Polaroid Film Artifacts

Sue Weiss

The Children's Memorial Hospital, Chicago, Illinois

James J. Conway

The Children's Memorial Hospital, and McGaw- Northwestern University Medical Center, Chicago, Illinois

A review of artifacts found on Polaroid Land films from several community nuclear medicine laboratories revealed that the great majority of artifacts were caused by improper operator technique and thus are completely preventable. In this paper we identify the types of arti­facts and their causes, and present techniques to prevent those occurring most frequently.

The observed frequency of artifacts on Polaroid Land film in the nuclear medicine laboratory at The Children's Memorial Hospital, Chicago, IL, prompted an investigation into the causes of the artifacts. Subse­quent discussions with other nuclear medicine users of Polaroid film revealed the problem to be widespread and costly, in terms of the amount of film discarded and studies blemished. These observations prompted a survey of film artifacts from several nuclear medicine laboratories. The collected artifacts were examined and categorized as to their cause.

Method

Polaroid film artifacts were collected from several community hospitals during a six-month period. The films were examined as follows.

First, the defective films were compared with arti­fact examples from technical information pamphlets available from Polaroid Corporation. The majority of artifacts was readily identified in this manner.

Second, artifacts whose etiology did not have an obvious explanation were forwarded to the technical assistance department of Polaroid Corporation for analysis by their technical experts. Artifacts were identified in most instances.

Finally, an attempt was made to reproduce each ar­tifact by purposely using improper techniques with Po­laroid type 107 edp code 084 Land film and a Polaroid camera on the A-scope of a Searle Radiographies Pho I Gamma HP scintillation camera. Patient images \\ere not produced on many of these test films so that the artifact would be more apparent. On occasion, arti-

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facts were purposely superimposed upon radionuclide images when adequate time to take extra films was available with cooperative patients. The causes of a few artifacts were also verified as equipment malfunctions and repair resulted in correction of those artifacts.

Results

Artifacts can be categorized into four main classes: (A) patient defects (attenuation or contamination); (B) film defects (faulty manufacture); (C) equipment de­fects (CRT burn); (D) operator error (improper tech­nique).

Approximately 90% of the collected artifacts were determined to be due to operator error. Over half of these were due to dirty rollers or developer spreader bars in the camera. Another 35% of the operator error artifacts were due to improper technique when pulling the film from the camera. The remaining operator er­rors were due to improper development technique.

Approximately 5% of the artifacts were due to defects caused by the patient and equipment malfunc­tion. The remaining artifacts were found to be due to defects caused by the film manufacturing process.

Discussion

Since the results of the survey indicate that over 90% of the artifacts are due to operator error, the technologist who is aware of the causes of Polaroid film artifacts and knows how to properly use the film will gain considerable monetary and time savings by reducing the number of films which must be repeated. Users of Polaroid film should thus become well ac­quainted with the mechanisms involved in the use of a Polaroid film pack. Detailed information is available from the technical assistance division of Polaroid Cor­poration in readily understood information pamphlets

For reprints contact: Sue Weiss, Division of Nuclear Medicine Children's Hospital, Chicago, IL 60614. '

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FIG. 1. Polaroid film components. (top) White tab attached to back of negative, draws yellow tab (arrow) from camera; (bottom) developer pod (arrow) ruptures when passing through rollers.

(1). A brief description of the film pack mechanism is offered as follows.

A pack of Polaroid type 107 film consists of eight negatives and eight positives which are connected by yellow tabs. Interconnecting white tabs are attached to the back of the negatives and also carry the developer pod (Fig. 1). The negatives and positives are separated by a pressure plate which holds the negatives in place against the lens side of the pack when placed into the camera. After the negative is exposed, the white tab is pulled, bringing the negative to superimposition with the positive. The positive and negative are then pulled via the yellow tab through the spreader bars or rollers which break the pod, spreading the developer evenly over the film as it is removed from the camera. The image is then allowed to develop for the recommended time.

Recognition of the Artifact Causes

Operator error. Improper operator technique can be divided into three distinct types: (A) incorrect "pulling" technique; (B) incorrect development tech­nique; (C) inadequate cleansing of the camera back, resulting in dirty rollers.

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One of the most common artifacts is streaks of white specks across the film (particularly at the end of the film pulled out of the camera first), which is caused by pulling the film out too rapidly (Fig. 2). Rapid pull­ing causes the developer to "bubble" or channel instead of spreading evenly over the film. Conversely, hesitation will also cause an uneven spread of the developer (Fig. 3). This results in a characteristic ap­pearance of a vertical streak from the ''hesitation.'' These operator errors are among the most common that will be encountered in routine clinical practice. It is recommended that a steady, even pull of the yellow tab become the practice instead of "ripping" the film from the pack, as is so commonly done in many labo­ratories.

Another operator error due to "pulling" has the ap­pearance of a partial "dry pod" (part of the film remains undeveloped) and is due to an "angle pull" (Fig. 4). This is caused by removing the film from the camera at an angle; up, down, forward, or backward.

FIG. 2. "Rapid Pull." Bubbling of the developer is produced particu­larly at area where pressure is applied to pull film from camera.

FIG. 3. "Hesitation Pull." Streaks (arrows) produced by uneven spread of developer can be avoided if film is pulled at steady rate.

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In order to determine whether "angle pull" is the cause of the artifact or inadequate developer, one must look at the developer pod on the negative to see if any dry areas are visible in the emptied pod. A wet pod will indicate a faulty pulling technique.

An infrequent but striking artifact is the ·'white tab impression" which produces a white "patch" on the developed film (Fig. 5). If the white tab is not com­pletely pulled from the camera back before the yellow tab is pulled, the white tab will be pulled back into the camera and folded onto the negative, coming through the rollers with the negative and positive. This will produce an uneven spread of the developer due to the extra thickness of the white tab as the film is compressed between the rollers.

All of the "pulling" artifacts can be avoided if the film is pulled straight out from the camera at a steady, moderate rate.

Frequent operator errors also include improper de­velopment technique. If the positive is peeled off the negative before a proper development time has passed, the film will appear light and splotchy (Fig. 6). Occasionally, the operator will recognize an obvious

FIG. 4. ''Angle Pull." Part of film remains undeveloped due to uneven emptying of developer pod. especially at edges.

FIG. 5. "White Tab Impression." "Image" of white tab is produced if it is not pulled completely out of camera. Extra thickness of tab produces uneven spread of developer.

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FIG. 6. "Improper Development." Recommended film development time on package insert must be carefully observed. Insufficient time will produce gray image. Premature opening of developing film and reposi­tioning of separated positive and negative produces uneven development resulting in splotches.

FIG. 7. "Outside Development." Type 42 and other Polaroid roll film must develop_ inside camera or "light leak" occurs. since film backing is not opaque to light. Images will have gray overtone.

inadequate development time and quickly superim­pose the negative and positive, hoping for further de­velopment to proceed. It is impossible to do this ac­curately and, therefore, an irregular development will occur on the film, resulting in a splotchy appearance.

Another development error is with the use of type 42 roll film, which is primarily used for copying with the Polaroid MP-3 or MP-4 vertical camera. The back­ing of this film is not lightproof and therefore must be developed within the camera back. Operators will frequently remove the last film from the camera by pulling it through the rollers completely in order to rapidly insert another pack. This last film (No. 8) will then appear evenly overexposed and have a faded gray tone overall (Fig. 7).

The most common type of artifact is due to failure to cleanse the rollers. It is recommended that the rollers be cleansed with each new pack of film since leakage of developer over the edges of the film to the edge of the roller occurs frequently, particularly if the films are not pulled directly in a straight line. This excess developer dries on the roller, accumulates dirt, and thus increases the distance between the rollers, which are very finely calibrated to accomodate only the thickness of the film. The excess thickness of the dirty roller will cause a repetitive splotchy pattern across the film (Fig. 8). On occasion, particularly in a

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busy department where technologists try to complete a study as quickly as possible because of the patient load, the accumulation of developer and dirt reaches such proportions that the film cannot be pulled from the camera at all and a "jam up" occurs. When this happens, it is necessary to open the camera back to clean the rollers. If done in the manner described, only one film will be exposed and the study can be resumed quickly. In order to salvage the remaining films in the pack, release the lock mechanism to open the back slightly and insert a pencil to hold the film pack firmly in place (Fig. 9). The back can then be swung com­pletely open without exposing the rest of the films and the jammed film can then be pulled through the rollers and discarded. The dirt and developer should then be cleaned off the rollers with an alcohol swab or soft cloth; never use a sharp instrument since it may damage the rollers (Fig. 10). After the rollers have been cleaned, the next white tab s~ould be unfolded

FIG. 8. ""Dirty Rollers."' Dried developer on spreader bars produces repetitive artifact pattern across image because of uneven spread of developer with each turn of roller.

FIG. 9. Pencil inserted between film pack and camera back. holds pack in place. If not done. jammed film pulls back out of place. exposing all remaining films.

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FIG. 10. Dirty rollers are cleaned with alcohol swab, while film pack remains in place. Remaining negatives will not be exposed to light in this position.

FIG. 11. White tab held out from camera while closing camera back so that next film may be pulled.

and held gently out from the camera (Fig. 11). The camera back can then be closed with the white tab in the proper position in order to pull the next film through and the study can then be continued. This un­necessary loss of time and film can be avoided if the technologist develops the good habit of checking and, if necessary, cleaning the rollers before each new pack of film is inserted. This can be done. quickly and saves much time and money in the end.

Approximately 5-7% of all artifacts are due to mal­function of the equipment or are due to the patient. Materials within the patient's clothing such as cigarette lighters will produce bizarre artifacts by at­tenuating the radiation. Motion of the patient might be considered an artifact since it does blemish the image and requires repeat exposure of films. Most technolo­gists are aware of the techniques necessary to prevent these problems. More rare in this category is an actual malfunction of the equipment (Fig. 12). This artifact affecting the quality of the image may be difficult to de­tect but does become more apparent with time. It is due to the image of the spectrum which is "burned" into the CRT of the scintillation camera. If the

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FIG. 12. Image of spectrum "burned" into CRT seen more read­ily on flood image (top) than patient image (bottom) illustrates another good reason for performance of daily flood images.

CRT display switch is turned to spectrum with a source in front of the camera and allowed to stay in that position for long periods of time, the phosphor on the face of the CRT will be "burned" in that area. Consequently, the spectrum image is superimposed on all images photographed off that CRT. The inherent danger in this is evident when one considers the subtle change that this may produce on an organ image such as the liver. It is conceivable that a normal image could be interpreted as abnormal due to this artifact. Newer scintillation camera models have devices to prevent such an occurrence. The operator should be aware of this problem when "peaking" the machine, turning the CRT display switch to the normal position as quickly as possible. A possible remedy for a "burned" CRT is to flood the camera with a flood field source for a long period of time to let the CRT phosphor "burn" over the entire surface until the spectrum image is no longer etched on the phosphor. The best remedy, however, is to replace the defective tube.

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The final category, comprising less than 5% of all artifacts, is due to film manufacturing defects. It is in­evitable that during any mass production process some defective film will be produced, slip through the quality control inspection, and eventually reach the nuclear medicine laboratory. These occurrences are relatively rare, and the following examples illustrat this type of artifact.

During manufacturing, quality control is performed by inspectors who place a rejection mark on any film deemed inadequate for further processing. Either a red or black crayon mark is slashed across the film (Fig. 13). This mark will appear on the positive when the film is developed. The inspector also marks the film before and after any defect so that they may be removed from the roll during production. Failure to detect the inspector's rejection mark will result in its incorporation within a normal film pack. Most com­monly, the rejection mark is incorporated in a normal

FIG. 13. "Inspector's Mark." When film is rejected during quality control. red or black crayon is drawn across film. Colored crayon mark is much more apparent on original film than black and white reproduction.

FIG. 14. "Film Splice." Silver foil used to splice film rolls together can appear at any position on film.

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Film manufacturing defects of the dry pod type 0 1 often are multiple within a given film pack. Return of

FIG. 15. Insufficient developer in pod will result in underdeveloped areas having appearance of "angle pull.'' However. pod (arrow) will have "dry" areas around it, indicat~ng insuff~cient amount of developer present.

pack when a new roll of film is spliced to the end of another during a production run. Another artifact found during the survey was the actual splice of the film rolls (Fig. 14), which was not detected by the in- spector and removed from the process of packaging. This is a most rare finding in any film pack.

The most common film manufacturing defect is due to insufficient developer chemicals in the pod (Fig. 15). When a film with a "dry pod" is pulled through the developer spreader, an insufficient amount of developer is available to coat the entire surface of the film and some of the areas will not be properly developed. The appearance of the "dry pod film" is characteristic but can resemble an improper pulling er- ror by the operator. A simple examination of the pod will readily determine whether any dry areas exist within the pod. This should not be confused with the "angle pull" described earlier in the paper.

such defective film to the manufacturer is recom- mended for reimbursement or replacement. It is ob- vious that the images derived during a nuclear imaging procedure are the most important aspects of the entire examination since the ultimate interpretation is depen- dent upon the quality of the images obtained. In addi- tion to quality, one must consider the economics in- volved in such studies since the imaging costs create a major proportion of the total overall expense of any given study. Most technologists believe that artifacts are due to faulty film and discard the rest of the pack when a bad film is produced. Faulty operator tech- niques which have been found to be responsible for al- most 90% of all artifacts reviewed are completely pre- ventable. The monetary loss and poor quality films found in many nuclear medicine departments must be recognized as due to operator error and not equipment malfunction or film manufacturing defects.

Acknowledgment

The authors wish to thank the Central Chapter technologists, including Lois Moore Koch and Carter Taliaferro, for contributions to this study. The authors also wish to thank Lillette Nyznyk and Gary Dettl for their assistance in the preparation of this paper.

Reference

1 . Brochure T570-2: Type 084 and type 667 handling. Cambridge, MA, Polaroid Corp., 1976

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1976;4:183-188.J. Nucl. Med. Technol.   Sue Weiss and James J. Conway  Polaroid Film Artifacts

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