
My opinion(for what it's worth) is that 40 x-rays is *way* too many.  
Guidleines have been set on the number of dental x-rays and chest x-rays 
that one should have over a given period of time because of all the 
environmental factors that can cause cancer in humans, ionizing radiation 
is one of the most potent(splits DNA and causes hydroxyl free radical 
formation in tissue cells).  Ultasound(like that used in seeing the fetus 
in the uterus) has been shown to be extremely good at picking up tumors 
in the prostate and gallstones in the gallbladder.  But kidney tissue may 
be too dense for ultrasound to work for kidney stones(any radiologists care 
to comment?).

Most stones will pass(but it's a very painful process).  Unlike gallstones, 
I don't think that there are many drugs that can help "dissolve" the 
kidney stone(which is probably calcium-oxalate).  Vitamin C and magnesium 
have worked in rabbits to remove calcium from calcified plaques in the 
aterial wall.  I have no idea if a diet change or supplementation could 
speed up the process of kidney stone passage(but I'm pretty confident that 
a diet change and/or supplementation can prevent a reoccurance).  If surgery 
is being contemplated, the stone must be in the kidney tubule.  A second 
opinion is a good idea because there are better(less damaging) ways to break 
up the stone if it's logged within the kidney(sonic blasts).  HMO's are 
notorious for conservative care and long waits for expensvie treatments.  
My condolences to your friend. 