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RAD 107 Exam 3
| What does the ACS breast cancer screening guidelines recommend? | Women with an average risk of breast cancer to have regular annual screening mammograms starting at age 45, with the choice to start as early as age 40. |
| What are annual mammograms for women ages 45-54? | The ACS mandates yearly screenings for women ages 45-54 because premenopausal breast tumors tend to grow more aggressively. Annual mammograms provide a higher chance of early detection. |
| What are biannual mammograms for women ages 55 and older? | Women can switch to screening every 2 years at the age of 55 due to postmenopausal breast cancers generally grow at a slower rate. |
| For women ages 40-44, what does the baseline/optional screening entail? | Women have the opportunity to begin annual mammograms if they choose to do so at this age as it serves as an optional baseline window for early, proactive screening |
| For women ages 45-54, what does the routine annual screening entail? | Routine screening must occur every single year |
| For women ages 55 and older, what does the routine biennial screening entail? | Routine screening transitions to every 2 years, or remains annual based on patient preference |
| What does the upper age limit entail? | There is no strict age to stop. Screening should continue as long as a woman is in good health and has a life expectancy of 10 years or longer |
| What happens when a woman has a high-risk screening exception? | The baseline rules change when a woman is at a higher-than-average risk due to a strong family history, a genetic mutation like BRCA1 or BRCA2 or prior chest radiation. The ACS guidelines recommend both an annual breast MRI and mammogram starting at 30. |
| What is breast compression? | It is necessary to achieve high-quality images while minimizing radiation. It minimizes motion blur, reduces patient dose and superimposition, and improves contrast and spatial resolution |
| What is breast tissue composition? | It changes over a woman's lifetime due to shifting hormone levels. |
| Do younger women have dense breast tissue? | Yes as they have more glandular and fibrous connective tissue. On a mammogram, the tissue appears white. Since abnormalities and tumors also appear white, dense tissue can mask potential cancers. |
| Do older women have fatty breast tissue? | Yes especially after menopause, estrogen levels drop. The glandular tissue naturally shrinks and is replaced by adipose tissue. They appear dark gray/black on a mammogram, creating high contrast, and makes white abnormalities and tumors easy to spot. |
| What is microcalcification? | They are tiny calcium deposits in breast tissue that serve as the earliest sign of ductal carcinoma in situ (DCIS). |
| What are the size constraints of microcalcification detection? | Mammography systems need to possess high spatial resolution to reliably resolve microcalcifications smaller than 500 micrometers. This helps dictate whether they are benign or require a diagnostic biopsy. |
| What is the automatic compression device? | It is a controlled motorized force between 25-45 pounds to flatten the breast. It automatically stops or releases based on pre-set tension limits to maximize tissue spread while ensuring patient safety |
| What are the high ratio grids in mammography? | They are moving anti-scatter grids (4:1 or 5:1 ratios) are used to absorb scattered radiation. This improves image contrast though it requires a slight increase in patient dose compared to gridless imaging |
| What are Molybdenum and Rhodium targets? | Specialized x-ray tube anodes used in analog and early digital systems. They produce low-energy characteristic x-rays which are perfectly suited for differentiating between similar mass densities of healthy dense glands, fat, and tumors. |
| What is the Mammography Quality Standards Act? | It is a federal law enacted by Congress to ensure all women have access to quality mammography for early breast cancer detection. It includes mandatory certification, annual inspections, personnel qualifications, and clinical image quality. |
| What is the responsibility of medical physicists? | They conduct annual surveys, dose assessment, and phantom evaluation. |
| What is the responsibility of technologists? | They conduct daily/weekly tracking, repeat analysis, image receptor function, and quality checks on display devices |
| What are radiography challenges for soft tissue? | Low subject contrast since breast is composed entirely of soft tissues, similar atomic numbers (Z about 6-7.5) and mass densities, and diagnostic hurdle since x-ray attenuation properties of a cancerous tumor are nearly identical to those that aren't |
| What are some techniques to enhance differential absorption? | Use ultra-low kVp selection, exploiting the photoelectric effect, target/filter material matching, and vigorous compression |
| What is the purpose of fluoroscopy? | To visualize anatomical structures and physiological processes inside the body in real-time, dynamic motion. |
| What is brightness gain? | The measurement of an image intensifier's ability to increase the illumination level of the image. Brightness Gain = Minification Gain x Flux Gain |
| What is minification gain? | It occurs because the large image captured at the input phosphor is compressed and focused down onto a smaller output phosphor, which increases the brightness of the final image |
| What is the formula for minification gain? | Calculated by dividing the square of the input phosphor diameter by the square of the output phosphor diameter |
| What is flux gain? | It represents the increase in light photons at the output phosphor due to the acceleration of electrons across the tube |
| What is the flux gain formula? | Flux Gain = Number of Output Light Photons / Number of Input X-ray Photons |
| What is the input phosphor? | It converts x-rays to light |
| What is the photocathode? | It converts light into electrons |
| What is the output phosphor? | It converts electrons into intensified light |
| What is photopic vision? | It is cone-mediated and functions in bright light conditions (daylight or well-lit rooms) to provide vibrant color vision and sharp detail recognition. Cones adapt to bright light changes within seconds |
| What is scotopic vision? | It is rod-mediated and functions in dim or near-dark environment. The rods are highly sensitive to low-light photons but completely blind to color and adapt slowly to darkness. |
| What is mesopic vision? | The transitional zone where both rods and cones operate simultaneously |
| What is visual acuity? | The capacity to resolve fine details and distinct shapes is not distributed evenly across the eye |
| What is the anatomical hotspot? | Highest acuity is concentrated in the fovea centralis which is a pit located at the center of the retina. It is completely rod-free and packed with high-density cones. |
| What is the contrast perception of the human eye? | The eye's ability to distinguish an object from its immediate background based on subtle differences in color or brightness |
| What is the typical mA for fluoroscopy parameters? | It is less than or equal to 5 mA |
| What is the magnification mode in fluoroscopy? | It increases spatial and contrast resolution and patient dose |
| What is hybrid subtraction? | It combines temporal and energy subtration |
| What is energy subtraction? | Uses kVp as the separating factor and takes advantage of the K-edge of Iodine. It rapidly alternates the x-ray tube between a low and high kVp within milliseconds, which requires high complexity of equipment |
| Motion artifacts in fluorocsopy? | It is low because two images are captured practically at the same time, which virtually eliminates involuntary and voluntary motion artifacts |
| What is the separating variable between temporal subtraction and energy subtraction? | Temporal subtraction is time (seconds between images) and energy subtraction is x-ray energy (kVp changed in milliseconds) |
| What is the equipment complexity in temporal subtraction vs energy subtraction? | The temporal subtraction is low (standard DSA software) and energy subtraction is high (rapid kVp-switching generators) |
| What is the motion artifacts in temporal subtraction vs energy subtraction? | It is severe in temporal subtraction and minimal in energy subtraction |
| What is contrast resolution in temporal subtraction vs energy subtraction? | It is excellent in temporal subtraction if the patient stays still and moderate from slightly degraded by beam crossover in energy subtraction |
| What is the power rating for interventional radiography tube? | It is greater than or equal to 20 kW |
| What is the focal spot size for magnification? | It is less than or equal to 0.3mm |
| What are sterile techniques in fluoroscopy? | The image intensifier or flat-panel detector must be encased in a sterile clear plastic cover before it is positioned over the patient's sterile field, C-arm clearance, sterile field boundaries, radiation safety apparel, and surgical scrub |
| What are patient monitoring in fluoroscopy? | ECG, BP, Pulse Ox, Capnography and tracking the reference point air kerma, kerma-area product, cumulative fluoroscopy, and action thresholds |
| What is the access and equipment for interventional radiology and angiography? | Femoral puncture uses an 18-gauge Seldinger needle and the x-ray tubes feature small target angles, large anodes, and high power capacity |
| What are the x-ray tube characteristics in IR and Angiography? | Small target angle, large anode, and high power |
| What is IV hydration for patient preparation? | Normal saline or sodium bicarbonate runs at 1 mL/kg/hr for 6-12 hours before and after the procedure |
| What are the pre-procedure labs for IR & Angiography? | Platelets must be greater than 50,000 and INR less than 1.5 to reduce puncture-site bleeding, GFR ideally greater than 45 and hold off on taking Metformin for 47 hours post-procedure if GFR levels are depleted |
| What are the diet restrictions for IR & Angiography? | Nothing by mouth/NPO for solid foods for 6-8 hours protects against aspiration and clear liquids are permitted up to 2 hours before the procedure to prevent dehydration |
| When would a chest x-ray be required for IR & Angiography? | Unless the patient exhibits acute cardiopulmonary symptoms or is undergoing a central thoracic intervention |
| What is the table and movement control in IR & Angiography? | Floor switch for smooth movement during imaging for ergonomics without breaking the sterile field |
| What is the 1st CT Generation? | Translate-rotate, single detector, long scan time. Beam Type: Pencil beam. Detectors: Single detector (or two side by side). Motion: Translates across patient, rotates, repeats. Scan Time: Very long (about 4-5 minutes per slice) |
| What is the 2nd CT Generation? | Translate-rotate, multiple detectors, reduced scan time, decreased translations |
| What is the 3rd CT Generation? | Rotate-rotate, fan beam, detector array, reduced scanning time, higher patient dose considerations. |
| What is the 4th CT Generation? | Rotate-stationary detector, reduced ring artifact |
| What is each sweep in CT Image Formation? | Rotation or projection/specifically to the linear translation movement found only in 1st and 2nd generation scanners |
| What is the backprojection step in CT? | Simple backprojection takes the attenuation profiles and smears them back across the image matrix. This creates a blurry image with a characteristic star artifact |
| What is the filtered step in CT? | To fix the blur, a mathematical filter (or kernel) is applied to the raw data before backprojection. This sharpens the boundaries and eliminates the star artifact |
| What is the reconstruction time in CT? | Duration it takes the computer to process raw data into final pixels. It is determined by matrix size, reconstruction algorithms (IR takes longer than FBP), and computer processing speed |
| What is the image matrix in CT? | A grid of rows and columns forming the image (typically 512 x 512) pixels in clinical CT |
| What is a voxel in CT? | A volume element. It represents the 3D tissue volume within the patient. Voxel size is determined by multiplying the 2D pixel area by the nominal slice thickness |
| What is pixel size in CT? | The physical size of a single picture element on the screen. It is directly calculated using the formula: Pixel Size = FOV/Matrix Size |
| What is the field of view in CT? | The diameter of the circular area being reconstructed (measured in millimeters or centimeters |
| What is the pre-patient collimator? | It sits between the x-ray tube and the patient. Directly defines the scan slice thickness and limits the width of the x-ray beam and prevents unnecessary radiation from striking the tissue outside the intended imaging volume |
| What is the pre-detector collimator? | It sits between the patient and the detector array, which remove scattered radiation originating from inside the patient’s body |
| What is the blurred-ripple artifacts in CT? | It happens if too few projections are acquired across the tube’s sweep angle. It appears as low-attenuation repeating waves or ripples. |
| What are truncation artifacts in CT? | Occurs when a portion of the patient’s body or an external object lies outside the active scan field of view, the anatomy extends beyond the physical boundaries of the x-ray beam or detector coverage during parts of the scan. |
| What is out-of-plane/ghost blurring in CT? | High-contrast structures located in one slice plane are not fully canceled out in neighboring slices and cast duplicate, blurred “ghost” images across adjacent depths |
| What is focal spot blurring in CT? | The X-ray tube continuously moves and fires while sweeping (rather than stepping, stopping, and shooting), the physical focal spot moves during the window of exposure, leading to inherent geometric blur |
| What is interpolation in CT? | It allows reconstruction at any z-axis plane as it takes raw projection data from the spiral paths immediately before and after a specific Z-position |
| What is sweep angle in DR and DRT? | Aka arc range between 15-50 degrees. A wider angle increases the angular sampling space, which provides narrower slice thickness and superior depth resolution |
| What is scan time in DR and DRT? | The duration of the tube's travel (typically 4 to 10 seconds). Short scan times are critical to prevent involuntary patient motion, which degrades image sharpness |
| What is the number of projections in DR and DRT? | The distinct exposures taken during the sweep (usually between 11 and 25 discrete projections). More projections reduce the "blurred-ripple" artifacts discussed earlier and improve the signal-to-noise ratio (SNR), but can increase electronic readout noise |
| What is the source-to-center-of-rotation distance? | The physical radius from the X-ray tube focal spot to the pivot point of the gantry. This distance establishes the geometric magnification factor and alters the size of the focal spot blur across the reconstructed planes |
| What is computer-aided detection (CAD)? | Early AI application in mammography/DRT (first reader vs. second reader, targeted detection profiles, and evolution to CADe/CADx) |
| What is the mask image in DF and Subtraction Techniques? | A static radiographic image captured right before the iodinated contrast medium reaches the target vessels. It contains all background anatomy (bone, gas, soft tissue) |
| What is the subtracted image in DF and Subtraction Techniques? | Real-time projection frames captured after contrast injection are electronically subtracted from the original mask image, pixel by pixel |
| What is brightness gain? | The Image Intensifier (II) tube increases the brightness of the exit radiation beam by a factor of 5,000–30,000× typically before it reaches the camera system. |
| What is minification gain? | The large input phosphor screen focuses its accelerated electrons onto a very small output phosphor screen, concentrating the signal |
| What is flux gain? | High voltage (about 25kV) applied across the tube accelerates the electrons, causing them to produce significantly more light photons when they strike the output phosphor |
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