Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-09-11
2004-02-03
Mercader, Eleni Mantis (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C601S003000
Reexamination Certificate
active
06685639
ABSTRACT:
TECHNICAL FIELD
This invention relates to an ultrasonic therapeutic apparatus, particularly a high intensity focused ultrasound (HIFU) scanning and treating system for tumor, which is an apparatus utilizing the sound intensity with high energy in the HIFU focal region to scan and treat the tumor tissues.
TECHNICAL BACKGROUND
Ultrasonic wave is a mechanic energy with good directivity which can penetrate into the human body. People began to apply ultrasonic wave to the treatment and diagnosis of diseases long ago, then the ultrasonic physical therapeutic apparatuses such as A-ultrasonic apparatus, B-ultrasonic apparatus, etc. were made. The common feature of these apparatuses is that they produce very low sound intensity in the target tissue; usually the average intensity is below 3W/cm
2
. In the past 20 years, great achievements had been made in the field of ultrasonic diagnosis, and ultrasonic therapies were developed gradually and then very quickly; of which the progress in the development of ultrasonic thermotherapy and high intensity ultrasonic therapy is specially obvious.
Medical researchers have discovered that the heat-resistance of cancer cells is poorer than that of normal cells. When the temperature is between 42.5 and 45 degrees centigrade, the cancer cells die within 30 minutes while the normal cells are injured slightly and the injury is reversible. By utilizing this difference between cells and the thermal effect produced by ultrasonic wave, the ultrasonic thermotherapeutic apparatus was produced.
By retrieval, it has been found that the patent invention CN91105010.8,—“Ultra-high speed extrinsic ultrasonic high temperature therapeutic apparatus”—belongs to the kind of apparatus mentioned above; the outstanding point of this patent invention is that treatments with sound intensity for a certain point (e.g. the center) of the target is carried out repeatedly; then the cells and tissues of the target (the tumor) are damaged by the diffusion of heat produced at the point. However, the effect of the apparatus is poor; the following are the reasons: 1. the active cancer cells are distributed mainly on the margin of the cancer mass; but the increase of temperature on the margin is relatively low; 2. The mass of cancer itself is irregular in shape, the shape of heat diffusion is difficult to control and there is temperature gradient; the non-invasive temperature measuring technique for tissues in deep parts of the body, especially the measurement of temperature increase and temperature gradient within the heat diffusion volume, is a worldwide difficult problem; 3. in order to put the irregular cancer mass under complete irradiation, it is unavoidable that the large amount of normal tissues are injured; 4. B-type echo detector is used within very short intervals between therapeutic wave beams to catch echo and to examine the A-type echo image of the degree of target damage during treatment; for this purpose, special image-storing circuit and sampling-comparing circuit are used; because only two successive A-type ultrasonic images are stored, it is difficult to observe the therapeutic effects directly; also it will make the apparatus complicated. 5. The therapeutic head can not aim at the target to carry out scanning movement, so the range of treatment is limited; it can not be used to treat the diffused point-like, branched, stripe-shaped, or other irregular shaped targets, or targets in relatively special locations.
Another patent application, CN93100813.1 shows “A Method and an Apparatus which aims at the Target of Human Tissues to Carry out Treatment”. It puts stress on the description of a method aiming at the target of human tissues; in the method, a real-time acoustic distance-measuring recording probe and a therapeutic wave beam generator probe are used, and a visible reference mark is used to determine the theoretical location of one reference point in two wave beams; by means of the relative focus F in the coordinate system and the reference mark R the predetermined displacement is made, and by causing the visible reference marks of the acoustic distance-measuring record image to coincide and then displacing the mentioned therapeutic generator until the mentioned first and second reference marks coincide, one focus F of the therapeutic wave beam and the mentioned target are made to coincide. The apparatus can be used to give localized treatment for prostate only and its application to other parts of human body shows no significance.
A Europeans patent number EP0734742A2 shows the characteristics of an ultrasonic therapeutic equipment: By the action of first grade base frequency, the therapeutic ultrasound generator has the property of resonance oscillation. The driver drives the therapeutic ultrasound generator to work with the driving signal of the first grade base frequency. Using the driving signal of the second grade base frequency, the driver drives the ultrasonic probe to get ultrasonic image within the body, and receive the reflected wave of the first grade ultrasonic wave produced by the therapeutic ultrasound generator as well as the reflected wave of the second ultrasonic wave generated by the ultrasonic probe. The inventor has made effort to make a perfect combination of therapeutic ultrasound and image-displaying ultrasound, in the document, 14 modes are listed.
In recent years, in order to avoid the disadvantages of thermotherapy, people have made a lot of researches on the treatment of cancer with high intensity focused ultrasound (HIFU); in the so called HIFU therapy, the ultrasound emitted by the probe with relatively low average sound intensity (usually several W/M
2
) is focused or made to converge on a point of space, then a focal region with an average sound intensity over 1000W/M
2
is formed; in the region instantaneous temperature elevation (>70 degrees centigrade) occurs, and cavitation or mechanical vibration occur, so the tissues in the focal region are damaged and the disease is cured.
A malignant tumor tissue has three marked characteristics: 1. because it is a tissue made up of juvenile cells, it is more sensitive to ultrasonic wave than the normal tissues. 2. it exists within the human body in three forms: a. in diffused point-like distribution, b. in the shape of a big mass, c. in the shape of tree-branches; 3. the malignancy degree of the tumor cells on the margin of the tumor is higher than that in the core of the tumor.
When the treatment of tumor tissue is carried out, injury of the normal tissue should be reduced as far as possible. The following are the difficulties in using HIFU technique to treat tumors: 1. a high energy point of ultrasonic wave (focal region) must be formed, and the ratio between the long axis and short axis of the focus region must be small; 2. the target tissue to be treated should be visible so that the location and shape of the tumor can be determined easily; 3. it should be possible to carry out scanning therapy for irregular tumors, and there should be various scanning forms for medical workers to choose. 4. it should be possible to perform real-time monitoring on the therapeutic effects. If B-mode ultrasound scanner is used for monitoring, strong ultrasonic reflection interfering B-ultrasonic image should be avoided, 5. the medium used should be a special liquid; the characteristic of its acoustic impedance should be similar to that of human tissues, and its acoustic attenuation should be little so that it will not interfere with the focused sound field.
GENERAL DESCRIPTION OF THE INVENTION
According to the technical difficulties found in the treatment for tumors with HIFU, the purpose of developing this invention is to provide a high intensity focused ultrasonic system for scanning and treating tumors. By means of focusing, the system causes ultrasonic waves to form a space-point with high energy (focal region); the energy of the region reaches over 1000W/M
2
and the temperature instantaneously rises to >70 degrees centigrade; besides, the focal region is made to enter the tumor tissue with
Bai Jin
Wang Zhibiao
Wang Zhilong
Wu Feng
Chongqing Hifu
Lowe Hauptman & Gilman & Berner LLP
Mantis Mercader Eleni
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