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	Helical scan - Wikipedia, the free encyclopedia
		Helical scan or striping is a method of recording higher bandwidth signals onto magnetic tape than would otherwise be impossible at the same tape speed with fixed heads.
		This is known as a helical scan because the tape wraps around the circular drum at an angle, traveling up like a helix.
		Helical scanning was a logical progression beyond an earlier system (pioneered by Ampex) known as quadruplex recording.
	en.wikipedia.org /wiki/Helical_scan (839 words)

	Spiral scan sees stroke blockage more clearly
		However, high-speed helical CT scans (sometimes called spiral CT), which use a contrast dye, give physicians a view of blood flow inside vessels and the pattern of blood distribution throughout the brain.
		Helical scanners also allow them to quickly determine if a stroke is ischemic and find where a blockage exists, says study author Michael H. Lev, M.D. The scan can also show the doctor if the vessel is partially or completely blocked, and can show which areas of the brain are not getting enough blood.
		At Massachusetts General, helical CT scans are standard for stroke patients brought to the emergency room.
	www.americanheart.org /presenter.jhtml?identifier=3001835 (773 words)

	AKU-AKUH Clinical Laboratories (Site not responding. Last check: 2007-10-21)
		During helical scanning the x-ray tube rotates in a circular path around the patient while the couch moves at a constant speed.
		As it is much faster than conventional scanning, it is possible to scan uncooperative patients with comparatively greater details and also the areas even in cooperative patients where it is impossible to control involuntary movements like chest which is a complex composite of multiple organs with involuntary movements of heart and surrounding vessels.
		Helical CT of circle of Willis, Thoracic aorta and abdominal aorta has become very common all over the globe as one of the best diagnostic and treatment planning modality for these vascular areas.
	www.aku.edu /akuh/hs/cl/labrad-23-th12.shtml (1325 words)

	Is Helical CT Angiography a Better Screen for Pulmonary Embolism? - October 1, 2000 - American Academy of Family ...
		During an 18-month period, 216 consecutive patients suspected of having acute pulmonary embolism were evaluated by helical CT angiography, ventilation-perfusion radionuclide lung scan and Doppler sonography of the lower extremities.
		Helical CT angiography was more sensitive and specific than the ventilation-perfusion radionuclide lung scan (94.1 versus 80.8 percent and 93.6 versus 73.8 percent, respectively).
		Helical CT angiography also had higher positive and negative predictive values and a higher degree of interobserver agreement than ventilation-perfusion scan.
	www.aafp.org /afp/20001001/tips/17.html (459 words)

	Chest x ray vs. helical-CT chest screening
		In helical CT, the patient is continuously moved through the scanner as the source and receptor rotate around the patient.
		With either a chest x ray (CXR) or a CT scan, the part of the body receiving the greatest exposure is the entrance skin in the field of view.
		Often helical CT scans are very useful in emergency rooms where a fussy child needs a critical x ray (or even a delirious or uncooperative adult).
	hps.org /publicinformation/ate/q2372.html (1375 words)

	Improved Diagnosis of Hepatic Perfusion Disorders: Value of Hepatic Arterial Phase Imaging during Helical CT -- Quiroga ...
		Helical CT scan obtained during the HAP shows a small, homogeneous lesion (arrow) of high attenuation (similar to that of the aorta) with distal wedge-shaped parenchymal enhancement (arrowhead), an appearance corresponding to a small APS.
		Helical CT scan obtained during the HAP shows early enhancement of a small branch of the right portal vein (large arrow), indicative of an APS, and THPE (small arrows) in segment VI.
		Helical CT scan obtained during the HAP shows a triangular area of THPE in the dorsum of segment IV (arrow).
	radiographics.rsnajnls.org /cgi/content/full/21/1/65 (5888 words)

	Full body scanning, ebt scans, ct scans, disease screening
		However, CT Scans, employing a computer helical CAT scan is also used for a wide range of body screening.
		In spiral CT scans, the x-ray tube rotates around the reclining patient as the examination table moves forward through the scanner.
		Faster than the basic CT scan, EBT has been approved by the FDA and is considered ideal for early detection of calcification in coronary arteries.
	www.bodyscan.md /body_scans.html (361 words)

	Helical CAT Scan (Spiral CAT Scan) - Health and Medical Information produced by doctors - MedicineNet.com
		A conventional computerized axial tomography scan (CAT scan or CT scan) is an x-ray procedure which combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body.
		A CAT scan is used to define normal and abnormal structures in the body and/or assist in procedures by helping to accurately guide the placement of instruments or treatments.
		A helical CAT scan is a new specialized CAT scan technique that involves continuous movement of the patient through the scanner with the ability to scan faster and with higher definition of internal structures.
	www.medicinenet.com /script/main/art.asp?articlekey=9624 (223 words)

	Helical scanner with variably oriented scan axis - Patent 6324246
		When the body axis is tilted, the scanning path of the X-ray tube relative to the axis no longer describes a simple, constant-pitch helix, but rather a more complex spiral figure.
		In one aspect of the present invention, angled helical scan data generated during different positions of the gantry (i.e., at different helical positions of the gantry) are combined to form a data set of a view for reconstruction of the image.
		In this case, the effective attenuation values are interpolated from measured attenuation data from adjacent rows of the signal matrix at a single view, i.e., signals that are acquired while the X-ray tube is at one, given position along the helical scan path.
	www.freepatentsonline.com /6324246.html (6710 words)

	Methods and apparatus for single slice helical image reconstruction in a computed tomography system - Patent 6408088
		A "scan" of the object comprises a set of views made at different gantry angles during one revolution of the x-ray source and detector.
		To perform a "helical" scan, the patient is moved while the data for the prescribed volume coverage is acquired.
		In known single slice helical reconstruction, the slice profiles and image noises of reconstructed images are primarily determined by x-ray collimation, the patient-feeding speed, the x-ray tube output, and the weighting function W(.beta.,.gamma.).
	www.freepatentsonline.com /6408088.html (2891 words)

	Helical Scan Technology (Site not responding. Last check: 2007-10-21)
		Helical scan was invented in 1961 and developed for the video recording industry.
		In the design of helical scan products the write and read heads are mounted on a drum that rotates at high speed.
		The head is mounted at a slight angle to the tape path, causing the recording of data on diagonal stripes across the tape.
	www.dpts.co.uk /hdm03.htm (858 words)

	helical - Search Results - MSN Encarta
		These have teeth that are not parallel to the axis of the shaft but are spiraled around the shaft in the form of a helix.
		A scanning principle called helical scan (or slant-track scan) is used...
		The viral protective shell, or capsid, can be either helical (spiral-shaped) or icosahedral (having 20 triangular sides).
	encarta.msn.com /helical.html (98 words)

	CAT Scan - Page 3
		In the 1990s, a form of CAT scan was developed called a spiral CAT scan (also called a helical CAT scan or volumetric CT).
		A helical CAT scan can often be performed while the patient holds a single breath, which limits patient movement and delivers a sharper picture.
		PET scans are most often used to detect cancer or evaluate signs of coronary artery disease.
	pain.healthcentersonline.com /painimagingtests/catscan3.cfm (592 words)

	Helical CT Features of Arrhythmogenic Right Ventricular Cardiomyopathy -- Kimura et al. 22 (5): 1111 -- RadioGraphics
		CT scans were obtained at the levels of the infundibular (a), inflow (b), and apical and inferior (c) regions.
		CT scans were obtained at the levels of the mitral valve (MV) (a) and tricuspid valve (TV) (b).
		Contrast-enhanced CT scan shows bulging of the inferior wall (arrow), which is compatible with aneurysm formation and is pathognomonic for ARVC.
	radiographics.rsnajnls.org /cgi/content/full/22/5/1111 (6436 words)

	LasCon Storage - Helical Scan Technology
		Tape recording based on helical scan is the same type of technology as that used in VHS video-tape recorders.
		However, data access on helical scan is slower that linear, so it tends not to be used for applications which need high performance.
		It is difficult to see how helical scan can scale up like linear tape, as it would be difficult to fit more pairs of heads to the rotating drum.
	www.lascon.co.uk /d010001.htm (356 words)

	Scan
		When Sony brought the transistor PV100 helical scan to market the next year, it forced Ampex to do the same.
		Ampex had previously developed helical scan technology but sat on it hoping to keep its (exclusive) quad business alive.
		Helical scan is sometimes called "slant track" because it is layed down as a diagonal on the tape.
	www.r-vcr.com /~television/TV/Scan.htm (1307 words)

	Helical CT in Emergency Radiology -- Novelline et al. 213 (2): 321 -- Radiology
		protocols for the helical CT diagnosis of thoracic aortic trauma;
		The role of helical CT in the diagnosis of acute pulmonary embolus
		Helical CT of traumatic avulsion of the gallbladder.
	radiology.rsnajnls.org /cgi/content/full/213/2/321 (10187 words)

	Primary radiation outside the imaged volume of a multislice helical CT scan -- Nicholson and Fetherston 75 (894): 518 ...
		Primary radiation outside the imaged volume of a multislice helical CT scan -- Nicholson and Fetherston 75 (894): 518 -- The British Journal of Radiology
		The pattern of film flening from a helical scan of 5.2 cm length using the multislice scanner with 4
		5 mm data acquisition (a) is contrasted with the pattern from a helical scan of 5.0 cm length and 5 mm data acquisition using the single slice scanner (b).
	bjr.birjournals.org /cgi/content/full/75/894/518 (2187 words)

	TOTAL BODY SCANS, VIRTUAL COLONOSCOPY FOR BOWEL CANCER, HELICAL CAT SCAN FOR LUNG CANCER - A LOT OF HYPE, BIG PROFITS, ...
		The problem is that there are as yet no studies that show it saves lives; and the only true measure of a screening test for cancer of the lung is that it actually saves lives.
		Helical CAT scan is now undergoing trials to determine whether it does or does not save lives; until those studies are completed, statements claiming helical CAT scan can result in very high cure rates (up to 80 percent) for lung cancer are undocumented hyperbole.
		One imaging center in New York is advertising a combination of total body scan and virtual colonoscopy for $1,400 each time.
	healthfullife.umdnj.edu /archives/bowel_lung_cancer_archive.htm (806 words)

	Thick-Section Reformatting of Thinly Collimated Helical CT for Reduction of Skull Base-Related Artifacts -- Alberico et ...
		Helical scans were reformatted to a 5-mm thickness with 5-mm
		Conventional CT scan limited by artifacts in posterior, middle, and anterior cranial fossa.
		Conventional CT scan near foramen magnum limited by artifacts that obscure medulla, lower cerebellum, and vertebral arteries.
	www.ajronline.org /cgi/content/full/175/5/1361 (3428 words)

	The Hindu : 300 children have undergone helical CT scan
		More than 300 children have undergone the new sub-second helical CT scan in just over a month, since the installation of the machine in the Kanchi Kamakoti CHILDS Trust Hospital here.
		With the chest, brain and abdominal scans topping the requests, both diagnosticians and paediatricians feel that the new scanner is a blessing in disguise, as its speed (0.7 seconds) is the most convenient for testing children.
		The helical scan also makes it easy to shoot images of the specified parts, even if children do move around, the diagnosticians say.
	www.hindu.com /thehindu/2001/11/23/stories/0423401b.htm (359 words)

	Subsequent Pulmonary Embolism: Risk after a Negative Helical CT Pulmonary Angiogram- Prospective Comparison with ...
		CT scan as a definitive indication to exclude PE.
		In the second approach, helical CT was substituted for scintigraphy.
		Detection of pulmonary embolism in patients with unresolved clinical and scintigraphic diagnosis: helical HCT versus angiography.
	radiology.rsnajnls.org /cgi/content/full/215/2/535 (5472 words)

	What is helical scan? - a definition from Whatis.com
		Helical scan began in the VCR world and uses a spinning read/write head and diagonal tracks.
		Called linear technology, it doesn't store as much data as helical scan but the heads don't touch the tape.
		Helical scan remains a viable option for high-capacity tape backup.
	searchstorage.techtarget.com /sDefinition/0,,sid5_gci214473,00.html (261 words)

	Detection of lung cancer by helical CT scan: a new method of mass screening -- Asamura 29 (2): 113 -- Japanese Journal ...
		In Japan, the new screening method using helical computed tomography (CT) scanning is being evaluated at the Shinsyu University, Matsumoto.
		A screening car equipped with a helical CT was sent to each city and village in the district for the subjects to undergo screening easily without visiting the medical center downtown.
		In three years, 12 344 subjects have undergone a helical CT screening and 65 (0.5%) lung cancers were found, which was ten times more than that by former screening system using a chest X-ray film.
	jjco.oxfordjournals.org /cgi/content/full/29/2/113 (1426 words)

	A Simple Algorithm for Increased Helical Pitch in Cone-Beam CT (ResearchIndex)
		Abstract: INTRODUCTION A goal of cone-beam CT is to decrease the scan time needed to image a volume of the patient.
		Four things are required to meet this goal: (1) a detector with multiple rows of sensors, (2) higher bandwidth data acquisition system and image processor to handle the increased data rates and need for fast reconstruction, (3) high helical pitch, (4) a practical reconstruction algorithm that lends itself to fast reconstruction times.
		1 Multi-slice helical CT: Scan and reconstruction (context) - Hu - 1999
	citeseer.ist.psu.edu /500304.html (449 words)

	Matrix Helical Scan Interleaver (Communications Blockset)
		The Matrix Helical Scan Interleaver block performs block interleaving by filling a matrix with the input symbols row by row and then sending the matrix contents to the output port in a helical fashion.
		The Number of rows and Number of columns parameters are the dimensions of the matrix that the block uses internally for its computations.
		Helical fashion means that the block selects output symbols by selecting elements along diagonals of the matrix.
	www-rohan.sdsu.edu /doc/matlab/toolbox/commblks/ref/matrixhelicalscaninterleaver.html (366 words)

	What is helical-scan cartridge? - A Word Definition From the Webopedia Computer Dictionary (Site not responding. Last check: 2007-10-21)
		The term helical scan usually refers to 8mm tapes, although 4mm tapes (called DAT tapes) use the same technology.
		Textron: Helical Gears - Specializes in the design and manufacture of industrial pumps, gears and gearboxes for the pump and power transmission industries.
		SERVICELINE: Helical - The SERVICELINE bevel gearbox is a low ratio gearbox that utilizes spiral bevel gearing and can be used in a wide range of applications.
	www.pcwebopedia.com /TERM/H/helical_scan_cartridge.html (213 words)

	Imaging: Danbury Radiological Associates - Computed Tomography Scan
		Thorsten L. Krebs, MD The section of Computed Tomography (CT Scan) offers state of the art computed x-ray imaging with convenient hours for outpatient appointments and 24-hour service for urgent and emergent patients.
		We also offer the full spectrum of CT diagnostic procedures and CT guided interventions as well as expert oncology imaging services available to our cancer patients and their specialist physicians.
		Patients may also turn to us for specialty scans including Helical/Spiral Scans, CT Angiography, 3-D Imaging, and Screening Low Dose Chest CT for early detection of lung cancer.
	www.danburyhospital.org /DH_imaging_layout.cfm?id=748 (306 words)

	VHS - Wikipedia, the free encyclopedia
		In fact it initially stood for Vertical Helical Scan, after the relative head/tape scan technique (making the popular version a backronym), some actually believe that it once stood for Video Head Set, due to the way the cassette's magnetic strip is read with a silver read head.
		VHS machines, in contrast to Betamax and Beta's predecessor U-matic, use an M-loading system, also known as M-lacing, where the tape is drawn out by two threading posts and wrapped around the head drum (and other tape transport components) in a shape roughly approximating the letter M.
		VHS tapes have approximately 3 MHz of video bandwidth, which is achieved at a relatively low tape speed by the use of helical scan recording of a frequency modulated luminance (fl and white) signal, to which a frequency-reduced "color under" chroma (hue and saturation) signal is added.
	en.wikipedia.org /wiki/VHS (3542 words)

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