CT Scan Registry Preparation Test

The proper patient positioning for axial CT scans of the orbits is supine, head first neutral position. This means that the patient lies on their back, with their head positioned first and in a neutral, straight position. This positioning allows for clear and accurate imaging of the orbits, as it ensures that the patient's head is properly aligned and stationary during the scan.

A proper IV contrast bolus for a soft-tissue scan of the neck is 20cc at 2cc/sec. This means that 20cc of contrast should be injected into the patient's bloodstream at a rate of 2cc per second. This specific amount and rate of contrast is necessary to ensure optimal visualization of the soft tissues in the neck during the scan.

The gantry angle for a sinus cavity CT scan should be parallel to the roof of the hard palate. This is because the hard palate forms the floor of the sinus cavities, and by aligning the gantry parallel to it, the images obtained will provide a clear view of the sinus cavities and their surrounding structures. This positioning ensures optimal visualization and accurate diagnosis of sinus conditions.

The correct answer is body temperature because heating the contrast agent to body temperature helps to lower its viscosity. This is important because a lower viscosity allows for easier injection and better distribution throughout the body. Heating the contrast agent to body temperature ensures that it is at the optimal temperature for injection and reduces the risk of complications or discomfort for the patient.

The first cervical vertebra (C1) is known as the atlas. The atlas is responsible for supporting the weight of the skull and allowing for the nodding motion of the head. It is named after the Greek mythological figure Atlas, who was known for carrying the world on his shoulders. The atlas is unique compared to other vertebrae as it lacks a body and has a ring-like shape. It also has special features that allow for the articulation with the skull and the second cervical vertebra (C2), known as the axis.

Phonation technique is sometimes employed in laryngeal CT scans. This technique involves the patient making specific sounds or phonations during the scan in order to visualize the movement and function of the vocal cords and laryngeal structures. It helps in assessing vocal cord function, identifying any abnormalities or pathologies, and planning appropriate treatment or interventions for voice disorders.

Collimation in CT scanning serves the functions of reducing scatter radiation to the patient, ensuring a consistent beam width received by the detectors, and improving the image resolution. However, it does not serve the function of reducing the number of slices needed for a full set of images. Collimation refers to the process of limiting the x-ray beam to a specific area of interest, which helps to reduce scatter radiation and improve image quality. It does not directly impact the number of slices required for a complete set of images, as that is determined by the specific scanning protocol and the desired anatomical coverage.

Phase enhancement refers to a technique used in medical imaging to improve the visibility of certain structures or tissues. Uniphasic, biphasic, and exponential decay are all types of phase enhancement techniques. Uniphasic refers to a technique where the contrast agent is injected in a single phase, biphasic refers to a technique where the contrast agent is injected in two phases, and exponential decay refers to a technique where the contrast agent is injected and then gradually decreases in concentration over time. These techniques help enhance the contrast between different tissues or structures in the image, improving the diagnostic quality of the image.

In an electron beam CT (EBCT) scanner, a fixed electron beam is used to produce the image. This means that a consistent and steady stream of electrons is directed towards the target area to generate the image. This fixed electron beam allows for precise and accurate imaging, as the beam remains constant throughout the scanning process.

The beam hardening artifact is also referred to as the cupping artifact. This artifact occurs when the X-ray beam passes through a dense object, such as bone, causing the beam to become harder or more penetrating. As a result, the surrounding tissues appear darker, creating a cup-like or shadowing effect around the dense object on the image. This artifact can affect the accuracy of the image interpretation and needs to be considered when analyzing radiographic images.

The occipital lobe of the brain is responsible for visual perception. This lobe is located at the back of the brain and is primarily involved in processing and interpreting visual information received from the eyes. It plays a crucial role in tasks such as object recognition, color perception, depth perception, and visual memory. The occipital lobe contains the primary visual cortex, which is responsible for initial processing of visual stimuli.

Most CT scanners are designed to recognize a maximum degree of percentage overlap of 50%. This means that if two structures in the scanned area overlap by more than 50%, the scanner may have difficulty distinguishing between them and accurately representing them in the resulting image. Therefore, a percentage overlap of 50% is the highest degree that most CT scanners can reliably recognize.

The correct answer is "mid mastoids to above the petrous ridge." This is because a temporal bone scan is used to evaluate the bones of the skull known as the temporal bones, which house important structures such as the inner ear and the facial nerve. To ensure a comprehensive evaluation, the scan coverage should include the mid mastoids, which are located on the sides of the skull, and extend above the petrous ridge, which is a bony prominence in the temporal bone. By including this entire region in the scan coverage, any potential abnormalities or pathologies in the temporal bones can be properly assessed.

The appropriate amount of contrast to deliver for a routine brain scan is 100 cc. Contrast is used in imaging studies to enhance the visibility of certain structures or abnormalities. In a brain scan, contrast is often administered intravenously to highlight blood vessels, tumors, or areas of inflammation. The amount of contrast needed depends on the specific scan and the patient's condition. In this case, 100 cc is deemed appropriate for a routine brain scan, as it provides sufficient contrast for clear imaging without excessive risk or side effects.

When preparing for a CT Scan Registry Examination, it is crucial to consider factors related to the safety and well-being of the patient and the accuracy of the scan. Allergic reactions to contrast agents used in CT scans are an essential consideration because some patients may be sensitive or allergic to these substances. Recognizing and managing allergic reactions is vital for patient safety during the scan and for the radiologic technologist's knowledge. The other options, such as dietary preferences, shoe size, and favorite color, are unrelated to the medical and safety aspects of CT scanning and the registry examination.

The tibial tuberosity is the roughened surface on the anterior surface of the tibia that serves as an insertion point for the knee cap ligaments. It is a prominent bony prominence located just below the knee joint. The ligaments, such as the patellar ligament, attach to the tibial tuberosity, providing stability and support to the knee joint during movement. The tibial tuberosity acts as a point of attachment for the muscles and tendons involved in knee extension and helps to transmit forces from the quadriceps muscles to the lower leg.

The acromion is the correct answer because it is a flat process that forms the highest point of the scapula. It is located at the top of the scapula and forms the outer edge of the shoulder. It serves as an attachment point for various muscles and ligaments and helps to stabilize the shoulder joint. The other options, such as the scapular spine, glenoid process, and coracoid process, are not described as forming the highest point of the scapula.

The tube current can be altered by the technologist from the scanner console. This means that the technologist has the ability to adjust the amount of current flowing through the X-ray tube during a scan. By increasing or decreasing the tube current, the technologist can control the intensity of the X-ray beam and therefore the amount of radiation exposure to the patient. This is an important feature as it allows for customization of the scan parameters based on the specific needs of each patient.

The rate of injection is not inversely proportional to contrast enhancement in CTA of the abdomen. In fact, a higher rate of injection of contrast material leads to a higher contrast enhancement in the images. This is because a higher rate of injection allows for a greater volume of contrast material to be delivered to the blood vessels, resulting in a more pronounced enhancement of the vessels in the images.

The minimum CT scan times have significantly decreased from 5 minutes per slice in 1976 to 0.375 seconds per slice in 2004. This indicates a remarkable advancement in technology and efficiency in performing CT scans. The reduction in scan time allows for quicker and more accurate diagnoses, benefiting both patients and medical professionals.

Adverse reactions to contrast media can include dyspnea (difficulty breathing), hypotension (low blood pressure), and urticaria (hives). However, a feeling of warmth is not considered an adverse reaction to contrast media.

The cricoid cartilage forms the lowest portion of the larynx. It is a ring-shaped cartilage located just below the thyroid cartilage. The cricoid cartilage provides support and serves as a landmark for various structures in the neck. It is also important for maintaining the patency of the airway and facilitating vocal cord movement during speech and swallowing.

The orbital meatus is the most appropriate landmark to use for orbital scans because it is a small opening in the orbital wall that allows for the passage of nerves and blood vessels. It is a reliable and easily identifiable point of reference for conducting orbital scans and imaging. The other options, such as the inferior and superior orbitocranial planes and the maxillary sinus, are not specifically related to orbital scans and would not provide accurate or relevant information for this purpose.

In choosing a non-ionic, lower-osmolality agent over an ionic, higher-osmolality agent, factors to consider include a history of asthma, adverse reactions to contrast media, and cardiac dysfunction. However, pregnancy is not a factor to consider when choosing between these two types of agents.

Proper patient positioning for CT of the knee is feet first and supine, with the feet internally rotated. This position allows for optimal visualization of the knee joint and surrounding structures. By internally rotating the feet, the patella (kneecap) is aligned with the femur (thigh bone), providing a clear view of the joint space. This positioning also helps to reduce artifacts and distortions that may occur during the imaging process.

The lateral localizer light should be situated parallel to the mid neck. This positioning ensures that the light is aligned with the neck anatomy and provides accurate localization for the scan. Placing the light perpendicular to the mid neck or midsagittal plane would result in incorrect positioning and potentially inaccurate scan results. Similarly, situating the light parallel to the level of the hyoid bone would not provide the necessary alignment with the mid neck.

The gantry of a CT scanner is a mechanical structure that houses various components required for the scanning process. It typically includes the x-ray tube, high-voltage generator, and slip-ring technology. However, an array processor is not likely to be found in the gantry. The array processor is responsible for processing the data acquired during the scan and generating the final images. It is usually located outside the gantry in the control room or a separate computer system.

The statement that is FALSE regarding the maxillary sinuses is that they lie lateral to but not within the maxillary bones. The maxillary sinuses are actually located within the maxillary bones. They are the largest sinus cavities, they lie above the roots of the upper teeth, and they drain through the infundibulum.

The major change in CT technology seen with fourth-generation scanners was the use of up to 2000 detectors in a fixed ring. This means that instead of using a single detector, these scanners had multiple detectors arranged in a fixed ring. This allowed for faster and more accurate imaging as the detectors could capture multiple slices of the body simultaneously. This advancement in technology greatly improved the efficiency and quality of CT scans.

The malleus is a small bone located in the middle ear, not the internal ear. The internal ear consists of the cochlea, semicircular canals, and vestibule. The cochlea is responsible for hearing, the semicircular canals are involved in balance and spatial orientation, and the vestibule helps with detecting changes in head position and linear acceleration. Therefore, the malleus is not part of the internal ear.

The craniofacial area consists of the bones that make up the skull and face. The mandible, or lower jawbone, is not considered a paired bone because it is the only bone in the skull that moves. The palatine, zygomatic, and lacrimal bones are all paired bones that contribute to the structure and function of the craniofacial area.

When contrast extravasation (leakage of contrast media into surrounding tissue) occurs, the technologist should stop the injection immediately, notify the radiologist, elevate the affected limb, and apply a cold or warm compress depending on protocol to manage inflammation and reduce damage. However, continuing the injection is contraindicated, as it can worsen tissue injury and lead to complications like compartment syndrome or necrosis. Therefore, the correct response is to not continue injecting—doing so goes against standard safety protocols.

One of the factors that affect the choice of a particular contrast agent is the cost. The cost of the contrast agent can vary and may influence the decision-making process when selecting a specific agent. Other factors mentioned in the question, such as an institutional contract with the manufacturer, the use of drip infusion vs power injector, and radiologist preference, can all play a role in the choice of a contrast agent. However, cost is the factor that is not directly related to these other considerations.

The vertebral arteries directly supply blood to the occipital lobe, cerebellum, and brain stem, but not the frontal lobe. The frontal lobe is primarily supplied by the anterior cerebral arteries, which arise from the internal carotid arteries.

The dorsal tendon group is responsible for extending the fingers and wrist. This means that these tendons are involved in straightening or stretching the fingers and wrist joint, allowing for movement away from the palm. Flexing the fingers and wrist refers to bending them towards the palm, rotating the wrist involves turning it, and pronating the wrist means turning it so that the palm faces downwards.

CT scanning of the lumbar spine is commonly performed to evaluate disc herniations. This imaging technique provides detailed cross-sectional images of the spine, allowing healthcare professionals to visualize the intervertebral discs and identify any herniations or bulges. CT scans can accurately depict the location, size, and severity of disc herniations, aiding in the diagnosis and treatment planning for patients with back pain or neurological symptoms associated with disc pathology. Other conditions, such as osteoporosis, spinal cord injury, or infection, may require different imaging modalities or clinical assessments for accurate evaluation.

Gastric tumors most commonly appear on CT as localized thickening of the gastric wall. This is because tumors in the stomach typically cause an abnormal growth or thickening of the gastric wall, which can be visualized on a CT scan. This thickening is often localized to a specific area of the stomach and can be a key indicator of the presence of a tumor. Other imaging features such as vascularization, dark spots, and stripe-like enhancement may also be seen in gastric tumors, but localized thickening of the gastric wall is the most common finding.

IV contrast is used in CT scans of the hip and pelvis to allow concomitant mapping of the iliac and femoral vessels. IV contrast is a dye that is injected into the bloodstream to enhance the visibility of blood vessels and soft tissues during imaging. By using IV contrast, the radiologist can accurately visualize and map the iliac and femoral vessels, which are important for assessing blood flow and identifying any abnormalities or blockages. This information can be crucial in diagnosing and planning treatment for conditions such as peripheral arterial disease or deep vein thrombosis.

The correct answer explains that the distal esophagus is difficult to distend with oral contrast agents. This means that it is challenging to fill this area of the esophagus with the contrast agent used in imaging tests. This could be due to various factors, such as the thick muscous lining at the gastroesophageal junction that absorbs the contrast agent or the high degree of gastroesophageal reflux caused by oral contrast agents, which makes it difficult to clear the area of residual stomach contents.

The maximum diameter of the patient aperture in the gantry of a CT unit is approximately 80 cm. This means that the opening through which the patient passes during a CT scan can accommodate a maximum diameter of 80 cm. A larger patient aperture allows for larger patients to be scanned comfortably without feeling claustrophobic or restricted. It also allows for more flexibility in positioning the patient during the scan.

CT angiography of the brain is not indicated in cases of trauma because it is primarily used to evaluate the blood vessels of the brain for abnormalities such as aneurysms, arteriovenous malformations, or stenosis. In cases of trauma, other imaging modalities such as CT or MRI are typically used to assess for any structural damage to the brain, such as hemorrhage, contusions, or fractures. CT angiography is not necessary for evaluating traumatic brain injuries unless there is a specific concern for vascular injury.

To obtain 3D images of the spine, scanning should be conducted using a minimum slice thickness of 1mm and an overlap of 50%. A thinner slice thickness allows for more detailed imaging of the spine, capturing finer structures and abnormalities. The overlap ensures that there is no information loss between adjacent slices, resulting in a more accurate and complete 3D reconstruction of the spine. Therefore, a minimum slice thickness of 1mm and an overlap of 50% are ideal for obtaining high-quality 3D images of the spine.

The CT urogram is a comprehensive protocol that is used to detect or rule out various conditions in the urinary system. It can help identify tumors, renal calculi, and lesions in the ureter. However, it is not specifically designed to detect or rule out renal artery stenosis, which is a narrowing of the arteries that supply blood to the kidneys. Therefore, the correct answer is renal artery stenosis.

The posterior lens is not a structure of the eyeglobe. The eyeglobe consists of the cornea, anterior lens, and vitreous fluid. The cornea is the clear outer layer of the eye, the anterior lens is located behind the cornea and helps to focus light onto the retina, and the vitreous fluid is a gel-like substance that fills the space between the lens and the retina. The posterior lens, however, is not a recognized structure of the eyeglobe.

Capture efficiency is the term used to describe the effectiveness with which the detectors gather the photons transmitted from the patient. It refers to how well the detectors are able to capture and detect the photons that pass through the patient's body. A higher capture efficiency means that more photons are successfully detected, resulting in better image quality and accuracy in medical imaging techniques such as X-rays or CT scans.

The "tentorium cerebelli" is a partition or fold of the dura mater, one of the protective membranes surrounding the brain. It separates the cerebellum (responsible for motor coordination and balance) from the cerebrum (responsible for higher cognitive functions). This division helps prevent interference and compression between these brain regions and maintains the brain's structural integrity within the skull.

The ideal kVp/mAs settings for a posterior fossa scan are 120-140/200. This means that the kilovolt peak (kVp) should be set between 120 and 140, while the milliampere-seconds (mAs) should be set to 200. These settings are optimal for obtaining clear and detailed images of the posterior fossa, which is the area at the back of the skull. The kVp determines the quality and contrast of the image, while the mAs controls the amount of radiation exposure.

The sciatic nerve carries nerve fibers from the vertebral interspaces most prominently at the levels L3-L5. This means that the nerve fibers originating from the spinal cord at the vertebral levels L3, L4, and L5 contribute to the formation of the sciatic nerve. These nerve fibers travel down the leg, supplying sensation and motor function to the lower limb.

To obtain a complete CT scan of the neck, it is recommended to have three display fields of view. This is because the neck is a complex area with various structures that need to be captured in the scan. Having three display fields of view allows for a comprehensive examination of the neck, ensuring that all necessary information is obtained.

The basilar artery, located in the brainstem, divides to form the posterior cerebral arteries. These arteries supply blood to the posterior part of the brain, including the occipital lobe responsible for visual processing. The anterior cerebral arteries supply blood to the frontal lobes, while the middle cerebral arteries supply blood to the lateral parts of the brain. The internal carotid arteries are major blood vessels that supply blood to the brain, but they do not directly arise from the basilar artery.

The correct Hounsfield unit measurement for acute intracranial hemorrhage is 55 to 75. Hounsfield units (HU) are used to measure the density of different tissues in a CT scan. Acute intracranial hemorrhage refers to bleeding in the brain that has occurred recently. This bleeding typically appears as a high-density area on a CT scan, which corresponds to a higher Hounsfield unit measurement. The range of 55 to 75 HU is characteristic of acute intracranial hemorrhage, allowing for its identification and differentiation from other brain abnormalities.

The field of view for pituitary gland scans should be 10-12cm. This range allows for a comprehensive view of the pituitary gland, which is located at the base of the brain. A larger field of view would include unnecessary surrounding structures, while a smaller field of view may not capture the entire gland. Therefore, a field of view between 10-12cm is ideal for accurately assessing the pituitary gland.

The appropriate DFOV in CT scans of the elbow is approximately 14 cm. This measurement refers to the diameter of the field of view, which is the size of the area that the CT scanner captures during the scan. A DFOV of 14 cm is considered appropriate for imaging the elbow, as it allows for clear visualization of the joint and surrounding structures without capturing unnecessary surrounding tissue.

When fast-moving electrons collide with matter, they lose kinetic energy. This lost energy is converted into electromagnetic radiation, including X-rays. Therefore, the emission of an X-ray photon occurs due to the loss of kinetic energy by the fast-moving electron upon collision with matter.

The correct answer is lateral obliques. The extraocular muscles of the orbital muscle cone include the superior recti, inferior recti, and inferior obliques. However, the lateral obliques are not part of the extraocular muscles.

The petrous pyramids do not form the antrum of the eustachian tubule. The antrum of the eustachian tube is actually located in the temporal bone, specifically in the mastoid process. The petrous pyramids do contain the middle and inner ear structures, extend medially beyond the sphenoid bones, and their upper surface forms part of the floor of the middle cranial fossa.

The appropriate length of scan delay in seconds following contrast injection for an orbital scan is 60 seconds. This delay allows enough time for the contrast to distribute throughout the blood vessels and tissues in the orbit, enhancing the visibility of any abnormalities or structures of interest. A shorter delay may result in inadequate contrast enhancement, while a longer delay may lead to excessive contrast washout and decreased image quality. Therefore, a 60-second delay strikes a balance between optimal contrast enhancement and image quality.

The viscosity of a contrast agent refers to the rate at which the agent can be heated to room temperature. Viscosity is a measure of a fluid's resistance to flow, and it is influenced by factors such as temperature. In the context of a contrast agent, viscosity is important because it affects how easily the agent can be injected into the body and how it spreads within the body. A lower viscosity means that the agent can be heated to room temperature more quickly, making it easier to handle and administer.

The correct answer is 23 cm prospectively/10 cm retrospectively. This means that when performing an internal auditory canal scan, the field of view should be 23 cm when scanning in the forward direction (prospectively) and 10 cm when scanning in the backward direction (retrospectively). This allows for a comprehensive view of the internal auditory canal both in real-time and during review.

The device in the gantry that measures the intensity of the x-ray beam emanating from the tube is called an air-reference detector. This device is specifically designed to measure the intensity of the x-ray beam by comparing it to the intensity of the air. It provides a reference point for the measurement and ensures accurate and consistent readings. The other options mentioned, such as array processor, anode, and photomultiplier tube, do not perform the specific function of measuring the intensity of the x-ray beam in this context.

The correct answer is platysma. The platysma is a superficial anterior muscle of the neck that is responsible for various facial expressions, such as lowering the jaw and corners of the mouth and wrinkling the skin on the neck. It is often referred to as the "muscle of facial expression" due to its involvement in these movements. The other options, including the masseter, sternocleidomastoid, and medial pterygoid, are not specifically involved in facial expressions.

The best quality CT images of the sternum are reformatted in the coronal plane only. This means that the images are taken from a vertical perspective, allowing for a detailed view of the sternum from front to back. This plane is particularly useful for evaluating the structure and alignment of the sternum, as well as any abnormalities or fractures that may be present. The sagittal and axial planes, on the other hand, provide different perspectives that may not be as beneficial for evaluating the sternum specifically.

CT scanning of the thoracic spine is used to rule out compression fractures, diagnose disc herniation, and determine the presence of fibrotic scar tissue. However, it is not typically used to diagnose congenital malformations. Congenital malformations are usually diagnosed through other imaging techniques or clinical examination.

The muscles of mastication are responsible for the movements of the jaw during chewing. The temporalis, masseter, and lateral pterygoid muscles are all part of the muscles of mastication. However, the proximal pterygoid muscle is not considered one of the muscles of mastication. It is actually part of the muscles involved in opening and closing the jaw.

The appropriate scan delay time for iodinated contrast used in scans of the humerus and forearm is 20-30 seconds. This delay allows for adequate distribution of the contrast agent throughout the blood vessels in the area, ensuring optimal visualization of the structures being scanned. A shorter delay may result in inadequate contrast enhancement, while a longer delay may lead to excessive contrast diffusion and blurring of the images.

The recommended maximum slice thickness for display of CT scans of the abdomen and pelvis is 6-7mm. This range allows for a balance between image resolution and scan time. A slice thickness of 6-7mm provides sufficient detail to visualize structures in the abdomen and pelvis while also minimizing the time required for image acquisition. This allows for efficient and accurate diagnosis of conditions in these regions.

The appropriate length of scan delay in seconds following contrast injection for CT angiography of the brain is 15-17. This delay allows the contrast to reach the blood vessels in the brain and enhance the visibility of the blood vessels during the scan. A delay that is too short may result in inadequate enhancement, while a delay that is too long may lead to excessive contrast washout. Therefore, a delay of 15-17 seconds is considered optimal for obtaining high-quality images of the brain's blood vessels.

The larynx is a structure located in the neck, responsible for producing sound and protecting the airway during swallowing. To visualize the larynx effectively, axial slices that are parallel to the plane of the inferior aspect of the mandible are ideal. This is because the inferior aspect of the mandible provides a reliable landmark for locating the larynx. By aligning the slices parallel to this plane, the larynx can be accurately visualized and assessed for any abnormalities or pathologies.

Prospective triggering is the technique of capturing cardiac CT images using estimates of the patient's RR interval based on initial electrocardiographic recordings of these intervals. This means that the imaging is triggered in real-time based on the patient's heart rate, allowing for more accurate imaging of the cardiac structures. This technique is different from retrospective triggering, which captures images based on the entire recorded ECG signal after the scan has been completed. Multidetector gating is a general term for techniques that synchronize image acquisition with the cardiac cycle, and prospective gating is not a recognized term in cardiac CT imaging.

In solid-state generators, scintillation crystals are typically not soluble, and they are used to convert ionizing radiation (such as X-rays) into flashes of light (photons), which can then be detected and converted into electrical signals. These electrical signals are used to create medical images, such as in CT scans and other imaging modalities. Soluble crystals would not be suitable for this purpose. The other statements are generally true about solid-state generators: they involve scintillation crystals near a photomultiplier tube, produce light flashes, and are useful in high-speed scanning.

The correct answer is 1. When performing pituitary scans, it is recommended to inject intravenous contrast at a rate of 1 cc/sec. This rate allows for optimal visualization of the pituitary gland and surrounding structures. Injecting the contrast at a slower or faster rate may result in suboptimal imaging quality and potentially affect the accuracy of the scan.

The proper kVp/mAs settings for a scan of the soft tissues of the neck are 120-140 kVp and 300 mAs. This combination of settings ensures that the image will have sufficient penetration and contrast for accurate visualization of the soft tissues in the neck region.