The methods comprise detection of gadolinium in human tissues and organs
by refining the position of malignant neoplasm and radiation treatment of
the neoplasm in order to damage its cells. Refined position of the
malignant neoplasm is determined by introducing gadolinium into the
patient body and scanning part of the patient body in which the neoplasm
is located. The scanning is performed by displacement of zone of
radiation concentration created by intersection of several X-ray beams
having radiation energy corresponding to K-edge of gadolinium atoms
absorption. The refined information is acquired using detectors sensitive
to K.sub..alpha.-radiation of gadolinium atoms, to which secondary
radiation is transported arising in zone of concentration. Scanning is
performed of the region of the malignant neoplasm location utilizing the
same means as in the first stage. Sources of X-ray radiation are switched
with control means into elevated intensity mode, sufficient for radiation
damage of the malignant neoplasm tissues.