> the radiologist had just measured from a different point on the image.

I had a similar experience when I was having a spinal curvature corrected. After a particular xray, several people -- a couple doctors, the xray guy, a med student or two, a mix of a couple people like this -- had measured my spine's then-current curvature and had come up with a huge range; to one, I had gotten worse... to another, I had some improvement... to the third, marginally the same with a smudge of improvement.

In the end I got the most improvement I was going to get given my specific situation and I'm happy for//with that. The point is, it was literally three measurements on the same xray from which three mutually exclusive conclusions//opinions were [literally?] drawn.

I'm therefore not surprised that there is similar with tumours.