CR 装置の高エネルギー X 線特性

概要

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A Computed Radiography (CR) with storage phosphor technology has advanced remarkably. Its application has been also discussed regarding the field of radiotherapy and studies have been made to shift from the film/screen system to the portal film using the CR system. The authors started to research CR portal imaging with high energy X-ray (10MV) on a regular scale in 1989. This paper deals with characteristics of high energy X-rays using the CR system. The results are : (1) The digital characteristic curve correspond with calculated value for dynamic range (L-value). (2) The monitor unit (MU) counts at pixel (digital) value saturation point were L-value 0.5 : 28MU, L-value 1.0 : 50MU, L-value 2.0 : 167MU, L-value 3.0 : 450MU, L-value 4.0 : 1614MU. (3) The image contrast with the Mix-Dp phantom was L-value 0.5 : about a 300 pixel value and L-value 4.0 : about a 30 pixel value by a phantom 10 to 18cm in thickness. (4) Optimum L-value was 0.5, and tone-scale was the straight type of CR portal imaging using the graphy count mode. (5) Optimum L-value was 4.0, and tone-scale was a rectangular wave type of CR portal imaging using theraputic doses, and those were also describe by the histogram analysis.
1993-06-01