Radiation image capture system and body system estimation method with scatter reduction

An x-ray image capturing system comprising:

• an x-ray image capturing apparatus including:
• a plurality of x-ray detection elements which are arranged two-dimensionally and generate electric charge according to a dose of x-rays with which the x-ray detection elements are irradiated;
• and
• a control unit which converts the electric charge generated in each of the x-ray detection elements into a signal value;
• an irradiation apparatus which, passing x-rays through a subject, irradiates the x-ray image capturing apparatus with the x-rays;
• and
• an image processing apparatus which generates a first x-ray image based on the signal values, which corresponds to the electric charge generated in each of the x-ray detection elements, wherein
• the image processing apparatus:
• generates the first x-ray image based on the signal values generated by irradiating the x-ray image capturing apparatus with the irradiation apparatus, wherein there is no grid attached to the image capturing apparatus;
• performs a low-pass filter process on a pixel values of the first x-ray image using a scattering kernel, thereby generating a low frequency image;
• estimates a body thickness of the subject based on the signal values;
• estimates a scattered ray content rate based on the body thickness;
• calculates a scattered ray component in the first x-ray image based on the low frequency image and the scattered ray content rate;
• and
• subtracts the scattered ray component from the first x-ray image, thereby generating a second x-ray image with the scattered ray component removed;
• and
• wherein the image processing apparatus (i) sets two regions of interest at different parts in the first x-ray image, a second region of interest of the two regions of interest having mainly larger pixel values relative to a first region of interest of the two regions of interest (ii) creates a histogram from both the signal values of each pixel belonging to the first region of interest and the signal values of each pixel belonging to the second region of interest, (iii) calculates a characteristic amount from the histogram and (iv) estimates the body thickness based on the characteristic amount, the characteristic amount being a difference between two signal values serving as references in a distribution of frequencies on the histogram.