Hi,
Density is therm applied for appearance of tissue on x ray.
In simple word hyper-dense means white on x ray and hypo-dense means black on x ray.
But most of the time only word density is used and it means hyper-density.
2mm density over the lower pole of the right
kidney and additional calculi noted in the kidneys or along the expected course of the kidney it means - There is one 2mm calculus (stone) at lower end of right kidney (may be in
ureter - tube connecting kidney to
urinary bladder {urine bag} )and some additional (more, number not specified) stones at the possible location of right kidney.
Pelvis : it is a part of kidney from where ureter {tube connecting kidney to urinary bladder (urine bag)} originate and blood vessels enter the kidney.
Phleboliths : it means stones in veins (blood vessels that carries blood away from kidney (to
Inferior vena cava which is a big blood vessel which carries blood from lower half of body to heart)
Back pain in your case is due to kidney stone.