Table 7: Recommendations for Prescribing Dental Radiographs a
Adolescent: Permanent Dentition
Type of Patient Encounter
Child: Primary Dentition Clinical judgment for need & type
Child: Mixed Dentition
Adult: Dentate or Partially Dentate Adult: Edentulous
New or recall patient monitor growth & development/assess dental/skeletal relationships. Patient with other circumstances.
Clinical judgment for need & type
Clinical judgment for need & type of images for assessment; panoramic or PAS for third molars. Clinical judgment for need & type
Usually not indicated.
Usually not indicated.
of images for assessment.
of images for assessment.
Clinical judgment for need & type
Clinical judgment for need & type
Clinical judgment for need & type
Clinical judgment for need & type
of images for assessment or monitoring.
of images for assessment or monitoring.
of images for assessment or monitoring.
of images for assessment or monitoring.
of images for assessment or monitoring.
PAS = periapical films; BWS = bitewing films; FM = full mouth set of films; NA = does not apply. a The recommendations in this chart are subject to clinical judgment and may not apply to every patient. They are to be used by dentists only after reviewing the patient’s health history and completing a clinical examination. Note. Adapted from Johnson, et. al., 2021. Filtration
scatter radiation. Rectangular collimation also significantly reduces radiation exposure to the thyroid compared with circular collimation with 13 studies concluding that there is a least a 40% reduction of radiation exposure when rectangular collimators are used. (Shetty et. al., 2019) Thyroid shielding be provided for children and adults when it will not interfere with the radiographic examination as thyroid collars have been shown to reduce radiation exposure to the thyroid gland by up to 33% in children and 63% in adults (Lintag, et. al, 2019). It should be noted that many states mandate the use of a lead apron and thyroid collar on all patients. Image receptors D-speed film, E-speed film, and F-speed film are currently available; the F-speed film provides the lowest radiation exposure to the patient, allowing 60% less radiation dose than D-speed film (Issrani, 2017). The use of F-speed film or digital image receptors significantly reduces patient exposure and is recommended for intraoral radiography. Digital image receptors include rigid solid-state wired or wireless detectors, such as a charge-coupled device (CCD) and the complementary metal oxide semiconductor, and a flexible wireless sensor, such as the photostimulable phosphor plate (PSP) or storage phosphor plate. Forming a digital image on the receptor requires less radiation because the sensor is more sensitive to radiation than traditional film and can produce an image that is comparable to the diagnostic quality of an F-speed film (Evearitt, 2016). Examples of acceptable intraoral image receptors include PSPs, rigid solid-state sensors, and F-speed film. With regard to extraoral imaging for panoramic and cephalometric projections, there is no appreciable dose reduction between film-based systems and digital systems (White & Pharoah, 2014). Current intensifying screens utilize rare earth elements, such as lanthanum and gadolinium, which significantly decrease patient exposure when compared to the calcium tungstate screens used in the past. Receptor instruments Beam alignment devices center the receptor and primary beam of radiation and are recommended for all intraoral exposures. The paralleling technique aligns the long axis of the tooth and receptor parallel to each other, giving the most accurate representation of the teeth and surrounding structures without dimensional distortion. The paralleling technique is easier to use than the bisecting angle technique and eliminates the need for the operator to estimate the correct angulations of the beam. Receptor instruments are recommended for intraoral imaging because they produce quality images and reduce the need for retakes.
The x-ray beam exiting the tubehead contains both high-energy and low-energy photons. Filters remove the low-energy, long- wavelength x-rays from the beam. The low-energy x-rays are detrimental because they are absorbed by the patient without contributing to the diagnostic information on the radiograph. Filtration involves placing aluminum disks in the path of the x-ray beam; federal law regulates the thickness of the aluminum. A dental x-ray machine operating below 70 kVp should have at least 1.5 mm aluminum filtration, while a machine operating at 70 kVp or higher should have at least 2.5 mm aluminum filtration (Iannucci & Howerton, 2017). Also, materials used in the manufacture of the tubehead, including the glass window, insulating oil, and the tubehead seal, provide additional filters to lower patient exposure to these low-energy x-rays (Iannucci & Howerton, 2017). Collimation The lead collimator restricts the size and shape of the x-ray beam as it exits the tubehead and therefore aids in reducing the radiation dose for the patient. Collimators can be circular or rectangular and can be placed within the tubehead or at the end of the lead-lined cylinder. Rectangular collimation is preferred over circular collimation because it decreases the area of exposure by 60% (Iannucci & Howerton, 2017). Circular collimators can be converted to a rectangular-shaped opening with commercially available devices. The beam of radiation shall be collimated so that it is no more than 2.75 inches in diameter when it makes contact with the patient’s face with the use of a shielded, open-ended, long (20- to 40-cm) position-indicating device, preferably with rectangular collimation (Augusta Exposure is further reduced when the patient wears a lead apron with either an attached thyroid collar or a separate thyroid collar. Lead aprons and thyroid collars provide shielding to reduce radiation exposure to the gonads and thyroid gland, respectively. The amount of scatter radiation to the abdominal area during dental radiographic examinations is negligible (Holroyd, 2018). The use of routine shielding may not be necessary as the benefits may be minimal given the decreased dose of radiation in today’s medical and dental x-rays (Jaklevic, 2020). However, clinicians must adhere to laws promulgated by their states about shielding during x-rays. Patients that have been shielded in the past may be reluctant to undergo dental x-rays without a lead apron. However, the thyroid gland in children is especially sensitive to radiation exposure (American Thyroid Association, 2019). Thyroid collars protect the sensitive thyroid tissue from University, 2018). Patient shields
Page 78
Book Code: DHFL2624
EliteLearning.com/Dental
Powered by FlippingBook