Abstract |
Purpose: Preamplifier and amplifier are very important
parts for developing a portable counting or imaging
gamma probe. They can be used for analyzing pulses
containing energy and position information for the
emitted radiations. The commercial Nuclear Instrument
Modules (NIMs) can be used for processing these pulses.
However, it may be improper to use NIMs in developing a
portable gamma probe, because of its size and high
price. The purpose of this study was to develop both
preamplifier and amplifier and measure their
performance characteristics. Materials and Methodes:
The preamplifier and amplifier were designed as a
charge sensitive device and a capacitor resistor-
rsistor capacitor (CR-RC) electronic circuit,
respectively, and they were mounted on a print circuit
board (PCB). We acquired and analyzed energy spectra
for Tc-99m and Cs-137 using both PCB and NIMs.
Multichannel analyzer (Accuspec/A, Caberra Industries
Inc., Meriden Connecticut, U.S.A) and scintillation
detectors (EP-047 (Bicron Saint-Gobain/Norton
Industrial EP-047 (Ceramics Co., Ohio, U.S.A) with
2″×2″ NaI (T1) crystal and R1535 (Hamamatsu
Photonics K.K., Electron Tube Center, Shizuoka-ken,
Japan) with 1″×1″NaI (T1) crystal) were used for
acquiring the energy spectra. Results: Using PCB,
energy resolutions or EP-047 detectors for Tc-99m and
Cs-137 were 12.92% and 5.01%, respectively, whereas
R1535 showed 13.75% and 5.19% of energy resolution.
Using the NIM devices, energy resolutions of EP-047
detector for Tc-99m and Cs-137 were measured as 14.6%
and 7.58%, respectively. However, reliable energy
spectrum of R1535 detector could not be acquired, since
its photomultiplier tube (PMT) requires a specific type
of preamplifier. Conclusion: We developed a special
preamplifier and amplifier suitable for a small sized
gamma probe that showed good energy resolutions
independent of PMT types. The results indicate that the
PCB can be used in developing both counting and imaging
gamma probe. |