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Every radiograph should be marked in such a way that positive identification can be made at a later date. It is obvious that if a medico-legal problem were to arise concerning a patient, a radiograph without proper identification would be of little value. A follow-up radiographic study made of a fracture case is of less value if the exact number of days elapsed since injury and reduction is not known. A radiographic study sent to another clinician for evaluation and consultation has a better chance of being returned if it is properly identified with a name of a hospital or veterinarian.
Every radiograph must be identified in such a way that the following basic information is available:
Lead Markers Lead numbers or letters are placed in a holder or taped directly to the face of the film holder at the time of film exposure. The lead letters attentuate the primary x-ray beam so that the film directly under the lead is unexposed and appears transparent on the radiograph. It is possible to purchase prepared identification markers that have the name and address of the hospital spelled out permanently in lead letters. It is then necessary to change only the date and identification of the patient .
Lead Blockers Used with Identification Card. Lead blockers placed inside on the face of the cassette protect the film during exposure. Following removal of the film but prior to processing, a typed or written card (Fig. 12-1) is placed between this unexposed portion of the film and a light source. The light is "flashed" and the written information recorded on the previously unexposed film (Fig. 12-2). The size of the lead block and the size of the card can vary. New cassettes can be ordered with the lead blocks placed inside. If new screens are being installed in old cassettes, it is possible to place the blockers at that time. It is also possible to place the lead blockers on the face of the cassette. The lead blockers should be placed in the same corner in all cassettes. This consistency will help to prevent placement of an important part of the patient's body over this corner since no exposure will reach the film. If lead blockers are placed on the inside of the cassette, it is of help to identify this corner by painting or otherwise identifying the corner on the face of the cassette. This will remind you not to position an important part of the body in this area.
The cards can be filed after use in identifying the radiograph, providing the hospital with an alphabetical card file of all radiographic examinations.
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Some of the flashing devices are automatic and terminate the time of the exposure of the card. Other markers are manual and the light remains on as long as the switch is depressed. Obviously it is possible to over expose the film marker. Other units have a switch that changes the time of exposure for screen and non-screen film. Obviously having that switch in the wrong position causes the film marker to be over or under exposed.
It is also possible to utilize lead blockers in cassettes in another manner. Following exposure but prior to processing, an identification card with lead letters and numbers is placed between the back of the cassette and a small x-ray source. The film is then "flashed" with an x-ray beam and the identification recorded while the film is still within the cassette.
Lead-Impregnated Tape (Fig. 12-3) Disposable lead impregnated tape can be placed on the outside of the film holder at the time of exposure. Tape is placed on a ''holder blocker" to which is permanently attached the name and address of the hospital in Iead letters. By "writing" on the tape with a ball-point pen other suitable smooth tip, or a typewriter, the powdered lead is displaced and a difference in density on the tape is created. This permits the Primary X-ray beam to be selectively absorbed. The tape permits easy identification of the patient and owner as well as the date of examination. It is also easy to cross out a "right" marker and write in a "left" marker as you finish radiographing one leg and start on the opposite. The time interval on a series of studies, such as in an upper GI examination, can be easily marked on the tape and then changed as successive new times are written. Tape is available in 50-foot or 100-foot rolls or in precut 3-inch strips, packaged 300 strips in each dispenser carton. Tape can be thrown away after the examination or attached to a filing envelope for use at a later date or for information required at a later date.
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There are in addition to the thin plastic plate both copper and aluminum sheets to be added as you use middle kVp and high kVp settings on the machine. The tape and plates can be obtained from X-Rite Company 4101 Roger Chaffee Drive S.E., Grand Rapids Michigan49508&endash; (616) 534-7663 or from Label-X, X-Ray Film I.D. System, Spectronics Corp., 29 New York Ave., Westbury, L.I., NewYork 11590. Either of these lead-impregnated tapes can be obtained from your x-ray supplier.
Right and Left Markers (Fig. 12-4) These are needed to identify a right or left limb or the right of the left side of the thoraxor abdomen. The markees are made of lead and taped onto the surface of the cassette or can be bought in the form of a clip and fastened to the cassette in this manner.
Medial and Lateral Markers These are needed principally in large animal work to identify the medial or lateral aspect of the leg when no prominent anatomical structures are included in the study. This is generally from the midshaft of the metacarpal or metatarsal bone distally. It is a good plan to consistently position other identification markers such as "L" or "R" either medially or laterally. This ensures that you can identify the medial or lateral side of the radiograph in a situation in which the medial or lateral marker is covered by a Iead glove, was not used, or fell of unnoticed during the examination. If a consistent plan of placing all markers either medially or laterally is followed faithfully, the location or any identification marker will identify the medial or lateral side.
Front and Hind Leg Markers A technique is required to identify the radiograph of the distal part of the front and hind leg on most large animals. This may be done by use of an "F" and "H" lead letter.
Markers to Identify the Direction of the Radiographic Beam Mitchell markers are "R" and "L" lead letters with a radiopaque mercury bubble in a plastic container. When the cassette is positioned on a table top or in a bucky tray, the mercury bubble moves to the center of the plastic sphere. If the cassette is positioned vertically, the mercury bubble fails to the bottom of the plastic sphere and indicates how the cassette was positioned during the exposure(Fig. 12-4).
It is also possible to use arrows cut from a lead sheet to identify the position of the cassette. The arrow is positioned to point up, thus indicating the side of the cassette that was upper most. It is also possible to buy specific markers that indicate "recumbent," "erect," "lateral decubitus," etc. These can assist in recording the position of the cassette and patient during the exposure.
Markers can be used that indicate the manner of passage of the x-ray beam through the leg of a large animal. These can be abbreviated as required: cranio-caudal (CrCa), dorso-palmar (DPa), and dorso-plantar (DPI).
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Technician Markers It may be desirable to have the technicians responsible for the study mark each radiograph with their initials.This accomplishes several things. It instills a sense of responsibility since it is easy to associate each radiograph with the responsible technician. In the event that it is important to recall certain information concerning the case, there is positive evidence of who made the exposures.
Time or Sequence of Exposure It may be necessary during special procedures to indicate the period of time that has elapsed following administration of contrast media or the time the radiograph was made. The need for this information exists in excretory urography, upper gas trointestinal studies, and some other special procedures. For this reason, it is desirable to have a small marker that can easily indicate elapsed time (Fig. 12-5). Often the flasher unit that prints the identification information on the film has a clock that prints the time of film processing.
It is also important to indicate the sequence in which exposures are made in certain procedures. The myelogram is a good example in which most exposures will be made during a brief period, perhaps as short as 5 minutes. It is not possible to record the elapsed time following the injection of contrast, but it is important to record the sequence in which the radiographs were made. This can be done simply by taping a series at numbers, 1, 2, 3, 4, 5, etc., on the outside of the cassette in a location that can be easily recognized.
Another example of the necessity of recording the sequence of the radiographs would be it two identical studies were done during the same day. This might be an acute abdomen that was first radiographed in the morning and then again later in the day for a progress check. Another example would be a thorax that was filled with fluid. A second study following an attempt at removal of the fluid must be identified as such. These can be identified by use at time marker that is a part of the unit that flashes the card on the radiograph.
Special Identification Markers occasionally it is desirable to mark a special area on the body of the patient that can be identified on the radiograph. An area of swelling, a point of tenderness, a break in the skin, or a skin abrasion suspected to cover a fracture would be examples. An area such as this can be identified by fastening a metaIIic instrument, such as a hemostat or towel clamps, to the skin. A simple procedure is the taping of a "B-B" over a point of interest. It might be more advantageous to simply place the metal marker on the cassette adjacent to the area of interest. In the event of a draining fistula or sinus tract, it may be desirable to insert a metallic probe into the lesion prior to radiography. This will identify the direction and give information as to the depth of the lesion. A needle used for intravenous injection can also be of use as a device for assisting in location of another foreign body.
Equine Beam Identification Device (Fig. l2-6) This device has been built to assist in recording the direction of the x-ray beam used to make radiographs of the equine carpus. It is of value because of the oblique projections that can be used in studying the carpus and the several ways this obliques can be made. The marker is placed over the cassette and the direction of the x-ray beam is recorded on the radiograph according to the following scheme .
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Writing on Film It is possible to write on the film prior to or following processing. Prior to developing the dry film, it can be written on with a pencil or other pointed device. The pressure will distort the film emulsion and record the information on the film that will remain visible after processing. During the final wash, the film emulsion is still soft and can easily be scratched by a pencil or other pointed device. The emulsion remains rough following drying of the radiograph. It is also possible to write on a dry radiograph with photographic white ink. All of these techniques should be considered only as temporary identification techniques. They are described only because radiographs will be made when more desirable identification methods were forgotten, and it is better to have a poor method of identification rather than none at all.
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