Utility model content
The purpose of this utility model is to provide a kind of collection efficiency that improves photon, thereby improves the radioactivity photodetector of picture quality.
For achieving the above object, the utility model provides a kind of radioactivity photodetector, generate radiomaterial distributed image for detection of the radiating matter in internal organs, described radioactivity photodetector comprises signal picker, several photomultipliers, summing circuit, examination device and imaging device, described signal picker is near internal organs; Several photomultipliers are arranged at the side of described signal picker away from internal organs; The input end of described summing circuit is directly electrically connected described photomultiplier, and the output terminal of described summing circuit is electrically connected described imaging device; The input end of described examination device is electrically connected the output terminal of described summing circuit, and the output terminal of described examination device is electrically connected described imaging device.
The radioactivity photodetector that the utility model provides, the output terminal of photomultiplier is directly connected in summing circuit; The output terminal of summing circuit is connected in examination device, screens device total electric signal of summing circuit output is screened to denoising, and the total electric signal after denoising is sent to imaging device.Compared with prior art, the radioactivity photodetector that the utility model provides, screens device the total electric signal after suing for peace is carried out to denoising, improves the intensity of output signal, thereby improve photon collection efficiency in effectively removing weak signal, improves picture quality.
Preferably, described in several, photomultiplier is near one end of described signal picker row plane that is arranged in a row, and described arrangement plane is parallel to described signal picker, and described arrangement plane is just to described signal picker.
Particularly, described in several, photomultiplier is the arrangement of honeycomb fashion matrix.
Embodiment
By describing technology contents of the present utility model, structural attitude in detail, being realized object and effect, below in conjunction with embodiment and coordinate accompanying drawing to be explained in detail.
Figure 1 shows that existing radioactivity photodetector.It described in Fig. 2, is the utility model radioactivity photodetector.The utility model radioactivity photodetector comprises signal picker 100 ', photomultiplier (PMT) 200 ', summing circuit 300 ', screens device 400 ' and imaging device 500 '.Identical with the existing radioactivity photodetector shown in Fig. 1: signal picker 100 ' is arranged near internal organs place; Several photomultipliers 200 ' are arranged at the side of signal picker 100 ' away from internal organs, and photomultiplier 200 ' is near signal picker 100 '; Different from existing radioactivity photodetector: the output terminal of several photomultipliers 200 of prior art is electrically connected respectively the input end of an examination device 400, several output terminals of screening device 400 are electrically connected respectively summing circuit 300; The output terminal of several photomultipliers 200 ' of the utility model radioactivity photodetector is directly electrically connected on summing circuit 300 ', and device 400 ' is screened in the output terminal electrical connection one of summing circuit 300 '.The output terminal electrical connection imaging device 500 ' of discriminator circuit 400 '.
More specifically, signal picker 100 ' and several photomultipliers 200 ' are for movably, and the relative position of signal picker 100 ' and several photomultipliers 200 ' is fixed.When initial, signal picker 100 ' and several photomultipliers 200 ' are positioned at initial position; Body to be detected move to target location and fixing after, signal picker 100 ' and several photomultipliers 200 ' move to the internal organs of signal picker 100 ' near body to be detected, and the both sides of signal picker 100 ' are respectively internal organs and the photomultiplier 200 ' of body to be detected.
Signal picker 100 ' is flat NaI (T1) crystal, and it absorbs the gamma-rays that the radiomaterial in internal organs sends, and produces faint light signal; Several photomultipliers 200 ' are honeycomb fashion matrix and arrange, and several photomultipliers 200 ' are near one end of signal pickers 100 ' row plane that is arranged in a row, arrange plane parallel in signal picker 100 ', and arrange plane just to signal picker 100 '.Several photomultipliers 200 ' gather respectively the fluorescence signal of the varying strength of diverse location, are transformed into the electric signal of several varying strengths through photoelectric effect, and multiple electric signal are sent to summing circuit 300 '.
Several photomultipliers 200 ', summing circuit 300 ', examination device 400 ' and imaging device 500 ' are electrically connected successively.Several electric signal that several photomultipliers 200 ' gather are through summing circuit 300 ', several electric signal are sued for peace in directions X or Y-direction, total electric signal after summation is outputed to and screens device 400 ', screen device 400 ' total electric signal is screened to denoising, subsequently, the total electric signal after denoising and the position signalling of photomultiplier 200 ' are sent to imaging device 500 '.Further, imaging device 500 ' comprises D/A converter module (not shown), and the total electric signal after denoising and the position signalling of photomultiplier 200 ' are converted to simulating signal by D/A converter module.
Existing radioactivity photodetector, before examination device 400 is arranged at summing circuit 300, several electric signal denoising one by one of exporting by photomultiplier 200, is sent to summing circuit 30 ' read group total by several electric signal after denoising.Although existing radioactivity photodetector can be removed the poor weak signal of signal to noise ratio (S/N ratio), also signal useful part can be removed simultaneously, reduce output signal, video imaging quality.To this, the radioactivity photodetector that the utility model provides, screen device 400 ' and be arranged at summing circuit 300 ' afterwards, after summing circuit 300 ' read group total, export to and screen device 400 ' by several electric signal of photomultiplier 200 ' output, screen device 400 ' total electric signal is screened to denoising, in effectively removing weak signal, strengthen output signal, improve image quality.
Be illustrated in figure 5 the schematic diagram of photomultiplier 200.Be positioned at the center of arrangement plane of photomultiplier 200 taking radiomaterial shining point as example: several photomultipliers 200 are just to signal picker 100, the fluorescence signal distance producing from signal picker 100 due to each photomultiplier 200 is different, the electrical signal intensity difference that each photomultiplier 200 is produced.In diagram in each photomultiplier 200 indicate numeral be photomultiplier 200 according to light signal strength difference, the electric signal of the varying strength of generation.In existing radioactivity photodetector, several photomultipliers 200 connect respectively an examination device 400, screen device 400 an electric signal examination threshold values is set.In the present embodiment, screen threshold values and be set to 200, be only arranged in the electric signal that the photomultiplier 200 of region A gathers effective, other electric signal are all removed.
Photomultiplier 200 ' as shown in Figure 4, in the utility model radioactivity photodetector, several photomultipliers 200 ' are through summing circuit 300 ' summation, and the total electric signal after summation enters screens device 400 ' examination denoising.Further, summing circuit 300 ' is added the electric signal of directions X or Y-direction after summation, screens denoising through screening device 400 '.In the present embodiment, screen threshold values higher value can be set, be set to 400 as example to screen threshold values, now, the electric signal that is arranged in the photomultiplier 200 ' collection of region B is useful signal.
Shown in Fig. 2, Fig. 3 and Fig. 5, the detection method of the utility model radioactivity photodetector is described in detail:
Body picked-up radioactive isotope to be detected enters the search coverage that enters radioactivity photodetector after internal organs; Signal picker 100 ' and several photomultipliers 200 ' are moved to target location from initial position, now, signal picker 100 ' is near the internal organs of body to be detected, and several photomultipliers 200 ' are positioned at the side that signal picker 100 ' deviates from body internal organs to be detected;
The ray that S1, absorption radiating matter send, produces fluorescence signal; Particularly, signal picker 100 ' absorbs the gamma-rays that radioactive isotope sends, and produces fluorescence signal;
S2, gather respectively fluorescence signal in some positions, produce electric signal through photoelectric effect, and some electric signal summations are generated to total electric signal; Particularly, several photomultipliers 200 ' are honeycomb fashion matrix and arrange, each photomultiplier 200 ' gathers respectively a fluorescence signal the corresponding residing position signalling of this photomultiplier 200 ' that generates, and changes the fluorescence signal of collection into electric signal through photoelectric effect; Several electric signal are sued for peace in Y-direction, generate multiple total electric signal;
S3, screen total electric signal; Particularly, discriminator circuit 400 ' arranges a default threshold values of screening, in the present embodiment, taking 400 as example, the electric signal gathering in B region in Fig. 5 is useful signal, other signals are invalid signals, and discriminator circuit 400 ' makes zero invalid total electric signal shielding, and effectively total electric signal and position signalling are sent to imaging device 500 '.
S4, generate radiomaterial distributed image according to the total electric signal after screening and the position signalling that gathers fluorescence signal.Particularly, imaging device 500 ' obtains effectively total electric signal and corresponding position signalling, and generates accordingly radiomaterial distributed image.
The schematic diagram of the photomultiplier 200 of the prior art radioactivity photodetector shown in comparison diagram 4, the examination threshold values of screening device 400 is 200 o'clock, and in diagram, only a-quadrant electric signal is useful signal, and in diagram, useful signal total value is 7300; The schematic diagram of the photomultiplier 200 ' of the utility model radioactivity photodetector shown in Fig. 5, the examination threshold values of screening device 400 ' can arrange high value, in the time that examination threshold values is 400, the electric signal of each photomultiplier 200 ' obtains total electric signal in Y-direction summation, total electric signal is deducted and screened after threshold values 400, electric signal in B region is useful signal, and in diagram, useful signal is 8300 in a word.Compared to existing technology, signal intensity increases by 13.6% to the utility model radioactivity photodetector, improves signal efficient, thereby improves the picture quality of the radiomaterial distributed image generating.
Above disclosed is only preferred embodiment of the present utility model, certainly can not limit with this interest field of the utility model, and the equivalent variations of therefore doing according to the utility model claim, still belongs to the scope that the utility model is contained.