胃X線画像を用いた病変部位推定アルゴリズムの考案: U領域における4方向撮影の幾何学的解析

摘要

The author considered algorithms to presume the lesion location from a series of X-ray images obtained by four direction radiography without blind area for the U region of the stomach. The objects of analysis were six cases that protruding lesions were noticed in the U region. Firstly, from the length of short axis and measure of the lateral width of U region projected on the film, we presumed the length of longitudinal axis and angle between short axis and the film. Secondly, we calculated the rate of length to stomach walls from right side and left side of every image to the lateral width at the height passing through the center of the lesion. Using the lesion location calculated from these values, we presumed that the values that almost agreed between two images to be the lesion location. As the result of analysis, there were some cases that the lesion location could be presumed certainly or un-certainly, on the other hand, there were some cases that the lesion location could not be presumed. Since the form of the U region can be distorted by a change of position, or the angle between longitudinal axis and sagittal plane was changed, the error might have been made in calculation, and so it was considered that the lesion location could not be presumed.%新・胃X線撮影法（間接・直接）ガイドラインは2011年に改訂され，対策型検診撮影法（住民検診型：従来の間接撮影法）と任意型検診撮影法（人間ドック型：従来の直接撮影法）の二つに集約され整合性が図られることになった．胃痛取り扱い規約では胃は上部（U領域），中部（M領域），下部（L領域）の三つに区分されている．その中でU領域の撮影法として前者の対策型検診撮影法では腹臥位二重造影第1斜位，右側臥位二重造影，立位二重造影第1斜位もしくは正面位の3方向撮影が，後者の任意型検診撮影法ではその3方向撮影に半臥位二重造影第2斜位を加えた4方向撮影が基準とされている．