Final answer:
The typical scan delay for helical CT examinations of the pancreas is 70-80 seconds after contrast injection to ensure optimal enhancement of the pancreatic tissue.
Step-by-step explanation:
The typical scan delay following the start of the injection for helical CT examinations of the pancreas is b. 70-80 sec. This time frame allows for optimal enhancement of the pancreatic parenchyma during the arterial phase, which is crucial for detecting lesions such as tumors. For comprehensive imaging, a multiphasic approach is often used, where additional phases might include late arterial, portal venous, and delayed phases, each with their own timing following contrast injection.