Research On Medical Ultrasound Image Denoising Based On Fractional Order

Ultrasound medicine has gradually become one of the most important diagnostic tools,because it has low cost,high efficiency,real-time,convenient and safe features.However,the speckle noise superimposed on a class of granular structures is widely found in coherent images of medical ultrasound images.The noise is manifested as a sudden change in pixel gray value,obscured or coverd the details of the image,but many clinical diagnoses are essential details of ultrasound images.Thus the spot is one of the major limitations of the low contrast of medical ultrasound images,and it can be seen as a source of noise that should be reduced.Ultrasound imaging technology is widely used in clinical medical treatment,but because of the influence of the system imaging mechanism,the image formed by the ultrasound imaging technique is relatively easy to form speckle noise which can lead to the relative reduction of image quality,which means it’s hard to satisfy the post-image analysis.In order to improve the image contrast,medical ultrasound image speckle de-noising technology has developed to retain the edge of the image feature information,inhibition of ultrasound images of the spots,so that clinicians can accurately identify and analyze the lesion.Therefore,medical ultrasound image de-noising technology research for clinical diagnosis has a very important practical significance.In this paper,based on the principle of ultrasonic imaging,ultrasonic B-mode imaging,ultrasonic speckle noise model and speckle performance evaluation are introduced in the first place.Next,several classical speckle suppression algorithms are analyzed.Such as the speckle reducing anisotropic diffusion(SRAD)technique,the detail preserving anisotropic diffusion(DPAD)technique and P-M model.Ultrasound images show a granular pattern of noise known as speckle that diminishes their quality and results in difficulties in diagnosis.To preserve edges and features,this paper proposes a fractional differentiation-based image operator to reduce speckle in ultrasound.An image de-noising model based on fractional partial differential equations with balance relation between k(gradient modulus threshold that controls the conduction)and v(the order of fractional differentiation)was constructed by the effective combination of fractional calculus theory and a partial differential equation,and the numerical algorithm of it was achieved using a fractional differential mask operator.The proposed algorithm has better speckle reduction and structure preservation than the three existing methods(P-M model,SRAD and DP AD).And it is significantly faster than bilateral filtering(BF)in producing the same experimental results.Ultrasound phantom testing and in vivo imaging show that the proposed method can improve the quality of an ultrasound image in terms of tissue SNR,CNR,and FOM values.