Biomedical subjects

U Malsch

Publications and source records attributed to U Malsch.

4 recordsLinked to original sources

PubMed2006

An enhanced block matching algorithm for fast elastic registration in adaptive radiotherapy.

Image registration has many medical applications in diagnosis, therapy planning and therapy. Especially for time-adaptive radiotherapy, an efficient and accurate elastic registration of images acquired for treatment planning, and at the time of the actual treatment, is highly desirable. Therefore, we developed a fully automatic and fast block matching algorithm which identifies a set of anatomical landmarks in a 3D CT dataset and relocates them in another CT dataset by maximization of local correlation coefficients in the frequency domain. To transform the complete dataset, a smooth interpolation between the landmarks is calculated by modified thin-plate splines with local impact. The concept of the algorithm allows separate processing of image discontinuities like temporally changing air cavities in the intestinal track or rectum. The result is a fully transformed 3D planning dataset (planning CT as well as delineations of tumour and organs at risk) to a verification CT, allowing evaluation and, if necessary, changes of the treatment plan based on the current patient anatomy without time-consuming manual re-contouring. Typically the total calculation time is less than 5 min, which allows the use of the registration tool between acquiring the verification images and delivering the dose fraction for online corrections. We present verifications of the algorithm for five different patient datasets with different tumour locations (prostate, paraspinal and head-and-neck) by comparing the results with manually selected landmarks, visual assessment and consistency testing. It turns out that the mean error of the registration is better than the voxel resolution (2 x 2 x 3 mm(3)). In conclusion, we present an algorithm for fully automatic elastic image registration that is precise and fast enough for online corrections in an adaptive fractionated radiation treatment course.

Algorithms↗

PubMed2006

Kilovoltage CT using a linac-CT scanner combination.

Modern radiotherapy techniques such as intensity modulation are capable of generating complex dose distributions whose high dose areas tightly conform to the tumour target volume, sparing critical organs even when they are located in close proximity. This potential can only be exploited to its full extent when the accumulated dose actually delivered over the complete treatment course is sufficiently close to the dose computed on the initial CT scan used for treatment planning. Exact patient repositioning is mandatory, but also other sources of error, e.g. changes of the patient's anatomy under therapy, should be taken into account. At the German Cancer Research Center, we use a combination of a linear accelerator and a CT scanner installed in one room and sharing the same couch. It allows the quantification and correction of interfractional variations between planning and treatment delivery. In this paper, we describe treatments of prostate, paraspinal and head and neck tumours. All patients were immobilized by customized fixation devices and treated in a stereotactic setup. For each patient, frequent CT scans were taken during the treatment course. Each scan was compared with the original planning CT using manual checks and automatic rigid matching algorithms. Depending on the individual case, the adaptation to variations was carried out offline after several fractions or in real-time between the CT scan and linac irradiation. We discuss the techniques for detecting and correcting interfractional errors and outline the procedural steps of a linac-CT scanner-supported radiation treatment course.

Humans↗

PubMed2001

Efficacy of kava-kava in the treatment of non-psychotic anxiety, following pretreatment with benzodiazepines.

A 5-week randomized, placebo-controlled, double-blind study was carried out to investigate the efficacy of kava-kava special extract WS1490 in non-psychotic nervous anxiety, tension and restlessness states. During the first treatment week, the study dose drug was increased from 50 mg to 300 mg per day and pretreatment with benzodiazepines was tapered off over 2 weeks. These dosage adjustments were followed by 3 weeks of monotherapy with WS1490 or placebo. Outcome measures were the differences between baseline and end of treatment on the Hamilton Anxiety Scale (HAMA) and on a subjective well-being scale (Bf-S), as well as the benzodiazepine withdrawal symptoms. Changes in the Erlanger Anxiety, Tension and Aggression Scale (EAAS) and Clinical Global Impressions (CGI) were analyzed as secondary measures. Treatment safety was checked by interviews, adverse event reports and laboratory investigations. Forty patients (2x20) were included into the study. WS1490 was superior to placebo regarding the HAMA (P=0.01) and Bf-S (P=0.002) total scores and all secondary efficacy measures. The tolerance of WS1490 was not inferior to placebo. The study confirms the anxiolytic efficacy and good tolerance of WS1490 and shows that a further symptom reduction is possible after a change-over from benzodiazepine treatment.

Adult↗

PubMed2001

[Monotherapy of Parkinson's disease with budipine. A double blind comparison with amantadine].

In a randomised double blind parallel-group study in three centers budipine, a diphenylpiperidin derivate, was compared to amantadine with respect to efficacy and safety in the monotherapy of mild to moderate Parkinson's disease (PD). From 53 patients of either sex 27 patients were randomised to 3 x 20 mg/d budipine and 26 patients to 3 x 100 mg/d amantadine. The duration of treatment was 4 weeks in 1 center (21 patients) and 12 weeks in the other 2 centers (32 patients). Safety was measured by vital signs, ECG, adverse event recording and clinical laboratory. Both drugs caused a clinically relevant and statistically significant (p < 0.001) improvement of Parkinsonian symptoms according to the Webster-Rating-Scale (WRS) as compared to pretreatment values. With respect to the total WRS score sum there was no difference between the groups (p > 0.05; n.s.), while budipine showed a significantly (p < 0.05) better effect on the main symptom tremor after 12 weeks. During amantadine treatment more adverse events were observed than after budipine intake. Two patients left the study prematurely, one in the amantadine group due to psychiatric adverse events and one in the budipine group because of insufficient efficacy.

Aged↗