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AAPM phantom and the CT machine CATPHAN motif detection in comparative analysis


amAAPM: 0.50mmAIM: 0.60toni3.2 low-contrast resolution of low contrast resolution and uniformity of the background of an object contrast of less than 1%,[link widoczny dla zalogowanych], CI. Function to distinguish objects in a certain shape and size capability. Procedures required by paragraph 5.9, new installation or repair of the CI. Machine should be able to meet the manufacturer's standard instructions and promotional materials or use of the technical indicators are expressed; use of the ET unit, should be able to identify a set of 3.5mm diameter hole at least 5 or more. Test results are as follows (model: CT / e): AAPM Contrast: O. 84% of the pore size can be distinguished: 2.5mmCATPHTAN Contrast: 0.95% can be resolved pore size: 2.0mm3.3CI. Value of the linear CI. C1 value used to indicate that the image on the flat unit area 'are x-ray attenuation coefficient. 5.7 shows the order of 6 AAPM phantom material CT value range, Table 3 for the same CI. Machine under the same conditions AAPM, CATPHAN two phantom measured CI. Value. Table 3 IAN type material from the PM volumes range cr Cr cr nominal value of the measured value of the material measured Cr cr / e have a loquat i glass + l02 +13 (+123.24 snapped a 10o a 95. Hok polycarbonate +92 +120 +101.27 a small boat of water a 3 a 1000-992.38 a +3-0. s7Tell ~ +99 o978.74 nylon 0o +85.4 +85 a +】】】 Ad_l jjc +】 2D +118 . 69 A ∞ _. .30-29.97 polyethylene polystyrene a printed one by one 75-66. plus 4 listed above discussion of the results, GE is our new CI. machine acceptance test when the test data, may still can not fully explain the problem, but can be seen; (1) the distribution of spatial resolution detection of different regions, for example, detection of AAPM phantom center region in the motif, and CATPHAN motif location on the edge, because both X-ray by absorbed energy and different exposure, so the image reconstructed by computer to form a difference. (2) The material of two different motifs,[link widoczny dla zalogowanych], so the measurement window width and window level also affected the final outcome different. ( 3) the measured results of the two motifs and their design values. By analyzing the above two motifs of the test data, cf state verification procedures, we believe, CATPHAN motif and the motif during the actual assessment of AAPM despite differences ,[link widoczny dla zalogowanych], but the results are similar and comparable. The above analysis and comparison, limited to the experience level and I can not fully summarize the performance of motif similarities and differences between the two, only for your reference, inappropriate, but also look peer correction. with two-stage transformer ratio bridge divider calibration Zhang Jian (Institute of Metrology,[link widoczny dla zalogowanych], Guangdong Province, Guangzhou, 510405) transformer transformer ratio bridge is widely used in factories, mines and related industries, enterprises, used to measure the ratio of the transformer and the transformer transformer than the error, in order to ensure the accuracy of transformers. before the calibration with standard voltage transformer transformer turns ratio than the existing bridge narrow measurement range, measurement points less. but with two-stage transformer ratio bridge divider calibration can overcome more than enough. calibration ambient temperature (20 ± 10) cI =, the relative humidity should be ≤ 80%, supply voltage AC 200V ± 10%, should be no significant vibration and shock. 'AA-level double-check variation pressure aa14-YY i a-pu Electro XX \date, and the input voltage. Calibration wiring diagram shown in Figure 1, the calibration method of direct measurement. with a two-stage transformer ratio bridge divider calibration, figure A, X as the primary side, a, X for the secondary side . Calibration Methods: Here with the more common QJ35-type transformer ratio bridge as being the school equipment. home than the bridge transformer turns ratio and two-stage variable ratio divider the same as in Figure 1, after wiring to be School plug in the power transformer ratio bridge, preheat 5min, adjust the bridge by the school swing errors than disk, so that galvanometer balance, this time by the school down transformer ratio bridge disc reading error, that is to be transformer ratio bridge School transformation ratio relative to the two-stage variable ratio divider relative error. change the transformer turns ratio than the bridge with the two-stage divider ratio, to measure other points. When the measurement error of the transformer ratio bridge are in line with technical specifications, the contracting of their compliance; when there is measurement error of the transformer ratio bridge over technical specifications,[link widoczny dla zalogowanych], the contractors of their failure. with two-stage transformer ratio bridge voltage divider ratio of the calibration standard calibration of transformer voltage transformer ratio bridge faster, more accurate, it is worth a try.

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