Radiation Characteristics And Radiation Protection PDF

Unit 7 Radiation Characteristics and Radiation Protection  Review: Ionization ⬤ Electrons remain stable in their orbits around the nucleus until x-ray photons collide with them ⮚ A photon is a minute bundle of pure energy that has no weight or mass ⬤ Ion...

Unit 7 Radiation Characteristics and Radiation Protection  Review: Ionization ⬤ Electrons remain stable in their orbits around the nucleus until x-ray photons collide with them ⮚ A photon is a minute bundle of pure energy that has no weight or mass ⬤ Ions are atoms that gain or lose an electron and become electrically unbalanced ⬤ X-rays have enough energy to push an electron out of its orbit, producing an ion (an atom that gains or loses an electron and becomes electrically unbalanced) in a process called ionization 2  Review: Properties of X-Rays ⬤X-rays are a form of energy that can penetrate matter ⮚ Like visible light, radar, radio, and television waves, they belong to a group called electromagnetic radiation ⬤Electromagnetic radiation is made up of photons that travel through space at the speed of light in a straight line with a wavelike motion ⬤The shorter the wavelength of the x-ray, the greater is its energy 3  Types of Radiation ⬤Primary radiation is made up of x-rays that come from the target of the x-ray tube ⮚ Useful beam or primary beam ⬤Secondary radiation is x-radiation that is created when the primary beam interacts with matter ⬤Scatter radiation is a form of secondary radiation that occurs when an x-ray beam has been deflected from its path by interaction with matter 4  Radiation Effects ⬤All ionizing radiation is harmful and produces biologic changes in living tissues ⬤The amount of x-radiation used in dental radiography is small, but biologic changes do occur ⬤The dental assistant must understand how the harmful effects of radiation occur and how to discuss the risks of radiation with patients ⬤Entire x-ray area is considered a radiation hazard area  Biologic Effects of Radiation ⬤Exposure to radiation can bring about changes in body chemicals, cells, tissues, and organs ⬤The effects of the radiation may not become evident for many years after the x-rays were absorbed ⮚ This time lag is called the latent period  Cumulative Effects ⬤Exposure to radiation has a cumulative effect over a lifetime ⬤When tissues are exposed to x-rays, some damage occurs ⬤Tissues have the capacity to repair some of the damage; however, they do not return to their original state ⬤The cumulative effect of radiation exposure can be compared with the cumulative effect from repeated exposure over the years to the rays of the sun Disorders of Critical Organs  Genetic and Somatic Effects ⬤X-rays affect both genetic and somatic cells ⮚ Genetic cells are the reproductive cells (sperm and ova) Damage to genetic cells is passed on to succeeding generations ⮚ All other cells in the body belong to the classification of somatic tissue X-rays can damage somatic tissue, but the damage is not passed on to future generations JUST REED THROUGH THIS ONE  Radiation Measurement ⬤Radiation can be measured in a manner similar to that used to measure time, distance, and weight ⬤Two sets of systems are used to define the way in which radiation is measured ⮚ The older system is referred to as the traditional or standard system ⮚ The newer system is the metric equivalent, known as the Système Internationale (SI)  Radiation Measurement (Cont.) ⬤Traditional units of radiation measurement ⮚ Roentgen (R) ⮚ Radiation absorbed dose (rad) ⮚ Roentgen equivalent [in] man (rem) ⬤SI units ⮚ Coulombs per kilogram (C/kg) ⮚ Gray (Gy) ⮚ Sievert (Sv)  Maximum Permissible Dose ⬤Maximum permissible dose (MPD) of whole- body radiation for those occupationally exposed to radiation is 5000 mrem (5.0 rem) per year, or 100 mrem per week ⬤This amount of radiation to the whole body carries very little chance of injury ⬤For nonoccupationally exposed persons, the current MPD is 500 mrem (5 mSv) per year ⬤Dental personnel should strive for an occupational dose of 0 by adhering to strict radiation-protection practices  HARP - https://www.ontario.ca/laws/statute/90h02 13  Responsibilities of the Dentist ⬤ Prescribe only images that are required for diagnostic purposes ⬤ Ensure that all radiographic equipment is maintained in safe working condition ⬤ Ensure that appropriate shielding protects the staff and patients from the effects of radiation ⬤ Require that all personnel who obtain images be properly trained, credentialed and appropriately supervised while exposing images ⬤ Use only techniques that will produce diagnostic-quality images with minimal radiation exposure to the patient and operator ⬤ Follow the province or territory’s radiographic licensing requirements, rules and regulations. ⬤ Participate in obtaining informed consent from patient and family ⬤ Review the patient’s record to determine when images were last taken JUST READ THROUGH THI|S 14  Protective Devices ⬤The dental tubehead must be equipped with certain appropriate components: ⮚ Aluminum filters ⮚ Lead collimators ⮚ PIDs ⬤Equipment should be checked on a regular basis by provincial or federal regulating agencies ⬤Faulty or malfunctioning equipment should be repaired immediately 15  Patient Protection ⬤Lead apron and thyroid collar: ⮚ A lead apron and thyroid collar must be used on all patients for all exposures ⮚ This rule applies to all patients, regardless of the patient’s age or sex or the number of images being exposed ⬤The lead apron should cover the patient from the neck to the lap to protect the reproductive and blood-forming tissues from scatter radiation ⬤This is a mandated practice! 16  Fast-Speed Film ⬤When using film-based exposures, the film speed refers to the amount of radiation required to obtain the image ⮚ The size of silver bromide crystals is the main factor in determining the film speed; the larger the crystals, the faster the film ⮚ A fast film requires less exposure to produce a quality radiograph ⮚ Fast-speed film is the single most effective method of reducing a patient’s exposure to x-radiation ⮚ Fast-speed film is available for both intraoral and extraoral radiography Image Receptor-Holding Devices ⬤The use of a film/receptor-holding instrument keeps the patient’s hands and fingers from being exposed to x-radiation ⬤These devices also keep the film or receptor in a stable position and help the operator to properly position the film or sensor and the PID  Proper Technique ⬤Proper technique is necessary to ensure diagnostic quality images and to reduce the amount of radiation to which the patient is exposed ⬤Images that are nondiagnostic must be retaken; this results in additional radiation exposure to the patient ⬤Retakes are a major cause of unnecessary radiation exposure in patients and must be avoided  X-Rays During Pregnancy ⬤The Guidelines for Prescribing Dental Radiographs, issued by the American Dental Association in conjunction with the Food and Drug Administration, state that dental radiographic procedures “do not need to be altered because of pregnancy” ⬤When a lead apron is used during radiographic procedures, the amount of radiation received in the pelvic region is nearly zero ⬤There is no detectable exposure to the embryo or fetus with the use of a lead apron  Radiation Monitoring ⬤Three types of monitoring devices are used to determine the amount of radiation exposure to personnel: ⮚ Film badge ⮚ Pocket dosimeter (pen style) ⮚ Thermoluminescent, or TLD 21  Equipment Monitoring ⬤Dental x-ray machines must be monitored for radiation leakage ⬤If a dental x-ray tubehead has a faulty tubehead seal, leakage results ⬤Dental x-ray equipment can be monitored through the use of a calibration device that can be obtained from the manufacturer or from the state health department  Patient Questions (Cont.) ⬤Here are some examples of comments you can make to patients during informal discussions: ⮚ “The doctor orders x-rays on the basis of your individual needs” ⮚ “Our office takes every step possible to protect you from unnecessary radiation” ⮚ “We use a lead apron and thyroid collar to protect your body from stray radiation” ⮚ “We use a high-speed film or sensor that requires only minimal amounts of radiation” ⮚ “Do you have any questions before we begin?”  Patient Issues ⬤Informed Consent – ⬤Confidentiality – before taking any images, images are part of the the operator must obtain patient’s record and document receipt of ⮚ Clinician is obligated to “informed consent” ensure privacy under state ⮚ Patient must be provided and federal laws (HIPPA) an explanation of the ⮚ Patient has the right to and procedure, why it is must give permission to necessary and associated have records forwarded to risks other providers ⮚ Patient signed and dated ⮚ Transfer of records is a consent form is the best common professional documentation courtesy Elsevier 24  Unit 6: Exposure and technique errors Chapters 38, 39 Copyright © 2012, 2009, 2005, 2002, 1999, 1995, 1990, 1985, 1980, 1976 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25 Unexposed Receptor Receptor May occur with digital sensors or film Appearance The image appears clear Cause Failure to turn on the x- ray machine Electrical failure Malfunction of the x-ray machine Correction Make certain the x-ray machine is turned on and listen for the audible exposure signal. Film Exposed to Light Receptor Occurs only with film Appearance The image appears black. Cause The film was exposed to white light. Correction Do not unwrap in a room with white light. Check the darkroom for light leaks. Turn off all lights in the darkroom except the safelight. Overexposed Receptor Receptor May occur with digital sensors or film Appearance Image appears dark or high in density. Cause Excessive exposure time, kilovoltage, milliamperage Correction Check settings and reduce as needed before exposing receptor. Underexposed Receptor Receptor May occur with digital sensors or film Appearance The image appears light or low in density. Cause The receptor was underexposed. Correction Check the exposure time, kilovoltage, and milliamperage settings on the x-ray machine before exposing the receptor. Absence of Apical Structures Receptor May occur with digital sensors or film Appearance No apices appear on the receptor. Cause The receptor was not positioned in the patient’s mouth to cover the apical regions of the teeth. Correction Make certain no more than ⅛ inch of the receptor edge extends beyond the incisal- occlusal surfaces of the teeth. Dropped Receptor Corner Receptor May occur with digital sensors or film Appearance The occlusal plane appears tipped or tilted. Cause The edge of the receptor was not placed parallel to the incisal-occlusal surfaces of the teeth. Correction Make certain the edge of the receptor is placed parallel to the incisal- occlusal surfaces of the teeth. Overlapped Contacts: Incorrect Horizontal Angulation Receptor May occur with digital sensors or film Technique May occur with paralleling or bisecting technique Appearance Overlapped contacts Cause The central ray was not directed through interproximal spaces. Correction Direct the x-ray beam through interproximal regions. Foreshortened Images: Incorrect Vertical Angulation Receptor May occur with digital sensors or film Technique May occur with the bisecting technique when beam alignment is not used Appearance Short teeth with blunted roots Cause Excessive vertical angulation Correction Do not use excessive vertical angulation with the bisecting technique. Elongated Images: Incorrect Vertical Angulation Receptor May occur with digital sensors or film Technique May occur with the bisecting technique when a beam alignment device is not used Appearance Long, distorted teeth Cause The vertical angulation was insufficient. Correction Use adequate vertical angulation with the bisecting technique. Cone-Cut with Beam Alignment Device Receptor May occur with digital sensors or film Technique May occur with either paralleling or bisecting technique when a beam alignment device is used Appearance A clear area appears on the image. Cause The PID was not properly aligned with the periapical beam alignment device. Correction Make certain the x-ray beam is centered over the receptor. Cone-Cut Without Beam Alignment Device Receptor May occur with digital sensors or film Technique May occur with bisecting technique when a beam alignment device is not used Appearance A clear area appears on the image. Cause The PID was not directed at the center of the receptor. Correction Make certain the x-ray beam is centered over the receptor. Incorrect Receptor Placement of Premolar Bite-Wing Receptor May occur with digital sensors or film Technique May occur with bite-wing technique when a beam alignment device or bite-tab is used Appearance Distal surfaces of the canines are not visible on the image. Cause The bite-wing receptor was positioned too far posteriorly in the mouth. Correction Make certain the anterior edge of the bite-wing receptor is positioned at the midline of the mandibular canine. Incorrect Placement of Molar Bite-Wing Receptor May occur with digital sensors or film Technique May occur with the bite-wing technique when a beam alignment device or bite- tab is used Appearance Third molar regions are not visible on image. Cause The bite-wing receptor was positioned too far anteriorly in the mouth. Correction Make certain the anterior edge of the bite-wing receptor is positioned at the midline of the mandibular second premolar. Overlapped Contacts: Incorrect Horizontal Angulation Receptor May occur with digital sensors or film Technique May occur with the bite-wing technique when a beam alignment device or bite-tab is used Appearance Overlapped contacts on the image Cause The central ray was not directed through the interproximal spaces. Correction Direct the x-ray beam through the interproximal spaces. Distorted Image: Incorrect Vertical Angulation Receptor May occur with digital sensors or film Technique May occur with the bite-wing technique when a bite-tab is used Appearance Image appears distorted Cause The vertical angulation was incorrect. Correction Always use a +10-degree vertical angulation with the bite-wing technique. Cone-Cut with Beam Alignment Device Receptor May occur with digital sensors or film Technique May occur with bite-wing technique when a beam alignment is used Appearance A clear area appears on the image. Cause The PID was not properly aligned with the beam alignment device. Correction Make certain the PID and the aiming ring are aligned. Cone-Cut Without Beam Alignment Device Receptor May occur with digital sensors or film Technique May occur with bite-wing technique when a bite-tab is used Appearance A clear area appears on the image. Cause The PID was not directed at the center of the receptor. Correction Make certain the x-ray beam is centered over the receptor. Bending Receptor May occur with indirect digital sensors or film Technique May occur with the paralleling, bisection, or bite-wing techniques Appearance Images appear stretched (on a film) and distorted (on PSP receptors). Cause Improper handling; receptor damaged Correction Check receptor placement before exposure. Creasing Receptor May occur with indirect digital sensors or film Technique May occur with paralleling, bisecting, or bite-wing technique Appearance A thin radiolucent line appears on the image. Cause Improper handling; receptor creased; film emulsion cracked Correction Do not over-manipulate the receptor. Debris Accumulation Receptor May occur with digital sensors Technique May occur with paralleling, bisecting, or bite-wing technique Appearance Debris on the surface of sensor may cause permanent radiopaque artifacts or radiolucent scratch marks on the sensor. Cause Sensors not handled carefully or wiped between uses; debris/dirt accumulates on the surface of sensor Correction Extreme care must be used when handling sensors. Phalangioma Receptor May occur with digital sensors or film Technique May occur with the bisecting technique when finger-holding method is used Appearance The patient’s finger appears on the image. Cause The patient’s finger was positioned in front of the receptor. Correction Make certain the patient’s finger is placed behind the receptor. Movement/Motion Unsharpness Receptor May occur with digital sensors or film Technique May occur with the paralleling, bisecting, or bite-wing techniques Appearance Blurred images appear on the image. Cause The patient moved during exposure of the receptor. Correction Instruct the patient to remain still while the receptor is being exposed. Reversed/Backward Placement Receptor May occur with digital sensors or film Technique May occur with paralleling, bisecting, or bite-wing techniques Appearance Light images with a herringbone pattern appear on the image. Cause The receptor was placed backward in the mouth and then exposed. Correction Always place the white side of the receptor adjacent to the teeth. Double Image Receptor May occur with indirect digital sensors or film Technique May occur with the paralleling, bisecting, or bite-wing techniques Appearance A double image appears on the image. Cause The receptor was exposed twice in the patient’s mouth. Correction Always separate exposed and unexposed receptors.  Unit 8: Quality Assurance, Legal considerations, Digital Radiography 50 Digital Radiography Has been used in The term digital image is used instead of dentistry since 1987 radiographs, x-rays, or Today, in many films Digital images are not areas of the United radiographs, but States and Canada, electronic signals that are dentists and dental captured by sensors and displayed on a computer schools are monitor almost changing from instantaneously These images can be e- conventional film- mailed to insurance based radiography companies and other to digital dentists Hard copies can be radiography printed on image quality paper 51 Digital Radiography (Cont.) A conventional x-ray machine is still needed to expose the image The positioning of the image receptor (sensor or phosphor storage plate) in the mouth is identical to positioning with film Strict infection control measures must be used because the sensors and PSPs are reused time and again FDA-cleared disposable, fluid impervious barriers must be used on digital image sensors and phosphor plates 52 Types of Digital Imaging Systems There are two basic methods of acquiring a digital x-ray image: Direct imaging Indirect imaging 53 Direct Digital Imaging A solid-state sensor is the image receptor It contains an x-ray sensitive silicon chip with an electronic circuit embedded in the silicon The charge-coupled device (CCD) sensor is the most commonly used digital receptor Like telephones, some CCDs are wireless Other types have a cable connected directly from the sensor to the computer 54 Indirect Digital Imaging Phosphor storage imaging The image receptor is a thin flexible plate, the size of conventional x-ray film, that has been coated with phosphor crystals The phosphor layer is able to store the energy of the x-ray photons for some time A scanner is required to “read” the information stored on the plate by using a laser beam to release the energy from the plate and convert it into a digital image 55 Phosphor Storage Imaging After the plates are scanned, they are exposed to bright light that erases all remaining energy, and the plates are ready to be used again For infection control, the imaging plate is inserted into a specially designed barrier envelope The barrier envelope is sealed by removing the adhesive strip and pressing the envelope closed 56 Phosphor Storage Imaging (Cont.) The imaging plate is positioned in the patient’s mouth using the same positioning techniques as with conventional dental x- ray film After exposure, the imaging plate is carefully removed from the barrier envelope and is then placed in a scanner that uses a laser to display the image on the computer The imaging plates cannot be autoclaved, and extreme care must be taken when handling to avoid scratches or dust 57 Digitizing Film-Based Radiographs Film-based radiographs may be digitized for viewing on a computer in much the same way as any other document Desktop scanners capture and digitize the light signal of whatever is placed inside them The process is similar to placing a film on a duplicator lightbox This type of indirect digital imaging is slightly less detailed than direct digital imaging because the resultant image is similar to a “copy” of the image 58 Digital Imaging Software Programs Most computer software programs that are used in digital imaging are capable of performing electronic image enhancement The operator can change the following image variables either together or separately: Contrast Brightness Image size (zoom) Sharpness Inversion (white to black and black to white) Pseudocolor alteration 59  Federal Regulations The use of dental x-ray equipment is regulated by both federal and provincial regulations All dental x-ray machines manufactured or sold in the United States after 1974 must meet federal regulations These include safety specifications for minimum filtration and accuracy of the milliamperage time and kilovoltage setting All x-ray equipment is also subject to regional or provincial radiation health codes 60  Provincial/Federal Requirements The Healing Arts Radiation Protection Act is a federal law that requires persons who take dental radiographs to be properly trained and certified It is up to the individual province to determine its own policy regarding the qualifications of individuals exposing radiographs HARP APPROVAL Ontario requires that Dental Assists either pass the National Dental Assisting Examining Board exam as a level II OR have proof of HARP approval from the educational institution, that the DA has graduated from a HARP approved course 61  Risk Management Risk management policies are designed to reduce the likelihood of a malpractice lawsuit against the dentist The dental assistant has an important role in risk management The dental assistant must be careful never to say anything negative about the x-ray equipment, or how it is working Statements made without thinking (such as “The timer must be off,” “This thing never works right,” or “The solutions are weak”) are unnecessary and can make the patient feel uncomfortable Statements made by anyone at the time of an alleged negligent act are admissible as evidence in court 62  Informed Consent It is the dentist’s responsibility to discuss the need for radiographs and treatment procedures with the patient The dental assistant may participate in the process of obtaining informed consent Patients must give informed consent for dental radiographs, as well as for other procedures 63  For Valid Informed Consent The patient must be provided with the following information in lay terms: The risks and benefits of imaging procedures The person who will be exposing the images The number and type of images The consequences of not having the images Any alternative diagnostic aids that may provide the same information as dental images 64  Ownership of Dental Radiographs Dental images are the property of the dentist, even though the patient, or the patient’s insurance company, paid for them This is because dental radiographs are a part of the patient’s records Patients may request a copy of their images; this request should be written and signed by the patients Make an entry in the chart stating when and to whom duplicate or digital dental images were sent Never give or send original radiographs to a patient 65  Quality assurance Chapter 40 Quality Assurance in the Dental Office Quality assurance (QA) is a way of ensuring that everything possible is being done to produce high-quality diagnostic images It includes both quality control tests that monitor dental x-ray equipment, supplies, and image processing It also involves quality administration procedures, including keeping schedules of maintenance and record-keeping logs 67 Types of Quality Control Tests X-Ray Machine Quality Control Steps Dental X-Ray Film: Traditional film Phosphorus Plates Check each box of film while opening it Reusable phosphor Follow these steps to test film storage plates for freshness: In the darkroom, unwrap one (PSP) require less unexposed film from the newly radiation exposure opened box Process the film with the use of than film Must be handled fresh chemicals Check the results If the processed film appears clean with a slight blue tint, the with care to avoid film is fresh and has been properly stored and handled and scratching the is safe to use If the processed film appears surface fogged, the film has been improperly stored or exposed to radiation and must not be used 70 View Boxes A properly functioning The view box should view box is necessary be periodically for the interpretation of conventional checked for dirt and radiographs discoloration of the The view box contains Plexiglas surface fluorescent bulbs that The surface of the emit light through an view box should be opaque plastic or wiped clean daily Plexiglas front Permanently The view box should discolored Plexiglas emit a uniform and or blackened subdued light when fluorescent bulbs functioning properly must be replaced 71 Darkroom Lighting Check the darkroom for light leaks every 6 months: While standing in the darkroom, turn off all the lights, including the safelight Once your eyes become accustomed to the darkness, look around the room for any signs of white light Check the results If the darkroom has no visible light leaks, the room is safe for processing films If light leaks are present, they must be corrected with weather stripping or black electrical tape before film processing is continued 72 Processing Solutions The most critical component in the quality control of film processing You must replenish the processing solutions daily and change them every 3 to 4 weeks, as recommended by the manufacturer As an alternative to using the calendar to determine the freshness of solutions, quality control tests can be used to monitor the strength of the developer and fixer solutions You should check the processing solutions each day before any patient films are processed 73 Stepwedge Radiograph A stepwedge is a device that is constructed of layered aluminum steps When a stepwedge is placed on top of a film and then is exposed to x-rays, the different steps absorb varying amounts of radiation When the film is processed, different densities are seen on the dental radiograph 74