Disclosed herein is a method comprising: causing emission of characteristic X-rays of a chemical element introduced into a human body; capturing images of a portion of the human body with the characteristic X-rays; determining a three-dimensional distribution of the chemical element in the portion based on the images.本文公開一種方法,其包括:引起被引入人體的一種化學元素的特徵X射線的發射;利用所述特徵X射線捕獲所述人體的一部分的圖像;基於所述圖像確定所述人體的所述部分中所述化學元素的三維分佈。