Title: Tests on reliability of a prostate biopsy telerobotic system
Author: prof. Alberto Rovetta N. AF-4

Alexander M. Mood, Franklin A. Graybill, Duane C. Boes, Introduction to the Theory of Statistics, Milano, McGraw-Hill, Inc., 1992

Development of a specific application of stereotaxic biopsies. These operations benefit from the use of a SR 8438 Sankyo Scara robot also remote-controlled, i.e. via telerobotics. They require accurate positioning in known points of three-dimensional space with a high degree of precision.
The methodology took the experience from the first two telerobotic biopsies on patients on Policlinico Hospital and Politecnico di Milano on 7th April 1995 and 1st September 1995. Before starting with the complete ambulatorial work on patients, inside a grant with National Council of Researches of Italy (C.N.R.), a series of test repetitive with echographic analysis on samples of meat with inserted probe, were applied.

More specifically, the system has the following functional modules:

  • Image diagnostic system to permit localization of lesion. This system uses equipment for ultrasound scans and CAT scans or stereotaxic X-ray apparatus. It is made of normal equipment appropriately interfaced with the supervisor computer in order to perform the operations required to localize the lesion (usually measurements) on the images.
  • Positioning system based on the use of a robot with degrees of freedom varying from 4 to 6 depending on the characteristics of the biopsy. The program will start using a common industrial robot and will later define, if this should be necessary, the specifications of a system dedicated to the taking of surgical samples.
  • Safety system to radically eliminate any possibility of uncontrollable functional abnormalities of the robot or of the system as a whole. Specifically, the safety system is organized on an active basis to prevent the occurrence of abnormal and passive situations to ensure that the robot cannot, under any circumstances, execute incorrect instructions. The system can intervene in relation to the movements of the robot that can be slowed down, interrupted or inverted, according to the problem that has arisen. The system will include a number of on/off-type sensors and detect possible contacts with the patient. A force sensor records the force exchanged between the patient and the sample-taking device while inside the patient.

Control system based on a personal computer equipped with appropriate cards for interfacing with the environment and particularly with the used safety sensors. Specifically, the computer is equipped with a card for image acquisition and processing, a digital I/O card and a card for the acquisition of analog signals. The dialogue with the robot normally takes place via a serial line. In the event of emergencies detected by the safety system or by the physician himself, it is possible to send the robot rapid “interrupt” commands via dedicated digital lines. The software controlling the application will be developed in a Windows environment to simplify the use by medical staff.
The remote control system makes possible for a remote station to take the control of the supervision software of a local station, which may be called the "supervision station". This station is basically constituted by a videoconferencing station that uses as a transmission support an ISDN basic attachment telephone line. Telecontrol is performed by using the classic interaction peripheral equipment with a personal computer (keyboard and mouse), exploiting the possibility of transmitting images, sound and data (sensorial information).

Future possible developments
The main innovations are:

  1. development of an auxiliary system for the execution of stereotaxic diagnosis with a view to surgery;
  2. analysis of diagnostic images on which operations are based;
  3. development of software that connects the analysis of images with the calibration of the robot in the operating room environment;
  4. development of mechanical, electrical and electronic hardware connected to the robot in order to obtain the surgical function required;
  5. development of robot control software.