You can use the "Lab/Diagnostic Test" category to categorize an entry as a CT scan, X-ray, MRI, or ultrasound. Then, use #rad to file it under radiology. Here's how:
First, tap the "New Entry" button.
Add any images using the camera button.
After adding the images, write down a description including the type of test. Use the tag button to categorize as Lab/Diagnostic test.
Then, tap the # button and select "#rad" to file as a radiology report.
You can find all your radiology reports by tapping "#rad" under the search bar in the Timeline view.