42 February 1952

Individual Miniature Radiography By OWEN CLARKE

Senior Medical Registrar, Papworth Village Settlement

It is just over one year since the subject of miniature radiography was discussed at a meeting of the British Tuberculosis Associa- tion in London and suggestions were first put forward for the more widespread use of miniature photo-tluorography in chest work. At that time, the two great advantages of the small film over full-size films were economy in cost and economy in storage space: today an even more urgent factor is forcing us to change our habits, because the shortage of x-ray film prcvcnts anything except the minimum essential radiography; in many clinics and hospitals only emergency work can be done.

In our present economic position it is unlikely that there will be any early im- provement in this situation, and even when film is again freely available there will still be a wide field in which miniature radio- graphy is of value. It is, therefore, worth considering the role which miniature radio- graphy can play, and since decisions are even now being made about the type of equipment it is important now to make clear the exact purpose and specifications of such films.

follow-up of patients who have had chest diseases, even though it is as yet unproven for use during treatment of active disease. The following list thercfore includes many types of work in which a miniature film can replace full-size ones:

(i) Survey of contacts of pulmonary tuberculosis.

(2) Follow-up of contacts and doubtful c a s e s .

(3) Patients referred by a general prac- titioner:

(a) because of suspicious symptoms; (b) after an illness such as bronchitis

or pneumonia. (4) Control of established A.P. and P.P.

during refills at clinic. (5) Follow-up of apparently quiescent and

inactive cases of pulmonary tuberculosis. (6) Routine examination of staff in hos-

pitals and sanatoria. (7) Routine chest x-ray of all out-patients

and new admissions to hospital. (8) Examination for such purposes as

insurance, immigration control etc. Other categories will doubtless arise as

the practice develops.

A. The Role of Individual Miniature Radiography

This must not be confused with Mass Miniature Radiography. I t is not intended to make any comment on the role of mass survey work which deals in an impersonal way with large sections of the community and has its own definite purpose and value as a public health measure. Individual miniature radiography is intended for clinical purposes.

It has been established that the technical standard of all sizes of miniature film, 35 mm., 7 ° mm., or 5 × 4 in., is so high that it is perfectly adequate for screening purposes to detect abnormalities and for the

B. The Essential Qualities of such a Film I f miniature film is to replace full-size films for these purposes certain qualities are absolutely essential.

(z) The technical standard must be absolutely reliable. This has been discussed at greater length in a previous article (Clarke, z95o ) where a full bibliography was given; the results in America, Canada and here are satisfactory.

(2) The individual film must be easily handled and filed with the patient's notes.

(3) The films taken over a period of time must be able to be compared directly at the same time.

(4) The films must be large enough to be

February 1952 T U B E R C L E 43

viewed against direct lighting, e.g. a view box or window, without enlargement.

(5) I f necessary, the wet film must be available for study within a short time of being taken, e.g. at the same out-patient session.

C. The Advantages of Miniature Film I f a new technique is to gain acceptance it must have definite advantages over well- established methods. The individual minia- ture film has the following very definite advantages:

(I) Economy of F i lm. - The cost of 5 × 4 in. film is about 5 d. compared to at least 3 s. 6d. for full size film. Thus, with a saving of about 3 s. on each exposure, £z ,ooo will be saved after about 7,ooo exposures.

(2) Economy of Chemicals.- The smaller film demands a much smaller consumption of developing and fixing chemicals, which are also increasingly difficult to obtain.

(3) Storage. - Miniature films require I / io of the storage space of full-size films, with a corresponding reduction in the weight. Furthermore, since the x-rays can easily be filed with the notes a further reduction in extra storage space is obtained.

(4) Reference.- Since the cost is small, extra films can easily and justifiably be made when a case is referred to another hospital.

(5) Reproduction. - Direct reproductions can be made with the. simplest of photo- graphic equipment.

D. The Type of Film and Equipment Required

To fulfil these requirements a miniature film should be of fine detail, large enough for direct study, easily processed, and capable of use as a separate record. Roll film is therefore quite unsuitable.

The extra equipment must be compact, reliable, and able to be used in conjunction with any ordinary x-ray tube designed for chest radiography. This requires a fluores- cent screen, tunnel and camera, on a movable stand, with a holder to allow full- size films to be used on the same set.

At the present time, two types of equip-

ment are under consideration, one which produces 5 × 4 in. cut film and the other 7 ° mm. film, either as roll film or cut film. In both cases the name and date can be photographed on to the film at the time of exposure. It is probable that the 5 × 4 in. film, being larger, is the more suitable, because it is more easily viewed by direct light and is more easy to handle both during processing and clinical examination. A roll- film which requires subsequent cutting into single frames has grave disadvantages in the x-ray department; moreover, the smaller film is less easy to view, is liable to curl, and is more likely to be mislaid.

In both cases the cost of equipment is estimated at about £I,5OO, which cost would easily be saved in one to two years at the average clinic or chest unit.

The advantage definitely lies with the 5 × 4 in. film, but if the 7 ° mm. equipment is more easily and more rapidly obtainable, and some means is devised to improve the convenience in handling and viewing of that film, it certainly warrants further trial. The decision must depend upon whether the film obtained is large enough for direct viewing, and can be easily stored with the notes, and studied in comparison with previous minia- ture films.

The 35 mm. film does not fulfil these criteria, although excellent for mass survey work; the 7 ° mm. film would seem to fall between the two, having the main advan- tages of neither. The 5 × 4 in. cut film is probably the ideal.

The purpose of this article, however, is to emphasize the wider field of miniature radiography for individual clinical work as well as mass surveys, and to stimulate the production and development in this country of tile best type of equipment. The need for economy and the serious shortage of x-ray film adds urgency to the problem, if the treatment of chest diseases is not to revert from its present high standards to the realms of guesswork and witchcraft.

Reference Clarke, O. (x95o) Lancet, u, 757-