Comprehensive Introduction to Ultrasound Physics, Procedures, and Sonographic and Sonography Basics
Physics and Fundamental Principles of Ultrasound
Nature of Sound Waves: Sound waves are mechanical waves consisting of cycles of compression and rarefaction that must be transmitted through a medium.
Pulse-Echo Principle:
Ultrasound pulses are generated by a transducer and sent into the patient's body.
These pulses produce echoes at organ boundaries and within specific tissues.
Echoes return to the transducer to be detected and processed.
Grayscale Imaging:
The detected echoes are presented as dots on a screen.
The brightness of each dot is directly proportional to the strength, amplitude, or intensity of the returning echo.
This process results in what is known as grayscale imaging.
Clinical Professionalism: The AIDET Framework
Acknowledge: Greet the patient by name to provide a welcoming environment.
Example: "Good morning/afternoon, Ms. Jones. We've been expecting you and we're glad you are here."
Introduce: Introduce yourself and state your credentials to build trust.
Example: "My name is Susan and I will be conducting your test today. I am a certified ultrasonographer and I do about of these procedures a day. The doctors say that my skills are among the best. Do you have any questions for me?"
Duration: Provide an accurate estimate of waiting times and procedure lengths.
Example: "Dr. Heart had to attend an emergency. He was concerned about you and wanted you to know that it may be before he can see you. Are you able to wait or would you like me to schedule an appointment for tomorrow?"
Explanation: Describe what the patient should expect during the procedure.
Example: "The test takes about . The first step is to drink this solution and then we'll have you wait before we take a blood sample. Would you like to read while you wait?"
Thank You: Express gratitude for the patient's choice of facility.
Example: "Thank you for choosing Sharp. It has been a privilege to care for you."
Pre-Examination and Patient Demographic Procedures
Safety and Verification Steps:
Check the patient's medical history.
Check the patient's laboratory values.
Verify the wristband and ask for at least two forms of identification (e.g., birthdate and last name).
Verify the Medical Record Number (MRN) from identification bracelets.
Interview the patient regarding symptoms, specific areas of pain, surgical history, and their adherence to exam preparation (e.g., fasting).
Patient Education: Explain the exam process and prepare the patient physically based on the specific exam requirements.
Demographic Page Input:
Input patient information correctly to ensure the right patient data is attached to the study.
Enter the sonographer's name and select the correct exam type.
Educational Requirement: For academic or training purposes, include the patient's name, a space, and then the sonographer's name on every image.
The Primary Role of a Sonographer: The essential duty is to provide interpretable, high-quality images that a physician can use to make a diagnosis.
Transducer Selection and Hardware
Frequency and Preset Selection: The sonographer must select the physical transducer (hardware) and the appropriate preset (software) for the specific exam.
Transducer Types and Applications:
Curvature (Curved Array) Transducer (): Used for Abdominal, GYN, and OB exams to visualize deep structures.
Sector Transducer (): Used for deep structures and intercostal scanning.
Linear Transducer (): High-frequency probe used for "Small Parts," including the thyroid, scrotum, and breast.
Transducer Anatomy:
Heel: The trailing edge of the probe.
Toe/Leading Edge: The front edge of the probe used for orientation.
Surface Landmarks and Body Regional Divisions
Surface Landmarks for Scanning:
Sternal notch, Sternum, and Xiphoid process of the sternum.
Medial and lateral angles of the ribs.
Inferior costal margin.
Umbilicus.
Iliac crest.
Symphysis pubis.
Midline of the body.
Abdominal Quadrants:
Right Upper Quadrant (RUQ).
Left Upper Quadrant (LUQ).
Right Lower Quadrant (RLQ).
Left Lower Quadrant (LLQ).
The Nine Abdominal Regions:
Top Row: Right hypochondriac region, Epigastric region, Left hypochondriac region.
Middle Row: Right lumbar region, Umbilical region, Left lumbar region.
Bottom Row: Right iliac (inguinal) region, Hypogastric (pubic) region, Left iliac (inguinal) region.
Anatomic Directions and Planes
Standard Anatomic Planes:
Sagittal Plane: A vertical plane dividing the body into left and right portions. The "Median Sagittal Plane" is the exact midline.
Coronal Plane: Divides the body into anterior (front) and posterior (back) portions.
Transverse Plane: Divides the body into superior (top) and inferior (bottom) portions.
Directional Terminology:
Anterior/Ventral: Toward the front.
Posterior/Dorsal: Toward the back.
Cranial/Cephalic/Superior: Toward the head.
Caudal/Inferior: Toward the feet.
Medial: Toward the midline.
Lateral: Away from the midline.
Proximal: Nearer to the point of attachment or trunk.
Distal: Farther from the point of attachment or trunk.
Superficial: Toward the surface.
Deep: Away from the surface.
Ipsilateral: Affecting the same side of the body.
Contralateral: Affecting the opposite side of the body.
Patient Positioning and Scanning Approaches
Standard Patient Positions:
Supine: Lying on the back.
Prone: Lying face down.
Lateral: Lying on the side.
Right Anterior Oblique (RAO).
Left Anterior Oblique (LAO).
Right Posterior Oblique (RPO).
Left Posterior Oblique (LPO).
Scanning Positions:
Subcostal: Transducer positioned below the ribs.
Intercostal: Transducer positioned between the ribs.
Image Orientation (Standard Protocol):
Longitudinal/Sagittal Section: Screen left is Cephalic/Superior; Screen right is Caudal/Inferior; Screen top is Anterior; Screen bottom is Posterior.
Transverse Section (Anterior/Posterior Surface): Screen left is Right; Screen right is Left; Screen top is Anterior; Screen bottom is Posterior.
Technical Image Optimization Controls
Depth Control: Optimizes the size of the image on the screen.
Increasing depth (deeper) makes the structures appear smaller.
Decreasing depth (shallower) makes structures appear larger.
Shallow depth typically provides superior resolution.
Focus Control (Focal Zone): Adjusts the narrowest portion of the beam to provide the best lateral resolution at a specific depth.
Time Gain Compensation (TGC): Also known as Depth Gain Compensation (DGC) or Swept Gain. This adjusts gain at specific depths to compensate for echo attenuation (loss of amplitude) as the sound travels deeper.
Overall Gain Control: Also called Imaging Gain, Gain, or B/M Gain. This amplifies all returning signals equally without changing the acoustic intensity sent into the patient.
Cine Loop: Uses the trackball to scroll back through recently captured frames after the image is frozen.
Annotation/Comment: used to identify the organ or region being documented.
Measurements:
Usually three-dimensional: Longitudinal Width AP (Anteroposterior).
Results are input into the calculation package.
Sonographic Echo Textures and Transmission Effects
Texture Terms:
Homogeneous: Uniform echo pattern throughout the tissue.
Heterogeneous: Irregular or non-uniform echo pattern.
Brightness Scales:
Anechoic: Completely echo-free; appears "black." Typically indicates fluid-filled structures (e.g., gallbladder, cysts) that transmit sound easily.
Echogenic: Structure that produces echoes; appears "bright."
Hyperechoic: Brighter compared to surrounding tissue.
Hypoechoic: Darker compared to surrounding tissue.
Isoechoic/Isosonic: Having the same color/brightness as the surrounding tissue (e.g., the liver and renal cortex are often isoechoic).
Transmission Effects (Artifacts):
Enhancement: Brighter echoes seen deep to a cystic or fluid-filled structure because sound travels through fluid with minimal attenuation.
Acoustic Shadowing: Darker area (void of echoes) seen deep to a solid or highly reflective structure (e.g., gallstones, bone) that blocks or strongly reflects the sound beam.
Post-Exam Workflow and Documentation
Finalizing the Study:
Print all necessary images.
Check all settings before freezing and printing each image.
Print the worksheet and complete the patient data sheet.
Standard Abdominal Scan Worksheet Fields:
Header: Medical Record (MR) number, Date, Patient Name, Exam Type.
History: Age, Gender, Diabetes (Y/N), Smoking (Y/N), Heart Disease (Y/N), Drug Use (Y/N), Hypertension (Y/N), Alcohol Use (Y/N), Surgical History.
Symptom Checklist: Chief Complaint, Nausea, Vomiting, Abdominal Pain, Fever, Jaundice, Weight Loss.
Technical Impressions: Specific fields for the Gallbladder (GB), Common Bile Duct (CBD), Liver, Right Kidney, Left Kidney, Pancreas, Spleen, Aorta, and additional comments.