| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2001: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
We studied three subjects. Firstly, we evaluated the effect of scattered X-rays on the sharpness of X-ray image. Secondly, we compared the elimination efficiency of scattered X-rays for air-gap method and anti-scatter grid method. Thirdly, we evaluated the performance of dosimeter for measuring patient dose.
1. It has been said that the response function of scattered X-rays agree with the primary fraction, when scattered X-rays incident in wide area of the image receptor. However, no report which confirmed the fact has been published as long as we know. We conducted the experiment using square wave chart. As a result, we confirmed the fact.
2. Air-gap method and anti-grid method are often used to eliminate scattered X-rays. However, it is nots clear that which method should be used in radiography. We measured scatter fraction, radiographic contrast and surface dose, changing the thickness of the object, field area, distance of air-gap and anti-scatter grid. As a result, it is clarified that air-gap method is useful when the field area is small enough, nevertheless we must consider how wide the field area is required for diagnosis.
3. Patient dose due to X-ray fluorography has been increased according to the rise in the number of patients who are treated with interventional radiology. For measuring patient surface dose including scattered X-rays in fluorography, some dosimeters have been developed. Skin dose monitor is one of them. We evaluated the performance of the skin dose monitor. It underestimates surface dose when short period fluorography is repeated comparing to one continuous exposure, even total exposure time is the same. We cannot measure surface dose correctly, when X-rays get in the detector in large angle. However, skin dose monitor is very useful to measure surface dose in real time, we hope it will be improved in the near future.
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