RADIATION' QUALITY AND BONK-MARROW DOSE IN RADIOLOGY 



dividing this by the average size of an X-ray film used. Since most of the 

 X-ray fihii used in this country is locally manufactured, the former quantity 

 can he determined with a fairly high degree of accuracy. The latter cjuantity 

 has been assessed from a know ledge of the number and size of X-ray film 

 used in three large diagnostic departments, as well as from the entire con- 

 sumj^tion of one importer of X-ray film. This leads to the figure of 4 x 10* 

 examinations annually of which some 3-5 million are on adults and some 

 li\e hundred thousand on children. The number of examinations /?fr ca/>//c 

 is, therefore, greater than in other countries.^ It is, however, relevant that 

 while the nimiber of doctors in Australia per head of population is rather 

 less than that in the United States^ the number of radiologists per capita is 

 some 15 per cent greater ^•'. The number of X-ray examinations of a particular 

 type carried out has been determined by surveying the records of five Australian 

 hospitals and the result of the survey is given in Table 2. 



Table 2. Percentage distribution of X-ray examinations in a number of Australian 



hospitals 



Based on the foregoing information, it is possible to calculate the bone- 

 marrow dose from each type of examination and the results are in Tables 3 

 and 4. In Table 3 are listed the values appropriate to normal techniques 

 (N.V.) and also those appropriate to the use of high voltage (H.\\) tech- 

 niques. It will be seen that the difference in the bone-marrow dose between 



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