In recent years, conventional encryption techniques cannot be used directly in the transmission of electronic health data. The main reason is the restrictions on data quantity, data multitude, and storage assimilation, particularly in the case that patient private data is sent through unsecured paths. Because image structure differs from textual information considering two unique elements which are damage to data and violation of confidentiality, some patients may miss out the privacy and in bad cases the integrity of owned data contents. So, an encryption scheme is required so that medical data and information can be privately shared over the Internet with other data centers without being concerned significantly about privacy breaches. This study aims at enhancing the privacy of medical images and offers protection from intrusion assaults. The proposed method makes encryption and decryption more secure and robust by using a key extension in the key schedule of the advanced encryption standard (AES) algorithm. Various safety evaluation metrics are used such as histogram, entropy, number of pixels change rate (NPCR), and correlation coefficient. The test of unified average changing intensity (UACI) is also computed. Finally, the test scores obtained show high values of the suggested medical image ciphering model is effective and convenient for health data transmission.