Fixing, washing, drying X-ray film. Developing, fixing and washing X-ray film. Typical mistakes during X-ray examination
Technique manifestations itself is simple (all that is required from the x-ray technician is attention and accuracy) and consists of the following.
Removed from cassette x-ray film sheet is clamped in a metal frame-film holder, after which it is carefully and smoothly completely immersed in the developing solution. Then the frame with the film is raised and lowered 2-3 times in a row to remove air bubbles from the film, and the developer tank is covered with a lid.
Specified subsequence ensures complete wetting of the emulsion layer with the developer solution and removal of air bubbles from its surface. If air bubbles are not removed, then in these places the developer’s access to the emulsion layer will be blocked and transparent dots of varying sizes will be obtained on the x-ray image. If the film is not completely immersed in the developing solution, the areas of the emulsion layer remaining exposed to air will undergo oxidation, followed by the appearance of a yellow veil in the image.
Development time is controlled according to darkroom hours, their sound signal reminds you that the time set for them has expired. The first visual control of the development progress and image quality is carried out after 5 minutes from the moment the film is immersed in the solution.
Until completion film developing process It is impossible to remove it from the developer often and for a long time, since a general gray veil (air veil) will appear on the picture. The cause of the appearance of an air veil is the oxidation of the developer on the surface of the film by atmospheric oxygen.
Upon completion of development frame with x-ray film removed from the developer and held for some time over the tank with an inclination to one of the corners, without removing it completely. This is done so that excess developing solution drains from the film and frame back into the tank. The X-ray film is then transferred to the stop bath.
Stopping a photo from developing
Before committing photo it is necessary to remove the developing solution from its emulsion layer.
For this, as well as to preserve the fixing properties The fixative is an acidic solution that stops the development - stop bath.
With each developed film, a certain amount of developer is transferred into the fixer (one sheet of dry film 30x40 cm absorbs up to 10 ml of developer).
In order to from the emulsion layer the developer residues were washed out faster and the alkali in the emulsion layer was neutralized, it is recommended to lower the film into a vessel with a stop solution, then remove it and let the solution drain, and then lower it into the solution again. This should be done 3-4 times for 20-30 seconds. After last time When the solution drains from the film and frame, the image is transferred to a vessel with a fixative.
If instead of using acid stop solution If you only rinse in ordinary water, then the action of the developer remaining in the emulsion layer of the photograph will continue, and the fixer will become alkalized and quickly become unusable.
Stop solution prepared from cold tap water with the addition of 20-30 ml ice acetic acid or 40 g of potassium metabisulfite per liter of water.
The middle of the three tanks of the chemical-photographic kit processing X-ray film is intended for stop solution. When developing in baths, a bath with stop solution must be placed between the developer and fixer.
The acidity of the stop bath should be checked with blue litmus paper.
The radiographic method is a method of X-ray diagnostics when pathological changes in the organ under study are determined by the shadow picture obtained on X-ray film or any other photosensitive material as a result of the action of X-rays on its photosensitive layer.
Radiography is possible because X-rays, like rays of ordinary light, act on the photosensitive layer of X-ray film. This layer is a frozen suspension of silver bromide (AgBr) crystals in gelatin. There are several theories for obtaining images on films. Without stopping to analyze all existing theories, we will present one of them as the most consistent with modern views.
Silver bromide crystals form crystal lattices in which negative bromine ions are bonded to positive silver ions by electrostatic attraction. The photosensitive layer, when exposed to x-rays, absorbs some of them. In this case, each absorbed quantum of radiant energy is spent on removing an electron from a bromine ion, resulting in a neutral bromine atom instead of a bromine ion. The removed electron neutralizes the positive silver ion, turning it into a metallic silver atom. Thus, in areas of the film exposed to X-rays, the photosensitive layer decomposes with the release of metallic silver. However, it is released in such quantity that the resulting image cannot be seen, which is why it is called hidden.
To obtain a visible image, the irradiated film is placed in a developer solution, which greatly enhances the decomposition of silver bromide. It occurs especially intensely in those places of the emulsion where more intense X-ray radiation has fallen, and as a result, the hidden image becomes clearly visible. As an example, let's take an x-ray of a finger. To do this, we place the X-ray film, coated with a photosensitive layer, in an aluminum cassette to protect it from light. Let's place a finger on the cassette and direct X-rays at it, which will freely pass through the wall of the cassette and fall on the film. In this case, the part of the film not covered by the finger will be equally intensely exposed to radiant energy. The part of the film covered with the finger will be exposed to a differentiated beam of X-rays.
As is known, the finger is a heterogeneous medium; it consists of tissues of different densities. Consequently, the degree of absorption of the X-ray beam passing through parts of the finger will not be the same. Where the rays along the way meet a highly calcified, compact part of the bone, they will hardly pass and at the corresponding place the emulsion layer will be subject to insignificant action of the rays. In places where the rays will pass through the less dense part of the bone - the spongy part, the absorption of the rays will be less and, accordingly, these places of the film will be subject to greater irradiation. Soft tissues will hardly retain x-rays, and these areas will be exposed to even more radiation.
If the exposed film is taken out of the cassette in a room under red light and developed, then in the picture we will see a completely black background, corresponding to the parts of the film not covered by the finger. Soft fabrics will give a background slightly lighter than black. The spongy part of the bone will give a special bone pattern, which is a complex interweaving of bone beams; and the compact part of the bone will give a continuous light line. Thus, the X-ray image on film resembles a shadow picture on a screen; but with that important difference that there will be a shadow light color, and the irradiated areas are dark. Therefore, the radiograph is a negative.
To carry out the radiographic research method, you must have: cassettes, intensifying screens, X-ray film and chemicals.
X-ray cassettes are used to protect films from extraneous light. The cassette is a flat box consisting of two walls fastened with hinges. The front wall of the cassette, facing the object during shooting, is made of a material that transmits x-ray radiation without significantly changing it (aluminum, getinax, wood, cardboard, etc.), and the back wall is made of a thick iron plate. There are sides on the front wall, and on the inner surface of the back wall there is a felt or felt pad, which, when closing the cassette, fits tightly into the recess of the front wall and prevents it from getting into the cassette. visible light. To ensure reliable contact between the walls of the cassette and to avoid arbitrary opening, two springy metal fasteners are provided on the outer surface of the rear wall. The cassette opens like a book. Intensifying screens are fixed on the inner surfaces of the cassette walls.
Standard cassette sizes: 13X18 cm; 18X24; 24x30; 30X40 cm.
In practice, soft cassettes are sometimes used; they are made in the form of bags made of black opaque paper.
Reinforcing screens. Intensifying screens are used to reduce shutter speed when taking photographs. The latter are cardboard or celluloid sheets, on which a layer of phosphorescent salt is applied on one side. Typically an emulsion consisting of a calcium tungstate salt (CaWo) is used. This salt, when exposed to X-rays, phosphoresces with blue-violet light, which has a strong effect on the photosensitive layer of the X-ray film.
The screen lying under the film (rear) has a thicker layer of phosphorescent salt, the screen located above the film (front), as it blocks the rays going to the latter, is covered with a thinner phosphorescent layer. During film exposure, the phosphorescent light of the screens, excited by X-rays, acts on the photosensitive layer of the film. Thus, the photosensitive layer of the film is exposed to X-rays and the light of phosphorescent screens, which makes it possible to reduce the shutter speed during photographs.
The gain of screens, that is, the ratio of the exposure time without screens to that with screens, can be considered on average to be in the range of 7-50, depending on the voltage and quality of the screens.
It should be remembered that intensifying screens require careful handling, since various mechanical damage and contamination lead to damage to the phosphorescent surface of the screens. When radiography with such screens, defects are obtained in the image, corresponding to the defects of the screens, which can lead to erroneous interpretation of the X-ray picture.
In addition to conventional intensifying screens, tin or lead foil with a thickness of about 0.02-0.2 mm is sometimes used. The enhancing effect of foil is based on the release of photoelectrons from the metal foil by X-rays. Electrons emitted from the metal are absorbed by the film emulsion, which causes additional darkening of the latter. The gain of foil compared to conventional intensifying screens is smaller and approximately equal to 2-3. The advantage of foil over screens is its fine grain and filtering of scattered radiation coming from the object, thereby increasing the clarity of the image.
X-ray film is a thin, transparent celluloid or nitrocelluloid plate coated on one or both sides with a photosensitive emulsion. The emulsion consists of microscopic crystals of silver bromide (AgBr) evenly distributed in hardened gelatin.
Different types of X-ray films differ in their sensitivity and contrast. For X-ray films, contrast is a more important quality indicator than sensitivity, since high-quality radiographs can only be obtained with high-contrast X-ray films.
X-ray film High Quality It is produced by our domestic factories and sold in light-proof boxes. The latter indicate a brief description of the film and the method of its processing.
Standard film sizes:
13X18 cm; 18X24; 24x80; 30X40 cm.
Chemicallip. To process exposed film, you need a developer and a fixer.
The developer contains the following main components: developing substances - metol, hydroquinone; substances that accelerate manifestation - soda (sodium carbonate), potash; preservative - sodium sulfite; retarding manifestation and anti-veiling agent - potassium bromide.
The composition of the fixative (fixer) includes the following substances: fixing agent - sodium hyposulfite; preservatives - sodium sulfite, sodium metabisulfite; tanning agents - boric and acetic acid.
As for the issue of preparing developer and fixer solutions, it will be discussed below when considering the issue of processing exposed film.
Photo production technique. Pictures are usually taken in two main projections - frontal and lateral. If necessary, additional oblique projections are used. Projection refers to the direction of the central beam of rays in relation to the object being photographed.
For photographs in direct projection, the anterior-posterior or posterior-anterior direction of the central beam of rays is used. In this case, the cassette is respectively applied either from the back or from the front.
In lateral projection, photographs are taken with the central beam of rays directed from right to left or left to right, applying the cassette either to the left or to the right side.
With oblique projections, the central beam of rays is directed at a certain angle to the object being photographed, for example, from the front to the side, inward and backward.
Before taking an image, the radiologist must familiarize himself with the results of the general clinical examination, which determine the nature of the image.
Depending on the intended photo, take the size of the cassette and the corresponding film format. X-ray film is loaded into a cassette in a darkroom under red light as follows: open the cassette and the box with the film, take one film from the box, place the double-sided film with either side in the recess of the front wall of the cassette, that is, on the front intensifying screen, and the one-sided film with the emulsion layer facing the front intensifying screen and the cassette is closed.
To take a picture, the charged cassette is tightly applied with the front side to the area of the animal’s body being photographed, and with opposite side install the X-ray tube with the exit window facing the object. The exit window is diaphragmed in such a way that the exiting cone of rays covers the entire area of the animal’s body being photographed. During radiography, it is important that the cassette and the object being photographed are stationary. If symmetrical areas are being removed, you need to indicate the side.
To obtain maximum detail and good quality of the X-ray image in the image, it is necessary to select the correct hardness of the rays, their direction and exposure time. In this case, it is necessary to take into account the thickness of the object under study, the degree of calcification of the bones, the sensitivity of the X-ray film and the focal distance to the film.
Radiation hardness. The hardness of X-rays depends on the operating voltage. Therefore, in order to obtain a sufficiently large effect of X-rays on the X-ray film emulsion, it is necessary to correctly select the operating voltage. If the rigidity is insufficient, the rays can pass through soft tissue, but will not be able to pass through the thickness of the bone. As a result, the image of the bone will be presented as a solid shadow without any indication of its structure. Rays that are too harsh will pass through large quantities and blur the details. Thus, the question of changes in bone cannot be resolved from such an image.
Exposure is the product of radiation intensity and duration of illumination. Exposure depends primarily on the current in the tube, measured in milliamps. The duration of illumination is expressed in seconds. Therefore, exposure is expressed as milliamps times seconds. For example, the current in the tube is 75 mA, the illumination time is 2 seconds. The exposure will be 75 maX2 sec. = 150 mA/sec.
Radiation hardness and exposure can be combined. By increasing the hardness, you need to reduce the exposure, and, conversely, by decreasing the hardness, you need to increase the exposure. The best combination of severity and duration of exposure is determined by experience.
An error in hardness or exposure can be determined from the image. For example, good picture soft tissues and complete absence The structure of the bone indicates low rigidity with good exposure. Insufficient contrast between soft and bone tissue, general grayness and vagueness of the pattern indicate excessive rigidity. If the photo turns out to be dark gray in which no details can be made out, this indicates excessive harshness and excessive exposure.
Choosing the direction of the rays is one of the conditions for getting a good picture, since the right choice The direction of the rays determines the exact projection of the object being photographed and the detection of pathological changes.
From the focus on the anticathode, the rays diverge in a cone up to 180°, and for practical work a small beam of rays is required. Therefore, it is necessary to focus the tube over the object so that the direction of the central axis of the working beam with the plane of the cassette forms a perpendicular.
There are a number of devices available to help the radiologist find the correct direction of the central beam. The simplest of them is a plumb center. Its device is very simple. They take a cardboard circle, in the center of which they strengthen the drink, and hang a small conical weight from the free end of the thread. A cardboard circle is attached to the flange of the tube casing so that the center of this circle coincides with the actual focus of the tube. It’s even better if, instead of a thread, you attach a rigid rod to the circle. Such a rigid plumb line has advantages over a thread in that it makes it easy to center a beam of rays even when the latter has a horizontal or bottom-up direction.
Focal length. When taking pictures, the best focal length is considered to be 70-100 cm. This distance can be increased or decreased.
By increasing or decreasing the focal length, the shutter speed must be changed accordingly, since changed focus-film distances require a change in shutter speed according to the law of the square of this distance.
To obtain the best images in the selected conditions, you need to ensure that as little scattered rays are generated as possible, since scattered radiation entering the image caused by the primary beam creates additional darkening of it, which deteriorates the quality of the image.
It is impossible to completely destroy this secondary, harmful radiation, but through certain measures it is possible to reduce its harmful effects. The thicker the object and the larger the irradiated field, the stronger the effect of scattered rays. Therefore, whenever possible, you should take pictures with small fields. To do this, limit the cone of rays emerging from the tube using tubes.
To filter out (filtrate) soft rays in the working beam, special filters are used. The simplest X-ray filters are aluminum and copper plates, the thickness of which ranges from 0.5 to 3 mm. Such a filter absorbs the spectrum of soft rays, while hard rays are slightly attenuated when passing through such a filter.
To destroy scattered rays generated in an object, special X-ray gratings (hoods) are used (Fig. 5). They are made of lead plates arranged in such a way that they transmit the primary beam of X-rays, going perpendicularly or at a slight angle to the film, and absorb scattered rays. To ensure that the picture does not contain an image of the lead plates themselves, the screening grid is set in motion during transillumination or shooting. As a result, the image of the plates is “blurred”.
Processing of exposed films. Manifestation technique. Development determines the quality of the image no less than the shooting conditions. Therefore, it requires a serious and attentive attitude.
They are developed in a separate, fairly spacious, well-ventilated and specially equipped room (dark laboratory), illuminated by a red glass lantern. All manipulations during film development should be carried out using tweezers.
The exposed, that is, exposed to x-rays, film is removed from the cassette and quickly immersed in a bath with a sufficient amount of developer solution so that its layer above the film is at least 1 cm. To ensure uniform development of the entire x-ray image and to avoid the formation of air bubbles on film it is necessary to shake the bath slightly from time to time and monitor the progress of development. During the development process, you should not often unnecessarily remove the film from the developer and examine it in transmitted red light; this does nothing except weaken the development and lead to the so-called air veil.
The temperature of the developer solution should be 18-20°C.
At a higher temperature of the solution, fogging of the film occurs, in addition, the gelatin layer begins to swell and peel off. At a solution temperature below 10-12°C, the development process slows down greatly, and it becomes impossible to obtain rich, contrasting radiographs.
As the film develops, the outlines of the design appear on the film, and then its individual details. However, this does not mean that you need to stop manifesting. Visualize all silver bromide crystals exposed to X-ray energy. Only in this case can you obtain rich, contrasting radiographs.
Rice. 5. Scheme of absorption of secondary (scattered) x-rays by the grating:
1. anode tube; O—body under study; aa points.
If the development process is stopped prematurely, only the superficial silver bromide crystals appear, and the bulk of the silver bromide crystals do not have time to develop; as a result, the underdeveloped image turns out to be pale, with reduced contrast, or, as they say, it turns out sluggish. Therefore, it is important to recognize the moment when the manifestation should be interrupted. The development process should be considered complete when, when examined in the drawing, no new details appear, and its contours begin to become slightly shaded.
If, subject to all development rules, the image appears quickly and disappears so quickly under a general gray veil, then the reason should be sought in the wrong choice of exposure or ray hardness. In this case, the photo should be repeated, changing the shooting conditions. If the film becomes covered with a veil before the image appears, this means that the film was exposed when inserted into the cassette or is very old, or the glass of the laboratory lamp allows extraneous light to pass through. In this case, the cause must be determined and eliminated.
If details still do not appear at the maximum development time, this means that either an old developer was used, or the shooting conditions were low. In this case, you need to add fresh developer without potassium bromide. If this does not help, then the photo should be repeated, changing the shooting conditions.
This method of manifestation is very painstaking and time-consuming. Therefore, when the cabinet is heavily loaded, you should use another, more productive and advanced so-called tank method (tanks are called tanks). The advantage of this development method is that it allows multiple films to be developed simultaneously and is less laborious. With the tank method of developing, films are clamped in special stainless steel film holders or using simple clamps and immersed in a tank with developer. Development is carried out at a temperature of the developer solution of 18°. The development time is regulated by the factory that produces this type of film. If the solution temperature is above 18°, then the development time must be reduced by 1 minute. every 2°;
at a lower temperature, the development time is increased by every 2" by 1 minute. If, while observing all the development rules, the radiograph turns out to be too dark, this does not mean that the radiograph is overdeveloped. This indicates that the shooting conditions were taken too great. B In this case, you need to change the shooting conditions, and leave the development time the same.
Domestic films should be developed in a standard developer of the following composition:
Metol - 2.0
sodium carbonate (soda -118.0
hydroquinone - 8.0
potassium bromide - 5.0
sodium sulfite
distilled water or
crystalline - 180.0
boiled—1l
The components should be dissolved in the order prescribed until completely dissolved.
Use no earlier than 24 hours after formulation.
The developer of the following composition works well:
Metol - 2.0
Potash - 50.0
hydroquinone - 8.0
potassium bromide - 3.0
sodium sulfite—80.0
distilled or boiled water - 1l
In 1 liter of developer you can develop films: 13 X 18 cm - 38 pieces; 18X24 cm - 20; 24x30 cm - 12; 30x40 cm - 7 pieces.
Fixation. At the end of development, the film is removed from the developer solution and washed for 10-15 seconds. in running water and placed in a fixing solution.
The fixation process is aimed at the following: stopping the further development process and removing undecomposed silver bromide from the gelatinous layer of the film.
Under the action of the fixing solution, the silver bromide remaining in the gelatin layer of the film, not changed by radiant energy, dissolves and a double salt of silver sulphate and sodium sulfate is formed. This salt dissolves quite easily in the fixing solution, but very difficult in water.
The temperature of the fixing solution should be 18-20°. At higher temperatures, the emulsion layer softens, and at low temperatures, the fixation process slows down greatly.
Recipes for fixing solutions:
1) crystalline hyposulfite - 250.0
ammonium chloride - 50.0
sodium metabisulfite - 16.0
water (warm) - 1l
2) crystalline hyposulfite - 200.0
potassium metabisulfite - 20.0
water (warm) - 1l
These acidic fixing solutions immediately stop developing, are preserved for a long time, and the solution remains light all the time. The yellow color of radiographs sometimes appears during development, but disappears in acidic fixing solutions.
If necessary, you can record radiographs in an ordinary fixing solution: crystalline hyposulfite - 250.0, water (warm) - 1 liter. This solution fixes quickly, but soon deteriorates and turns brown.
The number of films that can be processed in 1 liter of fixing solution is the same as for the developer.
Fixing is continued until the milky white tint (silver bromide) completely disappears on the film. After this tint disappears, as a precaution, the film should be kept in the fixer for some more time, approximately the same amount of time it took for it to disappear.
If the fixation is not long enough, this salt remains in the gelatin layer of the film, and after some time the radiograph becomes yellow. You should not use old, depleted fixing solution; radiographs fixed in it may also turn yellow in whole or in part.
Washing and drying. The fixed radiograph must be washed thoroughly. If there is insufficient washing, the x-ray image will quickly deteriorate and turn yellow.
Radiographs should be washed in running water for at least 20-30 minutes. If there is no running water, then the radiograph is placed in a bath of water; the water must be changed at least 5-6 times within an hour. Before removing the radiograph from the water, you should carefully, without disturbing the gelatin layer, remove the sediment with a cotton swab, which often remains on the gelatin layer during fixation and washing.
The radiographs are dried at room temperature in a suspended state. Drying should not be accelerated by heating, as this will melt the gelatin layer. If the radiograph is needed quickly, then to speed up drying, it can be immersed in 75-80° alcohol for 5-10 minutes. The pre-washed radiograph is shaken several times to free it from large drops of water. Once removed from alcohol, it dries completely in 10-15 minutes. A partially dried radiograph cannot be dried in alcohol, as it becomes covered with stripes.
Requirements for the photo. Based on the images, the condition of the photographed organ is determined, a number of clinical manifestations of the disease are explained, and the nature of the pathological process is clarified. Therefore, the image must meet the following requirements:
1) the picture should show the entire part of the body or organ being examined where there are pathological changes; 2) the picture must be contrasting, contour and structural, that is, one in which one tissue can be distinguished from another. For example, bone tissue should stand out sharply against the background of soft tissue, denser bone tissue should differ from less dense tissue and should not have a double contour; 3) bone structure and other details internal structure the bones should be well defined.
An X-ray image that does not meet these requirements loses its practical significance.
If we consider the types of medical X-ray film, it is divided into radiographic, used for general radiology, and fluorographic. There are also X-ray plates for specific purposes, but they are rarely used in medical practice.
Classically used film consists of sheets of various sizes (most often 40x40 cm), on which layers of emulsion are applied on both sides. These layers form a photosensitive surface, that is, such a film is double-sided. It is used in conjunction with 2 screens for amplification. This type of film is used to take photographs at a 1:1 scale.
Agfa films
The fluorographic type of film has an emulsion layer on one side. That is, these are one-sided films. They are used to take pictures at a reduced size. An optical system is designed for this purpose. Fluorographic film is produced in rolls.
Basic indicators of X-ray films
The sensitivity indicator is determined regardless of the type. There are films containing silver halides without dye impurities in the photosensitive layer. They are sensitive to the blue range of the spectrum. When dyes are added to the emulsion layer, the film is also sensitive to the green range of the spectrum. There are films that contain dyes that also make them sensitive to red light.
Blue light is used in the classic use of radiography, in the production of conventional x-rays. Fluorographic examination uses the green range of the spectrum.
Sensitivity is determined by the reciprocal of the number of roentgens required when taking x-rays. It is calculated in reciprocal roentgen units. The average gradient indicates the film's contrast setting.
Domestic and foreign products
Domestic films have been produced for a long time, and are intended mainly for manual development. These are blue-sensitive films RM-1 and RM-K. For fluorography, the domestic product RF-3 is produced. These films are not suitable for automatic development in a developing machine. In recent years, Russia has been producing RM-D film based on imported raw materials. It is suitable for developing machines and for manual development.
Commercially available imported films, on the contrary, are only suitable for developing machines. They cannot be developed with high quality manually. The following table reflects the types of imported films and their parameters:
| A country | Film | Developer | Development time (sec) | Development temperature (° Celsius) |
Medium Gradient | Sensitivity |
| Belgium | Agfa-Gevaert (CurixXP) | G230 | 480 | 20 | 240 x 10 -2 | 1000 |
| Germany | Retina (XVM) | P-2 | 240 | 240 x 10 -2 | 1200 | |
| TRM-103P | 240 | 300 x 10 -2 | 1200 | |||
| T93 | 360 | 260 x 10 -2 | 1500 | |||
| Czech | Foma (Medix MA) | P-2 | 120 | 240 x 10 -2 | 600 | |
| D.P. | 360 | 250 x 10 -2 | 1000 | |||
| Foma (Medix 90) | D.P. | 240 | 250 x 10 -2 | 950 | ||
| Fomadux | FOMADUX | According to instructions | 470 x 10 -2 | 650 | ||
| Poland | Foton (XS1) | R-2 | 120 | 230 x 10 -2 | 950 | |
| WR-1 | 360 | 290 x 10 -2 | 1200 | |||
| Foton (XR1) | WR-1 | 360 | 250 x 10 -2 | 850 | ||
| Doorman | Typon (TypoxRP) | P-2 | 240 | 260 x 10 -2 | 600 |
Agfa blue-sensitive film, especially Agfa D5, is popular in Russian radiology. It is successfully used in radiography of the lungs, bone structure, and angiography. She details the photo down to the smallest nuances. The manufacturer claims image stability when developing conditions change, and clarity when developed with weaker developers. When using Agfa D5 blue-sensitive film, Agfa recommends purchasing developer and fixer from the same company.
Exposure process
Domestic films for classical purposes are sold in cassettes to maintain light resistance. They come with sets of screens for reinforcement. Manufacturers make sure that the screens do not have mechanical damage. After use, the screens are wiped with cotton wool soaked in a solution specially developed for this purpose.
Photo exposure parameters depend on the screen parameters, the parameters of the X-ray film, the development conditions, and the developing and fixing reagents. All the necessary conditions are set automatically in the X-ray film developing machine. If development occurs manually, you must first take care of optimal conditions image processing.
Developing a photo
X-ray film developer X-ray-2 is popular among radiologists. On films produced in the Fatherland, there is a marking that says how long it takes to develop the film in the specified developer at a given temperature (20 degrees). If the temperature is increased by 1 degree, you need to reduce the photo development time by 10%. If the temperature is reduced by 1 degree, the photograph development period is increased by 10%. The temperature should not differ from the optimal temperature in any direction by more than 4 degrees.
More modern domestic developing reagents TRM-110R and Renmed-V have become available for sale. They develop the same photo in 20% less time. In 1 liter of such a developer you can develop 1 m 2 of the source material. Then the reagent is depleted.
Pre-washing and fixing
The developed film is thoroughly washed in normal cold water. In the room where the treatment takes place, it is necessary to have a washbasin with a tap and water. It is even better to rinse the film in a slightly acidified liquid. If you pour a 1.5% acetic acid solution into a basin and rinse the photograph in it, the development of the photo will stop.
Fixation is the destruction of unreduced silver from the emulsion layer of the photograph. This stage occurs gradually. First, the unexposed pieces of film lighten as the emulsion disappears from them, then the chemical process affects the exposed part of the sheet.
The time required to fix the film is written on the fixer packaging. It depends on the pH indicator. The pH for fixation should be between 4 and 6 units. In 1 liter of fixer, you can process from 1 to 2 m 2 of film, depending on its type.
Final washing and drying of the image
To remove residual silver ions, after fixation, the image is washed under running water for a quarter of an hour. Then, to prevent streaks from forming, it is rinsed in a bowl of distilled water.
The film is dried in a clean room, from which suspended dust and foreign substances have been removed, or in a drying cabinet at a temperature of 55-60 degrees Celsius. After drying, the photograph can be cut into pieces or the light edges of the sheet can be trimmed.
Using Processing Machines
The radiography rooms of paid clinics have acquired automatic machines for processing X-ray film. The entire procedure for developing and fixing the image takes place there according to pre-configured parameters. It occurs at a higher temperature in less time. The entire image processing process takes a few minutes.
After chemical processing of the film, the photographs themselves, the developer and fixer contain silver ions. This metal is subject to reuse in industry, therefore recycling of radiography materials is important. There are companies that deal with recycling.
When choosing X-ray film, it is necessary to take into account the parameters and conditions of image processing. Domestic films are suitable for manual processing, while foreign films are suitable for developing machines.
27.10.2012
The development of photographs involves the restoration of microcrystals of silver halides in areas of the film exposed to radiant energy.
The development of photographs involves the restoration of microcrystals of silver halides in areas of the film exposed to radiant energy. In tank development, the radiographic film is mounted in a stainless steel frame before being immersed in the solution. To remove air bubbles from the film, you need to smoothly lower it together with the frame into the developer, then slightly lift it 2-3 times and lower it again. After this, the tank is closed with a lid until the development is complete. The development time is usually indicated on the film packaging. In this case, they proceed from the optimal temperature of the developer solution (+ 18 ° C). However, in practical work It is not always possible to maintain a stable temperature of solutions. Additionally, as the amount of film developed increases, the developer becomes depleted. Therefore, it is necessary to adjust the development time taking into account the temperature of the developing solution and the amount of developed film.
With the correct organization of the photochemical process as in the project, processing 1 m 2 of radiographic film requires about 1 liter of developer and about 1 liter of fixer.
Obviously, counting the surface area of the developed film provides a clear picture of the condition of the developer. If the manifestation time at stable temperature developer increases by 2 times, which means that the developer has become unusable and its further use is impossible.
For a significant amount of work, the use of a refreshing reducing agent solution is very effective. The latter contains the same reagents as the developer, but in higher concentrations. The reducing agent is added to the tank in such a way that the level of developer in it remains constant, despite partial carryover of the solution along with the developed film. Thanks to this, it is possible to maintain stable activity of the developer for a longer time and increase the area of the developed film by almost 4.5 times. It is considered acceptable to add 1 liter of reducing agent for each liter of developer. After this, the developer should be replaced with a new one.
The developed X-ray film is removed from the developer and held for some time over an open tank, allowing the remaining solution to drain, then the film is washed in clean water.
Fixation involves the dissolution of silver halides, which remain unreduced and can decompose when exposed to light. For this purpose, a standard acidic fixer is used (a solution of sodium thiosulfate to which some acidic salt or acid has been added). The duration of fixation depends on the temperature and concentration of the solution, the degree of its depletion, etc. A 40% concentration of sodium thiosulfate is considered optimal. As the temperature of the solution increases, the rate of fixation increases. But at the same time, the mechanical strength of the gelatin film decreases. The temperature of the fixer is allowed to fluctuate from 10 to 24 C. It is desirable that it corresponds to the temperature of other solutions. When working in hot climates, use a standard tanning agent.
The time required to record radiographs is determined by the lightening of the emulsion layer (disappearance of the milky white color). Fixing is considered complete if the radiograph remains in the fixing solution twice as long as is necessary to completely brighten the film. As the fixative is depleted, the duration of fixation increases. If the duration of film lightening doubles, the fixer must be replaced.
It is advisable to rinse the radiographs in running water for at least 30 minutes. If this is not possible and the films have to be washed in stagnant water, then it should be changed every 5-10 minutes, increasing the washing duration to 1 hour. Checking the quality of washing of radiographic film can be done using a simple chemical reaction. The same amount of solution containing 0.01 potassium permanganate and 0.1% sodium hydroxide is added to the wash water sample. If traces of thiosulfate remain, the characteristic pink color of permanganate will change to green or yellow, indicating that the film has not been washed sufficiently.
To dry, radiographs are hung on metal hooks or clips in a dry, well-ventilated room, where they are kept for several hours at an air temperature not exceeding 30 J C. During drying, the films must be placed so that they do not touch when air moves, otherwise Possible gluing and damage to radiographs. It is better to dry films in special drying cabinets.
Tags: lecture on radiology
Start of activity (date): 10/27/2012
Created by (ID): 6
Keywords: x-ray at home
X-ray technique
Study of the internal structures of an object, which are projected using X-rays on photosensitive materials (X-ray film or paper)
Advantages of radiography:
Wide availability of the method and ease of research
Does not require special patient preparation
Relatively low cost of research
Radiographs can be used by other specialists, which avoids repeated examination and evaluates the dynamics of the pathological process
Is a medical document
Disadvantages of radiography:
Static image, which does not make it possible to assess organ functions
The presence of ionizing radiation that has a harmful effect on the object under study
The information content of classical radiography is below modern methods visualization due to projection layering of complex anatomical structures
Little informative for the study of soft tissues
Complex photochemical film processing process
Difficulty archiving film
Technical defects in production require re-examination
Requires considerable time to process film
Types of radiographs:
Survey X-ray
Sight radiograph
Contact radiograph
Tangent of radiographs
No. 5 Obtaining an X-ray image on the screen - the fluoroscopy method (method of obtaining the image, the main positions of the patient during X-ray). No. 6 Obtaining an X-ray image on a screen - the fluoroscopy method (advantages and disadvantages).
Fluoroscopy technique:
A study of the internal structure and functional changes of organs and systems, in which the image is obtained on a fluororeminiscent screen at the present moment in time.
Orthoscopy is an examination of the patient in a vertical position (in direct, lateral, oblique projections and with different inclinations of his body) with horizontal X-rays.
Trochoscopy is performed with the patient in a supine position with the X-rays directed vertically.
Lateroscopy – the patient is in a supine position, but the rays pass horizontally.
Advantages of fluoroscopy:
The research is carried out in real time (here and now)
Makes it possible to evaluate the function of the object under study
Makes it possible to quickly localize the pathological focus
Makes it possible to control the implementation of instrumental procedures and surgical interventions
Disadvantages of fluoroscopy:
High radiation dose to the patient
Low spatial resolution
Subjectivity in assessing the results obtained
Not a medical document
Does not allow assessment of the dynamics of functional changes
No. 7 Fluorography. The principle of image acquisition, advantages and disadvantages of the method.
Fluorography:
X-ray examination, which consists of photographing a fluororeminiscent screen onto which an x-ray image of the object being examined is projected
Types of fluorography:
Small frame - pictures measuring 24x24 mm or 35x35 mm
Large frame – pictures measuring 70x70 mm or 100x100 mm
Advantages of fluorography:
Speed of research
Low research costs
Low radiation exposure to personnel
Convenient archive storage
Disadvantages of fluorography:
Large dimensions of fluorographs
No. 8 Layer-by-layer X-ray examination (tomography) Principle of image acquisition, concepts: “tomographic layer”, “step”. No. 9 Layer-by-layer X-ray examination (tomography). Sonogram: the principle of obtaining an image.
Tomography - layer-by-layer x-ray examination
Tomography is a method of radiography of individual layers of the human body. A conventional radiograph produces a summation image of the entire thickness of the part of the body being examined. Images of some anatomical structures partially or completely overlap the images of others. Because of this, the shadow of many important structural elements of organs is lost. Tomography is used to obtain an isolated image of structures located in any one plane, i.e., as if to divide the summation image into its constituent images of individual layers of an object. Hence the name of the method - tomography (from the Greek tomos - layer).
The tomography effect is achieved through continuous movement while shooting two or three components of the X-ray system - emitter, patient, film. Most often, the emitter (tube) and film are moved while the patient remains motionless. In this case, the emitter and the film move along an arc, line or a more complex trajectory, but always in mutually opposite directions. With such movement, the image of most of the details on the x-ray image turns out to be unclear and smeared. A sharp image is provided only by those formations that are located at the level of the center of rotation of the tube-film system.
Structurally, tomographs are made in the form of separate X-ray machines or special devices(attachments) to conventional X-ray units. The attachment is a mechanism for moving the emitter and cassette during shooting.
“Tomographic layer” is a selectable layer of the organ under study, all elements of which are clearly imaged on the tomogram.
"Step" is the distance that determines the difference in height of two adjacent tomographic layers.
Sonogram is a type of tomogram in which images of layers of great thickness are obtained using small swing angles of the moving tomograph system.
No. 10 Computed tomography (CT). Method of obtaining an image, feature of radiographic film. No. 11 Computed tomography (CT). Advantages and disadvantages of the method. Scope of CT in medicine.
CT scan.
Method of layer-by-layer study of the internal structure of an object. Based on the measurement and complex computer processing of the difference in the attenuation of X-ray radiation by tissues of different densities.
The receiver is a Gantry ring. Same number, just different receiver.
1972 - the CT method was proposed (Kornik, Haunskind - scientists).
1969 – the first scanner was invented based on a mathematical model proposed in 1917 by the mathematician Rodin.
The first CT scans were step-by-step - we determined the size of this step. Processing time is 20 seconds per slice.
Fan CT – processing time was 10-15 seconds.
Spiral CT – the tube moved in a spiral clockwise direction.
Multislice CT since 1992 - several spirals and processing time of 0.7 seconds. The number of spirals is always a multiple of “4”.
The Gantry ring contained several layers of detectors - receivers.
In computer tomography systems, scanning and image acquisition occur as follows: the X-ray tube in radiation mode “walks around” the head along an arc of 2400, stopping every 30 of this arc and making a longitudinal movement. Detectors are fixed on the same axis with the X-ray emitter - sodium iodide crystals, which convert ionizing radiation into light. The latter goes to photomultipliers, which convert this visible part into electrical signals. Electrical signals are amplified and then converted into numbers that are entered into a computer. The X-ray beam, having passed through the absorption medium, is attenuated in proportion to the density of the tissues encountered in its path, and carries information about the degree of its attenuation in each scanning position. The radiation intensity in all projections is compared with the magnitude of the signal coming from the control detector, which records the initial radiation energy immediately at the beam exit from the X-ray tube.
An important condition for ensuring the performance of computed tomography is the patient's stationary position, because movement during the study leads to the appearance of artifacts - interference: dark stripes from formations with a low absorption coefficient (air) and white stripes from structures with a high absorption coefficient (bone, metal surgical clips ), which also reduces diagnostic capabilities.
Feature of radiographic/radiographic film.
X-ray film composition:
Photo emulsion
Analogue radiography
The film contains 7 layers.
Advantages of CT:
Very high resolution;
Opportunity mathematical analysis images and changes in density (the density of water is taken as “0”, measurements are made in Housefield units - Hu).
All the capabilities of digital radiography;
We can perform virtual angiography using iodinated contrast agents;
We can measure bone density;
You can build 3D of any pathological object and perform a virtual operation;
Qualitative bone examination can be performed;
The lungs are clearly visible;
The structure of the brain and liquor-containing spaces are clearly visible.
Soft tissues and parenchymal organs are less visible.
Flaws:
Expensiveness of research.
We get the image:
Thermal printer.
No. 12 MRI. MR tomograph device.
Types of MRI:
Ultra-low-field (0.1 tesla)
Low-floor (0.1 – 0.5 tesla)
Mid-field (0.5-1.0 tesla)
High-field (1.0-2.0 Tesla)
Ultra-high-field (over 2.0 Tesla).
Types of MRI:
Open MRI - open circuit;
Closed MRI – closed circuit.
Types of research:
MRI diffusion – supports a certain movement of water molecules in tissues;
MRI perfusion – determines the permeability of blood through tissue;
MRI spectroscopy – allows you to evaluate biochemical changes in tissues (metabolism);
MRI angiography – obtaining images of blood vessels (sometimes the contrast agent gadolinium is used);
MRI cholangiography;
Functional MRI – makes it possible to determine the position of various centers of the brain (speech, hearing, etc.).
Contraindications for MRI:
Installed pacemaker;
Ferro and electromagnetic middle ear implants;
Large metal implants and fragments;
Ilizarov ferrimagnetic devices;
All metal structures;
Hemostatic clips of cerebral vessels.
Relative contraindications:
Insulin pumps;
Stimulants;
Non-metallic middle ear implants;
Prosthetic heart valves;
Hemostatic clips, except brain clips;
Uncompensated heart failure;
First trimester of pregnancy;
Claustrophobia;
The need for physiological monitoring;
Artificial maintenance of body functions;
The patient's serious condition.
Any MRI scanner consists of:
a magnet that creates a constant magnetic field in which the patient is placed;
gradient coils that create a weak alternating magnetic field in the central part of the main magnet. This field is called gradient. It allows you to select the area of study of a part of the patient’s body;
transmitting and receiving radio frequency coils; transmitting are used to create excitation in the patient’s body, receiving are used to register the response of excited areas;
a computer that controls the operation of the coils, registration, processing of measured signals, and reconstruction of MR images.
The magnetic field is characterized by induction magnetic field, the unit of measurement is T (tesla) named after the Serbian scientist Nikola Tesla.
There are several types of tomographs (depending on the magnitude of the constant magnetic field):
0.01 T - 0.1 T → with ultra-low field;
0.1 - 0.5 T → with a weak field;
0.5 - 1.0 T → with average field;
1.0 - 2.0 T → with a strong field;
>2.0 T → with super-strong field.
There are three types of magnets for MRI scanners: resistive, permanent and superconducting.
Tomographs with a field of up to 0.3 Tesla most often have resistive or permanent magnets, above 3.0 Tesla - superconducting ones.
The optimal magnetic field strength is a constant subject of debate among experts.
More than 90% of magnetic resonance imaging scanners are models with superconducting magnets (0.5 - 1.5 Tesla). Tomographs with ultra-high fields (above 3.0 Tesla) are very expensive to operate. Permanent magnets on the contrary, they are cheap and easy to use.
No. 13 MRI. Obtaining an MRI image.
A tomographic method for studying internal organs and tissues using the physical phenomenon of nuclear magnetic resonance, based on measuring the electromagnetic response of the nuclei of hydrogen atoms to their excitation by a certain combination of electromagnetic waves in a constant high-intensity magnetic field.
Magnetic resonance imaging (MRI) uses a magnetic field to produce images. This causes all the hydrogen atoms in the patient's body to line up parallel to the direction of the magnetic field. At this moment, the device sends an electromagnetic signal perpendicular to the main magnetic field. Hydrogen atoms that have the same frequency as the signal are “excited” and generate their own signal, which is picked up by the device. Different types of tissues (bones, muscles, blood vessels, etc.) have different numbers of hydrogen atoms and therefore they generate a signal with different characteristics. The computer recognizes these signals, deciphers them and builds an image.
Normal cells of organs and tissues that are not affected by a disease process have one signal level, “sick” cells are always different, altered to one degree or another. Due to this phenomenon, in the image obtained during MRI, areas of tissues and organs changed by the pathological process look different from healthy ones.
Images obtained from MRI contain a huge amount of information about the structure of organs and tissues in a certain anatomical area. The structure, the relationship of organs with each other, their size, configuration - these are the main parameters that we evaluate during the study.
No. 14 MRI. Main indications and contraindications.
Contraindications for MRI
Absolute:
Presence of a pacemaker;
Availability of endoprostheses and stabilizing systems made of ferromagnetic alloys;
Middle ear implants (fixed hearing aids);
Condition after clipping of cerebral vessels;
Presence of foreign metal bodies (shards, bullets).
Relative:
(depends on the strength of the magnetic field)
1st trimester of pregnancy;
Presence of clips on vessels (except intracranial);
Prosthetic heart valves;
Sternal wire sutures;
Presence of intravascular stents;
Decompensated somatic conditions
Claustrophobia.
Indications for MRI:
Neurology and neurosurgery
Diagnosis of tumors of the brain and spinal cord and assessment of their dynamics before and after treatment
Diagnosis of demyelinating diseases of the brain and spinal cord (multiple sclerosis), determination of their activity, assessment of the dynamics of changes
Diagnosis of inflammatory diseases of the brain and spinal cord
Detection of arteriovenous malformations of the brain and spinal cord
Diagnosis of cerebral and spinal circulation disorders and their consequences
Diagnosis of traumatic brain injuries and their consequences
Diagnosis of malformations of the brain and spinal cord
Assessment of the condition of the pituitary gland, diagnosis of the presence of adenomas, assessment of the dynamics of changes
Evaluation of the results of surgical interventions on the brain, spinal cord, and spine
Traumatology + rheumatology
Injuries and diseases of the joints: shoulder joints, elbow joints, hands, hip joints, knee joints, ankle joints (tumors, degenerative diseases, chronic arthritis, fractures, tendon and ligament ruptures, meniscal injuries, dislocations, inflammatory diseases).
Injuries and inflammatory diseases of the spine
Osteochondrosis, diagnosis of hernias and protrusions of intervertebral discs
Tumors of bones and soft tissues
Gynecology
Diagnosis of tumors of the bladder, uterus, appendages and assessment of their spread to adjacent structures
Diagnosis of inflammatory diseases of the small organs (adnexitis)
Urology
Diagnosis of tumors of the kidneys, bladder, prostate gland and assessment of their spread to adjacent structures
Diagnosis of inflammatory diseases of the kidneys, bladder, prostate gland
Diagnosis of urolithiasis
Gastroenterology
Diagnosis of liver and pancreas tumors and their dynamic assessment
Diagnosis of cholelithiasis, incl. examination of the bile ducts for the presence of stones in them
Assessing the severity of organ injury abdominal cavity
Diagnosis of liver condition (fatty hepatosis, cirrhosis) and dynamic assessment
Diagnosis of acute and chronic inflammatory diseases of the abdominal organs (hepatitis, pancreatitis)
Study large vessels
Diagnosis of the presence of atherosclerosis
Aneurysms.
No. 15 Ultrasonography. Construction of an ultrasound image. Types of sensors. Scope of their application.
Ultrasonography
The use of ultrasound, whose frequency is approximately 30,000 Hz, to obtain images of deep structures of the body. The ultrasound beam is directed to the surface of the body being examined through a special sensor used to examine the abdominal organs (for comparison: transvaginal ultrasonography); The echo of the reflected sound is used to form an electronic image of various body structures. Based on the principles of underwater location, ultrasonography allows you to observe the development of the fetus in the uterus. It is also used to diagnose pregnancy, determine the duration of pregnancy, diagnose multiple pregnancies, malpresentation of the fetus and chorionic anomaly; Ultrasonography allows you to determine the location of the placenta and identify some abnormalities of fetal development. Types of sensors:
1. convex - abdominal
2. microconvex (vaginal, rectal, transcranial - through the fontanelle);
3. linear (breast glands, thyroid gland, muscles, tendons).
4. sector – used in cardiology;
5. through the esophagus (looking at the heart);
6. biplane - any 2 together;
7. 3D and 4D – volumetric;
8. pencil/blind – separate receiver and emitter;
9. video-endoscopic;
10. needle/catheter – intracavitary administration of drugs into hard-to-reach vessels.
No. 16 Bronchography. Two main bronchography techniques. The role of the x-ray technician.
Bronchography is an x-ray examination of the bronchial tree, which is carried out after the introduction of an iodine-based x-ray contrast agent into the bronchi. After the contrast envelops the walls of the bronchi from the inside, they become clearly visible on x-rays.
The value of bronchography
The main advantage of bronchography is that it allows you to study in detail the structure of the entire bronchial tree. In this regard, it is often more effective than endoscopic examination - bronchoscopy.
The main disadvantages of bronchography:
the examination must be carried out using general or local anesthesia, otherwise it will cause severe discomfort to the patient;
the use of general anesthesia in children is mandatory;
anesthetics and iodine-containing drugs that are used during bronchography can cause allergic reactions;
Bronchography involves radiation exposure to the body, so it cannot be done frequently; some groups of patients have contraindications.
Preparing for the study
If bronchography is performed under local anesthesia, the patient should not eat 2 hours before the examination. If general anesthesia is planned, this time will be longer.
The day before and on the day of bronchography, careful oral hygiene should be performed.
If the patient wears dentures, they must be removed before the examination.
Before performing a bronchography, you need to urinate.
Carrying out bronchography
Bronchography is carried out on a dental chair or on an operating table, which can be given a suitable configuration.
Mandatory room equipment for bronchography:
X-ray machine;
a catheter or bronchoscope to inject contrast into the lungs;
X-ray contrast agent;
resuscitation kit.
Progress of the study:
The patient is placed on the dental chair or operating table. He should take the most comfortable and relaxed position - this will facilitate the examination.
If bronchography is performed under general anesthesia. The anesthesiologist gives the patient mask anesthesia. After this, the mask is removed from the face and the trachea is intubated.
If bronchography is performed under local anesthesia. Using a spray, anesthesia is administered to the oral cavity. Then a bronchoscope is inserted, through which an anesthetic is administered, and then a radiocontrast substance.
Before injecting contrast into the bronchi, the doctor may perform a bronchoscopy - examine the mucous membrane using a bronchoscope.
The contrast should evenly fill the bronchi and be distributed along their walls. For this, the patient is turned over several times, giving him different positions.
Then a series of x-rays are taken - in direct, lateral and oblique projections.
No. 17 Digital radiography. Receiving a digital image. The role of the x-ray technician.
This is the transformation of a traditional X-ray image into a digital array with the subsequent possibility of processing X-ray images using computer technology.
The essence of digital image:
When converted to digital, an X-ray image is broken down into tiny elements called pixels.
The brightness of which is determined by the degree of absorption of radiation by tissues.
The result is a matrix (base) with the dimension: number of rows by number of columns.
The dimensions of the digital image matrix range from 1024*1024 to 4096*4096;
The brightness of a pixel in a digital X-ray image is represented by 12 bits (shades), which allows simultaneous differentiation of both dense and soft structures.
Thus, digital radiography has the following advantages:
Allows you to modulate the contrast and brightness of the image;
Perform image processing (filter, measure, enlarge);
Archive images on your hard drive and external media;
Reduce examination time and radiation exposure by 10 times.
Ways to form numbers:
1. Analogue:
Indirect
2. digital
Indirect
Analog
Receiving device – film/luminous screen. When performing a direct analog examination, there must be sufficient X-ray power to obtain a high-quality image at the receiving device.
Indirect analog X-ray examination: X-ray energy is converted into electricity using a special device (URI) = image on the screen.
Indirect digital technology – indirect analog + digital.
With this technology, X-ray energy is first converted into electricity using a URI, and then converted into digital (two intermediaries).
Advantages of indirect numbers:
Due to the lack of additional studies, radiation exposure is reduced;
It is possible to process an X-ray image using a computer;
Convenient archiving, the ability to replicate an infinite number of copies of an x-ray image;
Possibility of online consultations.
Ways to set the number:
Installation of the digitizer directly on the X-ray machine;
Using special electrical cassettes and processing them in a digitizer (a device in the cassette itself).
Flaws:
The image is virtual;
The cost of research increases.
Direct digit:
From the X-ray tube directly to digital. When using digital technology, X-ray radiation is converted into digital radiation at a lower radiation power and computer processing at a low radiation dose produces a high-quality X-ray image.
Advantages of numbers:
The reduction in radiation exposure is 8-10 times less than analog;
Higher resolution;
Makes it possible to more accurately assess the nature of the pathological focus;
Possibility of computer image processing and its mathematical analysis = we avoid subjectivity in image evaluation;
The speed of obtaining an image on a computer screen, since a lengthy photochemical process is eliminated;
Convenient archiving and analysis of the dynamics of changes;
Online consultations.
Disadvantages - see above indirect figure.
No. 19 Photochemical processing of X-ray films. Manual development. No. 20 Photochemical processing of X-ray films Automatic photoprocessing. No. 21 Photochemical processing of X-ray films. Types of developing machines. No. 22 Photochemical processing of X-ray films. Defects and artifacts during manual development. Reasons for their elimination.
Photolaboratory process in radiology.
An X-ray image can be obtained on many media containing photographic emulsion (cassette/X-ray film).
X-ray film composition:
Photo emulsion
Analogue radiography
The base is a flexible film, strong enough and transparent to visible light, made from cellulose (cellulose triacetate).
Photographic emulsion is applied to the base on both sides.
For a stronger fixation to the base, it is pre-lubricated with glue (gelatin + antibiotic).
To protect the emulsion layer from mechanical damage, this layer is coated on the outside with a special water-borne varnish.
The film contains 7 layers.
Composition of photographic emulsion:
The main ingredient is a photosensitive substance (silver bromide salt - silver halogen) that is most sensitive to x-rays and visible light.
Converting halogen silver to reduced silver.
Silver halogen ←light + x-rays
Developing agent Reduced silver
ArBr - under the influence of X-rays, the bond between them becomes less strong; to completely break the bond, you need a developing substance = lower the film into the developer (finally breaking the bond).
Silver halide is sensitive to light (blue-violet region) and almost does not react to yellow and red, infrared radiation.
Photo emulsion ↙↙↙yellow (orange
↘↘↘sensitized film.
Blue + yellow = green sensitive film.
Thus, the amount of silver was reduced, but the structure also decreased.
Silver halide is insoluble in water. It cannot be applied in a thin layer.
Photographic emulsion ↔colloids = dries and swells in cold water, becoming permeable to photographic solutions.
Colloids are gelatin, they are added to the photographic emulsion.
In X-ray film, the main layer is the emulsion. The most necessary component in it is a photosensitive substance (silver halogen).
During fluoroscopy, a latent image is formed in the film emulsion;
The development of an X-ray image is the first stage of the photochemical process, which allows the latent image to be converted into a visible image, followed by fixation.
Manifestation:
Automatic.
Manual processing of radiographs;
Manifestation;
Intermediate flushing;
Fixing/fastening;
Final rinsing;
Manifestation.
The first stage of the photochemical process, which allows you to convert a latent image into a visible one.
This is done in special tanks (4 pieces).
1 tank – developer – red cap, the developer consists of three components (A, B, C).
First, pour water at room temperature.
As you pour in each next component, mix everything together with a wooden stick. When everything is ready, let it sit for 5-10 minutes.
If component “B” is dark brown in color, it cannot be used!!!
The developer is a complex compound:
Developing agents;
Preservatives;
Accelerating substances;
Anti-vocal substances.
Developing substances:
Metol (detailed, but low-contrast manifestation) – image detail;
Hydroquinone (significantly increases image contrast) – blackening of the image;
Phenidone (in terms of its manifesting ability, it is weaker than metol, the effect is similar).
Preservatives:
Sodium sulfite;
Potassium metabisulfite.
The function is to neutralize oxidative processes in the developer. The developer environment is always alkaline. Hydroquinone cannot work in acidic environments.
Accelerating substances:
To maintain a constant alkaline environment
Improves the swelling of gelatin in emulsion
Increases the depth of contact of the developing substance with silver halide:
Sodium carbonate (potassium)
Anti-fouling agents
During development, the darkening of the film due to the optical veil is reduced.
Potassium bromide
Benzotriazole/benzimidazole
Bromine salts formed during development.
An optical veil is formed during development.
Intermediate rinsing – tank No. 2 (water, for 15-20 seconds).
To remove developer residues from the film surface so that the alkaline environment in the developer does not contaminate the alkaline environment of the fixer.
Tank No. 3 is an acidic environment.
Fixer/fixer – blue.
Fixation - after development in the emulsion, the image is restored in varying degrees metallic silver and its unreduced halide form, which requires removal from the emulsion.
An unfixed photo darkens and the image in it is destroyed.
Fixer composition:
Sodium sulfate hyposulfite (dissolves unreduced silver);
Sodium sulfate (stabilizes hyposulfite in solution);
Acids: sulfuric, acetic (creating an acidic environment - effectively fixing the image;
Ammonium chloride (ammonia) to speed up the fixation of the image, allows you to reduce the fixation time by several times.
When adding aluminum or chromium-potassium quartz to the fixer, they tan the fixer (prevent excessive swelling of the emulsion and its sliding off the substrate = for automatic development, at high temperatures. We heat the developer. We change the developer at the end of the working day (for manual development). Fixer - 2-3 days (manual development).
Final rinse:
Complete removal of the film of all chemicals from the emulsion (using running water) - the duration of this process is 25-30 minutes.
Average duration of individual stages of photochemical processing:
Auto development differs in the percentage of elements to be developed.
Manifestation;
Fixing;
Final rinsing;
Intermediate development is replaced by rollers that remove solution residues and excess water, and they also move pictures from one compartment to another.
Developing machines:
According to the principle of operation:
In a dark room;
In a bright room.
By speed: (dry to dry shot)
Medium speed (3.5 minutes; 28 degrees);
High-speed (90 seconds; 36 degrees);
Super high-speed (45-60 seconds; 40 degrees).
Developing machines consist of:
Three sections with processing solutions, rinsing water and drying;