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The author is establishing a relationship between film density duo to the light of intensifying screens and lack of focus. From this ensues a quality factor for x-ray intensifying screens.
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X-ray attenuation and intensity of light emitted were measured for nine intensifying screens used in mammography. Incident beam qualities with half value layers in the range of 0.38 to 2.68 mm Al were used to simulate the range of clinical conditions encountered in mammography. All the screens attenuated the x-ray beam to a similar extent at these beam qualities, but a wide variation in the intensity of light emitted was observed. The interrelation of the measured physical parameters in determining both the system speed and noise properties is discussed.
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The use of color pictures and displays for interpreting images obtained from computed tomography scanners, scintillation cameras, and ultrasound equipment is an interesting possibility. As currently supplied, color television monitors may add significantly to the cost of a system. A relatively simple way of converting an entertainment grade color television receiver to color monitor operation is described. The display system is significantly lower in cost than vendor supplied monitors and produces images of similar quality.
Reciprocity law failure was measured for four brands of medical x-ray films exposed with intensifying screens. Three of the films are green light-sensitized for use in combination with green light-emitting rare-earth screens. These films showed larger reciprocity failure effects than one conventional blue-sensitive film, Dupont Cronex-2. Development conditions had a small effect on reciprocity failure. As part of the investigation, a detector was constructed with a response that accurately monitors the light emission from the double screen-cassette combination over a wide range of x-ray photon energies.
Seven new and two conventional screens were investigated. Measurements were performed at different energies of the photon fraction interacting in the screens, and energy losses due to escape of K-fluorescent radiations were calculated. The speed of the screens was dependent on the energy; this was primarily due to the fact that x-ray absorption is dependent on energy. Rare earth and other new screens absorb a maximum of 1.5 times as much energy and emit twice as much light as comparable calcium tungstate screens. Reabsorbed K-fluorescent radiations might contribute to image unsharpness in the new screens.
Formats of full-size radiographs are determined by the dimensions of the anatomy to be recorded, the enlargement factor is always larger than unity. Given a certain film screen combination exposure and film-density cannot be chosen independently--whereas with X-ray I.I. fluorography this is possible. In the former case they depend on X-ray absorption, energy efficiency and the luminescent spectral emission of the screens in combination with the corresponding characteristics of the photographic film. The respective characteristics of standard film-screen combinations and those based on rear earth screens are discussed and compared. X-ray image intensifier fluorography is presented as a logical enlargement of I.I. fluoroscopy, in itself and indispensable tool in X-ray diagnostics. Its real or imaginary pro's and con's are elucidated.
A physical experimental study of intensifying screens for diagnostic radiography was set up. Experimental conditions were identical with those of medical practice. Spectra speeds of several films and spectral emission of intensifying screens were built up. Speeds of screen-film combinations, as well as definitions, were measured. Results are available to range the different screens-film systems after their speed factor, at 40, 70 and 120 kV, with mention of definition of these systems. It so objectively appears that rare-earth intensifying screens make possible a decrease of X-ray exposure for patient under a factor 2 to 2,5 and a less early wearing of apparatus, namely of X-ray tubes.
Accurate registration of a section 13 mm in depth in different patients or reregistration in the same patient during whole body computed tomography is a significant problem. The method described here attempts to overcome some of these difficulties. The feasibility of using the EMI Scanner X-ray tube and a pair of Kodak Lanex intensifying screens in a vacuum pack cassette has been examined. A registration system which as an accuracy to within 1 pixel has been described. This technique has its major application in the registration and recognition of the axial skeleton, on fixed bony structures. The registration of soft tissue structures, subject to greater physiological variation poses problems which are the subject of further investigation.
Intensifying screens based on Gd2 O2 S : Tb were analysed for x-ray exposure reduction and resolution using in mammorgraphy. The contrast of these screens coupled with a single emulsion film was tested and the density dominante was determined. A resolution grid on this density exposured shows the detail resolution and judge the quality profile of these new film-screen-combinations. To all factors was compared a non-screen industrial film for long time processing. The application of Gadolinium intensifying screens in mammography allowed an exposure reduction of 75% at the same image quality like a nonscreen industrial film.
An IVP optimum quality should be tailored to the particular needs of a given case and consequently most be supervised by the radiologist when it is being performed. The most meticulous technique is needed, the adequate amount of contrast medium should be used, compression of the ureters should be performed and under optimum conditions tomography during the nephrographic phase should be performed whenever the circumstances should require it. With only very few exceptions no significant differences between different contrast media exist. The use of medium speed high contrast x-ray films as well as the use of rare earth intensifiers screens avoid the need for extremely powerful generators that are very costly. Film processing is a critical step in obtaining a good study and should be automatic.
The paper is concerned with the use of rare-earth intensifying screens in order to overcome some of the exposure problems during magnification techniques using very small focal spots. Theoretical experiments and tests with biological objects indicate that the use of high intensifying screens under these circumstances is acceptable and useful. A comparison has been carried out between the results of conventional techniques without magnification and magnification techniques using very small focal spots and rare-earth intensifying screens.
Magnification radiography was applied for the diagnosis of the biliary tract diseases including cancer. Our X-ray unit was consisting of HITACHI DR-155-23 U-6M-55P and 0.1 mm focal-spot tube, FFD 80 cm giving a magnification of x2 with the conditions of 60 kVp, 20 mA, 0.8 sec. Intensifying screens such as Kyokko LH II (for a standard sized subject) or DuPont Q II (for an obese subject) were used in combination with Fuji RX films. We confirmed a high diagnostic value in revealing early lesions of this sytem. The skin dose test indicated that this technique was routinely applicable with safety for clinical use.
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Recently operative cholangiography has become an essential step in biliary surgery. However, an usual technique in which x-ray film is set beneath the patient has its limitation in visualization of fine changes. The author devised a new technique to resolve this problem. A triangular mammography film designed for good positioning is vaccum-packed, coupled with an intensifying screen of the same size, and then is sterilized in advance. Barium solution mixed with Gascon drop (a defoaming agent) is used as contrast material. The duodenum and head of the pancreas are mobilized. Usual cholangiography is performed at first, introducing angiographic media through a catheter placed into the catheter placed into the common duct via the cystic duct. After this study a triangle film pack is set beneath the second part of the duodenum. Two to three milliliters of barium, 1 to 2 ml of Gascon, and 15 ml of air are pushed in; thus a contact double-contrast cholangiogram is obtained. This technique promises clear demonstration of the distal bile duct without risk, and even fine mucosal plicae may be discernible in the film.
Important details are to be payed attention in comparison of different scrreens resp. screen-film-systems: 1. Physical characteristics of different groups of luminescent materials: f.i. calcium tung-state, rare-earths compounds, double halogenides. - 2. Different types of screens: highest details up to highest speed intensifying screens, have to be defined more specifically and differentiated against to each other too. - 3. Besides intensification, resolution has to be included into consideration since one of these dates alone does not allow any statement on the total function of a screen or a screen-film-system. - 4. The technical methodological conditions of apparatuses, object and its positioning have to be defined, f.i. X-ray quality, distances, grid, and in automatically controlled exposition, if necessary, position of ionization chamber as well as absorption of cassetts and screen. - 5. Considering these points gradation curves have to include the whole necessary or interesting diagnostic range. - 6. Due to functional correlation between intensification and resolution, the resolution has to be taken in consideration due to application; its interdependence of density and object (f.i. scattered radiation) is often not taken enough in consideration.
An image intensifier--70mm camera--fluoroscopy system combined with a conventional X-ray tube is used for routine examination of the infant's hip. The high quality of 85% of these 70mm exposures makes immediate diagnostic interpretation possible. An even higher percentage can be achieved by most exact positioning of the patients. Apart from the radiation protection of the gonades, the X-ray skin dose of the primary beam is reduced by 90-95% compared with full size radiography using film screen combinations. This exposure technique can certainly be used not only for the examination of the infant's hip.