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The purpose of this study was to investigate the features of CsI:Tl and Gd 2 O 2 S detectors with an indirect conversion method using phantom in the DR (digital radiography) system by obtaining images of thick chest phantom, medium thickness thigh phantom, and thin hand phantom and by analyzing the SNR and CNR.As a result of measuring the SNR and CNR according to the thickness change of the subject, the SNR and CNR were higher in CsI:Tl detector than in Gd 2 O 2 S detector when the medium thickness thigh phantom and thin hand phantom were scanned. However, when the thick chest phantom was used, for the SNR at 80∼125 kVp and the CNR at 80~110 kVp in the Gd 2 O 2 S detector, the values were higher than those of CsI:Tl detector. The SNR and CNR both increased as the tube voltage increased. The SNR and CNR of CsI:Tl detector in the medium thickness thigh phantom increased at 40∼50 kVp and decreased as the tube voltage increased. The SNR and CNR of Gd 2 O 2 S detector increased at 40∼60 kVp and decreased as the tube voltage increased. The SNR and CNR of CsI:Tl detctor in the thin hand phantom decreased at the low tube voltage and increased as the tube voltage increased, but they decreased again at 100∼110 kVp, while the SNR and CNR of Gd 2 O 2 S detector were found to decrease as the tube voltage increased. The MTF of CsI:Tl detector was 6.02∼90.90% higher than that of Gd 2 O 2 S detector at 0.5∼3 lp/mm. The DQE of CsI:Tl detector was 66.67∼233.33% higher than that of Gd 2 O 2 S detector.In conclusion, although the values of CsI:Tl detector were higher than those of Gd 2 O 2 S detector in the comparison of MTF and DQE, the cheaper Gd 2 O 2 S detector had higher SNR and CNR than the expensive CsI:Tl detector at a certain tube voltage range in the thick check phantom. At chest X-ray, if the Gd 2 O 2 S detector is used rather than the CsI:Tl detector, chest images with excellent quality can be obtained, which will be useful for examination. Moreover, price/performance should be considered when determining the detector type from the viewpoint of the user.

The preoperative diagnosis 01 intracranial arachnoid cysts has been simplilied, and made more rapid and accurate with computed tomography (CT). Using CT cisternography, detailed anatomic and physiologic inlormations 01 arachnoid cysts co uld be obtained' CT leatures 01 patho logicall y proven 21 a rachnoid cysts that we re examined at Chonnam Nationa l Unive rsi ty Hospital lrom)un e 1983 to May 1987 were analyzed The res미 ts we re as lo llows: 1. Prevalent age group was the 1st decade (8 cases) and male to lemale ratio was 17:4 2. Clinical leatures we re related to the location 01 arachnoid cyst, com mo n symptoms were headache (53. 3%),