Before as proceed In order to present the technique of manifestation, it is necessary to recall some truths that are often forgotten.
It should be remembered that contaminated developer cannot be used. Contamination of the developer with gelatin residues or pieces of film that rot over time leads to decomposition of the developer. Therefore, a foul-smelling and cloudy developer should be poured out immediately and the dishes thoroughly cleaned.
Developer contamination even a small amount of fixer is one of the reasons for the appearance of a dichroic veil on x-rays. An exhausted developing solution also cannot be used, as mentioned above.
Ignorance temperature solution and development time can lead to defective x-rays. Always know the temperature of the developer and the normal development time at that temperature. Knowing the conditions under which the picture was developed, one can judge the correctness of the choice of technical conditions when shooting. The readiness of the image is usually checked visually by the light of a laboratory lamp. If the picture has to be removed from the developer before the normal development time has elapsed, then this indicates overexposure when shooting. In this case, the photographic properties of the film (its sensitivity and contrast) remained partially unused, which means that both the image quality and the patient who received excessive exposure suffered.
manifest radiographs at temperatures developers below and above those indicated in the table should not be used, as this may lead to a deterioration in image quality and even complete unusability of the images.
When the film is developed in too much With a warm developer, a common gray or dichroic veil, reticulation, and other defects may appear on x-rays.
With a long stay of the exposed film in developing solution elevated temperature the emulsion layer may melt and slide off the substrate, or conglomerates may form, which will increase the blurring of the image by indirectly reducing the resolution of the x-ray film.
If time manifestations increase above normal, then at first the image contrast will begin to rise, and then a general gray veil will appear, which will cover the details of the X-ray image in the bright places of the X-ray image, up to their complete disappearance, and, naturally, the image contrast will decrease sharply.
If time manifestations is maintained and the temperature of the developer is below the allowable temperature, then a correctly exposed x-ray image will be underdeveloped.
If time manifestations is maintained and the temperature of the developer is higher than that specified in the recipe, then a correctly exposed x-ray will be overdeveloped.
Re-manifestation or underdevelopment of x-rays in order to correct errors in the exposure often leads to the marriage of pictures. This should always be kept in mind and exposed in such a way that significant deviations from normal development are not required. This reminder is not unfounded, since among some of the workers in X-ray diagnostic rooms there is a tendency to develop overexposed X-ray images in an old, depleted developer, and underexposed X-rays in a fresh, warm developer.
In addition, there are cases, especially when developing pictures in baths, when a warm developer is added to a cold one or a cold one to a warm one, or during development, the vessel with the developer is heated on one side, i.e., temperature unevenness is created in the developer. In such cases, x-rays may appear marbling, which cannot be corrected (the term "marbling" in photography refers to a defect on the negatives that has wavy light stripes in the form of honeycombs).
X-ray waste requires special collection, storage and disposal. Competent processing of x-ray film does not harm nature and the environment and is used in secondary production.
In other countries, the problems of preservation and collection of medical waste are given increased attention. Even at the initial stages, the garbage is sorted and then competently collected and stored. Russia is no exception. In Russia, special instructions and documents have been developed, in accordance with which actions are taken regarding the collection, storage and processing of X-ray film, which is a particularly dangerous class.
There are specialized organizations that have licenses and operate in accordance with established standards. Organizations have documents for equipment, instructions, qualified workers. It is also necessary to conclude an agreement with a medical institution with which the organization cooperates.
Storage of radiology waste
- diagnostic laboratories:
- x-ray rooms;
- departments in which work is associated with radioisotopes.
The huge danger to people and the environment of waste products of group D involves the collection and storage under control in accordance with regulations. Waste is collected first in disposable containers, then moved to reusable containers. All storage packages are blue in color and are marked with a radioactive sign.
The collection and storage of class D salvage is carried out upon generation and is packaged separately from other waste groups. Actions, including the collection, storage, transportation and processing of waste products of group D are recorded in a special accounting journal.
About what classes are divided into everything in our country, they briefly talk in the next video
X-ray film processing methods
For the production of X-ray film, mainly materials that contain precious metals are used. For this reason, the used film is recycled if possible, if not, then the material is disposed of.
In most cases, if recycling is not possible, the X-ray film waste is incinerated. For destruction, stoves are used, which are equipped with an electric filter. It serves to pass the gas that appears during combustion and retains approximately 90 percent of the dust. Almost pure gas with a small amount of impurities of various elements is emitted into the air. The remaining dust and ash is transported to enterprises where silver is extracted from them, which is the main task of processing.
Incineration of photo waste is not ideal, as it pollutes to some extent environment and do not save the basis of the material for later use.
In connection with this problem, several methods have been invented:
- Biochemical. It consists in placing the crushed waste in a vessel filled with water with the addition of enzymes and sulfuric acid. Due to the additives, the gelatin that is present in the emulsion coating is rapidly destroyed. A precipitate appears in the container, which contains silver. After drying, the substance is transported to production for further processing.
- Non-enzymatic. In this way, a large amount of silver is extracted. The solution is prepared from bleaching agent and alkali hydroxide. X-ray waste is placed in a container for a short period of time at high temperatures. The base is obtained clean and undamaged, and the precipitate is boiled, neutralized with acid from minerals and dried. The advantage of the method is that no grinding of materials is required and they remain intact.
- A special method is used for marriage and exposed materials. First, the materials are bleached with copper sulphate and table salt, then washed in stagnant water. After that, sodium thiosulfate removes the halide salts. In conclusion, washing again follows. This method allows you to extract 1 kg of silver from 1000 kg of x-rays, the base is disposed of.
- Chlorine treatment. Silver is removed in a 1.5% solution. After 3 hours of placing the materials in the solution, the paper is easily removed.
- Removing the base in hot water. The film is placed for approximately 10-15 minutes. in a container with water, the temperature of which is about 90 degrees. Then the base is removed and a new batch of materials is placed. The result is a substance in the form of a jelly containing silver. Sodium carbonate is added to this mass and everything is thoroughly mixed. The sediment that appeared at the bottom is dried and processed.
Note! Recycling of radiology waste is carried out by organizations that have a special permit!
How to dispose of x-rays
Disposal of x-ray film requires special rules. In addition to photographic film, organizations purchase waste fixing solutions, developers, X-ray tubes, etc. The images accumulated in the archives are disposed of by modern technological methods.
Important! In no case should the employees of X-ray rooms independently dispose of film and fixer on their own in order to avoid chemical burns and other kinds of injuries!
X-ray tubes are used as a source of ionizing radiation. Since X-ray tubes are generating, they do not contain radiation. They are sources of radiation after receiving voltage. Since de-energized tubes are not dangerous, their transportation and storage are made without special requirements.
Important! It is established by law that all actions related to the receipt, storage, disassembly and disposal of tubes for X-ray rooms should be carried out only by licensed companies!
For this reason, at the end of actions with generating radiation sources, medical institutions transfer X-ray tubes to third-party institutions, observing legal requirements and standards in order to ensure safe delivery and disposal. The law provides for the need to familiarize the body state power, which produces sanitary and epidemiological supervision on the transfer of a source of generating radiation.
It is not an easy task to properly collect and store waste from X-ray rooms, transport them to the appropriate places and dispose of them in an environmentally friendly manner. But there are special organizations that are professionally engaged in this type of activity, they should be contacted if there is a need to export x-ray film.
With the development of approximately 75% of the silver bromide in the emulsion layer, it is not restored to the metal and remains in the photographic layer, so the developed image is not transparent and fragile. It is impossible to take such a film out of the developer into the light, because under the action of light the unreduced silver bromide will decompose and the image will deteriorate. To make the image lightfast, it is necessary to remove the silver bromide remaining in the emulsion layer and, moreover, so as not to affect the metallic silver that makes up the image.
The process of removing silver bromide is called fixing , or fixing the visible image . The fixing agent, entering into chemical interaction with silver bromide, converts it into soluble compounds, which are removed by subsequent washing. In this regard, the image obtained during development becomes insensitive to light and is fixed. The removal of excess silver bromide from the film, which remains in the emulsion layer after development, is carried out using the basic substance - sodium thiosulfite ( hyposulfite ), and in fast-acting fixers - also ammonium thiosulfite .
Before immersing the developed film in the fixer, the developer must be removed from the film to interrupt the development process and prevent contamination of the fixer. To do this, after removing the film from the developer, hold the film for 7-8 seconds over it to drain the solution, and then spend intermediate washing in water . The flushing time is 20 - 30 seconds in running water and at least 40 - 50 seconds in still water. With a shorter time, the developer is not completely removed from the swollen gelatin.
Types of fixing solutions. In addition to the usual solution of hyposulfite in water, acidic, acidic tanning and fast fixing solutions are also used, which, in addition to hyposulfite, include acid salts or acids, tanning agents and accelerating agents.
Ordinary fixer is a neutral solution of hyposulfite in water. It has a slightly alkaline reaction, and since the development also occurs in an alkaline environment, the film immersed in a hyposulfite solution with traces of a developer in the emulsion layer continues to develop for some time. This additional development of the film in the fixer leads to the formation of a two-color, so-called dichroic veils. In addition, the oxidation products of the developer that got into the fixing solution stain the gelatin layer of the film in Brown color, as a result of which, after clarification, the image has yellow-brown shade .
Acid fixer additionally contains an acid or an acid salt that binds an alkali, while the development process stops instantly. Acidified solutions of hyposulfite are better preserved and do not stain for a long time, in addition, in an acidic environment, gelatin swells more strongly, it becomes more permeable, due to which the fixation process is accelerated. To acidify the hyposulfite solution, the following are used: potassium and sodium metabisulfites at the rate of 25 - 30 g per 1 liter of solution, but acetic and boric acids can also be used.
Acid tanning fixer additionally contains tanning agents, which increase the hardness of the emulsion layer and make it more resistant to elevated temperatures. It is used to work in the hot season, when the gelatin layer swells excessively, becomes fragile, and there is a danger of it slipping off the substrate. Used as tanning agents aluminum-potassium or chrome alum , at the rate of 25 - 30 g per 1 liter of solution. The tanning fixer treatment also speeds up the drying of the film.
Fast fixer works three times faster than regular fixers and twice as fast as acid fixers. Used as an accelerating agent in fast fixing solutions ammonium chloride (ammonia) . When using a fast fixer, the fixing time should not be delayed, since this causes a partial dissolution of silver, which makes up the image and weakens the latter.
Preparation of fixative solutions carried out in the same order as the exhibitors. The dissolution of hyposulfite in water is accompanied by the absorption of heat, as a result of which the solution is strongly cooled, therefore, to dissolve hyposulfite, it is necessary to take hot water. When preparing acid fixers with potassium metabisulphite, the hyposulfite must first be dissolved, and then the potassium metabisulphite. It is not recommended to store the fixative solution in bright light for a long time, as this decomposes hyposulfite into free sulfur and sulfite. film fixing process. On the first stage of the fixing process, the unreduced silver bromide of the emulsion layer under the action of hyposulfite passes into sparingly soluble silver salt ; it is difficult to wash out of the emulsion layer and further adversely affects the metallic silver that makes up the image, discoloring it. This first stage of fixation ends with the disappearance of the milky white color of the emulsion layer, i.e. fully coated film . Subsequently, over a time approximately the same as that required to eliminate the milky white color of the emulsion layer, hyposulfite converts the sparingly soluble silver salt formed at the first stage of fixation into easily soluble complex silver salt , which is then easily washed out with water from the emulsion layer. This second stage of fixation provides good image retention on the film and protects it from discoloration.
Minimum fix time is determined by the following rule: the duration of fixation should not be less than twice the development time at a given temperature . White light should not be turned on until the moment of complete enlightenment of the film. When it is turned on, immediately after the film is immersed in the fixer, a dichroic veil forms on it, and sometimes the fixation stops altogether. The second stage of fixation can be carried out in the light.
Fixing time is determined, first of all, hyposulfite concentration sodium in solution. With an increase in its concentration in the range up to 40%, it gradually increases. With a further increase in concentration, fixation slows down, and at a concentration above 60% it stops completely. Fluctuations in the temperature of the solution within ± 4° do not have a noticeable effect on the speed of fixation. Fixation of films in a stirred solution is about two times faster than fixation in a solution at rest. The speed of fixation is also determined by the composition of the fixer solution and the degree of its depletion. Introduction to solution ammonium chloride speeds up the fixation process by two to three times; the more depleted the fixer solution, the longer the fixing process takes. Prolonged use of the same fixing solution leads to its depletion of hyposulfite. As a result of fixation in such a solution, the films turn yellow and become stained.
In 1 liter of fixer, without the use of compensating additives, 2.5 - 3 m 2 of PM-1 film can be processed. Since the application of silver on it is 11.5 - 12 g / m 2, and about 50% of this amount goes into the fixer, then by the end of its work it contains from 15 to 18 g of silver per 1 liter. Due to the scarcity of silver, it is subject to regeneration - extraction from solutions, for which the spent fixer is handed over to special points for the processing of waste containing silver.
The X-ray method is a method of X-ray diagnostics, when pathoanatomical changes in the organ under study are determined by the shadow pattern 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 ordinary light rays, act on the light-sensitive layer of x-ray film. This layer is a solidified suspension of silver bromide (AgBr) crystals in gelatin. There are several theories for obtaining images on films. Without dwelling on the analysis of all existing theories, we present one of them as the most consistent with modern views.
Silver bromide crystals form crystal lattices in which negative bromine ions are bound to positive silver ions by electrostatic attraction. The light-sensitive layer, exposed to the action of X-rays, absorbs some of them. In this case, each absorbed quantum of radiant energy is spent on detaching an electron from a bromine ion, as a result of which a neutral bromine atom is obtained instead of a bromine ion. The split off electron neutralizes the positive silver ion, turning it into a metallic silver atom. Thus, in places of the film exposed to X-rays, the photosensitive layer decomposes with the release of metallic silver. However, it is released in such an amount that the resulting image cannot be seen, therefore 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 intensively in those places of the emulsion, on which more intense X-ray radiation fell, and as a result, the latent image becomes clearly visible. For example, let's take an x-ray of a finger. To do this, we place an x-ray film coated with a photosensitive layer to protect it from light in an aluminum cassette. Let's put a finger on the cassette and direct X-rays on 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 a finger will be exposed to a differentiated x-ray beam.
As you know, the finger is a heterogeneous medium, it consists of tissues of different density. Therefore, the degree of absorption of the X-ray beam passing through the parts of the finger will not be the same. Where the rays encounter a strongly calcified, compact part of the bone along the way, they will hardly pass through, and at the appropriate place the emulsion layer will be exposed to insignificant action of the rays. In places where the rays pass through the less dense part of the bone - spongy, the absorption of the rays will be less and, accordingly, these places of the film will be exposed to more radiation. Soft tissues will hardly delay x-rays, and these places will be exposed to even more radiation.
If the exposed film is removed from the cassette in a room under red light and developed, then we will see a completely black background in the picture, corresponding to the places of the film not covered by the finger. A background slightly lighter than black will give soft fabrics. The spongy part of the bone will give a special bone pattern, which is a complex binding of bone beams; and a continuous light line will give a compact part of the bone. Thus, an x-ray image on film resembles a shadow picture on a screen; but with the important difference that the shadow will light color, and the irradiated places are dark. Therefore, the x-ray is a negative.
To implement the X-ray method of research, you must have: cassettes, intensifying screens, X-ray film and chemicals.
X-ray cassettes serve to protect the films from the action of 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-rays without significant change (aluminum, getinaks, wood, cardboard, etc.), and the back is made of a thick iron plate. There are sides on the front wall, and on the inner surface of the rear wall there is a felt or felt pad, which, when the cassette is closed, fits tightly into the recess of the front wall and prevents visible light from entering the cassette. 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 dimensions: 13X18 cm; 18X24; 24×30; 30X40 cm.
In practice, soft cassettes are sometimes used; they are made in the form of bags of black opaque paper.
intensifying screens. Intensifying screens are used to reduce shutter speed in 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 under the action of X-rays phosphoresces blue-violet light, which strongly affects the light-sensitive 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), which delays the rays going to the latter, is covered with a thinner phosphorescent layer. During the exposure of the film, 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 allows you to shorten the shutter speed during shots.
The screen amplification factor, that is, the ratio of the duration of exposure without screens to that with screens, can be considered on average 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. In X-rays with such screens, defects corresponding to defects in the screens are obtained in the image, which can lead to an erroneous interpretation of the x-ray picture.
In addition to the usual intensifying screens, tin or lead foil with a thickness of about 0.02-0.2 mm is sometimes used. The reinforcing effect of the foil is based on the release of photoelectrons from the foil metal by X-rays. The electrons emitted from the metal are absorbed by the film emulsion, which causes an additional darkening of the latter. The amplification factor of the foil is less than that of conventional intensifying screens and is approximately equal to 2–3. The advantage of foil over screens lies in its fineness and filtering of the scattered radiation coming from the object, which increases the clarity of the image.
X-ray film is a thin, transparent celluloid or nitrocelluloid plate coated on one or both sides with a light-sensitive emulsion. The emulsion consists of microscopic silver bromide (AgBr) crystals evenly distributed in the hardened gelatin.
Different grades of x-ray films differ in their sensitivity and contrast. For x-ray films, contrast is a more important quality factor than sensitivity, since high-quality x-ray images can only be obtained on high-contrast x-ray films.
X-ray film of high quality is produced by our domestic factories, it is released for sale in opaque boxes. The latter are indicated brief description film and method of its processing.
Standard film sizes:
13X18 cm; 18X24; 24×80; 30X40 cm.
Chemicallip. To process exposed film, you need a developer and a fixer.
The composition of the developer includes the following main components: developing substances - metol, hydroquinone; substances that accelerate the manifestation - soda (sodium carbonate), potash; preservative agent - sodium sulfite; retarding manifestation and anti-veiling agent - potassium bromide.
The composition of the fixer (fixer) includes the following substances: fixing agent - sodium hyposulfite; preservatives - sodium sulfite, sodium metabisulphite; tannins - 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 the exposed film.
Image production technique. Pictures are usually taken in two main projections - front and side. If necessary, additional oblique projections are used. Projection is understood as the direction of the central beam of rays in relation to the object being photographed.
For pictures in direct projection, the front-back or back-front direction of the central beam of rays is used. In this case, the cassette is applied, respectively, either from the back or from the front.
In lateral projection, pictures are taken with the direction of the central beam of rays from right to left or left to right, applying the cassette either on the left or on 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, side, inward and back.
Before taking an x-ray, the radiologist should be familiar with the results of the general clinical examination, which determine the nature of the image production.
Depending on the intended image, the size of the cassette and the appropriate film format are taken. An x-ray film is loaded into a cassette in a darkroom under red light as follows: open the cassette and the film box, take one film from the box, put the double-sided film on 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 an emulsion layer to front intensifying screen and the cassette is closed.
To take an image, the charged cassette is tightly applied with its front side to the part of the animal's body to be filmed, and on the opposite side, an X-ray tube is installed with the exit window to the object. The exit window is diaphragmed in such a way that the outgoing cone of rays covers the entire area of the animal's body to be filmed. During the exposure, it is important that the cassette and the object to be photographed are still. If symmetrical sections are removed, the side must be indicated.
To obtain maximum detail and good quality of the X-ray image in the image, it is necessary to choose 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 bone calcification, the sensitivity of the X-ray film and the focus distance to the film.
Rigidity of radiation. The hardness of X-rays depends on the operating voltage. Therefore, in order to obtain a sufficient effect of X-rays on the X-ray film emulsion, it is necessary to correctly select the operating voltage. With insufficient rigidity, the rays can pass through soft tissues, but cannot 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. Too hard beams will pass through in large numbers and obscure the details. Thus, the question of a change in the bone from such a picture cannot be resolved.
Exposure is the product of radiation intensity and illumination duration. The exposure depends mainly on the current in the tube, measured in milliamps. The illumination duration is expressed in seconds. Therefore, the exposure is expressed as the product of milliamps times seconds. For example, the current in the tube is 75 mA, the illumination time is 2 sec. 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 hardness and exposure time is determined by experience.
An error in hardness or exposure can be determined from the image. So, for example, a good image of soft tissues and the complete absence of bone structure indicate low stiffness with a good exposure. Insufficient contrast between soft and bone tissue, general grayness and indistinctness of the pattern indicate excessive rigidity. If you get a dark gray image in which no details can be made out, this indicates excessive hardness and overexposure.
The choice of the direction of the rays is one of the conditions for obtaining a good image, since the exact projection of the object being photographed and the detection of pathological changes depend on the correct choice of the direction of the rays.
From the focus on the anticathode, the rays diverge in a cone up to 180°, and a small beam of rays is required for practical work. 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 cassette plane forms a perpendicular.
There are a number of tools available to help the radiologist find the correct direction of the central beam. The simplest of them is the offset centralizer. Its device is very simple. They take a cardboard circle, in the center of which they strengthen the drink, a small conical weight is hung 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 is even better if, instead of a thread, a rigid rod is attached to the circle. Such a rigid plumb line has the advantage over a thread in that it allows the beam beam to be easily centered even when the latter is horizontal or upward.
Focal length. When taking pictures, a focal length of 70-100 cm is considered the best. This distance can be increased or decreased.
By increasing or decreasing the focal length, the shutter speed must be changed accordingly, since the 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, it is necessary to ensure that as few scattered rays are formed as possible, since the scattered radiation that enters the image caused by the primary beam creates an additional darkening of it, which degrades the image quality.
It is completely impossible to destroy this secondary, harmful radiation, but by means of certain measures it is possible to reduce its harmful effect. The thicker the object and the larger the irradiated field, the stronger the effect of the scattered rays. Therefore, if possible, take pictures with small fields. To do this, limit the cone of rays coming out of the tube, using tubes.
To screen out (filter) soft rays in the working beam, special filters are used. The simplest X-ray filters are aluminum and copper plates, the thickness of which is 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 the scattered rays formed in the object, special X-ray gratings (blends) are used (Fig. 5). They are made from lead plates arranged in such a way that they transmit the primary X-ray beam, which is perpendicular or at a slight angle to the film, and absorb the scattered rays. In order to prevent the image of the lead plates themselves from being obtained in the picture, the sifting grating is set in motion during transillumination or shooting. As a result, the image of the plates is "blurred".
Processing of exposed films. manifestation technique. The development determines the quality of the picture to a lesser extent than the shooting conditions. Therefore, it requires a serious and careful attitude.
Develop in a separate, fairly spacious, well-ventilated and specially equipped room (photo lab), illuminated by a red glass lamp. All manipulations during the development of the film 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 radiograph and to avoid the formation of air bubbles on the film, it is necessary to shake the bath slightly from time to time and monitor the course of development. It should not be unnecessarily often removed from the developer during the development process and examined in transmitted red light, this does nothing but weakens the development and leads to the so-called air veil.
The temperature of the developer solution should be 18-20.
At a higher temperature of the solution, veiling of the film occurs, in addition, the gelatin layer begins to swell and peel off. When the temperature of the solution is below 10-12°, the development process is greatly slowed down, and it becomes impossible to obtain juicy, contrasting radiographs.
As it develops, the contours of the pattern appear on the film, and then its individual details. However, this does not mean that manifestation should be stopped. Develop all silver bromide crystals exposed to x-ray energy. Only in this case it is possible to obtain juicy, contrasting radiographs.
Rice. 5. Scheme of absorption of secondary (scattered) X-rays by a grating:
1.anodubule; O—tested body; aa points.
If the development process is terminated prematurely, only superficially lying silver bromide crystals appear, and the bulk of the silver bromide crystals do not have time to appear, as a result, the underdeveloped image turns out to be pale, with reduced contrast, or, as they say, it turns out to be sluggish. Therefore, it is important to catch the moment when the manifestation should be interrupted. The development process should be considered complete when, when looking at the drawing, no new details appear, and its contours begin to be slightly shaded.
If, subject to all the development rules, the image appears quickly and disappears so quickly under a common gray veil, then the reason should be sought in the wrong choice of exposure or beam hardness. In this case, the picture should be repeated by changing the shooting conditions. If the film is fogged before the image appears, this means that the film was exposed to light when loaded into the cassette or is very old, or the glass of the laboratory lamp allows extraneous light to pass through. In this case, you need to establish the cause and eliminate it.
If details are still not developed at the maximum duration of development, this means that either an old developer was used, or the shooting conditions were taken too low. In this case, fresh developer without potassium bromide must be added. If this does not help, then the picture should be repeated by changing the shooting conditions.
This method of manifestation is very painstaking and time-consuming. Therefore, when the cabinet is heavily loaded, another, more productive and perfect so-called tank method should be used (tanks are called tanks). The advantage of this development method is that it allows several films to be developed simultaneously and is less labor intensive. In tank development, the films are clamped in special stainless steel film holders or with simple clamps and immersed in the developer tank. The development is carried out at a temperature of the developer solution of 18°. The duration of development is regulated by the factory that produces this type of film. If the temperature of the solution is above 18°, then the development time must be reduced by 1 min. every 2°;
at a lower temperature, the development time is increased by every 2 "for 1 minute. If, subject to all the development rules, the radiograph turned out to be too dark, this does not mean at all that the radiograph is overdeveloped. This indicates that the shooting conditions were taken too high. In 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 of prescription until completely dissolved.
Apply no earlier than 24 hours after preparation.
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
Films can be developed in 1 liter of developer: 13 X 18 cm - 38 pieces; 18X24 cm - 20; 24 × 30 cm - 12; 30 × 40 cm - 7 pieces.
Fixing. At the end of development, the film is removed from the developer solution, washed for 10-15 seconds. in running water and placed in a fixing solution.
The fixing process pursues the following: termination of the further process of development and removal of the undecomposed silver bromide film from the gelatinous layer.
Under the action of the fixing solution, the silver bromide remaining in the gelatinous layer of the film, not changed by radiant energy, dissolves and a double salt of silver seronate and sodium sulphate is formed. This salt is fairly easy to dissolve in fixer solution, but very difficult to dissolve in water.
The temperature of the fixing solution should be 18-20°C. At a higher temperature, the emulsion layer softens, and at a lower temperature, the fixation process is greatly slowed down.
Recipes for fixative solutions:
1) crystalline hyposulfite - 250.0
ammonium chloride - 50.0
sodium metabisulphite - 16.0
water (warm) - 1l
2) crystalline hyposulfite - 200.0
potassium metabisulfite - 20.0
water (warm) - 1l
These acidic fixing solutions immediately stop development, remain for a long time, the solution remains light all the time. The yellow color of radiographs sometimes appears during development, but disappears in acid fixing solutions.
If necessary, radiographs can be fixed in an ordinary fixing solution: crystalline hyposulfite - 250.0, water (warm) - 1 l. This solution fixes quickly, but soon deteriorates, becomes brown in color.
The number of films that can be processed in 1 liter of fixer solution is the same as for the developer.
Fixing is continued until the complete disappearance of the milky-white color (silver bromide) on the film. After the disappearance of this shade, as a precaution, the film should be kept for some more time in the fixer, about the same time as it took for it to disappear.
If the fixation is not long enough, this salt remains in the gelatinous layer of the film, and after a while the radiograph acquires a yellow color. Do not use an old, depleted fixing solution, the radiographs fixed in it may also turn yellow in whole or in part.
Washing and drying. The fixed radiograph must be washed well. With insufficient washing, the x-ray image will quickly deteriorate - it will turn yellow.
Rinse radiographs 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, carefully, without disturbing the gelatin layer, remove the sediment with a cotton swab, which often remains on the gelatin layer during fixation and washing.
Dry the radiographs at room temperature in limbo. It is impossible to accelerate drying by heating, as this will melt the gelatinous layer. If the radiograph is needed quickly, then in order to speed up the drying, it can be immersed in 75-80° alcohol for 5-10 minutes. The pre-washed X-ray image is shaken several times to free it from large drops of water. Taken out of alcohol, it dries completely in 10-15 minutes. A partially dried radiograph must not be dried in alcohol, as it becomes streaked.
Photo requirements. Based on the images, the state of the captured 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 contain an image of the entire part of the body or organ being examined, where there are pathological changes; 2) the picture should 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 ones, denser bones should differ from less dense ones and should not have a double contour; 3) the bone structure and other details of the internal structure of the bone must be well defined.
An x-ray that does not meet these requirements loses its practical value.
X-ray technique
The study of the internal structures of the object, which are projected using X-rays on photosensitive materials (X-ray film or paper)
Benefits 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 re-examination and assesses the dynamics of the pathological process
Is a medical document
Disadvantages of radiography:
Static image, which makes it impossible to assess the functions of organs
The presence of ionizing radiation that has a harmful effect on the object under study
The information content of classical radiography is lower modern methods visualization due to projection layering of complex anatomical structures
Little informative for the study of soft tissues
Sophisticated photochemical film processing
Difficulty archiving film
Technical marriage during production requires re-examination
Required considerable time for film processing
Types of radiographs:
Plain radiograph
Target radiograph
contact radiograph
Tangent radiographs
No. 5 Obtaining an x-ray image on the screen - the method of fluoroscopy (method of obtaining an image, the main positions of the patient during transillumination). No. 6 Obtaining an X-ray image on the screen - the method of fluoroscopy (advantages and disadvantages).
X-ray technique:
The study of the internal structure and functional changes of organs and systems, in which the image is obtained on a luminous fluororeminiscence screen at the present time.
Orthoscopy - examination of the patient in a vertical position (in direct, lateral, oblique projections and with different inclinations of his torso) with a horizontal course of x-rays.
Trochoscopy - performed with the patient lying down with a vertical direction of x-rays.
Lateroscopy - the patient is lying down, but the rays pass horizontally.
Benefits of fluoroscopy:
Research is carried out in real time (here and now)
Provides an opportunity to evaluate the function of the object under study
Enables rapid localization of the pathological focus
Gives the opportunity to control the implementation of instrumental procedures and surgical interventions
Disadvantages of fluoroscopy:
High patient dose
Low spatial resolution
Subjectivism in the evaluation of the results obtained
Not a medical document
Does not provide an opportunity to assess the dynamics of functional changes
№7 Fluorography. The principle of obtaining an image, the advantages and disadvantages of the method.
Fluorography:
X-ray examination, which consists in photographing a fluororeminiscent screen, on which an X-ray image of the object under study is projected
Types of fluorography:
Small frame - pictures with dimensions of 24x24 mm or 35x35 mm
Close-up - pictures with dimensions of 70x70 mm or 100x100 mm
Advantages of fluorography:
Research Speed
Low research costs
Small radiation exposure to personnel
Convenient archive storage
Fluorography Disadvantages:
Large dimensions of fluorographs
№ 8 Layer-by-layer X-ray examination (tomography) The principle of obtaining an image, the concepts: "tomographic layer", "step". No. 9 Layered X-ray examination (tomography). Zonogram: the principle of obtaining an image.
Tomography - layered x-ray examination
Tomography is a method of radiography of individual layers human body. On a conventional radiograph, a summation image of the entire thickness of the examined part of the body is obtained. Images of some anatomical structures are partially or completely superimposed on the image 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 dismember the summation image into its component images of individual layers of the object. Hence the name of the method - tomography (from the Greek tomos - layer).
The effect of tomography is achieved through continuous movement during the shooting of 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 more complex trajectory, but always in mutually opposite directions. With such a movement, the image of most of the details on the radiograph is fuzzy, smeared. A sharp image is given only by those formations that are 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 machines. 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 visible on the tomogram.
"Step" is the distance that determines the height difference between two adjacent tomographic layers.
A zonogram is a type of tomogram in which images of thick layers are obtained using small rocking angles of the moving system of the tomograph.
No. 10 Computed tomography (CT). A method of obtaining an image, a 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. It is based on the measurement and complex computer processing of the difference in the attenuation of X-ray radiation by tissues of different density.
The receiver is the Gentry ring. The same number, only the receiver is different.
1972 - a CT method was proposed (Kornik, Haunskind - scientists).
1969 - the first scanner was invented based on the 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 - for one cut 20 seconds.
Fan CT - processing time was 10-15 seconds.
Spiral CT - the movement of the tube was in a clockwise helix.
Multispiral CT since 1992 - multiple coils and processing time of 0.7 seconds. The number of spirals is always a multiple of "4".
In the Gantry ring there were several layers of detectors - receivers at once.
In computed tomography systems, scanning and image acquisition proceed as follows: the X-ray tube in the radiation mode "bypasses" 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 - crystals of sodium iodide, which convert ionizing radiation into light. The latter falls on photomultipliers that convert this visible part into electrical signals. Electrical signals are amplified and then converted into numbers that are entered into the computer. The X-ray beam, passing through the absorption medium, is attenuated in proportion to the density of the tissues encountered on its path, and carries information about the degree of its attenuation in each scanning position. The intensity of the radiation in all projections is compared with the value of the signal coming from the control detector, which registers the initial radiation energy immediately at the exit of the beam from the X-ray tube.
An important condition for ensuring the performance of computed tomography is the immobile position of the patient, because movement during the study leads to the appearance of artifacts - pickups: dark bands from formations with a low absorption coefficient (air) and white bands from structures with a high coefficient of absorption (bone, metal surgical clips ), which also reduces diagnostic possibilities.
Feature of radiographic/radiographic film.
X-ray film composition:
Photo emulsion
Analog radiography
The film contains 7 layers.
Advantages of CT:
Very high resolution;
Possibility of mathematical analysis of the image and changes in density (the density of water is taken as "0", measurements are made in Hausfield units - Hu).
All the possibilities of digital radiography;
We can perform virtual angiography using iodine-containing contrasts;
We can measure bone density;
You can build 3D of any pathological object and perform a virtual operation;
You can perform a qualitative study of the bones;
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.
Disadvantages:
Expensive research.
We get the image:
Thermal printer.
No. 12 MRI. MRI device.
Types of MRI:
Ultra low field (0.1 tesla)
Low field (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.
Research types:
MRI diffusion - supports a certain movement of water molecules in tissues;
MRI perfusion - determines the permeability of blood through tissues;
MRI spectroscopy - allows you to evaluate biochemical changes in tissues (metabolism);
MRI angiography - obtaining images of blood vessels (sometimes a gadolinium contrast agent 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 shards;
Ilizarov ferrimagnetic devices;
All metal structures;
Hemostatic clips of cerebral vessels.
Relative contraindications:
insulin pumps;
Stimulants;
Non-metallic middle ear implants;
Heart valve prostheses;
Hemostatic clips, other than brain clips;
Uncompensated heart failure;
First trimester of pregnancy;
Claustrophobia;
The need for physiological monitoring;
Artificial maintenance of body functions;
Severe condition of the patient.
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 a gradient. It allows you to select the area of study of the patient's body part;
transmitting and receiving RF coils; transmitters are used to create excitation in the patient's body, receivers are used to register the response of excited areas;
a computer that controls the operation of the coils, registration, processing of measured signals, reconstruction of MR images.
The magnetic field is characterized by induction magnetic field, the unit of measurement is Tl (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 → ultra-weak field;
0.1 - 0.5 T → weak field;
0.5 - 1.0 T → with an average field;
1.0 - 2.0 T → strong field;
>2.0 T → with super strong field.
There are three types of MRI magnets: resistive, permanent, and superconducting.
Tomographs with a field up to 0.3 T most often have resistive or permanent magnets, above 3.0 T - superconducting.
The optimal magnetic field strength is a constant subject of debate among experts.
More than 90% of magnetic resonance tomographs are models with superconducting magnets (0.5 - 1.5 T). Tomographs with a superstrong field (above 3.0 T) are very expensive to operate. Permanent magnets, on the other hand, are cheap and easy to use.
No. 13 MRI. Acquisition of an MRI image.
Tomographic research method 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 magnetic field of high intensity.
Magnetic resonance imaging (MRI) uses a magnetic field to produce an image. 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, which have the same frequency as the signal, are "excited" and generate their own signal, which is picked up by the apparatus. Different types tissues (bones, muscles, blood vessels, etc.) have a different number of hydrogen atoms and therefore they generate a signal with different characteristics. The computer recognizes these signals, decodes them and builds an image.
Normal cells of organs and tissues, not affected by the disease process, have one signal level, “sick” cells are always different, changed to one degree or another. Due to this phenomenon, on the image obtained during MRI, parts of tissues and organs changed by the pathological process look different than healthy ones.
Images obtained with MRI contain a huge amount of information about the structure of organs and tissues in a particular anatomical zone. The structure, the relationship of organs to each other, their size, configuration - these are the main parameters that we evaluate in the course of the study.
No. 14 MRI. Main indications and contraindications.
Contraindications for MRI
Absolute:
The presence of a pacemaker;
The presence of endoprostheses and stabilizing systems made of ferromagnetic alloys;
Middle ear implants (fixed hearing aids);
Condition after clipping of cerebral vessels;
The presence of foreign metal bodies (shards, bullets).
Relative:
(depends on the strength of the magnetic field)
1st trimester of pregnancy;
The presence of clips on the vessels (except intracranial);
Heart valve prostheses;
Sternal wire sutures;
The presence of intravascular stents;
Decompensated somatic conditions
Claustrophobia.
Indications for MRI:
Neurology and Neurosurgery
Diagnosis of tumors of the brain and spinal cord and their evaluation in 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 disorders of cerebral and spinal circulation and their consequences
Diagnosis of traumatic brain injuries and their consequences
Diagnosis of malformations of the brain and spinal cord
Assessment of the state 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, 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 the 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 organs of the small ointment (adnexitis)
Urology
Diagnosis of tumors of the kidneys, bladder, prostate and assessment of their spread to adjacent structures
Diagnosis of inflammatory diseases of the kidneys, bladder, prostate gland
Diagnostics urolithiasis
Gastroenterology
Diagnosis of tumors of the liver, pancreas and their evaluation in dynamics
Diagnosis of cholelithiasis incl. examination of the bile ducts for the presence of stones in them
Assessment of the severity of organ injury abdominal cavity
Diagnosis of the state of the liver (fatty hepatosis, cirrhosis) and evaluation in dynamics
Diagnosis of acute and chronic inflammatory diseases of the abdominal organs (hepatitis, pancreatitis)
Examination of large vessels
Diagnosis of the presence of atherosclerosis
Aneurysms.
No. 15 Ultrasonography. Building an ultrasound image. Types of sensors. The scope of their application.
Ultrasonography (Ultrasonography)
the use of ultrasound, whose frequency is approximately 30,000 Hz, to obtain an image of the deep structures of the body. The ultrasonic beam is directed to the surface of the body to be examined through a special sensor used to examine the abdominal organs (for comparison: transvaginal ultrasonography); the reflected sound echo 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 for diagnosing pregnancy, determining the duration of pregnancy, diagnosing multiple pregnancies, malpresentation of the fetus and chorionadsnoma; ultrasonography allows you to determine the location of the placenta and identify some anomalies in the development of the fetus. Types of sensors:
1. convex - abdominal
2. microconvex (vaginal, rectal, transcranial - through the fontanel);
3. linear (mammary glands, thyroid gland, muscles, tendons).
4. sectoral - used in cardiology;
5. through the esophagus (look at the heart);
6. biplane - 2 together any;
7. 3D and 4D - 3D;
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 methods of bronchography. The role of the radiographer.
Bronchography is an x-ray examination of the bronchial tree, which is performed after the introduction of an iodine-based radiopaque substance 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 study 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 can not be done often, some groups of patients have contraindications.
Study preparation
If bronchography will be performed under local anesthesia, then the patient should not eat 2 hours before the study. If general anesthesia is planned, then this time is lengthened.
Thorough oral hygiene should be performed the day before and on the day of bronchography.
If the patient wears dentures, then before the study, he must remove them.
Urinate before a bronchogram.
Conducting bronchography
Bronchography is performed on a dental chair or on an operating table that can be configured to suit.
Mandatory equipment of the office for bronchography:
x-ray machine;
a catheter or bronchoscope to inject contrast into the lungs;
radiopaque substance;
resuscitation kit.
Research progress:
The patient is placed on a dental chair or operating table. He should take the most comfortable and relaxed position - this will facilitate the study.
If bronchography is performed under general anesthesia. The anesthesiologist gives the patient a mask anesthesia. After that, the mask is removed from the face, tracheal intubation is performed.
If bronchography is performed under local anesthesia. With the help of a spray, anesthesia of the oral cavity is carried out. Then a bronchoscope is inserted through which an anesthetic is delivered, and then a radiopaque substance.
Before injecting contrast into the bronchi, the doctor may perform a bronchoscopy - examine the mucous membrane with 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 is performed - in frontal, lateral and oblique projections.
No. 17 Digital radiography. Acquisition of a digital image. The role of the radiographer.
This is the transformation of a traditional radiograph into a digital array with the subsequent possibility of processing radiographs using computer technology.
Essence of digital image:
An x-ray image, when converted into a digital image, is divided into the smallest elements - pixels.
The brightness of which is determined by the degree of absorption of radiation by tissues.
The result is a matrix (basis) with the dimension: the number of rows by the 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 you to simultaneously differentiate 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 the hard drive and external media;
Reduce examination time and radiation exposure by 10 times.
Ways to form a number:
1. Analog:
Indirect
2. digital
Indirect
analog
The receiving device is a film / luminous screen. When performing a direct analog study, there must be sufficient X-ray power to obtain a high-quality image at the receiving device.
Indirect analog x-ray study: the energy of x-rays is converted into electricity using a special device (URI) = an image on the screen.
Indirect digital technology – indirect analog + digital.
With this technology, the energy of X-ray radiation is first converted into electricity using the URI, and then converted into a number (two intermediaries).
Advantages of an indirect figure:
Due to the lack of additional studies, radiation exposure is reduced;
It is possible to process the x-ray image using a computer;
Convenience of archiving, the ability to replicate an infinite number of copies of the x-ray image;
Possibility of consultations of on-line.
Number setting methods:
Installing the digitizer directly on the X-ray machine;
The use of special electrical cassettes with their processing in a digitizer (a device in the cassette itself).
Disadvantages:
The image is virtual;
The cost of research increases.
Direct number:
From the X-ray tube directly to the digital. When using digital technology, X-ray radiation is converted into digital at a lower radiation power and computer processing with a small radiation load, we obtain a high-quality X-ray image.
Benefits of digital:
Radiation load reduction is 8-10 times less than analog;
Higher resolution;
It makes it possible to more accurately assess the nature of the pathological focus;
Possibility of computer processing of the image and its mathematical analysis = we avoid the subjectivity of image evaluation;
The speed of obtaining an image on a computer screen, since a long photochemical process is excluded;
Convenience of archiving and analysis of the dynamics of changes;
Online consultations.
Disadvantages - see indirect figure above.
№ 19 Photochemical processing of x-ray films. Manual development. № 20 Photochemical processing of x-ray films Automatic photo processing. №21 Photochemical processing of x-ray films. Types of processing machines. No. 22 Photochemical processing of X-ray films. Defects and artifacts in 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
Analog radiography
The base is a flexible, sufficiently strong and transparent film for visible light, made of cellulose (cellulose triacetate).
A 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-permeable varnish.
The film contains 7 layers.
The composition of the photographic emulsion:
The main ingredient is a photosensitive substance (silver bromide salt - halogen silver) most sensitive to x-rays and visible light.
Converting halogen silver to reduced silver.
Halogen silver ←light + x-rays
Developer 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 agent = we lower the film into the developer (we finally break the bond).
Halide silver 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.
Photo emulsion ↔ colloids = dries and swells in cold water, becomes permeable to photo solutions.
Colloids are gelatin, they are added to the photographic emulsion.
In x-ray film, the main layer is an emulsion. The most necessary component in it is a light-sensitive substance (silver halide).
Under 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 with subsequent fixation.
Manifestation:
Automatic.
Manual processing of radiographs;
Manifestation;
Intermediate flush;
Fixation / fastening;
final flush;
Manifestation.
The first step in a photochemical process that converts a latent image into a visible one.
This is done in special tanks (4 pieces).
1 tank - developer - red cover, the developer consists of three components (A, B, C).
First, pour water at room temperature.
Pouring each next component, mix everything together with a wooden stick. When everything is ready let stand for 5-10 minutes.
If component "B" is dark brown, it cannot be used!!!
The developer is a complex compound:
developing substances;
preserving substances;
accelerators;
Anti-inflammatory substances.
Developing substances:
Metol (detailed, but low-contrast manifestation) - image detailing;
Hydroquinone (significantly increases the contrast of the image) - blackening the image;
Phenidone (in terms of showing ability is weaker than metol, the action is similar).
Preservative substances:
sodium sulfite;
potassium metabisulphite.
The function is to neutralize oxidative processes in the developer. The environment in the developer is always alkaline. Hydroquinone cannot work in an acidic environment.
Accelerators:
To maintain a constant alkaline environment
Improves swelling of gelatin in emulsion
Increases the depth of contact of the developer with the silver halide:
Sodium carbonate (potassium)
Antiveil agents
During development, the darkening of the film due to optical fog is reduced.
Potassium bromide
Benzotriazole/benzimidazole
Bromine salts formed during development.
An optical veil is formed during development.
Intermediate flushing - tank No. 2 (water, for 15-20 seconds).
To remove developer residue from the film surface so that the alkaline environment in the developer does not contaminate the alkaline environment of the fixer.
Tank number 3 - acidic environment.
Fixer/fixer - blue.
Fixation - after development in the emulsion, the image is in the form of reduced to varying degrees of metallic silver and its unreduced halogen form, which requires removal from the emulsion.
An uncaptured image darkens, the image in it is destroyed.
Fixer composition:
Sodium sulphate hyposulfite (dissolves non-reduced silver);
Sodium sulfate (stabilizes hyposulfite in solution);
Acids: sulfuric, acetic (creation of an acidic environment - effective fixing of the image;
Ammonium chloride (ammonia) to speed up the fixing of the image, allows you to reduce the fixing time by several times.
When aluminum or potassium chromium quartz is added to the fixer, it is a tanning fixer (prevents excessive swelling of the emulsion and its slipping off the substrate = for auto development, when high temperatures. Warm up 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 all chemicals from the film emulsion (with running water) - the duration of this process is 25-30 minutes.
The average duration of the individual stages of photochemical processing:
Auto development differs in the percentage of elements to be developed.
Manifestation;
fixing;
final flush;
Intermediate development is replaced by rollers that remove residual solutions and excess water, and they also move pictures from one compartment to another.
Processing machines:
According to the principle of work:
In a dark room;
In a bright room.
By speed: (dry to dry shot)
Medium speed (3.5 minutes; 28 degrees);
Speed (90 seconds; 36 degrees);
Super speed (45-60 seconds; 40 degrees).
Processing machines consist of:
Three sections with processing solutions, washing water and drying;