MEDICO-BIOLOGIC RESEARCH 



Round opening in lead 

 covered with 

 light proof filmsJ 



Top cover of 

 cassette, with 

 lead lifted 



(reduced size) 



Plastic 



Lead(2mni) 



Square opening 

 in top 



■Top cover 



Equal distance 



Base part of 

 cassette, seen 

 from side 



Depression (0,75mra) 



Base part, seen 

 from above 



Scheme of Microradiographlcal Cassette 



Fig. 6. Scheme of MRD cassette used by Bohatirchuk (explanation in text). 



base and cover of the cassette are made of 

 hard wood. 



The cassette proposed by Sherwood (104) 

 is much more complicated. In this "vacuum 

 exposure holder for microradiography" the 

 contact between specimen and emulsion is 

 achieved through the evacuation of air be- 

 tween object and emulsion. This is perfonned 

 with an air pump connected with the interior 



of the cassette (Fig. 7). Unfortunately, this 

 cassette cannot be used in microradiography 

 of medico-biological specimens because, ow- 

 ing to the vacuum inside the cassette, its 

 cover has to be made of a hard and thick 

 plastic material resistant to atmospheric 

 pressure. Such a cover absorbs soft and ultra 

 soft x-rays used in medico-biological micro- 

 radiography. 



O 



B C D E 

 / / / / 



^l 



Fig. 7. Schematic drawing of Sherwood's vacuum exposure holder. A — vacuum pump connection 

 B — opaque cover, C — specimen, D — photographic emulsion on glass plate, E, F — grooved trap (from 

 Sherwood) (104). 



599 



