Measuring process and sensor for on-line in-vivo determination o

Details Measuring process and sensor for on-line in-vivo determination o Measuring process and sensor for on-line in-vivo determination o

1997-08-06

1999-08-17

Smith, Ruth S.

Surgery

Diagnostic testing

Detecting nuclear, electromagnetic, or ultrasonic radiation

25037007, A61B 600

Patent

active

059386053

DESCRIPTION:

BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase of PCT/DE96/00174 filed Feb. 1, 1996 and based, in turn, upon German national application 195 03 647.6 filed Feb. 6, 1995.


FIELD OF THE INVENTION

The invention relates to a process for the in-vivo and on-line determination of the tissue equivalent dose in radiotherapy as well as to a device for carrying out the process.


BACKGROUND OF THE INVENTION

It is known to carry out an in-vivo measurement of an approximate tissue equivalent dose with miniaturized to thermoluminescence dosimeters in certain applications. A drawback, however, is this limitation to certain applications. In addition, the measurement results are only available after expensive evaluation of the thermoluminescense dosimeter at the earliest an hour after termination of the irradiation.
Furthermore, there are numerous proposals and investigations into fiberoptic measurements of the dose or, using semiconductor dosimeters in-vivo and on-line (U.S. Pat. No. 5,014,708 of May, 1991; H. Buker et al, Fiber-Optic Radiation Dosimetrie for Medical Application, SPIE, Vol. 1201, Optical Fibers in Medicine V. P. 419-429(1990); H. Buker et al., Physical Properties and Concepts for Applications of Attenuation-based Fiber-Optic Dosimeters for Medical Instrumentation, SPIE, Vol. 1648, Fiber Optic Medical and Fluorescent Sensors and Applications, P. 63-70(1992)).
According to the proposals and investigations, sensors are used whose material has an effective atomic number significantly deviating from the tissue or a reduced sensitivity. It is, however, a drawback that a precise measurement, especially in the case of photon radiation, is not possible since the material of the sensor always deviates from that of the tissue and the absorbed dose is material dependent. Further, the information regarding the tissue depth is not in principle available. It is therefore a drawback that the choice of material is limited.


OBJECT OF THE INVENTION

It is the object of the invention to overcome the indicated drawbacks by providing a measurement process and device for carrying out the process which enables on-line and in-vivo determination of the tissue equivalent dose in radiotherapy.


SUMMARY OF THE INVENTION

This object is achieved as follows:
In detail, the process can be carried out as follows:
A radiation dosage is measured by at least two sensors with an energy-dependency differing from one another for ionizing radiation and at least one quotient is formed from the measuring signals obtained from the sensors. That quotient is used to derive the tissue equivalent dosage.
Initially the radiation dose at a location is measured by at least two sensors. The sensors are so selected that within the measurement range the radiation dose varies in proportion to the measurement signal. It is sufficient in this case to determine by a compensating calculation the proportionality between the measurement signal and the radiation dose.
At least two measured signals S.sub.i and S.sub.j of the sensors i and j used must show an energy dependency of the detection sensitivity for ionizing radiation differing from one another. Such a difference in dependency is obtained with optical sensors with different effective atomic numbers Z.sub.eff. The different indications can however also be achieved by a different shielding of each of the sensors.
At least one quotient Q.sub.ij =S.sub.i /S.sub.j between, measured signals S.sub.i and S.sub.j of these sensors i and j is formed. One signal S.sub.i can be obtained from one of the sensors i or j or as a mean value of a number of measurement signals from a plurality of sensors used, which has the same dependency on the detection sensitivity for ionizing radiation. It is decisive that a value dependent on the dose be used for the further evaluation. As an alternative to simple quotient formation, quotients like (S.sub.i -S.sub.j)/(S.sub.i +S.sub.j) or their inverses can be used. In the description below, the simple quotient formation Q.sub.ij is used.
Further the

REFERENCES:
patent: 5014708 (1991-05-01), Hayashi et al.
"Fiber-Optic Radiation Dosimetry for Medical Applications" by Bueker et al., SPIE vol. 1201 Optical Fibers V(1990).
"Physical properties and concepts for applications of attenuation-based fiber optic dosimeters for medical instrumentation" by Bueker et al. SPIE vol. 1648 (1992).
A Tissue Equivalent Semiconductor Detector for In-Vivo Dosimetry by G. Jacob et al. (Nuclear Instruments and Methods 101 (1972) North-Holland Publications.

Affiliated with

Also associated with

Rating

Measuring process and sensor for on-line in-vivo determination o does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Measuring process and sensor for on-line in-vivo determination o, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Measuring process and sensor for on-line in-vivo determination o will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-309980