Axial views

Eldh, Per

doi:10.1002/ccd.1810020402

Cited by 8 publications

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“…Consequently, also in hemiaxial System positions these calculations realize one of the prerequisites of optimal angiographic imaging, the System orthogonality [4].…”

Section: Discussionmentioning

confidence: 99%

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Biplane Multidirectional Angiocardiography: Exact Orthogonal Positioning of the X-Ray Systems (Laterally Mounted C-Arm-L-Arm-Systems). Biplane multidirektionale Angiokardiographie: Exakte orthogonale Positionierung der Röntgensysteme (Seitlich montierte C-Arm-L-Arm-Systeme)

Wollschläger¹,

Lee²,

Bonzel³

et al. 1984

Biomedizinische Technik/Biomedical Engineering

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Orthogonal Biplane Angiography 261 gegen unendlich, so daß die genannte Auflösungsbeschränkung natürlich entfällt. Gleichzeitig gehen die Ewald-Halbkreise in Geraden über. Es entsteht somit für k -» oo eine Meßwertverteilung in der Fourier-Ebene, die exakt mit derjenigen für Röntgen-Parallel-Scanner übereinstimmt. Daß daher für -» o diekomplexeren -Algorithmen der Ultraschall-Transmissions-CT auch in die der Röntgen-CT übergehen, erscheint sicher plausibel.Bei der in der Diskussion befindlichen Mikrowellen-CT, bei der die Dielektrizitätskonstante rekonstruiert werden soll, treten gegenüber der Ultraschall-CT weitere Probleme auf. Zunächst darf der Brechungsindex hier nicht mehr als nur schwach veränderlich angenommen werden, wodurch die Voraussetzung für die Störungsrechnung 1. Ordnung verletzt ist. Außerdem zwingt die stark frequenzabhängige Dämpfung zur Verwendung von Mikrowellen von mehreren cm Wellenlänge im Gewebe, wodurch gemäß obiger Bemerkung die Auflösung ebenfalls auf wenige cm be-schränkt ist. Die bekannten Stabilitätsprobleme mit superauflösenden Rekonstruktionstechniken lassen es daher fraglich erscheinen, ob mit Mikrowellen Auflösungen erreicht werden können, die in der medizinischen bildgebenden Technik sonst üblich sind.Key-words: Angiocardiography, biplane X-ray equipment, orthogonal projections. automatic steering of X-ray Systems For optimal angiographic imaging of an anatomical object a t least two projections, vvhich are perpendicular to each other, are needed. When hermaxial projections are usod, the orthogonal positioning of the Systems is diffieult to achieve. This problem is evident when mulhdiivctional biplane angiography equipment is used. The potentials of these Systems can onlv be fully utih/.ed when simuitaneous orthogonality is realized. To solve this problem, the geometric properties of a muH idireet ional X-ray system (demonst rat öd in a lateral.lv mounted C-arm-L-arm system) are analyzed The mathomatu'ai formulas toi the calculation of the exact positions of sueh biplane X-ray Systems are denved if one öl the paramplers (C-arm or L-arm rotation) of one X-ray system is known, this system ean br positioued under a predefined inelination in relation to a serond one These calrulationft ean be made with a mieroeinuputer du ring the an^iographic in \esiijbjation After implementatinn into a eomputer these formulas can be used foi (jsomi )aulonu*1u x\xtcm sleering Limilalione are given by ponsible collision i»f bot h X-ray svstews 01 of the c-^inpmcnt with the patlent The pienented formul«« are furthermore nuitabie for positionii^ of the X ra> Ä\NI«MUS prrpen dieular to arty given spatial axi« (r g the long HXI* of the vonti u le) Brought to you by | University of Queensland -UQ Library Authenticated Download Date | 6/24/15 12:28 AM

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“…Consequently, also in hemiaxial System positions these calculations realize one of the prerequisites of optimal angiographic imaging, the System orthogonality [4].…”

Section: Discussionmentioning

confidence: 99%

“…For optimal reproduction of anatomical details with imaging Systems, projections of at least two planes which are perpendicular to each other are mandatory [4].…”

Section: Introductionmentioning

confidence: 99%

Biplane Multidirectional Angiocardiography: Exact Orthogonal Positioning of the X-Ray Systems (Laterally Mounted C-Arm-L-Arm-Systems). Biplane multidirektionale Angiokardiographie: Exakte orthogonale Positionierung der Röntgensysteme (Seitlich montierte C-Arm-L-Arm-Systeme)

Wollschläger¹,

Lee²,

Bonzel³

et al. 1984

Biomedizinische Technik/Biomedical Engineering

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Special angulated projections in coronary arteriography: A confusion in terminology

Aldridge

McLoughlin

Taylor

1977

Cathet. Cardiovasc. Diagn.

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In recent years a number of reports (1-1 1) have pointed out the importance of supplementing conventional oblique projections of the coronary arteries with cranial and caudal angulated projections to minimize foreshortening and overlap of vessels and to improve examination of eccentric coronary artery lesions. Two of these reports provide statistical data on the value of routine use of these projections. Greatly improved diagnostic information was obtained in 46% of studies of the left anterior descending coronary artery (1) and in 54% of studies analyzing the whole coronary arterial tree (2).These angulated projections have been obtained using a number of different x-ray systems, viz: serial film changers with either lateral or overhead x-ray tubes ( 1 , [3][4][5]; an undertable x-ray tube with a cradle in which the patient is propped up 30" with wedges or pillows (4); an undertable x-ray tube coupled to an overhead image intensifier that can be angled from 30" cranially to 15" caudally (General Electric System); C-arms (4, 6); U-arm systems with horizontally rotating isocentric tables (2,7-9); and parallelogram systems ( 10, 1 1). There is little doubt that C-arm, U-arm, and parallelogram systems are the most flexible and convenient in obtaining these special projections.This varied methodology has resulted in a confusing array of terms to describe the views obtained. These include half-axial ( I ) and axial (12); angulated views in the sagittal plane (6); lordotic (3. 5); caudocranial and craniocaudal projections (CCI, and CCII) (8); cranial and caudal angulated oblique views (2); longitudinal angulated projection and superior oblique left anterior oblique projection. Angulation of the x-ray beam is also specified in different ways. Thus there is a need for a) a simpler terminology for all projections and b) a uniform method of specifying angulation of the x-ray beam. NAMING THE PROJECTIONSIn conventional terminology x-ray projections are named either from the position of the imaging device (image intensifier, film changer, etc.) relative to the patient or

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A decade or more of cranial and caudal angled projections in coronary arteriography—another look

Aldridge¹

1984

Cathet. Cardiovasc. Diagn.

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The introduction of selective coronary angiography by Mason Sones [l] was a milestone in the diagnosis and treatment of heart disease. This has been paralleled in the advances in X-ray techniques dedicated to the examination of the heart and coronary circulation. The current metal-input cesium iodide image intensifiers capable of resolving over seven line pairs/mm are a far cry from the old zinc cadmium sulfide intensifiers, which resolved less than 1.5 line pairdmm. Similarly, the development of high-resolution television systems, the improvement in X-ray tubes, and the advent of computerized generators have made a major contribution to superior imaging of the heart. Not infrequently, patients restudied on the new X-ray systems are found to be surgical candidates, having been previously turned down because of apparent disease in the distal vessels in films obtained with earlier generation image intensifiers.The mounting of image intensifiers and X-ray tubes has also been substantially changed. In the sixties, the projections were usually limited to the transverse oblique plane. Often the patient had to be propped up uncomfortably on pillows or wedges. The introduction of the rotating cradle in the mid-sixties certainly made the procedure more comfortable for the patient but did not significantly improve the diagnosis. The importance of these angled views gave rise to a totally new generation of X-ray equipment for cardiac use. Modified C-or U-arms were developed, which allowed the equipment to be rotated around the patient with the heart placed in the isocentric point of the X-ray system. Now, not only cranial but also caudal angles were easily obtainable. This mechanical sophistication, however, was also associated with an increased cost for X-ray equipment. Some institutions found that financial constraints did not permit the scrapping of their existing X-ray systems. Thus a number of simple structural mechanisms were devised [7] to obtain at least cranial angles, such as those published in this issue. There is, however, no doubt that caudal angles are as important as cranial angles [lo-131. An analysis of the early experience with special angled projections showed that a substantial improvement in diagnosis could be obtained in 54 % of patients studied [9]. More recent reports based on large numbers of patients suggest that in certain instances improved visualization can occur in up to 93% of studies [12,14,15]. Thus, by today's standards, the nonuse of such special Address reprint requests to

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Axial views

Cited by 8 publications

References 0 publications

Biplane Multidirectional Angiocardiography: Exact Orthogonal Positioning of the X-Ray Systems (Laterally Mounted C-Arm-L-Arm-Systems). Biplane multidirektionale Angiokardiographie: Exakte orthogonale Positionierung der Röntgensysteme (Seitlich montierte C-Arm-L-Arm-Systeme)

Biplane Multidirectional Angiocardiography: Exact Orthogonal Positioning of the X-Ray Systems (Laterally Mounted C-Arm-L-Arm-Systems). Biplane multidirektionale Angiokardiographie: Exakte orthogonale Positionierung der Röntgensysteme (Seitlich montierte C-Arm-L-Arm-Systeme)

Special angulated projections in coronary arteriography: A confusion in terminology

A decade or more of cranial and caudal angled projections in coronary arteriography—another look

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