Masanori Takeshita

Exposure Dose in Gastric Cancer Mass Screening using High Concentration Barium Sulfate — Comparison with Moderate Concentration Barium Sulfate —

The efficacy of high-concentration barium sulfate has been reported from several perspectives, but not in terms of radiation exposure. This study compared the exposure doses used with high-concentration and moderate-concentration barium sulfate. The exposure dose was evaluated with an experimental method, using a gastric phantom, and with a clinical examination. In the former, the exposure dose and X-ray tube load were measured on the phantom applied with both concentrations barium sulfate. In the latter, the fluoroscopic exposure dose, the radiographic exposure dose, and their sum, the total exposure dose, were investigated in 150 subjects (112 males, 38 females) treated with both concentration barium sulfate. The results of the experimental evaluations indicated that the exposure dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (P < 0.05). The results of the clinical evaluations indicated that the fluoroscopic exposure dose was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (P < 0.05), but the radiographic exposure dose was quite the reverse, so the total exposure dose was the same with both concentrations barium sulfate. We conclude that high-concentration barium sulfate does not increase the radiation exposure in mass screening for gastric cancer.

Exposure Dose Reduction of Lead Acrylic Filter for Gastric Cancer Mass Screening

It is important to reduce x-ray exposure in subjects who undergo mass screening for gastric cancer. We constructed three types of lead acrylic filters and evaluated their ability to reduce exposure. X-ray tube load increase, dose area reduction, density of gastric phantom images and lead acrylic filter shadows were evaluated. Three different thicknesses of lead acrylic filters were examined, one was a regular thickness, another was half the thickness, and the other was twofold the thickness. Objectivization, reduction rate of exposure, x-ray tube load increase, and the density of each gastric phantom image was taken with or without the three types of lead acrylic filters. The filter shadow in the image of the gastric phantoms using the three types of lead acrylic filters were evaluated with 4 levels. Dose area reductions using the three types of filters were 6.03%, 10.92%, and 13.64%, for the half thickness, regular thickness, and twofold thickness, respectively (p 0.05). There was no significant difference between the density of gastric phantom images with or without the filters (p>0.05). The lead acrylic filter shadows were significantly difference among the three types filters (p<0.05). We conclude that the use of lead acrylic filters is effective for the reduction of exposure in screening for gastric cancer. A lead acrylic filter of twofold thickness is most effective for the reduction of exposure.