Slide 1

To test, measure , validate and develop the hitch of the components in the TransCam gamma camera1. 4 Power supply modules (12Volt, 15Volt, +5Volt/ 12Volt & HV module)2. Scintillation crystal4. 37 Pre-Amplifiers 3. 37 Photomultiplier tubes (PMTs) 5. Data acquisition cards

PMT, CRYSTAL, POWER SUPPLY AND DAQ OF TRANSCAM GAMMA CAMERA

Nor Arymaswati Abdullah, Glam Hadzir Patai Mohamad Dr, Mohd Ashhar Hj Khalid Dr, and Ramzah MohamadPusat Instrumentasi dan Automasi, Bahagian Sokongan TeknikalMalaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor, Malaysia arymas@nuclearmalaysia.gov.my

ABSTRACT

Gamma camera is one of the commonly used equipment in medical especially diagnostic scanning to generate radionuclide image. A gamma camera of TransCam model manufactured by ADAC Laboratories was bought by Malaysian Nuclear Agency in 1992. The aim of this paper is to describe the hitch of the components in the TransCam gamma camera. The most of analogue and digital electronics were tested and measured including develop new 15V power supply board as well as to validate all 37 photomultiplier tubes functionality, scintillation crystal and data acquisition card status.

THE TRANSCAM SYSTEM

CRYSTAL

PMT1Preamp 1PMT2High VoltagePreamp 2PMT37Preamp 37Summing amplifier X+Summing amplifier Y+Summing amplifier X-Summing amplifier Z+Summing amplifier Z-Summing amplifier Y--+-+X Y Z X Y Z X Y Z X Y Z Network resistor

THE OBJECTIVE

+12v+3v5+5v45362178AGINU+U-100R500KTP2TP1The camera-headThe gantry The acquisition/ correctionOther controlling system Motion control AGC boardPreamplifierMotherboardCollimatorThe detector assembly located in the camera headconsist of (6.5mm , d=315mm) NaI(TI) crystal, a glass light guide, an array of 37 PMTs and scintillation crystal

Figure 3 HV, 15Volt and +5Volt/ 12Volt module Figure 2 Physical placement of PMTs (left) and PMTs figure (right) Figure 4 Preamplifier diagram (left) and preamplifier placement on camera-head (right)15672134591317818191016201429212212272823242526373834353231303611Figure 1 Block diagram of the camera head

Yellow words = the basic componentThe computer system for data acquisition, counting system and image construction such as AGC and motion control. The gantry = arm system, column & camera bow-TransCam was equipped with 24V battery, which sources the 950Volt power supply. The vertical movements of the detector arm system were using motorized system. The horizontal movements are done by the detector head by hand, while pressing the brake switch.

1 METHODOLOGY

Different component, different approach; Power supply modules - tested by supplying 240VAC to each modules - measure the reading Photomultiplier tubes (PMTs) - place Co60/1Cu to each PMTs - tap the signals from the PMTs output - measure frequency signal level Scintillation crystal - open the camera-head - clean & spot the yellowish area Pre-Amplifiers - place Co60/1Cu to dedicated PMT - the PMT output is substitute into preamp input - tap the signals from the preamplifiers output - measure frequency signal level Data acquisition cards - Connect the socket to the PC port RESULT

CONCLUSION

Different component, different approach; Power supply modules - 3 functioning - 15Volt module damaged replaced OWN BUILDScintillation crystal - few yellowish area exist PMTs - 35 functioning - 2 PMTs damaged (No. 3 & 15) Pre Amplifiers - 37 Functioning but Data acquisition cards - Not functioning due to bursting fuse

There are few main components are damaged. To build the minimum system, the TransCam gamma camera needs new data acquisition board, PC, motion control system and few others accessories such as foot brake and replacement of two broken PMTs including Scintillation crystal.ACKNOWLEDGEMENTThe authors are very grateful to BTP, PDC and PIA technical people by the support of this work as well as all everybody who involve direct and indirectly.PMTFreq (kHz)1112193104851261871389913101911181271312141315121611171418171911PMTFreq (kHz)206217222123324925152622714282129630133116327331134935236163712PMTFreq (kHz)12322430423521624723822924102511251222132214241501622172418241921PMTFreq (kHz)1921201821222224231724222524261627232823292030243124321933223421351736243722PMTs output (left) and preamp output (right)

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