Final answer:
Statement A, which suggests that the large bowel must be completely empty prior to the examination, is not necessarily true for large bowel radiography as small amounts of fluid or stool may be acceptable. The goal of large bowel radiography is to clear the colon to the extent that does not obscure the pathology, and while a complete emptying is ideal, it is not always strictly necessary.
Step-by-step explanation:
The question pertains to which statement about large bowel radiography is not true. The correct answer is A. The large bowel must be completely empty prior to examination. While this is commonly a goal for clarity during the procedure, small amounts of fluid or stool do not necessarily preclude an effective examination and sometimes, enemas or other preparation methods are used to clean out the colon before the imaging. Retained fecal material could potentially obscure pathology, which makes statement B true. Statement C is accurate because single-contrast studies help to highlight large intraluminal lesions. Regarding statement D, double-contrast studies are more effective in demonstrating mucosal lesions due to the detailed view of the bowel wall they provide, thus making this statement true as well.
A radiopharmaceutical's half-life is relevant in nuclear medicine but not typically involved in conventional large bowel radiography. Instead, a barium sulfate suspension might be used, as it coats the intestinal tract and enhances the X-ray detail. The radiographic examination aims to assess conditions like inflammatory bowel disease, diverticulosis, and possibly detect colorectal cancers, often indicated by symptoms like constipation, abdominal pain, and rectal bleeding.