Experimental studies of the microangioarchitecture of tumors using synchrotron radiation at SPring-8

The purpose of the present study was to compare differences in the depiction of small vessels in tumors on microangiograms obtained with a conventional soft X-ray system and with a synchrotron radiation (SR) system, and to evaluate the microangioarchitecture of these tumors and the process of their growth neovascularization. The SR system consisted of a monochromatic X-ray source of 37.6 keV just above the K absorption edge of barium and two fluorescent-screen CCD-camera lens-coupling systems. One of the CCD systems had a 24 μm equivalent pixel size and an input field size of 24×24 mm. The other system had a 6 μm equivalent pixel size and an input field of 6×6 mm. Microangiograms using the soft X-ray system depicted small vessels (diameter 20–50 μm), but the microangioarchitecture of the tumors could not be evaluated from conventional images. The monochromatic SR system allowed depiction of small vessels with a diameter of less than 25 μm. In addition, this system allowed us to confirm the process of growth neovascularization in the tumors.