Signal & Image Processing : An International Journal (SIPIJ) Vol.6, No.2, April 2015 DOI : 10.5121/sipij.2015.6203 29        Aayesha Hakim 1 , K.T.V Talele 1 and Rajesh Harsh 2 , Dharmesh Verma 2 1 Department of Electronics & Telecommunication Engineering, S.P.I.T, Mumbai 2 Society For Applied Microwave Electronic Engineering and Research, Mumbai ABSTRACT a-Si Electronic Portal Imaging Device (EPID) is an important tool to verify the location of the radiation therapy beam with respect to the patient anatomy. But, Electronic Portal Images (EPI) suffer from low contrast. In order to have better in-treatment images to extract relevant features of the anatomy, image processing tools need to be integrated in the Radiology systems. The goal of this research work is to inspect several image processing techniques for contrast enhancement of electronic portal images and gauge parameters like mean, variance, standard deviation, MSE, RMSE, entropy, PSNR, AMBE, normalised cross correlation, average difference, structural content (SC), maximum difference and normalised absolute error (NAE) to study their visual quality improvement. In addition, by adding salt and pepper noise, Gaussian noise and motion blur, we calculate error measurement parameters like Universal Image Quality (UIQ) index, Enhancement Measurement Error (EME), Pearson Correlation Coefficient, SNR and Mean Absolute error (MAE). The improved results point out that image processing tools need to be incorporated into radiology for accurate delivery of dose. KEYWORDS Amorphous Silicon (a-Si) detector, electronic portal imaging, image enhancement, image processing. 1. INTRODUCTION For accurate delivery of radiotherapy it is mandatory to maximize the dose delivered to well defined targeted tumour volume and minimize the exposure to healthy surrounding tissues. [4] The use and development of active matrix flat panel amorphous silicon (a-Si) electronic portal imaging devices (EPIDs) for verification of Radiation Therapy (IMRT) is increasing. Electronic Portal Image (EPI) quality is poor due to Compton effect. [5] To produce higher quality EPI for assessment and to increase the treatment throughput, we tested an aggregation of image processing techniques to refine their visual aspect. [15] The operations were performed on 5 images of different organs under treatment - pelvis, chest, head, neck, thorax. Extending the work done in [15], this paper gives a qualitative and quantitative analysis of the effect of various operations on EPI thus proving the need of integration of image processing tools in radiation therapy process for error free delivery of treatment. 2. LITERATURE SURVEY In the past decade, quite a less amount of work has been done on improving electronic portal image quality. Experiments were conducted to increase the contrast of portal images based on local enhancement to pixel values of image matrix and found that the processed images were superior in quality, however it was time consuming. [8] The influence of contrast enhancement,