Final answer:
The general rules of contrast media injection, which encompass injection rate and scan delay, do not apply to coronary angiography due to its requirement for dynamic imaging synchronized with the heart's motion.
Step-by-step explanation:
The general rule of contrast media injection regarding injection rate and scan delay do not apply to coronary angiography. When performing a CT scan for courses such as routine abdominal scanning, thoracic scanning or brain scanning, physicians follow standardized protocols for the injection rate of contrast media and the delay before scanning to enhance the quality of the images. However, coronary angiography, which is an examination of the blood vessels of the heart, involves dynamic imaging where the timing of contrast media injection is synchronized with rapid imaging sequences in order to capture the coronary arteries in motion. Therefore, the general rules of contrast media injection do not apply in the same way.