The Improved Design Of Medical Industrial Frequency X-ray Machine

As the progress and improvement of the medical undertaking,digitized high frequency X ray equipments have gradually founded their usage in the clinics.Because of the high price,many mid/small size hospitals can not afford such machines even though they have many advantages. Now many middle or small size hospitals still use industrial frequency X-ray machines,compared with the popular program controlled X-ray machines or mid/high frequency X-ray machines which are controlled by single chip microprocessors,these machines have many defects such as being crassitude and cumbersome,poor looking,difficult to operate,slow response to KV adjustment for auto roentgenoscopy(IBS) that can not meet the demand of clinical application, low control accuracy for photography KV and mA setting,KV and mA setting are not accurate when the radiation is on so the photography effect is poor.1,Using CPU as the controller,pasted film keys are used as the operating keys,photography conditions are displayed with LED which looks good.The corcuit is simple and the malfunction rate is low.2,Employing automatic voltage control technique,the machine modulates the voltage of the power circuits according to the supply voltage to keep the machine in the best condition.3,Improving IBS,the KV response time (real time) is shorter for 2s-4s than the domestic program control X-ray machines. so that the roentgenoscopy effect is better than that of the domestic X-ray machines.The primary high voltage is modulated by modulating the conducting angle of the SCRs so the roentgenoscopy KV is modulated.This method is much better than the motor driven carbon wheel voltage modulate method in that the voltage is modulated faster and the roentgenoscopy effect is better.4,Using the single chip microprocessor to modulate the conducting angle of the SCRs to modulate the photography KV precisely,so,the KV is precise,stable without being affected by any outside conditions when the radiation is on so that the photography effect is better.5, Using the single chip microprocessor to modulate the conducting angle of the SCRs so as to modulate the photography mA precisely,so,the mA is precise,stable without being affected by any outside conditions when the radiation is on so that the photography effect is better.6,The protecting system is improved and becomes more perfect.The single chip microprocessor protecting function is added(including maxKV,maxmA,maxmAs)this makes many circuits protected dualy by both circuits and single chip microprocessor such as rotating anode protecting citcuits,maxKV protecting circuits,and single chip microprocessor controlled time limit and primary time limit protecting circuit,etc.A series of experiments have been carried out on the domestic industrial frequency X-ray machine(FSK202-2) based on the above mentioned design.The said circuit was made first,then debugged,and then mounted on the industrial frequency X-ray machine.1) Measuring the auto voltage-modulate data:When the input voltage of the equipment varies for±10%,the 100V output voltage of the machine remains 100V±1V,this function works.2) Auto roentgenoscopy (IBS) data:When the thickness of the water box for experiment varies between 15cm-25cm,the brightness of the image on the monitor always keeps moderate,the images are clear.When doing chest roentgenoscopy,the voltage at the sampling point for the high tension subsidiary side keeps 1.30V±0.02V(78KV),when the bed is moved from chest to abdomen,the the voltage keeps 1.70V±0.02V(102KV),it takes 0.8s±0.1s for the voltage to change from 78KV to 102KV.The KV can be modulated fast,the the brightness of the imageS on the monitor always keep moderate,the images are clear.3) Photography KV modulating circuit data:When the outside voltage rises for 20V,the amplitude of the primary side and the subsidiary side of the high tension becomes bigger compared with the normal situation,but the SCRs turn on later,so the direct current voltage level(1V±0.02V) at the sampling point for the KV+ keeps unchanged. When the outside voltage falls for 20V,the amplitude of the primary side and the subsidiary side of the high tension becomes smaller compared with the normal situation,but the SCRs turn on earlier,so the direct current voltage level(1V±0.02V) at the sampling point for the KV+ keeps unchanged.when the voltage varies for 20V,the exposure of the X-ray film and the X-ray penetration keeps the same as that of the normal condition.4) Photography mA control circuit data:when the voltage of the heater rises for 10V,the amplitude of the subsidiary side of the heater transformer becomes bigger,but the SCRs turns later,so the direct current voltage level(1V±0.02V) at the sampling point for mA keeps unchanged.When the voltage of the heater falls for 10V,the amplitude of the subsidiary side of the heater transformer becomes smaller,but the SCRs turns earlier,so the direct current voltage level(1V±0.02V) at the sampling point for mA keeps unchanged.this means that the radiation is stable and accurate.5) Roentgenoscopy and photography max KV protecting circuit data:Choosing the roentgenoscopy voltage of 110KV for exposure,during the process of exprosure,monitor the voltage of pin 3 and 6 of opa 8,the instantaneous value of the two pins can reach 1.85 V±0.02V and +15V respectively,KJ2 is energized and self locked,turning off the path through which JC1 is energized,roentgenoscopy is interrupted,a KV too high signal is input to the CPU. Choosing the photography 123 KV ( 50mA,0.5S ) for exposure,during the process of exposure,monitor the voltage of pin 3 and 6 of opa 7,the instantaneous value of the two pins can reach 2.05V±0.02V and +15V respectively,KJ2 is energized and self locked,turning off the path through which JC5 is energized,exposure is interrupted,a KV too high signal is input to the CPU.This means that the KV protecting circuit works. 6) Max mA and mAs protecting circuit data: :Choosing the photography current of 300 mA(60KV,0.5S) for exposure,during the process of exprosure,monitor the voltage of pin 3 and 6 of opa 11,the instantaneous value of the two pins can reach 3.00V±0.02V and +15V respectively,KJ1 is energized and self locked,turning off the path through which JC5 is energized,exposure is interrupted.Choosing photography 60KV,200mA,3s for exposure, during the process of exprosure,monitor the voltage of pin 3 and 6 of opa 13.When the voltage of pin3 reaches gradually to 1.97V±0.02V,the output voltage of pin6 reaches up to 15V, KJ1 is energized and self locked,turning off the path through which JC5 is energized,exposure is interrupted. This means that the mA and mAs protecting circuit works.Scientific analysis and summary is made aiming at these data,a discussion about the current problems and the future development is presented.Aiming at the defects of the industrial frequency machines this paper gives improved designs,compared with the domestic X-ray machines,these improvements are: The roentgenoscopy KV is controlled by modulating the conducting angle of the SCRs,the photography KV is controlled by modulating the conducting angle of the SCRs using single chip microprocessors closed loop control method.This is better than domestic X-ray machines.The photography mA is controlled by modulating the conducting angle of the SCRs using single chip microprocessors closed loop control method.This is better than domestic program controlled X-ray machines and domestic mid/high frequency X-ray machines.