0.2 Design of an in-vivo radiation measurement scheme using a  (Page 2/2)

Finally, this project implements the idea of measuring radiation dose in terms of changes in MOS transistor characteristics. Since all of the processing is done at the receiver side, no complex circuitry will be placed next to the sensor (except an RF transmitter). With this the power and size requirements will be lot lesser than other commercialized devices. As the sensors are not custom-made devices, the results did not render high resolution.

11. Future Work:

In this project, we can observe that the timing measurements show a smaller range for the total range of radiation dosages. So, custom-made MOS transistors can be used to improve this range and also the resolution to a greater extent.

The whole design should be fabricated into mm wide ICs which can be implanted inside human body. This is achievable with today’s nano scale fabrication technologies. Also the RF transmitter should reside on the same chip along with the sensor. For this, an elaborated design of the transmitter is required.

Apart from the sensor, no other device should be affected by radiation. Specialized SOI (Silicon On Insulator) or SOS (Silicon on Sapphire) fabrication techniques provide embedded protection against the radiation damage. With this, normal commercial-grade chips can withstand between 5 and 10K CGy which is far above the working range of our sensor.

As the On and Off time values of sensor output depend on the input signal frequency, a radiation sensor array network can be designed in such a way that each sensor in the array operates at a specific frequency. All these signals can be transmitted wirelessly and processed at the receiver side (by using a DSP circuitry) to obtain each sensor’s output signal characteristics separately.

References:

1) Vivek Agarwal, V. P. Sundarsingh, and V. Ramachandran“A Comparative Study of Gamma Radiation Effects on Ultra-Low Input Bias Current Linear Circuits Under Biased Conditions ”IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 52, NO. 2, APRIL 2005

2) Khalil I. Arshak, Member, IEEE, and Olga Korostynska“ Gamma Radiation Nose System Based on In2O3=SiO Thick-Film Sensors ”IEEE SENSORS JOURNAL, VOL. 6, NO. 2, APRIL 2006

3) M. N Darwish M. C Dolly C.“A Goodwin Modeling of Radiation Induced Burnout in DMOS Transistors “

4) A.S. Beddar, M. Salehpour, T.M. Brire, H. Hamidian, M.T. Gillin,“Preliminary evaluation of implantable MOSFET radiation dosimeters,”Phys.Med. Biol. 50:141-149 (2005).

5) C.W. Scarantino, C.J. Rini, M. Aquino, T.B. Carrea, R.D. Ornitz, M.S.Anscher, R.D. Black,“The initial clinical results of an in vivo dosimeterduring external beam radiation therapy,”Int. J. Radiat. Oncol. Biol. Phys.62(2):606-613 (2005).

6) C.W. Scarantino, D.M. Ruslander, C.J. Rini, G.G.Mann, H.T. Nagle, and R.D. Black,“An implantable radiation dosimeter for use in external beam radiation therapy,”Med. Phys. 31:2658-2671 (2004).

7) R.D. Black, C.W. Scarantino, G.G. Mann, M.S. Anscher, and R.D. Ornitz,“Ananalysis of an implantable dosimeter system for external beam therapy,”Int. J. of Radiat. Oncol. Biol. Phys. 63(1):290-300 (2005).

8) T.M. Briere, A.S. Beddar, and M.T. Gillin,“ Evaluation of precalibratedimplantable MOSFET radiation dosimeters for megavoltage photon beams ,”Med.Phys. 32(11):3346-9 (2005).

9) Project Website: www.tc.umn.edu/~vadla005

www.tc.umn.edu/~vadla005

10) George C. Messenger, and Milton S. Ash, "The Effects of Radiation on Electronic Systems," Van Nostrand Reinhold Company, New York, NY, 2005