The current dose threshold for lens opacities is 0.5 Gy with a single exposure and 5 Gy with highly fractionated or protracted exposures. The formation of cataracts, however, is a deterministic effect, which means that the dose must be above the threshold level for that tissue effect. At high enough exposures, the risk to the eyes from irradiation is cataract formation. It is also of value to consider the dose to the lens of the eyes. This is a stochastic risk with increased dose resulting in increased risk. The radiation risk for these organs is cancer induction. The key organs of interest when investigating exposure from panoramic radiography are the thyroid, salivary glands, brain and red bone marrow. This is owing to increased radiosensitivity of the tissues and a longer life span. In comparison with adults, children are inherently at greater risk of cancer induction from radiation exposure. If a child height slit is not available, however, the extent of irradiation above the jaw cannot be reduced for a small head. On some, but not all, panoramic system exposure factors can be fully adjusted to appropriately irradiate a large or a small head. The dose delivered to the patient will be determined by the radiographic exposure factors (kilovoltage, milliamps, exposure time) as well as the selected collimator slit height. The consequence of this is the likely increase in dose to the radiosensitive organs in the head when taking panoramic radiographs on children.
#Panorama x ray on two year old install
Dental clinics or hospital departments often install panoramic radiography systems that have only the longer collimator slit. Although, many systems are sold without the child slit option. Collimator slit heights at the image detector are typically 140 mm for an adult head and 110 mm for a child's head. Where the panoramic imaging system is to be used to image both adult and paediatric patients, there should be a choice of at least two different collimator slit heights. 1 The irradiated volume should be limited to produce an image showing only the anatomy necessary for clinical diagnosis. The European guidelines on radiation protection in dental radiology published in 2004 recommended that during panoramic radiography, the radiation field should be restricted. In the healthcare environment panoramic radiographs are usually taken on children in support of either orthodontic treatment or the management of facial trauma.
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