160 15 July 1967 BxmaMEDICAL JOURNAL

PREPARATIONS AND APPLIANCES

Apparatus for Automatic Preparation and Scanning in Cervical CytologyMr. M. M. BODDINGTON and Dr. R. A.DIAMOND, of the Clinical Cytology Labora-tory, Churchill Hospital, Oxford, write:Population screening for carcinoma of thecervix has been limited by the lack of trainedtechnicians as well as by inadequate labora-tory facilities. This problem could largelybe solved by automation by means of amechanized system with a computer capableof analysing cells and arriving at a decisionat high speed.The apparatus described here is an aid to

visual scanning of cervical smears by a cyto-logist, but is also applicable to automaticscanning by a computer technique. To en-able a computer to scan cells rapidly anautomated strip method with an even celldistribution is essential (A. Ward, personalcommunication, 1966).The Vickers Cytology Screening Apparatus

is divided into three parts: the first is thegraphing machine, which places a line ofcells on to a clear transparent strip. Thisis then transferred to the second part, whichis a continuous staining apparatus that alsoautomatically covers the cells with a clearScotch tape. The final machine is the view-ing apparatus.

Collection of Specimen.-The specimenis presented to the graphing machine as a cellsuspension. To do this the cervical smear is

FIG. 1

collected in the usual way and then thespatula is placed into a solution of 1 %Carbowax in 40% ethyl alcohol and trans-ferred to the laboratory. By using a narrowcontainer with a conical bottom containinga measured amount of fixative, the containercan be placed direct into the centrifuge afterremoving the spatula. Suspending cells in aCarbowax alcohol solution allows them to bedried on the film strip previous to stainingwithout spoiling the specimen.

GRAPHING MACHINEThe graphing machine has three functions:

(1) aspirating excess fluid from concentratedcells ; (2) pretreating a transparent film strip(Melinex I.C.I.) with celloidin (NecoloidineB.D.H.); and (3) drawing along the centreof the Melinex a linear film of cells.A spool of Melinex 250 metres long is

mounted on to the machine and laced underthe Necoloidine writer through a guide overwhich the cell writing pen is located. Afterthe cell writer the film is passed through thenumbering mechanism, thence through thespecimen dryer, and on to the take-up spool(Fig. 1).The Necoloidine is applied to the Melinex

by what might be described as an outsize ballpen. It is hoped that when in production

the film will be supplied already coated withNecoloidine. Because the cells are fixedin solution Necoloidine-treated film must beused to prevent the cells from being washedoff the film.The cell writing pen is a linear recipro-

cating peristaltic pump. It differs from thenormal peristaltic pump in that it draws fluidinto its pliable plastic tubing and exhausts itout of the input. The unique feature of thepen is that the contaminated tubing is with-drawn, cut, and discarded. The plastictubing is fed through the top of the pen froma reel, so that on drawing the contaminatedtubing out it is automatically replaced byfresh tubing.

After centrifuging the tube is placed undera pipette and the excess fluid aspiratedthrough a pump. The amount of fluid with-drawn is controlled by the attendant and thecell deposit thoroughly resuspended.The pen is loaded by sucking up the con-

centrated cells ; it is then placed over thecentre of the Melinex strip with the protrud-ing plastic tubing, which acts as a nib touch-ing the strip. A motor is started, the tapeis drawn beneath the pen, and the peristalticpump reverses and deposits a line of cells for61.5 cm., which corresponds to the areascanned on a normal microscope slide when a5-cm. coverslip is used.

FIG. 3

FIG. 1.-Graphing machine, showing the peristaltic pen (centre) whichdeposits a line of cells on the transparent film strip as it passes. FIG. 2.-Continuous staining apparatus, showing the series of rollers over whichthe film strip is looped. Beneath them is the unit containing the indi-vidual staining-baths which, when raised, immerses the rollers. FIG. 3.-Viewing apparatus. The prepared film on the left passes under the ob-jective of the microscope (centre) for viewing on the screen or through

the binoculars.

FIG. 2

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15 July 1967 New Appliances BDICALJORNAL 161

Materials.-(a) Melinex, 16 mm. wide by0.075 mm. thick by 250 m. long (I.C.I. pro-duct); (b) 1% solution of Necoloidine inequal parts of ether/alcohol; (c) translucentsilicone rubber tubing size 1 by 0.5 mm.Quality P.C. 156.

STAINING APPARATUS

The spool from the graphing machine isloaded on to the continuous stainingapparatus and the free end of the preparedfilm is welded on to a leader strip of Melinex,which is already fed through the apparatus.The prepared film is thus fed backwardsthrough the staining process; the last 9.3 m.must be clean film to act as a leader for thenext spool (see Fig. 2).The staining and clearing process consists

of 20 baths, the Papanicolaou techniquebeing used. After the specimen has beencleared in xylene a line of D.P.X. mountingmedium is drawn over the line of cells. Thefilm is then covered by Scotch tape, 2 mm.narrower than the film, by passing them to-gether through a roller system so that thetape is pressed evenly over the Melinex. Theapparatus is fitted with five safety switches,which stop the machine if any faults developduring the processing.The prepared specimen is taken up on an-

other spool ready for immediate use on theviewing apparatus, having taken 13.25minutes for the first specimen to be com-pleted and then 1 minute for each subsequentspecimen.

VIEWING APPARATUS

The specimen reading unit is a standard-type microscope, but differing from today'smechanical practice in that the body isfocused and the stage remains fixed. Thespool of specimens is loaded on the left ofthe microscope and the strip is located beneaththe objective by a simple gate. The strip isdrawn past the objective, the operator con-trolling the scanning speed through a start-stop and variable-speed control (Fig. 3).The operator can reverse the strip by motor

and centre any given field by normal stagecontrol for examination under high power.A precision punch is provided for accuratelymarking abnormal cells, so that instant reviewof these can be made when the punched holepasses through a trigger-switched clamp. A

similar electromechanical clamp holds eachspecimen number for reference during thepassing of that specimen.The specimen is viewed through binoculars

or on a screen with the normal low- andhigh-power lens system.The specimens are conveniently stored on

the spools, each 250-m. reel containing upto 200 smears.

DiscusSIONInitially this apparatus was designed to fit

a computerized scanning system, and it isexpected that ultimately a pattern recognitioncomputer or similar prescreening device willtake over much of the human effort involvedin scanning cervical smears (Ward and Mc-Master, 1966). When this ideal set-up isestablished the positive material must still bechecked by a cytologist, and this continuous-feed mechanism must be readily adaptablefor human use.The first essential is that the cells should

be recognizable to the human observer andthat the staining technique should thereforebe the Papanicolaou method. The techniqueof suspending the cells in a Carbowax-alcohol solution and allowing them to drygives a staining reaction almost identical withthat by the routine "wet fixation" methodused for smears on glass. The suspensiongives an even distribution of cells with lessclumping, and the gross appearances aresomewhat different from those in a direct-smear preparation.Our experience is similar to that of Davis

and Jones (1966) using the cytopipette inthat cellular patterns are different and re-quire experience in interpretation. The cyto-pipette method is readily adaptable to thisautomated system. Abnormal cells do notappear in natural collections, and, though notso readily picked up by the human eye, thescatter distribution is necessary for a com-puter " eye."A method of making and staining strips

of cervical smears having been developed, theviewing machine was the next essential. Thishad to be capable of scanning the film stripswithout computer aid, and the present modelcan therefore be used for routine screeningidentical with the glass-slide method in speedand efficiency.A detailed time comparison between the

routine slide method and the Vickers CytologyScreening Apparatus shows them to be very

similar. The staining time is slightly in-creased; but this is no disadvantage, becauseit does not involve technician time. More-over, the " smears " are in numerical orderand are ready to scan immediately. Thetechnician time involved in the process isequivalent, apart from 51 seconds required tomake each smear on the graphing machine.The advantages of the system are the uni-

formity of the preparations, the fixednumerical sequence of forms and smears, andthe consequent ease of filing. Staining oflarge numbers can be carried out overnight,and the automatic selection of previouslymarked cells for checking is an added refine-ment.The main advantage of such a system

would be felt in large population surveys.The greater the number of smears to bescreened and the larger the laboratory themore efficient will be an automated apparatusof this nature.

Further trials are in progress to substantiatethe efficiency of the Vickers Cytology Screen-ing Apparatus in enabling malignant cells tobe more readily detected and to shorten thetime involved in scanning. Attempts arebeing made to improve the initial cell suspen-sion and to produce a differential nuclearstain, so that investigations into the effective-ness of a prescreening device attached to thisapparatus can be completed.The application of this system to other

pathological services is under investigation.This work was initiated in the Churchill

Hospital Cytology Department by Dr. A. I.Spriggs, who has encouraged and advised usthroughout the development of the project.This work was supported by grants to one ofus (R. A. D., Research Assistance Area Depart-ment of Obstetrics and Gynaecology) fromTenovus and Vickers Instruments, and to Dr.Spriggs by the British Empire Cancer Cam-paign. The instruments have been designedand constructed by Vickers Ltd., VickersInstruments, under licence from Mr. P. A.Rock (U.K. Patent No. 1036776 and variousoverseas patent applications) and under thesupervision of Mr. F. H. Smith and Mr. J. F.Taplin (Research Department), and the com-bination of the complete system was the workof Mr. E. W. Meyer (Forward Development).

REFERENCESDavis, H. J., and Jones, H. W., jun. (1966). Amer.

7. Obslet. Gynec., 96, 605.Ward, A., and McMaster, G. W. (1966). Sci. 7.,

August.

ANY QUESTIONS ?We publish below a selection of questions and answers of general interest.

Health in Malawi

Q.-Are the dangers to health for Europeanchildren greater in Malawi than at home?Are comparative mortality figures availablefor children under 5 years of age? Whatare the main causes of sickness and death inthis group?

A.-Comparative mortality figures forchildren under the age of 5 years in Malawiare not available. The most recently avail-able data on this subject are those contained

in the Last Report on the Public Healthof the Federation of Rhodesia and Nyasalandduring the Year 1963 Presented to theFederated Liquidating Agency.' In thisreport the infantile mortality rate amongEuropeans in Malawi is given as 3.9 per1,000, but it is based on only one infantiledeath. The crude death rate among Euro-peans in Malawi is reported as 3.3 per 1,000.

In general, those living in this part ofAfrica would need to take special precautionsagainst malaria and bacillary and amoebic

dysentery. The usual precautions again tsmallpox, yellow fever, and poliomyelitisshould also be taken. Though the dangersto health for European children in Malawiare greater than they are in Britain, standardprecautions will reduce these dangers to avery low level. Details of such precautionswill be found in the publication entitledNotes on the Preservation of Personal Healthin Warm Climates.2

REFERENCES

Last Report on the Public Health of the Federa-tion of Rhodesia and Nyasaland during the Year1963 Presented to the Federated LiquidatingAgency. Government Printer, Salisbury.

2 The Preservation of Personal Health in WarmClimates. 1967. Ross Institute, London.

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