I rated the x-ray film at between ISO 100 and ISO 50. Development time in HC-110b is very short, on the order of 2 minutes, otherwise the highlights get very dense. My ISO is based on getting shadow detail. The second emulsion layer does seem (in my opinion) to cause some softening and blooming of the image, thus the X-ray negatives are not as sharp as single emulsion conventional film negatives.
X-ray film is available from a wide variety of on-line vendors of X-ray supplies. A goggle search will turn up quite a few. You should expect to pay from between $26 to $36 a box of 100 8x10 sheets.