radiograph.pdf

RADIOGRAPHIC TECHNIQUE IN PEDIATRIC DENTISTRY PRESENTED BY DR: MOHIRA EZZELDIN  Wilhelm Conrad Roentgen’s discover the x-rays on November 8, 1895.  First dental radiographs ever taken by Otto Walkhoff in January 1896.  Two-dimensional intraoral and extraoral radiography were...

RADIOGRAPHIC TECHNIQUE IN PEDIATRIC DENTISTRY PRESENTED BY DR: MOHIRA EZZELDIN  Wilhelm Conrad Roentgen’s discover the x-rays on November 8, 1895.  First dental radiographs ever taken by Otto Walkhoff in January 1896.  Two-dimensional intraoral and extraoral radiography were the only radiographic options; but a little more than two decades ago, three-dimensional imaging in dentistry (cone beam computed tomography [CBCT]) became much more readily available.  other advanced imaging modalities, such as multi-slice computed tomography (MSCT), magnetic resonance imaging (MRI), and ultrasound imaging, are also available.  The risks of radiation exposure must be balanced against the clinical knowledge that dental radiography provides:  Only way to obtain the necessary information.  The exposure benefits the patient and outweighs the inherent risks.  Cumulative exposure to ionizing radiation over a patient’s lifetime is of chief significance (as opposed to dose per single exposure).  Because the risks associated with radiation are higher for fast-dividing cells and tissues, children are more vulnerable to radiation exposure than adults  The three basic rules for safe radiographic exposure are:  justification,  limitation  optimization.  The Justification Principle: o states that one should expose patients to ionizing radiation only if there is no other way to obtain the diagnostic information or if this exposure will positively influence the diagnosis, the treatment, and the patient’s health.  Limitation principle: o states that one should always try to keep the radiation dose as low as reasonably achievable (ALARA).  Optimization principle: o means that one should obtain the best quality images possible.  Proper technique and the implementation of strict safety protocols are critical steps during pediatric imaging.  Radiographs are used to :  diagnose interproximal caries.  diagnose periapical infection  impacted teeth  dental fractures.  name a few common conditions.  follow up on treatment outcomes.  PROTECTION OF THE DENTAL STAFF  The best method for protecting dental staff from ionizing radiation is the use of shielding. Solid walls (preferably with a lead glass window) are the best protection one can achieve.  The radiographer should stand either at 90 degrees to or behind the radiation source; at least 6 feet (2 m) from the radiation source is safe.  If, for whatever reason, insufficient distance is maintained, one should wear a lead or lead-free apron with thyroid shielding and stand in the appropriate position relative to the radiation source.  The 6-feet rule also applies to panoramic and cephalometric imaging.  For CBCT imaging, one should always stand behind a radioprotective barrier.  PROTECTION OF THE PATIENT In addition to the three basic principles of radiation protection (justification, limitation, and optimization), one can apply the following additional techniques to reduce the radiation burden to the patient:  Lead or lead-free apron with thyroid collar  Rectangular collimation of the x-ray beam.  Correct focus-to-skin distance.  More radiation-sensitive image receptors  The use of rectangular collimation is better because it:  limits the surface being irradiated to the size of the image receptor, reducing the radiation dose by about 50%, compared to circular collimator.  decreases the amount of scatter in the patient’s tissues, which in turn results in better image quality  The focus-to-skin distance is the distance between the x-ray machine’s anode (where x-rays are created) and the skin of the patient’s cheek or lip.  Ideally, this should be a minimum of 8 inches (20 cm) to reduce the amount of low energy x-radiation reaching the patient.  Fast image receptors, which require less exposure time, are advised since their use will enable the lowest possible radiation dose to be absorbed by the patient.  If direct exposure film is used, either E- or F-speed film is strongly recommended.  D-speed film is not recommended  Digital image receptors and E- or F-speed film are considered to achieve similar lower radiation doses for patients.  Correct positioning of the patient, image receptor, and tube head as well as appropriate exposure factors will decrease the need for retake x-ray and will help keep the patient’s dose ALARA  Radiographic Image Receptors: 1. ANALOG FILM: Analog film is still used by a significant number of clinicians. A. Direct Film: Is the film of choice for intraoral radiography. It is called direct because of its high sensitivity to x-rays. Only E- or F-speed film should be used( require shorter radiation exposure thus a lower radiation burden for the patient).  Disadvantages include: o Double exposures, o Difficulty sharing the films with colleagues and insurance companies, o Need for sufficient office space to store chemicals, processor, and radiographs. B. Indirect Film:  More sensitive to light than it is to x-rays and should be used only in a cassette with an intensifying screen.  The intensifying screen converts the x-ray energy into light, which reaches the film and forms the latent image  In dentistry, this type of film is used in panoramic imaging and cephalometric radiography.  Short exposure time but the images are less sharp. 2. DIGITAL FILM:  Photostimulable Phosphor Storage Plates  Referred to as indirect digital imaging.  Image is captured in an analog format and converted to a digital image when scanned.  PSPPs come in different sizes.  Can be used for either intraoral or extraoral applications.  When used for intraoral radiography, they should be wrapped in a single-use plastic light-tight barrier (to avoid cross-contamination and the toxicity of the phosphor layer).  Acceptable for intraoral radiography in pediatric patients and patients with special needs.  The biggest disadvantage of PSPPs is their susceptibility to scratches, bite marks, and creasing, which could damage the phosphor layer.  This damage is irreversible and will always be visible as a radiopacity in the image.  Solid-State Sensors  also known as direct digital receptors because they display the radiographic image instantaneously following exposure.  Direct digital sensors are available in sizes 0, 1, and 2  The primary disadvantage is:  They are relatively bulky and not always easy to position in the patient’s mouth  The majority of direct digital sensors are attached to a computer by a shielded wire cable, which can be damaged by repeated biting.  Radiographic Techniques The patient’s size and ability to cooperate must be considered when a radiographic technique is selected.  INTRAORAL RADIOGRAPHY  The timer must be accurate to allow for short exposure times.  Radiation-sensitive (rapid) image receptors should be used at all times  Rectangular collimation of the radiation beam is advised to reduce the irradiated surface area to the size of the image receptor.  The use of film positioning devices or image receptor holder is strongly recommended. 1. Periapical Radiography Periapical radiographs should show the crown of the tooth and at least 3 mm beyond the apex of the tooth.  Two technique: A. Paralleling Technique.  This is the most accurate technique for taking intraoral radiographs.  The image receptor positioned parallel to the long axis of the teeth.  The x-ray beam is directed perpendicular to the image receptor.  Image receptor holders should be used B. Bisecting Angle Technique.  The image receptor is placed as close to the teeth as possible,  The central x-ray is directed perpendicular to a line that bisects the angle created by the tooth and image receptor  Drawback:  Elongation or foreshortening (vertical angulation errors)  Interproximal overlap (horizontal angulation errors) 2. Bitewing Radiography  Intended to assess interproximal caries and interproximal bone height.  Image receptor is placed parallel to the teeth and the x-ray beam is aimed perpendicular to the receptor. 3. Anterior Maxillary Occlusal Technique.  The patient’s occlusal plane should be parallel to the floor  The sagittal plane should be perpendicular to the floor 4. Posterior Maxillary Occlusal Technique.  The patient’s occlusal plane parallel to the floor  The sagittal plane should be perpendicular to the floor 5. Anterior Mandibular Occlusal Technique.  identical to that for the anterior maxillary occlusal technique..  The patient’s head is positioned so that the occlusal plane is at an angle of 45 degrees to the floor.  The cone is then aligned at a –15-degree vertical angle, and the central x-ray is directed through the symphysis. 6. Localization Techniques  One method of localizing embedded or unerupted teeth involves the buccal object rule (also referred to as the parallax technique or the “same lingual opposite buccal,” i.e., SLOB rule).  States that the image of any buccally oriented object appears to move in the opposite direction from a moving x-ray source. Conversely, the image of any lingually oriented object appears to move in the same direction as a moving x-ray source.  The practitioner makes two radiographs of the unerupted tooth.  Positioning the patient’s head so that th sagittal plane is perpendicular to the floor and the ala-tragus line is parallel to the floor.  An intraoral periapical film is placed in the mouth and then exposed by the paralleling technique.  Subsequently, a second film is placed in the mouth in the same position as the first film, with the patient’s head position remaining the same, but with the horizontal angle shifted either anteriorly or posteriorly.  The object in the projection that moved in the direction opposite to the x-ray machine was moved is located more buccally and vise versa  EXTRAORAL RADIOGRAPHY 1. Panoramic Imaging  The panoramic image is obtained through tomography.  panoramic images are magnified (by a factor of around 1.3) and therefore measurements taken from a panoramic image will also be magnified.  Most current panoramic machines enable one to take bitewing look-alike images.  Panoramic machines are available with solid-state sensors or with a cassette system. 2. Cephalometric Imaging: This technique is usually used in orthodontics and orthognathic surgery. 3. Cone Beam Computed Tomography:  This technology has become very popular since 2002  This modality is ideal for imaging hard tissues, including bone and teeth.  CBCT delivers higher radiation than traditional radiographic techniques.  Provides detailed and critical information in very specific situations.  justification to expose pediatric patients to CBCT should not be taken lightly  Indications for the use of CBCT includes :  localization of impacted canines and third molars.  visualization of maxillofacial pathologies for assessing extension or surgery planning.  visualization of the condyles and glenoid fossa.  visualization of the maxillary sinuses. 4. Ultrasound Imaging  Excellent for investigation of soft tissues, such as the floor of the mouth, salivary glands, and lymph nodes in the head and neck region.  Does not involve ionizing radiation  Appropriate when fine-needle aspirations are required. 5. Magnetic Resonance Imaging  The MRI evaluates the hydrogen content of tissues and uses this technique is especially useful with soft tissue.  The most common dental indication for the use of MRI is for imaging the soft tissues of the temporomandibular joint  Contraindications for MRI include : o Claustrophobia( a fear in being in closed place). o presence of metallic clips or metallic foreign bodies.  Interpretation of Radiographs  The initial diagnosis should not be made at the chairside monitor, but rather in an area of the office where the light is dimmed.  In case one has an image that cannot be diagnosed, the assistance of an oral and maxillofacial radiologist may be advisable.