The effective energy is often determined from the thichness(half value layer)of a material through which X-ray have permeated and the dose hase been reduced to 1/2. This kind of dosimetry which frequently avails of the ionzation chamber requires some correction of the atmospheric conditions. In the present study, the effective energy was determined from the half value layer using such a dosimeter(themoluminescence dosimeter : TLD)as makes the above correction unnecessary. The present method is reported in view of its usefulness for dose assessment in case of remarkable changes in atmosopheric conditions and of extensive determinations(requiring international data, for example).
The effect of heating on the radiation crosslinking behavior or poly(vinyl alcohol)film(PVA obtained by drying an aqueous solution of PVA)has been studied. For use as medical polymer, the heat stability of crosslinked PVA hydrogel prepared by water immersing has been investigated. Tensile strength reduction of hydrogel by irradiation was inhibited ever though PVA film heated before irradiation required a longer dose for crosslinking than that without heating. The tensile strength before 100℃ sterilization(boiling water)of hydrogel(obtained by 200 kGy irradiation of after heating)was approximately 100 kg/cm^2. The tensile strength of hydrogel reduced by 100℃ sterilization is due to destruction of hydrogen bonds. However, no dissolution and decomposition in this hydrogel were observed after 15 min at 100℃ sterilization. The original shape of hydrogel before water boiling was maintained, althougth some swelling did occur. This hydrogel had higher elastic properties even after boiling.
Hypoxemia was seen during one-lung anesthesia because of the obstruction of the left upper lobe bronchus by the bronchial branch of a double-lumen tube. The cause is the long distance between carinal hook and tip of twin-lumen endotracheal tube(Portex). Therefore we cut a bevel of twin-lumen endotracheal tube rectangularly. As a result, blood gas deterioration during one-lung anesthesia decreased from 14 to 0%, However, impossibility to separate the two lungs increased from 0 to 7.5%. There were morphological changes of trachea and/or branchus in all cases not separating the lungs.