The Internet of Things (IoT) enables the interconnection of devices that collect massive amounts of data, making IoT security requirements crucial and secured through encryption. However, traditional encryption protocols are no longer suitable for all IoT scenarios. We propose a new lightweight encryption method optimized for patient information protection in healthcare, considering the limited capacity of portable medical devices. Our method has been experimentally demonstrated to be effective, with a largest entropy of 7.9917 in medical images (computed tomography) and average coding and decoding times of 3.8952 sec and 3.0584 sec, respectively. The encoded image exhibits an even distribution of pixels and lower correlation coefficients between neighboring pixels, supporting the effectiveness of our less complex method compared to current state-of-The-Art methods.