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Biomedical subjects

H P Busch

Publications and source records attributed to H P Busch.

At least 19 recordsLinked to original sources
PubMed2006

Image quality and dose management in digital radiography: a new paradigm for optimisation.

The advent of digital imaging in radiology, combined with the explosive growth of technology, has dramatically improved imaging techniques. This has led to the expansion of diagnostic capabilities, both in terms of the number of procedures and their scope. Throughout the world, film/screen radiography systems are being rapidly replaced with digital systems. Many progressive medical institutions have acquired, or are considering the purchase of computed radiography systems with storage phosphor plates or direct digital radiography systems with flat panel detectors. However, unknown to some users, these devices offer a new paradigm of opportunity and challenges. Images can be obtained at a lower dose owing to the higher detective quantum efficiency (DQE). These fundamental differences in comparison to conventional film/screens necessitate the development of new strategies for dose and quality optimizations. A set of referral criteria based upon three dose levels is proposed.

Humans↗
PubMed2005

[Digital radiography und fluoroscopy. Basics of technology, imaging properties and applications].

For 110 years, x-rays and special x-ray films have been used in medical diagnostics. New developments in the field of x-ray techniques, and especially new computer applications, have led to new imaging techniques which have substantially expanded the spectrum of radiological examinations. In spite of significant technological and medical advances in the field of MRI and multidetector-CT, radiographic images of the lungs, skeleton and organs still comprise up to 80% of the routine radiological workload. The increasing availability of digital detectors has led to the continual replacement of conventional film/screen systems. The inclusion of digital mammography was delayed due to the higher requirements for spatial resolution. For about 2 years, dynamic flat panel detectors have started to replace the image intensifier which has been used in fluoroscopy for 40 years.

Biotechnology↗
PubMed2003

[Image quality and exposure dose in digital projection radiography].

PURPOSE: Comparison of the imaging capabilities of storage phosphor (computed) radiography and flat plate radiography with conventional film-screen radiography to find new strategies for quality and dose management, i. e., optimizing imaging quality and dose depending on the imaging method and clinical situation. MATERIALS AND METHODS: Images of a CDRAD-phantom, hand-phantom, abdomen-phantom and chest-phantom obtained with different exposure voltages (50 kV, 73 kV, 109 kV) and different speeds (200, 400, 800, 1600) were processed with various digital systems (flat plate detector: Digital Diagnost [Philips]; storage phosphors: ADC-70 [Agfa], ADC-Solo [Agfa], FCR XG 1 [Fuji]) and a conventional film-screen system (HT100G/ Ortho Regular [Agfa]). RESULTS: The evaluation of CDRAD images found the flat plate detector system to have the highest contrast detectability for all dose levels, followed by the FCR XG 1, ADC-Solo and ADC-70 systems. Comparison of the organ-phantom images found the flat plate detector system to be equal to film-screen radiography and especially to storage phosphor systems even for low exposure doses. CONCLUSIONS: Flat plate radiography systems demonstrate the highest potential for high image quality when reducing the exposure dose. Depending on the system generation, the storage phosphor systems also show an improved image quality, but the possibility of a dose reduction is limited in comparison with the flat plate detector system.

Hand↗
PubMed2003

[High resolution contrast-enhanced 3D MR-angiography of renal arteries using parallel imaging (SENSE)].

PURPOSE: To compare three dimensional contrast enhanced MR angiography with parallel imaging technique (sensitivity encoding) to standard MR angiography technique. MATERIAL AND METHODS: CE-3D MRA of renal arteries was performed in 22 patients (23 examinations) on a 1.5 T MR- scanner (Gyroscan Intera, Philips, Netherlands). For contrast enhanced MRA a single dose of Gd-DTPA (0.1 mmol/kg b.w.) was administered. Group I: The following standard 3D gradient echo (GE) sequence was performed in 9 of the 22 patients: TR: 4.3 ms, TE: 1.5 ms, flip angle: 40, 40 slices, scan duration: 19 seconds. A spatial resolution of 1.96 x 1.76 x 3.0 mm (3) (1.76 x 1.76 x 1.5 mm (3) interpolated) was obtained. Group II: 14 examinations were acquired in 13 patients: TR, TE and flip angle were equal compared to the first protocol. The k-space lines were acquired with CENTRA (contrast-enhanced time robust angiography) and parallel imaging technique (SENSE). 60 slices were acquired, scan duration was 24 seconds. The spatial resolution of this sequence was 1.19 x 1.08 x 2.0 mm (3) (0,84 x 0,84 x 1,0 mm (3) interpolated). Original images and calculated maximum intensity projection (MIP) images were analysed by two radiologists. Image quality and the visibility of renal arteries were rated on a four-point scale. RESULTS: In the first group the image quality was rated "good" in 8/9 patients. The renal arteries were detected in all cases and rated "good". The anterior and posterior segments were rated "good" in only 5/9 and the lobar arteries were detectable only in 3 of 9 cases. The interlobar arteries could not be seen in these patients. In the second group the image quality was rated excellent in 5 examinations and good in 9 of 14 examinations. The rating for the renal arteries was excellent in all examinations (14/14). The results of the anterior and posterior segment were as followed: excellent 5/14, good 7/14, insufficient 2/14; the lobar arteries: good 6/14, insufficient 6/14 and not detectable 2/14. Interlobar arteries could be seen in 7/14 examinations, but the quality was insufficient. In 7/14 the interlobar arteries could not be detected. CONCLUSION: The use of parallel imaging technique improves image quality and the delineation of small vessels in renal MRA.

Aneurysm↗
PubMed2003

Is a combination of Tc-SPECT or perfusion weighted magnetic resonance imaging with spinal tap test helpful in the diagnosis of normal pressure hydrocephalus?

OBJECTIVE: The aim of this study was to evaluate the combination of spinal tap test (STT) with cerebral perfusion measurement assessed either by Tc-bicisate-SPECT (Tc-SPECT) or perfusion weighted MRI (pwMRI), or both, for a better preoperative selection of promising candidates for shunt operations in suspected idiopathic normal pressure hydrocephalus. METHODS: 27 consecutive patients were examined with a standard clinical protocol (assessed by the Homburg Hydrocephalus Scale (HHS)) as well as with 99m Tc-bicisate-SPECT (n=27) or additionally by pwMRI (n=12) before and after STT. The results of these examinations were compared preoperatively for each patient and correlated with postoperative clinical outcome after shunt surgery. RESULTS: Nine patients showed both, a clinical improvement, and increased cerebral perfusion after STT. They underwent shunt surgery with good to excellent results. In another nine patients increasing cerebral perfusion was detected although they did not show a clear clinical improvement after STT. Six of them also received a shunt operation with good to excellent outcome. Three patients of the last group could have an operation. Nine patients did not show any clinical improvement or any kind of increasing cerebral perfusion after STT. Therefore, they did not undergo surgery. The results of SPECT and pwMRI correlated in 92 % of the patients (11 of 12). CONCLUSION: It is concluded that a combination of clinical assessment with SPECT or pwMRI is helpful in the preoperative selection of patients for shunting procedures with suspected NPH syndrome. This combination is a minimal invasive and objective test modality that is superior to STT alone. Further studies are necessary for a comparison of the described imaging techniques with different diagnostic tests in this difficult field of cerebral disease.

Adult↗
PubMed2001

[Influence of tandem optics and television tube of modern digital fluoroscopy equipment on image quality].

The influence of the tandem optics and the TV-tube to the image quality of 1k- and 2k-radiographs of a modern fluoroscopy equipment should be assessed on the basis of objective parameters and clinical requirements. Radiographs of different phantoms with 1k- and 2k-image matrix, different illumination point corrections (IPC) and signal gray levels were taken, examined and evaluated, in order to determine the objective image parameters and the clinical relevancy of these parameters. On the one hand, the digital images data could be used directly for evaluation; on the other hand, the radiographs could be visually evaluated by experienced radiologists within the framework of a blind study. The IPC is controlled by the aperture of the iris diaphragm and the insertion of a neutral gray filter in the tandem optics. The larger the aperture of the iris diaphragm (at constant image receiver dose) the higher were gradation, signal to noise ratio (SNR) and image homogeneity. Furthermore, the larger the aperture, the lower was the square wave response function (SWRF). The insertion of a gray filter in the tandem optics decreases gradation, SNR and homogeneity, and improves the SWRF.

Fluoroscopy↗
PubMed2001

[MR angiography of pelvic and leg vessels with automatic table movement technique ("Mobi-Trak")--clinical experience with 450 studies].

PURPOSE: By a retrospective clinical evaluation of 450 MR angiograms of the lower extremity arteries the question was posed of whether MR angiography can replace i.a. DSA. MATERIAL AND METHODS: Image quality of 450 MR angiograms was graded by 4 radiologists; in 102 patients who underwent radiological intervention a comparison between MR angiogram and i.a. DSA was done. Additionally, MR angiography was compared with the results of surgical intervention in 106 cases. RESULTS: 6% of 450 examinations showed a significant limitation of diagnostic information. 5 examinations (1%) had to be redone by i.a. DSA. In all cases the diagnosis from MRA was proven by the results of the following i.a. DSA or surgical procedure. CONCLUSION: The retrospective clinical evaluation of 450 examinations demonstrated that MR angiography of the lower extremity arteries can replace i.a. DSA in routine use.

Adult↗
PubMed2000

[Examination of the image quality from digital fluoroscopy equipment with 1k- and 2k-image matrix].

PURPOSE: The image quality of 1k- and 2k-radiographs from digital fluoroscopy equipments (Sireskop SX and Polystar SX--Siemens) are characterized by comparison with each other to evaluate the relevance of this technique in clinical routine. MATERIAL AND METHODS: We examined fabricated and evaluated images with 1k- and 2k-image matrix from several high and low contrast phantoms and from skeleton phantoms. On the one hand, the digital image values can be used directly for the evaluation, on the other hand the comparing evaluation by experienced radiologists resulted from a visual consideration in a blind study. RESULTS: The quality difference of the 1k- and 2k-images depends mainly on the distance of the investigated sector of the object to the image intensifier and on the scattering of the radiation in the object positioned between the investigated sector and the image intensifier. The nearer the investigated object is located to the intensifier and the smaller the radiation is scattered in the object, the more the image quality of a radiograph with a 2k-matrix is increasing in comparison to an image with 1k-matrix. The higher the tube voltage, the smaller are the differences. CONCLUSION: The image quality enhancement because of the more sensitive sampling of the Saticon target in the 2k-matrix is limited by the opening of the iris positioned in the light distributor. Therefore the image quality differences of medical 1k- and 2k-radiographs in many cases are small.

Bone and Bones↗
PubMed1999

[MR angiography of the lower extremities with an automatic table translation (Mobitrak) compared to i.a. DSA].

PURPOSE: Comparison of the diagnostic information obtained by MRA using a moving bed ("MobiTrak") with i.a.DSA for angiography of the lower extremities. MATERIALS AND METHODS: In 20 patients, i.a.DSA and MRA were performed within a few days. The image quality and diagnostic information were evaluated by two radiologists and two surgeons. RESULTS: The radiologists assessed the quality of MRA higher for 18%, for 79% image quality was equal, for 3% the quality was graded as lower in comparison to i.a.DSA. The surgeons found the quality of MRA higher for 16%, equal for 75% and lower for 9%. In all cases, MRA was sufficient for planning of further treatment. CONCLUSIONS: For examinations of the arterial vessels of the lower extremities, MRA with a moving bed ("MobiTrak") can be used instead of i.a.DSA. The diagnostic information from MRA is sufficient for planning the further treatment. The advantages of MRA (no radiation, no i.a. puncture, no contrast medium with iodine) will lead to an increasing application of this method.

Adult↗
PubMed1998

[Clinical aspects of image quality and doses in gated pulsed imaging].

PURPOSE: The relations between image quality in last image hold images and dose in grid controlled fluoroscopy in comparison to the continuous mode need to be characterised and recommendations for the clinical application of this technique should be given. MATERIAL AND METHODS: Spatial resolution, signal-noise ratio and, contrast-detail visibility were evaluated by phantom measurements in grid controlled pulsed and continuous fluoroscopy. Dose was measured at the image intensifier entrance. Image quality of last image hold (LIH) images of clinical examinations was graded in relation to single shot exposures. RESULTS: Signal-noise ratio and contrast-detail visibility depend on the dose per puls. Spatial resolution and contrast-detail visibility in grid controlled fluoroscopy are superior than to in the continuous mode. Image quality of the LIH images from the grid controlled fluoroscopy was improved. Radiation exposure could be reduced to 10-46%. CONCLUSIONS: Combinations of puls-dose and -frequency are recommended for achieving extensive dose reduction and improved image quality of LIH images.

Diagnostic Imaging↗
PubMed1998

[Iodine delivery rate in catheter angiography under pressure conditions in manual injection].

PURPOSE: The aim of this study was to record the flow-rate and to calculate the "iodine delivery rate" (IDR) of contrast media of various viscosities when the contrast media are injected by hand. METHODS: Five different catheters for coronary angiography were tested with the injection system Medrad Mark V Plus. Injections were performed with pressures of 100, 200 and 400 PSI. The contrast media examined were Imeron 350, Imeron 400, Omnipaque 350 and Ultravist 370. The IDR was calculated on the basis of the measured flow rate and the Iodine content of the contrast medium. RESULTS: As was expected, the IDR was higher as the pressure increased. In addition to the Iodine content the viscosity of the contrast medium is a very important factor for the IDR. At both 100 PSI and 200 PSI the increase of the IDR was higher with Imeron 350 than with Imeron 400. The comparison of contrast media with identical Iodine contents but differing viscosities (Imeron 350, Omnipaque 350) clearly showed that the IDR depended on viscosity. CONCLUSION: The "iodine delivery rate" is a decisive factor in the opacification of arterial vessels. Both Iodine content and viscosity of a contrast medium are important for the IDR. Because of the low pressure at manual injection, contrast media with low viscosities should be used. A further possibility to increase the IDR is warming-up the contrast medium to body temperature.

Contrast Media↗
PubMed1997

[Digital radiography--results of a user survey (A) and consensus conference (B)].

Digital radiography is increasingly replacing conventional radiography in imaging. For some years now, the pros and cons of this new method have been subject to intense discussions. For further discussion, the present article describes the results of an inquiry among users and of a consensus conference held in March 1996 in Munich. Comments and interpretations have been omitted on purpose.

Attitude of Health Personnel↗
PubMed1997

Digital radiography for clinical applications.

In the field of radiological research methods, digital imaging is becoming increasingly prevalent. Apart from computerised tomography, magnetic resonance tomography and angiography, also in projection radiography, traditional film/screen imaging is more and more being replaced by digital imaging using digital image-intensifier and storage phosphor technology. Digital imaging offers various new possibilities in image processing, storage and transmission. This may yield additional diagnostic information, dose reduction and fast availability of images. However, an inappropriate parameter selection for imaging and post-processing as well as a lack of integration in the entire organisation may lead to a rejection of this innovative technology.

Humans↗
PubMed1997

Digital radiography. Results of a survey (part A) and a consensus conference (part B).

Digital imaging (digital image intensifier radiography, storage phosphor/selenium radiography) is increasingly becoming commonplace in radiology departments for diagnostic purposes. Despite 10 years of experience, the advantages and disadvantages of those methods are still heavily discussed among users, financiers and prescribers. This paper is to offer additional arguments for a thorough and objective discussion. No further comments or interpretations have been added to this paper. This paper consists of two main parts, A and B. The first part deals with the results of a user survey, the other part presents the results, i.e. statements, of a consensus conference.

Humans↗
PubMed1997

[Studies of image quality and dose in digital subtraction angiography].

METHODS: The dose needed for high image quality in l.a. DSA, was determined by investigation of the necessary relationship between dose and image quality. This method is based on measurements of the signal-to-noise ratio and of the contrast-detail detectability. It has been tested on two different systems (Philips integris V3000, Philips Diagnost 97). RESULTS: Our measurements prove that an image intensifier entrance dose of 1.1 microGy (image intensifier diameter 38 cm) is sufficient for high image quality in DSA. An increased dose value does not lead to an improvement in image information. For details larger than the pixel size the 512 matrix produces a higher signal-to-noise ratio with a higher contrast-detail detectability, whereas higher spatial resolution results by the use of a 1024 matrix. In rotational angiography, high image quality can be achieved at an image intensifier entrance dose of 1.1 microGy. In contrast to sequences without rotation, image quality is decreased through movement unsharpness. As the maximum exposure time 25 ms should be selected. The use of a 1024 matrix does not lead to a better spatial resolution in rotational angiography.

Angiography, Digital Subtraction↗