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A Bäuml

Publications and source records attributed to A Bäuml.

10 recordsLinked to original sources
PubMed1999

[Assessment of the effective dose for routine protocols in conventional CT, electron beam CT and coronary angiography].

PURPOSE: To compare the effective dose applied by sequential CT (SEQ), spiral CT (SCT), electron beam CT (EBT) and coronary angiography for investigations of the chest, abdomen and the heart. METHODS: The Alderson Phantom was used to compare the effective dose for all modalities. In addition, the effective dose for conventional CT (SEQ and SCT) was estimated with a mathematical phantom. RESULTS: For CT investigation of the chest and abdomen the dose was highest for the EBT (11 mSv and 25 mSv, respectively) and slightly lower for the SEQ (7.8 mSv and 21.5 mSv, respectively), whereas spiral CT required the least dose (5.3 mSv and 8.8 mSv, respectively). For coronary calcium screening (0.8 mSv) and EBT coronary angiography (1.7 mSv) the dose was lower than for coronary catheter angiography (3.3 mSv). For conventional CT the difference between the effective dose derived by the mathematical phantom and by the Alderson phantom was 2% to 20%. CONCLUSIONS: For investigations of the chest and abdomen the effective dose applied by SCT is significantly lower than that with EBT and SEQ. For investigation of the coronary arteries the effective dose applied by EBT is lower than that for coronary catheter angiography.

Body Burden↗
PubMed1998

[Radiation exposure during CT examination of thorax and abdomen. Comparison of sequential, spiral and electron beam computed tomography].

Comparison of radiation exposure applied by different types of CT scanners for the investigation of the chest and abdomen. Determination of radiation exposure applied by multi-phase spiral CT. Estimation of the dose in air in the system axis of the scanner, the CT dose index (CTDI) and the effective dose for electron beam tomography (EBT) and two conventional CT scanners (sequence, SEQ; spiral, SCT). For EBT, dose in system axis for investigation of the abdomen was above 50 mGy. Effective dose for investigation of the chest and abdomen was higher with EBT (11 and 26 mSv, respectively) than with conventional CT (SEQ, 4 and 20 mSv; SCT, 2 and 7 mSv). The effective dose for a biphasic investigation (liver 5 mSv, kidney 4 mSv) was below, for a triphasic investigation (liver 7 mSv) above the effective dose of the investigation of the abdomen (6 mSv). Investigation of the abdomen with the EBT should only be performed for certain indications. With spiral CT, effective dose is much lower than with EBT.

Abdomen↗
PubMed1998

[Virtual colonoscopy using CT and MRI].

PURPOSE: To evaluate experimentally and in patients the sensitivity and effective dose of virtual electron-beam tomography (EBT) colonoscopy for detecting small colon tumors and to compare the methods and results with virtual colonoscopy using spiral CT and MR imaging in a review of the literature. MATERIALS AND METHODS: Six polyps with diameters between 3 and 12 mm were created and randomly placed in resected pig colon. After distension with air, the pig colon was scanned with continuous volume scanning (CVS, 3 mm collimation) and a pitch of 0.4, 0.8 and 1.5. Twenty patients positive for the fecal blood test were examined after rectal CO2 insufflation and i.v. administration of 1 mg glucagon. A 13 s CVS scan was used to cover the entire colon within one breath-hold. 3D volume-rendered fly-throughs were evaluated by two independent radiologists. Effective dose equivalent was estimated using an Alderson phantom equipped with thermoluminescence dosimeters. RESULTS: In the tumor model, all polyps were detectable at a pitch of 1.5. A further reduction of the pitch ratio did not improve the conspicuity of the polyps. In patient studies, all tumors (n = 4) and polyps (n = 3) were correctly identified on 3D fly-throughs. Two false positive results were obtained. Effective dose equivalent was calculated at 3.2 mSv per scan. CONCLUSIONS: Our preliminary results indicate that virtual EBT colonoscopy holds promise for fast screening for colon polyps. The best technique for virtual colonoscopy (Spiral CT, EBT, MRI) has not yet been determined and the future role of virtual colonoscopy must still be defined.

Colonic Polyps↗
PubMed1998

[Dosimetry in conventional and spiral CT in 8 spiral CT scanners of the latest generation].

PURPOSE: Measurement of scanner-dependent differences in PCTDI for conventional and spiral CT and evaluation of PCTDI/100 mAs in eight spiral CT scanners of the latest generation. METHODS: Central PCTDI was evaluated in a PMMA phantom for different scan lengths of conventional and spiral CT in four scanners. Central and peripheral PCTDI/100 mAs, average dose and the quotient between peripheral and central PCTDI/100 mAs were measured with a dedicated 10 cm ionisation chamber positioned within a PMMA phantom using the parameters of a standardised liver protocol and a high-resolution inner ear protocol for eight spiral CT scanners. RESULTS: Depending on scanner type and scan length PCTDI for the spiral mode is in a range between 11.3% higher and 4.3% lower than that for the conventional mode. PCTDI/100 mAs varies considerably between different CT scanners. For the standardised liver protocol PCTDI/100 mAs varies up to a factor of 2, for the inner ear protocol up to a factor of 4. CONCLUSION: Even in comparable modern CT scanners there are considerable protocol and scanner-dependent differences in PCTDI/100 mAs. The values for his own scanner should be known to each CT user so that he can develop a dose-optimised, patient and problem-orientated examination strategy.

Ear, Inner↗
PubMed1996

[Studies on radiation exposure in retrograde sclerotherapy of the testicular vein].

PURPOSE: Prospective evaluation of different radiation exposure parameters in a large series of varicoceles. The dependency of the square area product on the different therapists was calculated in addition. MATERIAL AND METHOD: Between 5/91 and 12/93 a total of 737 sclerotherapies were performed on 465 patients. The following parameters were measured prospectively: Square area product (n = 737), fluorotime (n = 737), symphysis surface doses (n = 24), gonadal doses (n = 49), catheterisation time (n = 737). 608 of the sclerotherapies were performed by 4 similar experienced radiologists (U1 - U4). The individual fluorotimes, square area products and the average square area product per minute fluorotime were calculated. RESULTS: The average gonadal doses was 0.01 mSv. Calculation of the square area product per minute fluorotime revealed a useful parameter to demonstrate the potential for further dose reduction, because the results ranged from 566 mGy x cm2/min to 988 mGy x cm2/min. There is no need for a time limit for this interventional procedure. CONCLUSION: The gonadal doses is so low that it can be considered negligible. However, in view of the considerable differences in the square area product per minute, close attention must be paid to the technique by which th fluorotime is determined.

Adolescent↗
PubMed1988

The World Health Organization and International Atomic Energy Agency second interlaboratory comparison study in 16 countries on quality performance of nuclear medicine imaging devices.

Sixteen European countries participated in this WHO-IAEA intercomparison for which transmission CAP (College of American Pathologists) thyroid and IAEA-WHO liver phantoms were used. A total of 257 laboratories submitted 428 image evaluation reports. Overall results showed differences in performance between the various countries but similarities in performance for two gamma camera subgroups defined by year of manufacture, before and after 1980. A unique review of current European liver imaging practice is presented in terms of technical parameters, imaging conditions and evaluation procedures, and quality control procedures. The WHO-IAEA intercomparison demonstrated the need to establish new, or to improve the existing, quality control programmes in certain countries. However, the large number of participating laboratories, 257 compared with 70 in the previous WHO study, (Volodin et al. 1985), shows that these international studies are serving a useful purpose in promoting quality control in nuclear medicine imaging laboratories.

Europe↗