1、EIA TEPIOS BI m 3234b00 O007440 8 m OCTOBER 1981 7 TEST CRITERIA . FOR X-RAY IMAGE INTENSIFIER TUBES FORMULATED BY EIA TUBE ENGINEERING PANEL ADVISORY COUNCIL (TEPAC) TEPAC PUBLICATION No. 109 (Revision of TEPAC Suggested Standard No. 9) EIA TEP307 83 W 3234600 0007443 T NOTICE EIA Engineering Stand
2、ards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitatirig interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for h
3、is particular need. Existence of such Standards and Publications shall not in any respect preclude any member or non-member of EIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of auch Standards and Publications preclude their volun
4、tary use by those other than EIA members, whether the standard is to be used either domestically or internationally. Recommended Standards and Publications are adopted by EIA without regard to whether or not their adoption may involve patents on articles, materials, or processes. By such action, EIA
5、 does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Recom- mended Standard or Publication. This document has been developed to recommend a standardized method of measurement of x-radiation from CRTS for tube manufacturer compliance w
6、ith HHS Bureau of Radiological Health Regulations on this subject, Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street, N.W. Washington, D.C. 20006 .- PRICE: $5.50 Printed in U.S.A. c- -. EIA TEPLOS BL m 3234b00 00074i.12 L m TEPAC Publication No. 109 Paragraph 1.0
7、2, o 3.0 4.0 FIGURE 1: FIGURE 2: FIGURE 3: FIGURE 4: FIGURE 5: FIGURE 6: FIGURE 7: FIGURE 8: FIGURE 9: FIGURE 10: FIGURE 11: APPENDIX I: APPENDIX II: TEST CRITERIA FOR X-RAY IMAGE INTENSIFIER TUBES TABLE OF CONTENTS Purpose and Scope Definitions . Measurements Conversion Factor Useful Area and Field
8、 Diameter Useful Area (Calculated) X-Ray Test Resolution Chart Radiation Meacuremen t Se t-Up Resolving Power Measurement Set-up Resolving Power Test Plot Contrast Test Phantom Radiation Measurement Set-up Contrast Measurement Set-up Radiation Measurement Set-up Output Screen Brightness Page 2 2 3 5
9、 7 7 0 9 9 10 11 12 12 13 13 14 15 -1- - / EIA TEPLOS 81 m 3234600 0007443 3 m I- TEST CRITERIA FOR X-RAY IMAGE INTENSIFIER TUBES EIA/TEPAC PUBLICATION NO. 109 PREFACE The material herein was developed by the JT-4 Committee on Photosensitive Electron Tubes and previously issued in the form of a JEDE
10、C suggested Standard entitled “Test Standard for X-Ray Image Intensifier Tubes“ (JEDEC Suggested Standard No. 9, dated March 1969). a The document was transferred to the JT-20 Committee on Electro-Optic Devices who reaffirmed the publication for distribution under the cognizance of the EIA Tube Engi
11、neering Panel Advisory Council (TEPAC) as TEPAC Pub1 ication No. 109. EIA TEPLOS 81 = 3234b00 O007444 5 1.0 1.1 2.0 O 2.1 2.2 2.3 2.4 2.5 TEST CRITERIA FOR X-RAY IMAGE INTENSIFIER TUBES Purpose and Scope .- This document provides recommended test methods for the measurement and ratings of X-ray imag
12、e intensifier tubes. CAUTION: SAFETY CONSIDERATIONS Measuring instruments should be properZy grounded. Cau-bion should be -taken to avoid shock hazard, particularly in the vicinity of the anode connection and the voltage metering systems, . ment procedue. Safety glasses -should be worn at al2 times
13、during the measure- X-ray film badga skould be worn in accordance with estabZishsd plant safety practices for mon%torZng radiation dosage. Defini ti ons . X-ray Image Intensifier Tube - A vacuum tube containing an input screen which converts an X-ray pattern into an electron pattern and in which the
14、 electrons are accelerated and focused on to an output screen which converts the electron pattern into a light image of brightness greater than that of a fluoroscope screen, Useful Area - The area of the input plane enclosed by a circle having a radius over which the resolution is specified (see Fig
15、.1). Useful Field Diameter - The diameter of the X-ray beam, measured at the location of the object, which produces an X-ray shadow covering the useful area (see Fig. 1). Image Quality - The faithfulness of the reproduction of an X-ray pattern (see definitions 2.8 and 2.9). Input Screen - The surfac
16、e, either flat or curved, in which X-radiation is absorbed and in which the X-ray image is converted into either an image of fluorescent light or of electric charge. EIA TEPLOS BL m 3234600 0007445 7 m 2.6 2.7 2.8 2.9 2.10 3. O 3.1 3.1.1 3.1.2 3.1.3 Output Screen - The surface in which is located th
17、e phosphor which 9 displays a light image. Conversion Factor - The quotient of the brightness in foot lamberts (or candelas/m2) at the output screen by the input radiation in mR/minute. The P number phosphor of the output screen and the quality of the input radiation must be specified. 1 candela/m2
18、= 0.2919 foot lambert. 1 foot lambert = 3.426 candela/m2. Maximum Resolving Power - The number of space and bar combinations per cm (inch) of high x-ray contrast at the entrance plane such that the bars still can be discerned visually as separate entities at the output screen. Minimum Visible Contra
19、st - The difference in thickness of the X-ray absorption fil ter expressed as a percentage of the maximum thick- ness that produces a perceptible difference in brightness on the output screen at a specified exposure rate (see Fig. 7). The Entrance Plane - The plane in front of the input screen, thro
20、ugh which, according to the specifications of -the manufacturer, no part of the image intensifier will protrude (see Fig. 1). I ! , o Measurements - For the evaluation of an X-ray Image Intensifier, the fol lowing measurements chal 1 be made: 1) Useful Area 2) Image Quality 3) Conversion Factor The
21、Useful Area Place an X-ray tube at a distance of 71 cm entrance plane. 28 inches) from the Confine the X-ray beam in order to irradiate exactly the useful area Measure the diameter of the X-ray beam at the entrance plane = a cm (inches). O 3.1.4 3.1.5 3.1.6 3.1 7 3.2 3.2.1 O 3.2.2 EIA TEPLOS 81 3234
22、600 0007446 9 Reduce the X-ray-tube-entrance plane distance to 35.6 cm (14 inches). Confine the X-ray beam in order to irradiate exactly the useful area. Measure the diameter of the X-ray beam at the entrance plane = b cm (inches). The diameter of the useful area can now be calculated by the for- mu
23、la D = ab/2b-a cm (inches), (see Fig. 2). The Image Quality per, X-ray Exposure Rate - This measurement is sub-divided into determination of the maximum resolving power and minimum visible contrast. Maximum resolving power shall be measured with a test phantom as indicated by Figure 3 and Appendix 1
24、. The measurements shall be made as follows: (a) Radiation measuring Set-up (see Figure 4). (b) Measurements shall be done at 60 KVP and the current adjusted in order to produce an exposure rate of 100 mR per minute at the entrance plane. (c) Resolving power measurement Set-up (see Figure 5). (d) Me
25、asurement of the resolving power shall be done with a suitable optical means of sufficient magnification, in the center, at a 2.5 cm (1 inch) radius from the center, 5,l cm (2 inches), 7.6 cm (3 inches), etc., and plotted in a curve giving the resolution as the ordinate and the distance from the cen
26、ter as the absissa (Figure 6). Minimum v-isible contrast shall be measured with a test phantom as indicated by Figure 7 and Appendix 2. The measurement ishall be made as fol lows: (a) Radiation measuring Set-up (see Figure 8). (b) Radiation values are 80 KVP and the current adjusted to obtain (c) Co
27、ntrast measuring Set-up (see Figure 9). (d) Contrast shall be measured by observation with a suitable optical means in the center of the useful area at each of 1, 10 and 100 mR/min. at the entrance plane of the tube. EIA TEPLOS 81 m 3234600 0007447 O m above mentioned exposure rates with the remaind
28、er of the photo cathode shielded by lead from the unattenuated X-rays. 4.0 Conversion Factor - The conversion factor shall be measured by obtaining the quotient of the brightness of the output screen in Foot lamberts (or candelas/m2) by the input X-ray exposure rate of 100 mR/min of specified qualit
29、y (half value layer). The X-ray input exposure rate shall be measured as follows: Radiation measuring set-up (see Figure 10). 4.1 4.1.1 4.1 2 X-ray qual i ty. The conversion factor shall be measured with X-rays having first half value layers of 5, 7, 9, 11 and 13 mm aluminum. reproducibility the fol
30、lowing procedure shall be followed: (a) X-ray generators-single-phase, full wave. (b) Distance from the exposure-meter sensor of the X-ray tube focal spot to the exposure-meter should be 71 cm (28 inches). (c) Filters - commercially pure aluminum. (d) Distance from filter to exposure meter sensor an
31、d entrance For maximum plane of Image Intensifier 20 cm (8 inches) minimum. This is important for the elimination of scatter X-ray genera- ted in the aluminum filter). (Note: (e) ni tiai Settings Approx, Milliamperes First Half Approximate for 100 mill i Value Layer Fi 1 ter KV P Roentgens/Mi nute 5
32、 mm Al. 9 mm Al. 60 1-2 80 1-2 7 mm Al. 9 mm Al. 11 mm Al. 13 mm Al. 59 mm Al. 140 1-2 Note: 20 mm Al. 32 mm Al. 1 O0 1-2 45 mm Al. 120 1-2 To arriveat the proper half value layer, it is recommended that corrections can be made in kilovolts peak. -5- EIA TEPLOS AL m 3234600 0007448 2 m 4.1.3 The X-r
33、ay beam shall be collimated to expose only the entire useful area. The brightness of the output screen shall be measured over 90% of the diameter of the useful area with an eye-corrected optical sensor (see Figure 11). An example of a suitable lightmeter is the Spectra brightness spot meter made by
34、Photo Research Corp. O 4.2 4.2.1 Hollywood, California, Model #U B 1-1/2. -6- EIA TEPLOS 81 W 3234600 0007449 4 W O .X-ray tube Useful field diameter Useful field diameter = FIGURE 1 - USEFUL AREA AND FIFLD DIAMETER I X-ray tube X-ray tube Input Lntrance plane plane Y6 cm (14 i -71 cm (28 in.-d FIGU
35、RE 2 USEFUL AREA (CALCULAEED) -7- EIA TEPLOS BL 3234600 0007450 O 15.9 mm (0.625 in) P O O O O O 23.8 mrn -(0.937“) -. - -m -u Ill Ill Ill IIi Ill Ill 111 A O. o o 0.0 e O. O o. O a e eo oe 0.0 0.0 *e. -u_- FIGURE 3 X-RAY TEST RESOLUTION CHART Naterial - Copper 0.254mm (0.Ol1) . (Darkened areas are
36、openings in oopper sheet) EIA TEPLOS BL 3234600 0807453 2 X-ray. tube 1. _ . -/ X-ray tube 71 cm (28 in.)-J F 1GW-L RADIATION MEASUREMENT SET-UP .1 Entrance plane Resolution test phantom (See Figure 3) O 71 cm (28 in.) FIGURE 5 - RESOLVING POWER MEASUREmNT SET-UP I -9- EIA TPLOS BL 3234600 0007452 4
37、 111 O 2.5/1.0 5.1/2,0 7.6/3. O 10.2/4.0 12.7/5 .O cm/ inches (From center of input screen) FIGURE 6 RESOLVING POWER TEST PLOT . -lo-. f- EIA TEPLOS 81 3234600 O007453 b H t -11- LI. O 5! 2 O d 4 v I 3 EIA TEPLOS BL m 3234600 0007454 8 m - -. X-ray tube 71 cm (28 in.- _I FIGURE 8 R4DIATION MEASUREmE
38、NT SET-UP - meter FIGURE 9 -I_ . CONTRAST WSURmNT SET-UP L EIA TEPLOS BL 323qb00 O007455 T H X-ray tube me ter X-ray tube FIGURE 10- RADIATION MEASUREMENT SET-UP O Diametor of the useful area. -_ , covering corresponding PO$ of diameter of useful area of output screen. FIGURE If OUTPUT SCREEN BRIGHT
39、NESS -1 3- ELA TEPLOS 81 = 3234600 0007456 L 1.0 2.0 3.0 4. O APPENDIX I The resolving power test phantom (see Figure 3), has the following features : The resolution can be measured locally because the test pattern occupies an area of no more than 2.5 cm X 2.5 cm (1 in. X 1 in). It provides resoluti
40、on increments of 20%. covered is from 6 line pairs per cm to 6 Lp/cm-33.5 Lp/cm (15 Lp/in-85 Lp/in). The complete range The conipiete range comprises: 6 - 7 - 8.5 - 10 - 11.5 - 14 - 17 - 20 - 25 - 28 - 33.5 line pairs/cm, corresponding with 15 - 17.5 - 21 - 25 - 30 - 35, - 42 - 50 - 60 - 70 - 85 lin
41、e pairs/inch. The hole pattern consists of the following diameters: 0.85 - 0.7 - 0.6 - 0.5 - 0.42 - 0.35 0.3 - 0.25 - 0.21 - 0.175 - 0.15 mm The triangle indicates 20 Lp/cm (50 Lp/in). The bar array is the recommended ASA pattern for light test charts. The location of the bar array makes it possible
42、 to scan its image with a micro-densitometer. from Buckbee Mears Co., St. Paul, Minnesota. This type of phantom can be obtained -. 14 - EIA TEPLOS BL m 3234b00 0007457 3 m APPENDIX II 1 .o The contrast phantom (see Figure 7) has a maximum absorption of 20 mm Al, and consists of 10 disks of 2 mm Al.
43、hole. a depth of 0.3 - 0.35 - 0.42 - 0.5 - 0.6 - 0.7 - 0.84 - 1.0 - 1.2 - and 1.4 mm, representing a contrast range of 1.5% to 7%. Each disk has one In the disks are milled holes of 6 mrn (.25 in) diameter and 2.0 This phantom has the following features: It measures with 20% increments between 1.5%
44、to 7% contrast, the full range is 1.5 - 1.75 - 2.1 - 2.5 - 3 -.3.5 - 4.2.5 - 6 - 7%. Disks can be turned with respect to each other in order to make objective measurements. 2.1 2.2 2.3 The observer can be requested to write down 1 oclock visible, 2 oclock visible, 3 oclock visible, etc., 12 oclock being the register pin. a minimum effect on the contrast measurement. The holes are so large that the resolving power has - 15 -
