Hazards of dental radiography (1953)

the properties of X-rays and the problems of radiation protection are part of the research program of the National Bureau of standards because x-rays are widely used by the dental profession safe operating procedures are needed to protect the dentist his assistants and patients the value of dental radiography is universally recognized however the dangers of dental radiography are not universally recognized sometimes in order to help a patient or to save time the dentist holds the film in the patient's mouth this procedure which places his hand directly in the primary beam of radiation is a very dangerous thing to do over a period of time this dangerous practice results in x-ray Burns these Burns rarely heal and often become malignant there are other hazards in the use of x-radiation in the dentle office which are less obvious to avoid this type of burn and and to avoid the other hazards which may endanger himself his personnel and patients the dentist should be aware of the nature of X-rays and the proper rules of safety in the radiation Physics laboratory of the National Bureau of Standards studies of x-rays are conducted such studies require highly specialized equipment and Personnel in this work Phantom dummies are used the material used in them simulates human tissue in the way it absorbs and scatters x-rays after many such measurements are taken the data are recorded and analyzed this work leads to the publication of radiation protection handbooks andbook 41 medical x-ray protection up to 2 million volts gives specific recommendations for use by the dental profession although x-rays are more dangerous they have many characteristics in common with visible light visible light travels in straight lines from the heated filament of the bulb as indicated by the shadow of the object placed in the path of a beam x-rays also travel in straight lines from the target within the X-ray tube the light from a bulb varies with the voltage or pressure which forces the amperage or amount of current through the filament the characteristics in the quantity of radiation from an x-ray tube are also dependent upon the voltage applied to the tube and the current passing through it it is common knowledge that the intensity of light changes as the distance from the light source varies this is also true of X radiation the Rays diverge becoming less intense as the distance increases the intensity varies inversely with the square of the distance this is referred to as the inverse Square law the intensity is inversely proportional to the square of the distance 8 in from an x-ray tube this meter reads 40 while it's 16 in or twice the distance the meter reads only 1/4 of the previous value substances which permit X radiation to pass through are called radiolucent these are materials of low atomic weight such as this board substances which do not permit the passage of X-rays are called radioopaque These are materials of high atomic weight such as this lead plate the amount of x-rays which will go through a material also depends on thickness for example x-rays easily pass through a single Master board a double thickness reduces the amount while x-rays are invisible they can be represented by the red light coming from this pointer cone when x-rays strike an object secondary x-rays are produced and Scatter in all directions as is represented by the glow from within this object when the x-rays stop the secondary rays are no longer present everyone is familiar with the effect of strong sunlight or ultraviolet light upon the skin and that there is a latent period between the exposure and the Emma or burn there is also a latent period between x-ray exposure and the appearance of tissue damage however tissue cells do not adjust or become less sensitive to x-radiation even though these exposures are of short duration holding the film is to be condemned for all x-radiation is dangerous repeated exposures such as these hands are receiving may result in x-ray Burns these are the hands of dentists who disregarded or were unaware of the dangerous nature of x-radiation the x-rays have a pronounced effect upon the proliferative tissues as these tragic examples indicate the cells of the fingernails and skin are the first to be affected when the hands are held in the direct path of the X-ray beam other proliferative cells such as those of the blood forming tissues are easily damaged by excessive X radiation to protect himself his personnel and his patients the dentist should know and apply the recommended safety rules of the National Committee on radiation protection these rules are easily followed as this dentist and his assistant demonstrate the beam of radiation should be confined to as small a cross-section as is consistent with the radiographic requirements the lead diaphragm fitted inside the pointer cone allows radiation to escape only through this aperture which determines the size of the primary beam use a manual timer switch that will operate only when the button is pressed this switch cannot be accidentally left on the operator or his assistant should never hold the film only the patient shall be in the primary beam of the x-rays this primary beam continues in a straight line past the patient the direction of the primary beam is not the same for all exposures of the teeth therefore it is important to change one's position as the various exposures are made do not be as careless as this assistant who is not watching the direction of the primary beam such carelessness is very dangerous to avoid exposure by the secondary or scattered radiation which are produced about the patient and the X-ray tube during the exposure it is necessary to stand a minimum distance of 4 ft from the patient and the X-ray tube further precautions are necessary if the apparatus is used for more than 15,000 milliamp seconds per week this corresponds to 500 32 10 milliamp exposures per week because of the excessive amount of secondary radiation present it is necessary that the operator stand behind a lead Shield during every exposure only the patient shall be in the room when the equipment is operated for more than 15,000 milliamp seconds per week x-rays present A Hazard to nearby Personnel because they go through ordinary building construction such construction must be shielded by using at least 3 and 1/2 in of concrete 36 18 in of iron or 132nd in of lead to cover walls ceiling floor and doors x-rays are necessary to good dental practice and they can be used with complete safety to the patient the operator and the office Personnel if the following rules are observed for less than 15,000 mamp seconds per week usage one use a small beam of radiation two use an approved timer switch three stay out of the primary beam of radiation four stand at least 4 ft from patient and x-ray tube for more than 15,000 mil seconds per week usage one use a small beam of radiation two use an approved timer switch three stand behind protective screen during all exposures four cover walls floors and ceilings with a protective shielding [Music]