Final answer:
The system control used mainly in cardiac imaging to correct for dropout on the sides of the image is Single-photon-emission computer tomography (SPECT).
Step-by-step explanation:
The system control that is mainly used in cardiac imaging to correct for dropout on the sides of the image is called Single-photon-emission computer tomography (SPECT).
SPECT is a nuclear imaging technique that uses a gamma camera and a CT scanner to create a detailed three-dimensional image of the heart. However, it has poor spatial resolution, which may result in dropout on the sides of the image.
To correct for this dropout, various techniques can be used, such as software algorithms that interpolate missing data or collimators that are designed to limit the field of view and reduce side dropout.