Search

The introduction of multislice CT scanners and the associated dose increase compared to single and dual slice scanners has concerned many radiologists, health and medical physicists, as well as members of the regulatory community. Since multislice CT scanners are inherently post-patient collimated, they are less dose efficient than single slice CT scanners, which use prepatient collimation. The x-ray beam must be wide enough in the Z axis so that the beam remains on the detector in spite of typical movements due to thermal and mechanical flexing. We describe the x-ray beam tracking system that is employed on a GE LightSpeed QX/i scanner to substantially reduce the multislice dose. The tracking system stabilizes the beam on the detector allowing a narrower x-ray exposure profile compared to the x-ray exposure profile without tracking. The tracking system measures the position of the beam every few milliseconds and continually repositions a source aperture to hold a narrow beam fixed on the detector. Using a standard LightSpeed QX/i source collimator and segmented detector, dose reductions of up to 40% were measured when tracking was employed. We also show that tracking has the potential to provide a dose efficiency approaching single slice scanners.

This paper presents a calibration and correction method for detector cell gain variations. A key functionality of current CT scanners is to offer variable slice thickness to the user. To provide this capability in multislice volumetric scanners, while minimizing costs, it is necessary to combine the signals of several detector cells in z, when the desired slice thickness is larger than the minimum provided by a single cell. These combined signals are then pre-amplified, digitized, and transmitted to the system for further processing. The process of combining the output of several detector cells with nonuniform gains can introduce numerical errors when the impinging x-ray signal presents a variation along z over the range of combined cells. These numerical errors, which by nature are scan dependent, can lead to artifacts in the reconstructed images, particularly when the numerical errors vary from channel-to-channel (as the filtered-backprojection filter includes a high-pass filtering along the channel direction, within a given slice). A projection data correction algorithm has been developed to subtract the associated numerical errors. It relies on the ability of calibrating the individual cell gains. For effectiveness and data flow reasons, the algorithm works on a single slice basis, without slice-to-slice exchange of information. An initial error vector is calculated by applying a high-pass filter to the projection data. The essence of the algorithm is to correlate that initial error vector, with a calibration vector obtained by applying the same high-pass filter to various z combinations of the cell gains (each combination representing a basis function for a z expansion). The solution of the least-square problem, obtained via singular value decomposition, gives the coefficients of a polynomial expansion of the signal z slope and curvature. From this information, and given the cell gains, the final error vector is calculated and subtracted from the projection data.

For estimations of the complaint pattern after comparatable operations per pelviscopiam versus per laparotomiam, in a retrospective study 114 patients after pelviscopic operation and 117 patients after laparotomy were examined. The most important significant differences with an advantage for the pelviscopycally operated patients had been found in asking for postoperative spontaneous miction (84.2% versus 37.2%), spontaneous defecation (68.0% versus 8.1%), the time of completely being free from pain when climbing stair (11.9 compared to 20.8 days), the time when the patient absolutely feel no pain any longer (15.8 compared to 51.7 days), in the average hospitalisation time (3.8 compared to 8.9 days) and the time for unfitness for work (24.5 compared to 48.7 days). Under consideration that also after pelviscopic operations pain occur which are to be treated the present studies confirm the clear improvement of life quality pelviscopic operations.

Taking account of the gestational age (28th to 42nd completed week of pregnancy) the sex-related ratio of birth weight to length (g/cm) for newborn infants is reported. This shows that observation of the correlation between birth weight and length with reference to gestational age makes a more accurate classification of newborn infants possible, rather than using a two dimensional classification (birth weight week of gestation).

A rise in the rate of premature childbirth from six to eight per cent was recordable in some region of the GDR, in recent years. This figure added to the statistical record of perinatal mortality and accounts for something between 60 and 80 per cent. -- Aggravating neurovegetative irritability, next to foetal and maternal causes as well as to factors of the environment, has been quoted as the major cause of premature onset of labour. Rise in vegetative tension may be determined by means of rheobase measurement of neuromuscular excitability, on the basis of central nervous coupling of the striated muscle. -- Rheobase measurements were applied to pregnant women and statistically evaluated, between 1977 and 1979. -- The RS 12-1 electrostimulator and AP 202 arterial pulse indicator were used for rheobase measurement proper. Contractions were recorded by means of the DT-500 tocograph and Hewlett-Packard cardiotocograph. -- As a whole, 167 rheobase data were recorded from 101 patients. The rheobase data recorded from patients with premature onset of labour were significantly below those obtained from women with normal course of pregnancy. The rheobase threshold (critical value) may be defined as 3.5 mA. Statistical evaluation of follow-up rheobase measurements on pregnant women with premature labour showed that the values underwent significant change towards the normal in response to tocolytic therapy. Decline in rheobase in response to tocolytic therapy will be followed, with high probability, by termination of pregnancy. -- Rheobase is a parameter which was found to correlate properly with the risk of premature childbirth and, therefore, should be used in diagnosis (score to determine risk of premature childbirth) and therapy (supervision of tocolytic treatment).

As early as about the turn of the century the causes for the discharge of the meconium under labour were studied and the attempt was made to record alterations of the cardiac sound under the influence of labour pain as well as the behaviour of the fetal heart by means of the electrocardiogram. In the development of obstetrics certain stages can be observed which in the past few decades entailed a great many changes, such as changing from delivery at home to delivery at hospital, parasitological clarification of intrauterine infections and the revelation of the pathogenesis of the Mhn. Studies of the physiology of intrauterine respiration, direct measurements of the oxygene pressure in the fetal blood represent the base for the future development of perinatal medicine. An essential improvement of the fetal supervision has come about ever since amnioscopy, cardiotocography, supersonic diagnostics, hormono- and enzyme analyses were introduced. Problems of organization and the future tasks of perinatal medicine are shown on the basis of maternal mortality at district level and perinatal mortality of the hospital.

First experiences and results in 14 tubal pregnancies are reported operated on by laparoscopy. In 11 cases the tubes were removed. In 3 patients there was a conservative operation with preservation of the tubes. A laparotomy had to be done in one patient for a hemorrhage from the mesosalpinx. Duration of stay in the hospital lasts from 4 to 5 days. Second-look-laparoscopies of 9 patients whose fallopian tubes had been removed resulted in 7 normal findings. In two cases there were adhesions between omentum majus and uterus on that side operated on. Following expressions of the gestational sac in two patients there was one normal tube and in the other one slight peritubal adhesions. Two patients who were operated on conservatively had been delivered afterwards.

The value of the ambulant tocography was tested in 127 cases by ambulant tocograph T 500. The average frequency of uterine contractions was in 66 normal cases 0,5/30 min. This frequency of uterine contraction was higher in a group with anamnestic risk (1,1/30 min) and in patients with tocolytic medication (2,3/30 min). Nearly term all groups tended to higher frequency of uterine contractions. The ambulant tocography is a new method to completed the diagnostic.

A comparison of twin deliveries from 1966 to 1971 (140 = 1,23%) and from 1972 to 1974 (65 = 1,07%) indicates a decrease of the uncorrected perinatal mortality from 10,35% to 6,15% caused by early diagnosis, gestation prolonging measures, diagnosis of placental insufficiency and management of delivery. Concerning the first twin the decrease of perinatal mortality was more evident from 7,86% to 1,54% compared with the second twin from 12,86% to 10,77%. Nevertheless the following statement can be made: up to 1971 perinatal mortality was mainly a problem of prematurely born infants; it is changed now to a problem of antenatal mortality of small for date infants. Prematurely birth and mortality of twins may be well influenced by: 1. Early diagnosis. 2. Widely used hospitalisation, beginning from 28 th week of gestation. 3. Widely used cervix-cerclage and uterotocolysis. 4. Intensive antenatal care. 5. Intranatal intensive care of both infants (cardiotocography, blood gas analysis). 6. Limitation of the interval to 5 to 10 minutes. 7. Widened caesarean section indication (breech presentation, small for date infants).

8 years after sterilization was in force in GDR it is stated, that this way of female healthy protection was different performed in the varions countries of GDR. The portion of the country Rostock amount to 56,6%. --85,3% of the women were elder than 30 years. 60% of the applicants have had legal abortions. 66,8% of the propositions were based by medical indication. --The rate of complications and failures amount to 0,3%. --By reason of the results it is recommended to regard the sterilization as the adequate method of contraception, if reproduction is finished.

The techniques and diagnostic accuracies for histologic sampling of endometrial tissue after suction curettage performed on 161 patients are discussed. In 90% no tissue was retrieved by sharp curettage after suction curettage. Tissues with higher consistence like polyps were obtained only for 50%. However, it will be expected, that Crumbling tissues of cancer will be obtained.

In cases of acute adnexitis laparoscopy is an excellent diagnostic method. By this way we found in 182 patients with clinical symptoms only 50,5% acute inflammatory diseases of adnexa. On the other hand there was a normal genital status in 18,1%, acute appendicitis in 9,9%, ectopic pregnancy in 7,7% etc. Clinical examinations and second-look-laparoscopy 6--8 weeks after ending the treatment cases of salpingitis alone showed the best results. Patients with more extensive inflammatory reactions had more adhesions too. An early diagnosis and treatment under hospital conditions is recommended. We have good experiences with immediately operation in cases of suppurative inflammation of the adnexa, which are only diagnosticate by laparoscopy.

In 81 women's hospital, in which 35,013 gynaecological laparoscopies were made, 42.9% of the specialists are able to perform laparoscopies by themselves. 51.9% of the questioned hospital directors recommend learning how to perform laparoscopies during specialization, and 48.1% plead for laparoscopy training only for gynaecologic specialists. 64.2% of the questioned ones were in favour of laparoscopy courses. Performance of diagnostic laparoscopies was recommended for all gynaecological institutions by 82.7%. In the opinion of the majority (74.8%) operative laparoscopies should be done only in larger central hospitals. It was generally agreed that chronic diseases of the lower abdomen, sterility and suspected ectopic pregnancy are indications for laparoscopy. Other acute complaints have been diagnosed less frequently by means of laparoscopy. Second-look-laparoscopies were made by 59.3% and 55.6% of the questioned doctors, mainly for checking the situation operations because of ovarian cancer and sterility. In 61.1% of all hospitals other diagnostic and therapeutic operations per laparoscopiam are done. The rate of severe complications was 0.21%, and the mortality rate amounted to 0.057%.

Cultures of abdominal bioptic material from 102 cases of acute pelvic inflammatory disease diagnosed laparoscopically revealed that anaerobes were involved in 42.2% of the cases; 18.6% of the cultures were sterile. There were no signs that anaerobes predominate in cases, in which an abscess has already formed. The proportion of predominantly polymicrobial multiple infections was 54.2%, the remaining 45.8% of the cases involving mono-microbial infection. Scrutiny of the abdominal and cervical distribution of the germs in 42 of our female patients confirmed that cervical smears are inadequate for detecting the causal germ involved in a case of acute pelvic laparoscopy it seems advisable to use abdominal cultures of tissue taken from the locality of the inflammation in order to identify exactly the causal germ and to test these cultures also for anaerobes and gonococci.

For clinical use we divide the cardiotocographic parameters in 4 groups with the following percentages for antenatal or intranatal period. Normal criterias (antenatal: 80%; intranatal: 40%) Warn symptoms (antenatal: 5%; intranatal: 10%) Umbilico-placental circulatory disturbances (antenatal: 6%; intranatal: 45%) Signs of hypoxia (antenatal: 9%; intranatal: 5%). Variable decelerations are typically for disturbances in the umbilico-placental circulation. The clinical reasons are as well cord compressions as uterine hyperactivity or supine hypotensive syndrom. A prospective management of labor is possible only by means of CTG. The fetal death during labor is avoidable. The number of fetal micro-blood-samplings was reduced (in our hospital 10%) and the feto-maternal relationship was included. The operative frequency is the result of objective obstetrical decisions. We have before and after introduction of fetal monitoring a constant frequency of caesarean sectio of about 3%. A rise in operative frequency simultaneously with the beginning of fetal monitoring is due by a high operative activity in cases of umbilico-placental circulatory disturbances. The rate of neurological findings in newborn infants can be decreased. This result is not valid in preterm or small for date infants.

Two years experiences with a computer-assisted program for early detection of prestages and early cervical cancer in Rostock-city are reported. 65% = 27028 women finally cooperated. Pathological papsmears were found in 0,52%. 9 cases of severe dysplasia, 30 carcinomata in situ, 3 cases of early invasion, 3 micro- and 5 macrocarcinomas were observed. Accessory findings were seen in 10,2%.

A report is given of 10 years experiences with a computer assisted mass-screening-programme to detect pre-stages and early stages of cervical carcinoma in Rostock city. The participation in the age-groups up to 40 years was over 75%. With this programme it is possible to make statistical analysis, to control the quality of Pap-smears and colposcopical results and to identify the risk-group of unscreened women for special examinations. As a result of the programme a decrease of cervical carcinomas since 1980 of about 25% was noticed. The same situation was found in pre-stages. Inert of all registered cervical carcinomas the number of stage one-cases increased.

A report is given on 119 patients suffering from abscessforming adnexitis, mainly tubo-ovarian abscesses (40.3%) and pyosactosalpinges (38.7%). These women were operated on within the first 24 hours after admission to the hospital. Before the operation was performed 70.6% of the women had been submitted to laparoscopy. The other ones (28.4%) had unequivocal primary sign of the disease. Laparoscopic diagnosis is recommended because especially in the early phase of abscess formation no clear diagnosis by clinical examination and paraclinical findings is possible. Operation as early as possible in case of formation of a tubo-ovarian abscess is recommended by reason of the good experience and results which become apparent by small intra- and post-operative complication rate of 1.7% respectively, the short hospital stay of 12.8 days and the short time of risamblement of 53 days. The extent of the operation should depend on degree of severity of the illness, reproductive aspects.