Complex sentence: In nuclear medicine, it serves to calibrate the equipment needed like single photo-emission computer tomography systems (SPECT) to make x-rays to produce images of radioisotope distribution inside the patient.
Split into simpler sentences: In nuclear medicine, it serves to calibrate the equipment needed like single photo-emission computer tomography systems (SPECT) to make x-rays. It ensures that the machines work correctly to produce images of radioisotope distribution inside the patient.