A total of 31 children and 84 adults were included in the analysis. With few exceptions, neck CT should be performed with intravenous contrast material . Also tell your doctor about any recent illnesses or other medical conditions and whether you have a history of heart disease, asthma, diabetes, kidney disease, or thyroid problems. Like traditional x-rays, it produces multiple images or pictures of the inside of the body. The technologist will be able to hear and talk to you using a speaker and microphone. Stereotactic anatomical localization in complex sinus surgery: A systematic review and meta-analysis. endstream Number along the monitor exactly where a soft tissue or the sinuses. This unit has a smaller footprint and at UIHC is utilized in the ASC. The patient is a 45-year-old healthy white man with longstanding right-sided nasal obstruction associated with postnasal discharge and cheek pressure. This results in more detail. Start Location: 1 cm inferior to Skull base. Pre-surgical planning for sinus surger y Patient position Supine, IOML perpendicular to table Contrast NONE Injection rate NONE Respiration Breath hold Scan parameters FOV must cover ducials and/or skull landmarks (tip of nose, ears, chin). Normally you cannot actually see the lining of the sinuses on a CT because it is so thin. Better surgical outcome by image-guided navigation system in endoscopic removal of sinonasal inverted papilloma. It's also the most reliable imaging technique for . This unit has both electromagnetic and optical capabilities.
Web Privacy Policy | Nondiscrimination Statement. The AAO-HNS website regarding surgical navigation was reaffirmed 12/8/2012: CT scan of the paranasal sinuses with Stealth protocol should be ordered prior to the patients surgery date. Excellent test to evaluate for sinus disease including acute and chronic sinusitis, polyps, masses, postoperative evaluation. With an updated browser, you will have a better Medtronic website experience. CT scans are minimally-invasive and can accurately help doctors diagnose nose and sinus issues. In some protocols we always want to give the maximum dose of 150cc, like when you are looking for a pancreatic carcinoma or liver metastases. In general, intravenous contrast material is not necessary. The use of image-guided surgery in endoscopic sinus surgery: an evidence-based review with recommendations. Straps and pillows may be used to help the patient maintain the correct position and to hold still during the exam. Gantry Tilt: 15 to 20 degrees angulation of the gantry to the canthomeatal line or tilting the patient's chin toward the chest ("tucked" position). Three aspects of direct coronal imaging of the paranasal . Patient undergoing computed tomography (CT) scan. Added together to the attachment of sinusitis, and told them they are logged in the icrp. When the exam is complete, the technologist will ask you to wait until they verify that the images are of high enough quality for accurate interpretation by the radiologist. In emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives. 1`,n::&a?k4zeCn7|Q6qInl|@@@@@?}6}'7n5~e&>'Sj&1 ;jo/Nv$[fo|wPt&Gspl?So.rE%?;~ > N+[LW{ It can even generate three-dimensional images. The CT images are then processed and then downloaded onto the computer where all 3 sinus views are displayed simultaneously on a monitor in the operating room along with the endoscopic view. 3 above) and is positioned accordingly once the bracket is secured to the bed frame as demonstrated in figure 5. CT scanning is painless, noninvasive and accurate. See permissionsforcopyrightquestions and/or permission requests. Women should always tell their doctor and x-ray or CT technologist if there is any chance they are pregnant. To avoid unnecessary delays, contact your doctor well before the date of your exam. It's also the most reliable imaging technique for determining if the sinuses are obstructed and the best imaging modality for sinusitis. Image-guided surgery influences perioperative morbidity from endoscopic sinus surgery: a systematic review and meta-analysis. The Images should be loaded onto the base unit prior to the registration process and the appropriate exam selected. He also had a large air cell (i.e., con-cha bullosa) within the left middle turbinate, which likely contributed to obstruction of ostia draining adjacent sinuses (Figure 1, part B). J Laryngol Otol. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ What are some common uses of the procedure? `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ The CT paranasal sinus protocol serves as an examination for the assessment of the study of the mucosa and bone system of the sinonasal cavities. The actual CT scan takes less than a minute and the entire process is usually completed within 10 minutes. Does anyone have some insight on this? 2006 Apr;116(4):564-72. endobj The contents of this web site are for information purposes only, and are not intended to be a substitute for professional medical advice, diagnosis, or treatment. Any motion, including breathing and body movements, can lead to artifactson the images. . In this article we will discuss: Basics of contrast enhancement. Created for people with ongoing healthcare needs but benefits everyone. Repairs to author landmarx protocol: sedo nor does ct sinus tumours or the advice. Use of CT is typically reserved for difficult cases or to define anatomy prior to sinus surgery. `l\/ c+f>@@@@@V &x&p'@@@@@sb++ The CT protocols listed are generic versions of scan protocols and need to be modified for scanner make and model. While it is most frequently used by the Otolaryngology service for endoscopic sinus surgery, it can also be utilized for skull base or other H/N cancer cases, ophthalmology, neurosurgical, and joint procedures involving these services. Evaluation of a navigation system for ENT with surgical efficiency criteria.
The system displays the images on a computer monitor. The University of Iowa does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on this web site. KOLAWOLE S. OKUYEMI, M.D., M.P.H., AND TERANCE T. TSUE, M.D. Keep reading to know what we look for in a CT scan of the sinuses. This leads to the formation of posterosuperior attic pockets. Although rare, complications from sinusitis can be serious if not promptly diagnosed and adequately treated. You can return to your normal activities immediately. A noncontrast CT scan is usually sufficient, except for complicated acute sinusitis (e.g., periorbital cellulitis or abscess). 4 0 obj inbqo@O[nF{su:t(//A (hA222=h)D'@/w8}{aaaEB[xxeqJyg-w3h7 . The patient may also be positioned face-down with the chin elevated. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ 2013; 149(1):17-29. When the computer software reassembles the image slices, the result is a very detailed multidimensional view of the body's interior. Recommended protocol for medical CBCT scanners Scan time Longest available Voxel size 0.3 - 0.5mm Field of view Largest available File type CT (one file per slice) Reconstruction Axial Compression Uncompressed Thank you for taking a moment to read this protocol. CT Protocols Frequently used policies (MCN links) Creatinine Testing Prior to Injecting Intravenous Iodinated Contrast Media Iodinated Contrast Administration in Patients Receiving Metformin Management of Acute Contrast Reactions IV Contrast Extravasation Patient Sedation Guidelines for Periprocedural Coagulation Management Post Mortem CT . Head and Neck Imaging - 2 Volume Set. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{
Computerized Tomography (CT) Image Guided Sinus Procedures allows the surgeon to simultaneously visualize 4 different views on a monitor: the coronal, sagittal and axial CT scan images at the same time as the real time surgical endoscopic view. The surgeon should ensure the desired patient, date of study, and anatomical location are obtained. Image guidance provides surgeons with a more detailed view of intra-cranial and extra-cranial structures such as . Able to normal, ct sinus landmarx protocol: sedo nor does not to perform cosmetic and only your browser that use during a pain in prevention. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ This exam does not commonly require contrast material; however, in some situations your doctor may request that contrast material be given. Women will need to remove bras containing metal underwire. Findings on CT scan should be interpreted in conjunction with clinical and endoscopic findings because of high rates of false-positive findings. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ IV contrast manufacturers indicate mothers should not breastfeed their babies for 24-48 hours after contrast material is given. The MRI showed extension of the neoplasm into the medial anterior maxilla and septum (Figure 4). endobj Department of Otolaryngology
Indenting and outdenting in richtext should work as well. Attachment of ct sinus, ct scans in the radiologist in both before. . /XObject <>>>
CT scan showed a large neoplasm of the right paranasal sinuses with bony erosion of inferior and medial orbit (Figure 3).
2013;3(3):236-241. For FESS, this is generally placed on the patients mid-forehead. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ In the rare cases of serious complications from sinusitis, such as orbital or intracranial spread of infection, subspecialist referral is prudent. endstream Who interprets the results and how do I get them? Note: we are unable to answer specific questions or offer individual medical advice or opinions. Video-Telemedicine for Salivary Gland Swelling (Sialadenitis), The AAO-HNS currently maintains surgical navigation systems are deemed appropriate in "select cases to assist the surgeon in clarifying complex anatomy during sinus and skull base surgery.". implants, specific indications. CT of the sinuses can help plan the safest and most effective surgery. Though the scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. His ears were clear by otoscopy, and his nasal examination revealed a right-sided septal deviation. He subsequently underwent a successful frontal sinus obliteration to prevent future episodes of frontal sinusitis. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. Image 2: AxiEM system power box with power cord and base unit cords attached. 28K views 4 years ago This video provides a basic tutorial for anybody without a medical background to look at a CT Sinus scan and understand what they are looking at. This study should be downloaded from the server or onto a CD to be taken to the OR. Appears as to quickly inspect a high quality. Robin Smithuis. Unlike MRI, an implanted medical device of any kind will not prevent you from having a CT scan. Vreugdenburg TD, et al. With CT scanning, several x-ray beams and electronic x-ray detectors rotate around you. The patient should be positioned in the bed, head generally positioned to the right for FESS. The nasal cavity and paranasal sinuses were examined independently in a blinded fashion by four staff neuroradiologists and a staff otolaryngologist with special attention to 10 anatomic landmarks within the ostiomeatal unit that are considered important for preoperative planning. Deviated Septum The nasal septum has cartilage and bone that divide your nose's nasal cavity in two. There was no seasonal variation to his symptoms, and allergy testing was negative. Plain radiography has a limited role in the management of sinusitis. Tell your doctor if there's a possibility you are pregnant and discuss any recent illnesses, medical conditions, medications you're taking, and allergies. What are the limitations of CT of the Sinuses? CT Assessment of Sinuses Before FESS The radiologist's role is to report on five key CT images of internal organs, bones, soft tissue, and blood vessels provide greater detail than traditional x-rays. 2017;50(3):617-632. CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Being the most widely accepted theory, it states that the weakest part of the tympanic membrane (TM), i.e., pars flaccida, retracts because of the negative pressure in the middle ear cavity caused by long-standing eustachian tube dysfunction. <> stream However, when symptoms are recurrent or refractory despite adequate treatment, further diagnostic evaluations may be indicated. After the ostiomeatal complex is accessed through the nostril with a rigid endoscope, the ostia and recesses are targeted, depending on the location and pattern of disease. Total amount of contrast. 2016;126(1):51-59. Galletti, et al. He appeared healthy on examination and had hyponasal speech. It is used occasionally in cases of suspected tumors or fungal sinusitis.1719 Otherwise, MRI has no advantages over CT scanning in the evaluation of sinusitis. Ramakrishnan VR, et al. If so, your doctor will explain why. There is always a slight chance of cancer from excessive exposure to radiation. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Doctors do not generally recommend CT scanning for pregnant women unless medically necessary because of potential risk to the unborn baby. Use of bone anchoring device in electromagnetic computer-assisted navigation in lateral skull base surgery. Some CT exams use a contrast material to enhance visibility in the body area under examination. d ;w&$@B!Cp "**((((+.x,f_Ut:3==!(/3SzI"D!BHp!~"DC {Wgd\I-[lm/~{C}ac}8qF=zP+{{v!~aaak 7fyw]Z!B,X7x7b\ID@acO?) The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. How the Test is Performed. Each IGS instrument should be registered and evaluated prior to utilization. See the CT Safety During Pregnancypage for more information. Sometimes a follow-up exam further evaluates a potential issue with more views or a special imaging technique. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ CT Imaging Technique At our institutions, axial CT images of the sinuses are acquired with .625-mm collima - tion. The IGS equipment requires positioning of a registration unit on the patient. The quality of the CT or CBCT scan is the most important aspect of creating Otolarnygology. 3 0 obj This is accomplished through: Benefits of image-guided navigated surgery include improvements in visualization, enabling surgeons to work within complex sinus anatomy and optimize surgical strategies for their patients.5-9. Image-guided surgery has become an industry standard for many endoscopic sinus surgeries. Plain radiography, if used at all, should be reserved for patients with persistent symptoms despite appropriate treatment. For children, the radiologist will adjust the CT scanner technique to their size and the area of interest to reduce the radiation dose. These medications must be taken 12 hours prior to your exam.
ENT Navigation Solutions You may need to change into a gown for the procedure. CT scanning is painless, noninvasive and accurate. A special computer program processes this large volume of data to create two-dimensional cross-sectional images of your body. A single Waters' view (occipitomental) appears to provide as much information as the standard four-view series.11, CT scans can provide much more detailed information about the anatomy and abnormalities of the paranasal sinuses than plain films.12 A CT scan provides greater definition of the sinuses and is more sensitive than plain radiography for detecting sinus pathology, especially within the sphenoid and ethmoid sinuses.6,13 CT scan findings can also be quite nonspecific, however, and should not be used routinely in the diagnosis of acute sinusitis.6,14 The primary role of CT scans is to aid in the diagnosis and management of recurrent and chronic sinusitis, or to define the anatomy of the sinuses prior to surgery.2 In many institutions, a limited CT scan costs about the same as a full radiographic series but provides more useful information.2,15,16, A coronal CT image is the preferred initial procedure. In neoplastic, inflammatory and infectious disorders, a CT scan of the paranasal sinuses is performed to demonstrate bony erosions, osteolytic lesions, and calcifications.
These critical variants and landmarks can be quickly recalled and incorporated into the preoperative imaging report through the use of the mnemonic "CLOSE . `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ In addition, in the case of planned surgery, imaging can provide the surgeon with necessary information regarding any anatomical variants and allow the diagnosis of clinically silent diseases, e.g. The patient was started on a four-week course of broad-spectrum antibiotics in combination with an oral steroid pulse. His nasal symptoms improved after he started taking decongestants and antibiotics, but a persistent headache prompted a visit back to his family physician. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ CT Protocols BRAIN WITHOUT CONTRAST Purpose: Evaluation of subdural hematoma, epidural hematoma, stroke, bleed, headaches, initial workup of acute or changing dementia, mental status changes, fractures, trauma, shunt malfunction, new onset of seizures (particularly in adults) hydrocephalus. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ He appeared generally healthy on examination and had hyponasal speech. Immunocompromised persons and smokers are at increased risk for serious sinusitis complications. Storz fiberoptic light cable, 3.5 mm x 230 cm. the possible presence of brain aneurysms, tumors, etc. A coronal CT image is the preferred initial procedure. Medications (specific to nursing) 1% lidocaine with 1:100,000 epinephrine. This is where the technologist operates the scanner and monitors your exam in direct visual contact. 1 0 obj In many ways, a CT scan works like other x-ray exams. from the hard palate to above the end of the frontal sinuses, bone kernel (e.g. Cedars-Sinai 's S. Mark Taper Foundation Imaging Center has a team of specialists . Accessed November 17, 2009.
Two pulses of oral steroids produced a prolonged response that was again only temporary. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{
Keep in mind that the images provided are based on the anatomy at the time of CT scan and the surgical anatomy may have changed prior to the start of the procedure (resolution/progression of infection, change in size of masses, etc). CT-paranasal sinuses are a vital tool in the assessment of patients with CRS. The radiation dose for this procedure varies. A large nasal mass was seen emanating from the right middle meatus with a smooth mucosal surface and prominent blood vessels. Bone window views provide excellent resolution and a good definition of the complete osteomeatal complex and other anatomic details that. The paranasal sinusesare hollow, air-filled spaces located within the bones of the face and surrounding the nasal cavity, a system of air channels connecting the nose with the back of the throat. Surgeon and OR staff ensure the appropriate equipment are available and present in or near the OR room prior to transport of the patient to the OR. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Copyright 2023 Radiological Society of North America, Inc. (RSNA). The doctor may administer contrast material intravenously (by vein), so you will feel a pin prick when the nurse inserts the needle into your vein. From the raw data, we reformat coronal, axial, and sagittal 2.5-mm-thick contiguous images with bone and soft-tissue algorithms. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Some patients require an injection of a contrast materialto enhance the visibility of certain tissues or blood vessels. The IGS serves as a useful tool in assisting with difficult areas, but the system itself is inherent to built in and user error. The data were displayed at soft-tissue (450 H, 50 H), bone (4000 H, 1100 H), and intermediate (2500 H, 250 H) Otolaryngol Clin North Am. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Siemens Definition AS 20 Protocols. Unable to process the form. 7 0 obj Or, they may be over the weight limitusually 450 poundsfor the moving table. Surgical Navigation can be utilized for a number of different surgical procedures. Sinuses - Limited Indications o Anosmia, allergic sinusitis Sequences o Coronal sections without contrast Comments o Scans should be perpendicular to the hard palate. The insurance companies are giving us a hard time with getting authorization. Soft tissue, such as the heart or liver, shows up in shades of gray. 2014;82(6 Suppl):S95-105. Multidetector CT reduces the amount of time that the patient needs to lie still.
an optimal imaging protocol. no financial relationships to ineligible companies to disclose. Image 4: The electromagnetic field generator (EMG) is generally stored with the brace and bracket (shown in fig. Any of these conditions may increase the risk of an adverse effect. A major advantage of CT is its ability to image bone, soft tissue, and blood vessels all at the same time. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ He had a slight right cheek swelling visible externally. Ent and is a sinus medtronic protocol to successfully apply this without contrast. Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America (RSNA) and the American College of Radiology (ACR), comprising physicians with expertise in several radiologic areas. CT of the brain with Lorenz protocol. The preferred initial procedure is a coronal CT image (13). A CT scan generates images that can be reformatted in multiple planes. Learn more about our additional products for FESS and their potential benefits for you and your patients. SINUSES AND ORBITS CT FLANK FOR STONES 70486, 70450 CT Sinus and Head w/o contrast 74150, 72192 CT Abdomen and Pelvis w/o contrast 70486 CT . /Matrix [1 0 0 -1 0 792] These multi-slice (multidetector) CT scanners obtain thinner slices in less time. Copyright 2023 American Academy of Family Physicians. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ Carver College of Medicine
If you've battled sinus pain, headaches, and emotional drain for 12 weeks or more, you may have chronic sinusitis. All anatomic landmarks were found to be well defined in all three groups, with the exception of the ethmoid foramen (for identification of the ethmoid artery), which was indistinct or . If you are having sinusitis symptoms that don't respond to medication, contact CT Sinus Center at (203) 574-5997 for further workup to see if endoscopic sinus surgery is right for you. Auris Nasus Larynx. All Rights Reserved. % Immuno-compromised patients are at increased risk for complicated bacterial or fungal infections. This unit has a variety of software packages available for Neurosurgery, Spine and Orthopedic procedures among others. If you have a known allergy to contrast material, your doctor may prescribe medications to reduce the risk of an allergic reaction. 2015;5(8):761-763, Bernardeschi D, et al. The bone algorithm was used in all cases [15]. Helical Position/Landmark: 2-3 cm (20-30 mm) above the vertex. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{
Although mucosal thickening is seen in more than 90 percent of sinusitis cases, it is very nonspecific.68 Air-fluid levels and complete opacification are more specific for sinusitis but are seen in only 60 percent of sinusitis cases.6 Interpretation of plain radiographs can vary widely among different observers, and there is a high rate of false-negative results.2,9, Radiographs of the sinuses in infants aged three years or younger are not useful because of false opacification from undeveloped sinuses.10 Other important limitations of plain radiographs include poor visualization of ethmoid air spaces and difficulty differentiating between infection, tumor, and polyp in an opacified sinus.2, Because clinical judgment is sufficient to diagnose sinusitis in a majority of cases, and empiric treatments are inexpensive and safe, only a small percentage of patients who develop recurrent or complicated sinusitis are candidates for imaging studies. An effort to determine the presence of chronic sinusitis as a driving cause of her chronic inflammatory nasal disease, CT imaging is indicated. After watching this. Procedure Report: Frontal sinuses are well developed and exhibit no mucoperiosteal thickening. With pediatric patients, a parent may be allowed in the room but may need to wear a lead apron to minimize radiation exposure. The CT scan data will be used as an interactive anatomy "road map" for Stealth device guided surgery. How the Test is Performed 3-D reconstructions are done as needed. 256 Slice CT - Updated 01-25-2022 Head: Temporal Bones. You may need a follow-up exam. Some policies are stating that they won't allow the three codes to be billed together. CT of the head with fiducials. Update my browser now. Next, the table will move quickly through the scanner to determine the correct starting position for the scans. The paranasal sinuses are hollow, air-filled spaces located within the bones of the face and surrounding the nasal cavity, a system of air channels connecting the nose with the back of the throat. If a Stealth protocol CT cannot be obtained, a normal sinus CT can be utilized but may not provide the same level of accuracy. Recurrent or refractory symptoms, despite treatment, or suspicion of complicated infection, abscess, or neoplasm, warrants further evaluation. After this treatment, his symptoms improved approximately 50 percent, and he received a limited CT scan of the sinuses. Because children are more sensitive to radiation, they should have a CT exam only if it is essential for making a diagnosis. Preoperative computed tomography (CT) affords radiologists the opportunity to prospectively identify anatomic variants that predispose patients to major surgical complications; however, these critical variants are not consistently evaluated or documented on preoperative imaging reports. Anterior ethmoid sinuses exhibit no mucosal disease. endstream The technologist or nurse, under the direction of a physician, may offer you some medication to help you tolerate the CT scanning procedure. `l\/ c+f>@@@@@V &x&p'@@@@@MlP_TEc+ kr>R8 N+[LW{ These occur as the CT scanner's internal parts, not usually visible to you, revolve around you during the imaging process. You may feel a need to urinate. Sinusitis is one of the most common conditions encountered by primary care physicians, accounting for approximately 25 million office visits annually1 and costing more than $2 billion annually in direct medical expenses.2,3 According to the National Ambulatory Medical Care Survey, sinusitis is the fifth most common medical diagnosis for which antibiotics are prescribed.4,5. The CT protocol itself is based on certain technical parameters, and the patient wouldn't notice any difference between Stealth CT protocol and standard CT protocol. Institutions have their bloodsupply by clicking and of bone. Referral will occasionally be needed in unusual or complicated cases. CT imaging allows providers to have a more in-depth look at your sinuses to determine the cause of blockages. 70486- CT Maxillofacial without contrast A person who is very large may not fit into the opening of a conventional CT scanner.