Research On The Key Technology Of The Radioactive Drugs Pinhole ?-ray Imaging System

American medicine in 2011 for the first time puts forward the concept of"precision medicine",in 2016,China has launched a major project of scientific research called"precision medical",and radioactive drugs is an important part of it.Currently,studies on radioactive drugs mainly obtain real data through living biological experiments.Due to the particularity of their research,small animals are usually used as the research object.How to evaluate the diagnosis,treatment and prevention effect of radioactive drugs must rely on advanced medical diagnostic methods.Currently,micro-single photon emission tomography?micro-spect?and micro-positron emission tomography?micro-pet?are mainly used.Both devices rely on import,because product monopoly,technology blockade,expensive price,huge volume,it is difficult to meet the domestic demand such as convenient,low cost and multi-channel in biological and medical research.Therefore,on the basis of many years'research on nuclear instruments and instruments in our laboratory,this paper proposes to carry out the research on the radiopharmaceutical pinhole gamma imaging system.The system is convenient,the price is low,and radiopharmaceutical correlation analysis was carried out by image,which will help to promote our country individual"precision medical"research.The radiopharmaceutical pinhole gamma imaging system developed in this paper works like this.Radioactive drug release gamma rays that interact with animals,then the gamma rays,containing small animal's information to carry through the thick pinhole with scintillator and convert to visible light.The weak light is enhanced by the MCP?Micro Channel Plate?image intensifier,and then the gamma-ray image is acquired through the CCD?charge-coupled Device?camera.Due to the effects of MCP image intensifier and CCD camera device such as the limitations of the spatial resolution and the impact of noise,the gamma ray image degenerates,and it is difficult to reflect the real spatial distribution of radioactive drugs in small animals.Therefore,it is necessary to carry out special research on gamma image denoising and image restoration technology in order to improve the diagnosis and analysis level of radioactive drug pinhole gamma imaging system.This paper based on the national natural science fund project?grant no.:61401049?and the relevant state science and technology projects,high-end medical equipment in new product research and development of"key technology and new product research and medical imaging equipment"project?project number:cstc2015zdcy-0072?,studied the radioactive drugs pinhole gamma ray imaging system's basic theory,equipment,method,technology and application,research and development of a set of radioactive drugs pinhole gamma imaging system.The research contents and achievements of this paper are as follows:1.By theoretical calculation and experimental measurement,study the point spread function of thick pinhole,scintillator,MCP image intensifier and CCD camera.Then the modulation transfer function was established based on Fourier transform model.And finally evaluate the spatial resolution of the pinhole imaging system.2.By theoretical analysis and experimental measurement,the research analyzes each device of the pinhole imaging system.Then radioactive drugs pinhole gamma ray imaging system is established.Final,the imaging effect is verified by the system response,positioning,the lower limit of ¹³⁷Cs measurable dose rate,viewing Angle,etc.3.The image noises are decomposed into gamma noise and gaussian noise and poisson noise by analysis and research of the imaging characteristics and noise characteristics of the image.In the wavelet transform domain,poisson noise and gaussian noise is similar.With the help of a gaussian noise model,this paper proposes a noise reduction algorithm of wavelet domain hybrid model image based on coefficient classification and an image adaptive threshold noise reduction algorithm based on Contourlet.For images of the general noise pollution,the noise reduction algorithm of wavelet domain hybrid model image based on coefficient classification reflects both dependency and correlation between wavelet coefficients in tiny scale.What's more this method protect the details and reduces the noise in the image at the same time.It has the high efficiency.For SNR of images,the image adaptive threshold noise reduction algorithm based on Contourlet better recover the image edge,has better ability to protect the details than the noise reduction algorithm of wavelet domain hybrid model image based on coefficient classification.?4.The paper proposes a new method for the restoration of the Wavelet-Lucy-Richardson gamma image based on the research and analysis of Wavelet de-noising principle and Lucy Richardson iteration principle.It is proved that this method has better image effect.It Integrate the wavelet de-noising algorithm into the L-R algorithm,restrain the noise amplification,balance the details'restoration and noise amplification,and finally improve the spatial resolution image.5.The experiment was carried out by ¹³¹I labeled porphyrin with needle hole gamma imaging.The image quality of tumor gamma-ray images obtained in the experiment was significantly improved by using two noise reduction algorithms proposed in this paper.In addition,in the pinhole gamma imaging experiment of^99mTc labeled phosphonic acid compound,the obtained rabbit bone image was obfuscated and noisy.The proposed Wavelet Lucy-Richardson algorithm was used to restore it,and the details were better,the image quality was significantly improved,and the spatial resolution of the image was also improved.