Key, the radiologist is giving the doc some idea of the landmarks of where organs are located within the body since not everyone has organs in exactly the same location. CT is very useful to visualize the bowel and localize the normal appendix once the ileocecal valve is identified.
For instance, the appendix is usually located arising from the cecum approximately 3 cm below the ileocecal valve - and the radiologist would then say something like the position (can vary: deep within the pelvis, paraumbilically in the RLQ, or retrocecally), length of the appendix (may be up to 10 cm in length) if the doc is worried about that structure and it's placement. So you might read its 'collapsed, air-filled, or contrast-filled. etc.
And there are a number of anatomic variations and locations of the cecum. The cecum itself typically may lie in the right upper quadrant or deep within the pelvis. In saying deep within the pelvis, the report is telling the doc that the cecum made it's normal embryologic migration from the right upper quadrant down into the pelvis where they're typically used to finding it.
Welcome to the gastroenterology community! Cecum deep in the pelvis means that your cecum (which is the first part of your large intestine in the lower right part of your abdomen) is lower down then usual. This doesn't really mean much and probably isn't causing your pain. Good luck.