DEN-112 Final Review PDF

# DEN-112 Final Review ## Part 8, Ch. 38, 39, 40, 41, 42 **Lauren Brown** **Fall 2024** ## History - Who discovered x-rays in 1895? * Wilhem Conrad Roentgen - experimented with vacuum tubes & fluorescent screens - Who exposed the first dental radiograph in the US? * C. Edmund Kells (1...

# DEN-112 Final Review ## Part 8, Ch. 38, 39, 40, 41, 42 **Lauren Brown** **Fall 2024** ## History - Who discovered x-rays in 1895? * Wilhem Conrad Roentgen - experimented with vacuum tubes & fluorescent screens - Who exposed the first dental radiograph in the US? * C. Edmund Kells (1896) - When was the first intraoral sensor used? * 1987 ## Radiation Physics - Electrons (-) and Protons (+) - What is an ion? An atom that gains or loses an electron & becomes electrically unbalanced. - What results when an electron is removed from an atom in the ionization process? * Ion Pair - What is ionizing radiation? * Radiation is capable of producing ions by removing or adding an electron to an atom. ## Uses of Dental Images - Detect lesions - Confirm or classify suspected disease - Localize lesions or foreign objects - Provide information during dental procedures - Evaluate growth and development - Illustrate changes secondary to caries, periodontal disease, and trauma - Document the condition of the patient - Aid in development of clinical treatment plan ## Wave Concept Characterizes electromagnetic radiations as waves: - **Velocity:** Speed of the wave (how fast wave is moving) - **Wavelength:** Distance between crest of one wave to another - **Frequency:** Number of wavelengths that pass in a certain amount of time - **Are longer or shorter wavelengths more penetrating?** * Shorter ## Parts of the X-Ray Machine - **Control Panel:** Controls KVP, MA & Time - **Extension Arm:** Suspends xray tubehead & houses electrical wires from control panel to tube head - **Tubehead:** Has metal housing, insulating oil, tubehead seal, xray tube, transformers, aluminum disks, lead collimator & PID ## What is the heart of the x-ray machine? The **Filament** and **Electron Cloud** ## Electricity and Electrical Currents - **Amperage (Volume) → MA** * Increases or decreases the # of electrons passing through the cathode * Contributes current speed passing - **Voltage (Speed / Power) KVP** * From cathode to anode. * ↑KVP = ↑ MA = ↑ Intensity (quantity) * ↑KVP = ↑ Brays Energy (quality) **In terms of water:** * Amperage = more water volume (quantity) - ↑ = more water volume in the stream * Voltage = faster flowing water (quality) - ↑ = White Water Rapids ## Interactions of X-Radiation - **No reaction**: Black or extremely dark image. * Photon passes through the atom unchanged. - **Absorption of energy and photoelectric effect**: * Back total energy = photoelectron (30%) * Ejected photoelectron is absorbed by the atom - **Compton Scatter**: 42% * Photons path is altered by matter - **Coherent Scatter**: * Photons path is altered by matter ## Types of Radiation Produced - **General:** 70% of x-rays - **Characteristic:** Only occurs at JokVp & above * 1. **Primary (primary beam)** * 2. **Secondary (less penetrating)** * 3 **Scatter (most detrimental to patient & operator)** ## What is a free radical? - Caused by indirect theory - x-ray *photons absorbed in cell & cause formation of toxins, that damage cells. * highly reactive & unstable * when they build up they cause cancer or genetic mutations ## Sequence of Radiation Injury 1. **Latent Period (short or long)** * Time between exposure & appearance of observable clinical signs * Change in cell function. 2. **Period of Injury** * When injury occurs: abnormal mitotic activity - cells divide * Low level radiation is repaired - cell damage is followed by repair 3. **Recovery Period** 4. **Cumulative Effects** * Occurs before repair is complete - unrepaired damage accumulates in tissues * Too frequent use ## Somatic and Genetic Effects - **Somatic:** Affects the person themself * All cells except reproductive - **Genetic:** Causes damage to the next generation (offspring) * Reproductive cells only ## Determining Factors for Radiation Injury - Total Dose - Dose Rate - Amount of tissue irradiated - Cell sensitivity - Age ## Effects on Tissues and Organs - **Radiosensitive Organs:** * Lymphoid tissue (head & neck) * Bone marrow * Any reproductive organs * Intestines * Salivary glands * Kidneys - **Radioresistant Tissues:** * Liver * Skin * Critical Organs * Lens of the eye * Thyroid * Bone Marrow ## How are we protecting our patients? - **ALARA:** Proper prescribing, proper control panel settings, proper technique - **Lead Aprons** - **Properly Functioning Machines** ## Protection using proper equipment - **Filtration:** .5-1.0mm of Aluminum * Filters out lower energy x-rays * 70kVp = 1.5 mm * Above 70kVp = 2.5mm - **Collimation:** Restricts size and shape of x-ray beam * Round produces 2.75" beam - **Position-Indicating Device (PID):** * SIN = larger beam * WIN = smaller beam - **Image Receptors:** * Digital --> less radiation --> longer wavelength --> lower energy - **Beam Alignment Device:** Stabilizes receptor (film) and aims PID ## Operator Protection - **Distance:** Stand far away from or behind a lead-lined wall - **Position:** Avoid primary beam - stand perpendicular or @ 90-135 degree angle. - **Monitoring Devices:** Badges ## ALARA Concept Every possible method of reducing exposure to radiation should be employed. ## Maximum Permissible Dose (MPD) - **Occupationally Exposed Persons:** 50mSv/year or.5Sv/year - **Non-Occupationally Exposed Persons:** 1mSv/year or 1rem/year ## mA, kVp, Time | Factor | Effect | |-----------------|------------------------------------------| | Milliamperage (mA) | ↑ = Increased Density | | | ↓ = Decreased Density | | Kilovoltage Peak (kVp) | ↑ = Long-Scale Contrast: Low Contrast | | | ↑ = Increased Density | | | ↓ = Short-Scale Contrast: High Contrast | | | ↓ = Decreased Density | | Time | ↑ = Increased Density | | | ↓ = Decreased Density | ## Radiation Characteristics **Quality:** - **KVP** * ↑ KVP = darker image * ↓ KVP = lighter image * ↑ KVP = less contrast * ↓ KVP = more shades of gray & density **Quantity** - **MA & Time** * ↑ MA = darker image * ↑ MA = ↑ Time * ↑ MA = ↑ Density ## Digital Imaging - Exposure times are less than that required for conventional (film) radiography. - **Direct Digital Imaging:**: CCD (charge coupled device) - **Indirect Digital Imaging:** PSP (phosphor storage plate) ## Advantages of Digital Imaging - Superior gray-scale resolution - Reduced exposure to radiation - Increased speed of image viewing - Lower equipment and film cost - Increased efficiency - Enhancement of diagnostic image - Effective patient education tool - Eco-friendly tool ## Disadvantages of Digital Imaging - Initial set-up costs - Image quality - Sensor size and thickness - Infection control - Wear and tear - Legal issues ## Intra-Oral Imaging Techniques - **Paralleling:** Sensor parallel to long exis of tooth - **Bisecting:** Only used in alternative - **Bitewing:** Shows crowns & interproximal ## Extra-Oral Projection Techniques - **Lateral Jaw Projection:** Evaluate premolars and molars, large fractures, lesions - **Skull Imaging** * Evaluate facial growth, development, trauma & disease - **Posteroanterior:** * Waters: Maxillary sinus area - **Submentovortex:** Analyze the base of skull & zygomatic arch - **Extra-Oral Bitewing:** - **TMJ Imaging** * **Transcranial:** Evaluate condyle & articular eminence * **TMJ Tomography:** Examine TMJ ## 3-D Imaging **Advantages** - Lower radiation dose - Brief scanning time - Anatomically correct images - Ability to save and transport **Disadvantages** - Pt movement & artifacts - Size of FOV - Cost of equipment - Lack of training in interpretation ## 3-D Imaging Uses - Implant placement - Extraction or exposure of impacted teeth - Definition of anatomic structures - Endodontic assessment - Airway and sinus analysis - Evaluation of TMJ disorders - Orthodontic evaluation - Evaluation of lesions and abnormalities - Trauma evaluation ## Review Chapter 32-25 Power Points