Medical acoustics

Works on use of acoustical effects and phenomena when creating different types of medical techniques have been carrying out in Acoustics Institute since its formation. Elaboration of medical instrument and apparatus is carried out under creative co-operation with medical specialists. Investigations of ultrasound applications efficiency when creating surgical instruments began at the end of 60-s. It was found out that application of ultrasonic oscillations to the element affecting the biological tissue causes the next results:

  • strain, which is necessary for penetration into the tissue is decreased ( 5...10 times);
  • destruction of pathological neoplasm occurs;
  • noticeable bactericidal effect is reached;
  • blood wastes are lowered significantly and purulent formations in opened wounds coagulate.

In 70-80-s as a result of collaboration with progressive native surgical clinics ultrasonic surgical devices of different destination including those for ophthalmology and infantile lung surgery were elaborated and applied in practice.

On the basis of investigations of Acoustics Institute small branch production of ultrasonic surgical devices for infantile lung surgery ("Alveolus") and ophthalmology ("Lora" and "Lora-Don") was arranged.

By this time in Acoustics Institute, as a result of works carried out, necessary scientific and technical beginning for development activity on creation of special set of microsurgical ultrasonic instruments for operations on cerebrum and spinal cord is available.

Research efforts towards application of ultrasonic surgical devices for treatment of oesophagus stenosis are being planned. These works are provided with necessary experimental techniques, they permitting to apply in practice an unique scientific and technical beginning after having extended the field of low traumatic surgery.

Studies into the application of focused ultrasound in different fields of medicine and physiology have begun in the Acoustics Institute from the beginning of 70-ies. With the use of focused ultrasound systems, it is possible to achieve in a focal region the intensity of ultrasound of about hundreds and thousands W/cm2, while the intensity on a surface of an ultrasound transducer does not exceed of a few W/cm2. The main advantages of using of focused ultrasound in medicine are:

  • the method is essentially noninvasive, i.e., it does not require destruction of tissues for irradiation of deep-seated structures;
  • locality of action can be controlled and changed by altering the operating frequency of the focused transducer to stimulate locally predetermined volumes of tissues and selected structures;
  • possibility of inducing a wide variety of different biological effects, from stimulation of neural structures to ablation of tissues, is available with the same equipment.

In the course of investigations, focused ultrasound technique and devices of different modifications were designed, the detailed examinations of mechanisms of biological action of focused ultrasound were carried out, and the possibilities of applications of focused ultrasound in the different fields of medicine were investigated and grounded together with a number of leading research and clinical Institutes of the Academy of Sciences, Medical Academy of Sciences and Ministry of Health. These applications are the following:

  • in experimental and clinical neurosurgery for local ablation of deep brain structures, including their irradiation through the intact skull bone;
  • in ophthalmology for acceleration of "maturing" of cataracts in lens and for the treatment of glaucoma;
  • in urology for "remote" destruction of gallstones without damage of a gall-bladder;
  • in oncology for hyperthermia of tumors, and also for increasing the efficacy of anti-tumor activity of ionizing radiation and crio-therapy;
  • in cardiology for local ablation of definite structures of heart.

Opportunity of application of focused ultrasound for local stimulation of superficial and deep-seated receptor neural structures of human beings was discovered for the first time. A method and the designed ultrasonic devices have already been used in clinics for diagnosis of different diseases (for example, neurological, dermal, hearing, etc.), accompanying by changes in sensory perception, by means of comparison of thresholds of different sensations in persons with normal sensory perception and in patients with different kinds of pathology. Besides, the opportunity of application of the method in the following fields has been grounded:

  • in therapy for relief of pain and for the treatment of diseases by means of noninvasive ultrasound stimulation of deep-seated neural structures, in particular acupuncture points without the use of needles;
  • for evaluation of the efficiency of anesthetic and analgesic drugs ("painkillers") by determining pain thresholds before and after drug administration;
  • for introduction of hearing information to some of deaf people and for the selection amongst deaf patients those who are the most suitable for cochlear implantation.

The development and fabrication of a small series of devices for diagnostics of neurological, dermal and hearing diseases, as well as the equipment for ultrasound hyperthermia of tumors, and also the individual and collective nebulizers were executed. The methods and technique for metrological control of safety of medical applications of focused ultrasound were designed. In particular, the remote methods of measurement of parameters of ultrasound and thermal fields induced in tissues by focused ultrasound have been developed.

During the last several years, alongside with the development of improved designs of focused transducers based on the use of single-element piezoceramic elements, the multiple elements focusing system allowing to steer electronically the focal region (or multiple foci) over the given volume of tissues were investigated. In particular, together with the Imperial College, London, Great Britain, a linear phased array for thermotherapy of the prostate has been designed and manufactured. The methods of computer modeling of ultrasonic fields of linear and two-dimensional arrays intended for application in surgery and hyperthermia of tumors has been developed. The opportunity of generation in tissues of considerable number of foci (for example, 25) has been shown. There was developed a new design of multiple elements 2-D arrays, which, in contrary to the traditional designs of the arrays with the regular distribution of elements on the array surface, was based on the random distribution of elements. This approach allows to reduce essentially the level of secondary maxima of the intensity in the ultrasound field of the array and therefore to increase the safety of its practical use in medicine. The results on the use of focused ultrasound in medicine and physiology obtained in the Institute have been published in books and scientific journals.

Priority of the Acoustics Institute in creation of methods and devices for application in medicine is confirmed by certificates of authorship and patents.