, it is necessary for 3-D imaging to use specific technologies that take the inherent characteristics of the ultrasonic echo data into account. In this paper, I broadly divide manners of 3-D image rendering into "direct" methods and "i ndirect" methods. Direct methods have recently prevailed in the area of ultrasonic 3-D imaging, as these methods are particularly appropriate for processing ultrasound data. In terms of trends, both technologies of segmentation and real-time imaging for the 3-D ultrasound will emerge as the dominant technologies in the future.

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Pulse compression techniques were developed mainly for radar systems. And the technology allows a radar to utilize a long pulse to achieve radiated energy, but simultaneously to obtain the range resolution of a short pulse. It accomplishes this by employing frequency or phase modulation to widen the signal bandwidth. Coded excitation is an ultrasound technique which has only been made commercially available in the last 3 years. It improves SNR without loss of resolution by transmitting a long binary phase-encoded pulse sequence and then compressing its echo into a short, high-amplitude pulse on receive. Different types of codes, e. g. Golay, may be used to suppress range side lobes. And a new technique called B-Flow for imaging blood flow also uses advanced digital signal encoding/decoding techniques to provide direct visualization of blood echoes. Coded excitation together with tissue equalization forms the basis for B-Flow, which extends the wideband resolution and high frame rate capabilities of Bmode to flow and tissue imaging. A key aspect of B-Flow is tissue equalization, which uses decoding to preferentially reduce non-moving tissue signals to the level of the flow signal such that both may be displayed simultaneously without machine prioritization and overlay (as in color flow).

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There are problems for contrast imaging using LevovistTM contrast agent. In case of Doppler mode, poor resolution and large blooming area are the problems. In case of 2nd harmonic imaging and pulse inversion imaging, tissue harmonic image(THI) becomes the problem because Levovist needs high mechanical index(MI). THI increases under the high MI condition and THI interferes with the contrast image of Levovist. And also bubbles of Levovist are easily collapsed under the high MI condition, so it is hard to visualize the bubbles successively.
Dynamic Flow has solved the above problems. Dynamic Flow uses Doppler technique, but Dynamic Flow image has higher resolution and less blooming area than the conventional Doppler image. Dynamic Flow doesn't display THI, so the detectability of bubbles is superior to the other mode as far as Levovist. Dynamic Flow is so sensitive that it can show the bubbles in real time.
Advanced Dynamic Flow(ADF) has greatly improved in sensitivity and presentation ability from conventional Dynamic Flow. In the contrast application, ADF image looks very similar to B-mode image thanks to the high resolution and wide dynamic range, in spite of using Doppler technique. Detectability of the bubbles is much better than conventional Dynamic Flow. ADF can detect bubbles in much smaller vessels and has much more penetration, with uniform enhancement from shallow to deep regions. ADF is very suitable for Levovist. ADF can also be used without contrast agents. ADF can show small tiny vessels with high resolution and high frame rate. Directional information can be added by different colors. The sensitivity is close to conventional Color/Power Doppler images.

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Ultrasound has two major biological effects potentially to be utilized fortumor treatment: heating and cavitational effects. In coagulation treatment, the tissue in the focal spot is heated above the coagulation temperature in a relatively short period of time with high intensity focused ultrasound so that the irreversible change in tissue is completed much earlier than the temperature distribution blurs due to heat conduction. However, the smallness of the coagulation volume formed by an ultrasonic shot causes the problem of low treatment throughput. The split focus technology, in which the focal spot is enlarged in the lateral rather than longitudinal direction, multiplies the coagulation volume so as to solve this problem. Sonodynamic treatment was proposed based on the recent in vitro and in vivo experimental findings that ultrasonic cavitation can activate certain porphyrins and thereby induce significant antitumor effects. It was also found that the ultrasonic intensity threshold for producing cavitation can be significantly reduced by superimposing the second harmonic onto the fundamental. The threshold to form a focal lesion in murine liver tissue was reduced by orders of magnitude, especially in combination with administration of a certain xanthene dye.

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The augmented Lagrangian method was applied to emission CT image reconstruction to attain the satisfactory elimination of negative pixels using a modified form of the original nonnegativity constraints. A penalty function was included in the augmented Lagrangian method to suppress image noise due to statistical noise in the projection data. A slight change in the original constraint form achieved almost complete nonnegativity without loss in the closeness of reconstruction to the original image.

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A Monte Carlo simulation code was developed for simulating PET scanners with the Monte Carlo program package GEANT. The present simulation code can handle not only conventional types of PET scanners, but also any complex detector systems with arbitrary geometrical configuration. All the relevant interactions of photons and electrons are taken into account in all the defined objects while optical tracking in the scintillation crystals is approximated by simple analytical simulation. In addition to basicP ET scannerP erformancfea ctors, s uch as sensitivitya nd scatterf ractionv, aluable but un-measurablien formations, u cha s photont rajectoriesa nd interactionp osition distributionc, a nb e obtaineda ndr epresentedg raphicallyin variousw ays. T his simulation codeh as provedu sefuli n analyzingth e physicsc haracteristicos f existingc ommercialP ET scannersa nd relateds hieldsa, nd in designs tudieso f new PET scanners.

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