BIOLOGICAL EFFECTS OF RADIATIONS 703 



allowed the passage of the rays. It was also found that the radia- 

 tion would darken a photographic plate entirely protected from 

 light. These new rays which he called "x-rays" are usually spoken 

 of as "roentgen rays" in his honor. These x-rays were found to 

 V penetrate paper, wood, aluminum, etc., but were completely ab- 

 sorbed by thick sheets of heavier metals, such as iron and lead. 



It was not long after the physicists had perfected the roentgen- 

 ray machine until physicians began to apply it in diagnosis of bone 

 injuries and in locating bullets and other foreign objects embedded 

 in the tissues of the body. By having the patient ingest a barium 

 compound it is now possible to obtain a detailed radiograph of the 

 digestive tract. Use of the fluorescent screen has allowed imme- 

 diate diagnosis of gastrointestinal disorders and has been of value 

 in the setting of broken bones. The roentgen ray machine has also 

 proved of great value to the dentist in locating cavities and pus 

 pockets in teeth, and in finding teeth that have never broken through 

 the gums. 



The biological effectiveness of roentgen radiation was discovered 

 in a tragic manner. Many technicians and physicians, who had been 

 exposing their hands and other parts of their bodies to the radiation 

 while making radiographs or using the fluoroscope, began to de- 

 velop severe burns on the exposed areas. Before the severity of the 

 affliction could be appreciated and before the knowledge of the 

 danger could become widespread many pioneers in the field of x-ray 

 diagnosis had unwittingly become martyrs to the cause of medical 

 science. It was thus realized that the radiation was biologically 

 effective, and that even low dosages delivered at frequent intervals 

 might result in incurable burns. Short exposures, such as are em- 

 ployed in diagnosis, are not sufficient to be harmful to the patient, 

 but the technician who is around an x-ray machine day after day 

 should be protected by lead shields. White blood cells and germinal 

 tissues are especially susceptible to roentgen radiation, whereas 

 other tissues such as those of the nervous and skeletal systems are 

 more resistant. This differential susceptibility of cells has allowed 

 the application of roentgen radiation to the treatment of cancer. 

 Malignant growths arising from radiosensitive tissue are susceptible 

 to roentgen radiation. If a cancer is composed of undifferentiated, 

 rapidly growing cells, it is usually more sensitive to the injurious 

 action of the roentgen radiation. There are a few notable excep- 

 tions to the above generalizations. 



