Terminology, positioning, and imaging principles: Rad Tech

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. Terminology, positioning, and imaging principles formed the foundation of a radiographic practice.
These concepts provide a common language for healthcare professionals and help ensure accurate patient positioning. As a radiologic technologist, understanding the names and locations of body structures allows you to communicate effectively, position patients correctly, and produce high quality diagnostic images that support patient care.
Now, the body can be divided into planes. The four planes commonly used in radiography are sagittal, coronal, horizontal, and oblique.
The sagittal plane divides the body into right and left portions. If the sagittal plane divides the body into equal halves, it's called the mid-sagittal plane.
The coronal plane divides the body into front and back portions. Next, the horizontal plane divides the body into upper and lower portions.
Finally, the oblique plane divides the body at an angle. Many radiologic procedures are done to examine the bones and joints.
Osteology is the study of bones, while arthrology is the study of joints. To understand how these bones and joints are organized throughout the body, let's first look at the overall structure of the skeleton, which is divided into the axial skeleton and the appendicular skeleton.
The axial skeleton contains the bones along the body's central axis, including the skull, vertebral column, ribs, and sternum.
The appendicular skeleton contains the bones of the upper and lower extremities, including the shoulders and pelvis. Bone markings are used to describe projections or depressions on bones.
A projection extends outward from a bone and can be described as a crest, process, head, or spine. Depressions are hollowed or recessed areas of bone and can be described as a fossa, fissure, or sinus.
When there's a break in the continuity of a bone, it's called a fracture. Fractures can be classified as closed, open, displaced, or non-displaced.
Radiologic technologists use standardized anatomical and positioning terminology to communicate clearly and accurately and to ensure consistent patient positioning and image evaluation.
Common anatomical relationship terms describe where one structure is in relation to another. For example, anterior refers to the front of the body and posterior refers to the back of the body.
Superior describes a structure closer to the head while inferior describes a structure closer to the feet. Other commonly used relationship terms include medial, meaning toward the midline of the body.
Lateral meaning away from the midline. Movement terminology is also important when positioning patients.
Flexion decreases the angle between two body parts while extension increases that angle. Abduction refers to movement away from the body's midline, and abduction refers to the movement towards the midline.
Other common movement terms include pronation and supination, which describe rotation of the forearm and hand. Positioning terminology describes how the body is placed for imaging.
Common terms include projection, position, view, and method. Projection describes the path of the X-ray beam through the body, including where the beam enters and exits.
Common examples include the anterior posterior or AP projection and the posterior anterior or PA projection. Position may describe the patient's overall body posture, such as standing, seated, prone, or supine.
It can also describe how a specific body part is placed in relation to the image receptor, such as oblique, lateral, or decubitus positions.
View describes the anatomy as it appears on the image receptor because it reflects the anatomy's perspective rather than the X-ray beam's path.
A view is considered the opposite of a projection. Lastly, a method typically refers to a specific positioning technique that was named after the person who developed it, such as the Towns, Waters, or Caldwell methods.
Now most radiographic examinations require a minimum of 2 projections taken at 90 degrees from each other. Obtaining images from these mutually perpendicular perspectives helps demonstrate anatomy accurately and reduces the chance that important structures will be hidden by superimposition, which is an overlap of different anatomical structures.
Additionally, when imaging long bones, ensure that both the proximal and distal joints are included on the image receptor to provide a complete diagnostic evaluation.
Radiologic technologists use established positioning routines and essential projections to consistently demonstrate the anatomy of interest.
These routines are based on the anatomy being examined, the patient's condition, and the clinical indication for the imaging study.
After an image is acquired, it must be evaluated to determine whether it meets established evaluation criteria, including demonstration of anatomy, position, and exposure.
The anatomy of interest should be clearly demonstrated and properly centered on the image receptor. Positioning evaluation includes assessing body part placement, alignment with the image receptor, centering accuracy, and collimation.
Exposure evaluation focuses on image brightness, contrast. And the absence of motion that could reduce image quality.
Bony landmarks are used to identify the location of specific body areas. These topographic landmarks are often identified through palpation, which involves gently locating anatomical structures through touch.
Radiologic technologists should ask for permission before touching the patient. Another important positioning principle is aligning the image receptor with the anatomy being examined.
In most cases, the image receptor is oriented to match the longest dimension of the body part. The direction of the image receptor, landscape, or portrait is selected to ensure proper alignment with the anatomical area.
For viewing, PA and AP images are displayed as if the patient is standing in the anatomical position facing the radiologic technologist.
Lateral images are marked with either an L for left or R for right. Upper and lower limb images are also marked with an L or R to ensure consistent interpretation among healthcare professionals.
Image quality is influenced by several technical factors, often called radiographic technique factors. The goal of these factors is to obtain the highest quality diagnostic image while keeping patient radiation exposure as low as reasonably achievable or alara.
One crucial factor influencing image quality is receptor exposure, which is simply the total amount of radiation that reaches the image receptor.
This is controlled by three main factors milliaperesconds, or MAS, which combines the electrical current with exposure time to control the quantity or total number of X-rays produced kilovoltage peak or KVP, which controls the quality or energy level of the X-ray beam, determining how easily it penetrates the body.
And source to image receptor distance or SID, which refers to the physical distance between the X-ray tube and the receptor, which affects the intensity of the beam reaching the target.
Although not a controlling factor, grids are used to limit the amount of scatter radiation that can reduce image quality.
Grids contain thin lead strips and are placed between the patient and the image receptor. The lead strips will absorb scatter radiation before it reaches the image receptor.
Resolution refers to the sharpness of the image. The degree of resolution depends on positioning accuracy and the absence of motion.
The types of motion that affect resolution are voluntary and involuntary. Voluntary motion is movement that the patient can control, whereas involuntary motion, such as shivering or tremors can't be controlled by the patient.
Distortion affects image quality when the size or shape of anatomy appears inaccurate on the image. Distortion can be influenced by SID object to image receptor distance or OID, alignment of the anatomy to the image receptor, and central ray alignment.
Finally, the characteristics of digital imaging depend on spatial resolution, contrast resolution, and image signal. Spatial resolution is influenced by the number and size of pixels.
In general, smaller pixels provide greater image detail. Contrast resolution refers to differences in brightness between adjacent areas of an image.
Image signal refers to the amount of radiation reaching the image receptor that is needed to create a diagnostic image. Patient safety is a fundamental responsibility of every radiologic technologist.
Radiation exposure should be minimized for both patients and healthcare workers whenever possible. Radiation protection is based on three core principles time, distance, and shielding.
Reducing exposure time, increasing distance from the radiation source, and using appropriate shielding all help reduce radiation dose.
Radiation exposure is monitored using established radiation units and personnel monitoring devices. Dosimeters worn by healthcare workers monitor occupational exposure, while imaging equipment may display information related to patient dose.
Dose limits are established to reduce the risk of radiation-related injury. The annual occupational dose limit for radiation workers is 50 millisievert or MSV.
Fluoroscopy procedures require additional attention because they may involve longer exposure times. Regulatory standards establish maximum exposure rates for fluoroscopic equipment.
Other safety practices include following established imaging protocols, monitoring exposure indicators, and reviewing technical factors when exposures are beyond the acceptable range.
Patient protection measures may also include shielding radiosensitive tissues like blood forming and reproductive organs when clinically appropriate and in accordance with current practice guidelines.
All right, as a quick recap, terminology, positioning, and imaging principles provide the foundation for radiographic practice.
Understanding anatomical planes, skeletal anatomy, relationship terms, and positioning language helps technologists communicate clearly and position patients accurately.
Applying positioning principles and image evaluation criteria helps ensure diagnostic image quality while knowledge of imaging factors and radiation safety supports effective and safe patient