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[CAD/CAM technology-elaboration of electronic model through optical impression in the fabrication of the dental prostheses by a computer assisted device].

In modern CAD/CAM technology of dental prosthetics, the "optical impression" taken by special video cameras deploying 3D-recording of the oral situation (Cerec 1, Cerec 2) initiates the computer-generated production of a digital model. The computer receives and renders the digital data obtained through "optical impression" i.e. data acquisition not as a "negative" of the oral situation but as a "positive" copy of it, namely as a digital model in a virtual environment which can be displayed on the screen and be further used in the fabrication of dental prostheses by means of a computer-assisted device (CAM or CIM).

Computer-Aided Design↗

PubMed2003

Solid cancer risks from radiation exposure for the Australian population.

Estimates are made of the risks to the Australian population as a function of age and gender for mortality or morbidity for all solid cancers after exposure to radiation. Excess relative risk (ERR) and excess absolute risk (EAR) models are used. The model coefficients are re-evaluated for radiation doses expressed as effective dose using data from the Japanese Life Span Study. Life-table methods are used throughout and the risk measures studied are: the risk of exposure related death, RERD and the risk of exposure related cancer, RERC. Australian life-table data and the age-specific cancer incidence and mortality rates of Australian males and females are taken from recent published tables. No dose and dose-rate effectiveness factor is applied. Sources of uncertainty used to calculate the confidence regions for the estimated risks include the statistical uncertainties of the model parameters and of the extrapolation of the risks beyond the period supported by the epidemiological data. Summary values of the risks are reported as averages of those calculated from the ERR and the EAR models. For males, the mortality risks per sievert range from 14% for 0-9 year age group, 7% at 30-39 years and 4% at 50-59 years. Corresponding values for females are 20%, 10% and 6%. Incidence risks are higher: for males the estimates are 32% for the 0-9 year group, 12% at 30-39 and 5% at 50-59. Corresponding values for females are 56%, 20% and 8%. The 90% confidence regions are about +/- 50% of these values. Estimates are given for the risks from CT whole-body scanning or virtual colonoscopy which could be used for cancer screening. If used at 3 year intervals and the effective dose per procedure is 10 mSv, then the RERD for males beginning screening at 40, 50 and 60 years is 0.4%, 0.3% and 0.1%, respectively and for females, 0.6%, 0.4% and 0.2%, respectively. RERD estimates for a 5 year interval between screens are about one-third smaller.

Adolescent↗

PubMed1978

[Screening of blood donors for the prevention of post-transfusion hepatitis by means of gamma-glutamyl transpeptidase determination].

The authors describe the application for determining gamma-glutamyl-transpeptidase (GGTP) activity in donors in order to prevent posttransfusion hepatitis. They particularly refer to the high susceptibility of this method for detecting latent and chronic liver diseases virtually unable to be recognized by other methods. Regular GGTP screening having been introduced in the past 4 years, a rapid lowering of the occurrence of posttransfusion hepatitis could be observed. The authors recommend this method of examination as a valuable aid to the prophylaxis of hepatitis transferred by blood preparations.

Hepatitis↗

PubMed2006

[Chances and risks of prevention in elderly people for the three major cancers: breast-, prostate- and colorectal cancers].

The big three, breast cancer (BC), prostate cancer (PC) and colorectal carcinoma are the most frequent malignancies world wide and also typical tumors of advanced age. Therefore the question to screen and how to screen for these tumors in the elderly is the main question for reduction of the total cancer burden and mortality in all western countries. BREAST CANCER (BC): The age related risk of BC increases from 1 : 2,500 at age 30+ to > 1 : 10 at age 80. Nevertheless, most of the national BC-Screening-Programs stop at age 60 or earlier. Therefore the majority of all advanced i. e. T (4) stages of BC are found in women age > 60. Frequently it is suggested that age related comorbidity should eliminate the benefit of treatment. Recently two longitudinal studies have clearly shown that correct standard treatment is as effective in elderly as in younger individuals. Mammography (MG) has been shown to reduce mortality of BC significantly with best results for specificity and sensitivity at age 70+. PROSTATE CANCER (PC): The screening situation of PC is quite different to BC, because risk profiles are poorly defined and the benefit of radical prostatectomy is not clearly demonstrated in the early non symptomatic stages of PC. At the other side watchful waiting leads to an elevated frequency of incontinence and enuresis as well. Two studies are now under progress and may possibly change the situation; but the final results are expected 2005-2008 at the earliest. Therefore an assisted individual decision making is the only recommendation at this time. COLORECTAL CANCER (CC): Risk groups are clearly defined. Risk of the elderly (> 60) is the average risk. The incidence increases from < 50/10 (5) to more than 500 at age 75+(male) and 500 (female). When to start and when to stop screening? Experts give the advice to begin at age 50 and to end at age 80; but this is not really evidence based. There are several unanswered questions and open problems: we are not exactly informed about complication rates of colonoscopy during the screening programs. There is a lack of data according accuracy of barium enema, virtual colonoscopy and genetic stool test in comparison to colonoscopy in combination with fecal occult blood test (FOBT). And adherence to screening is not well documented among informed patients. However, effectiveness of CC-screening (FOBT alone or in combination with colonoscopy) has been documented in three high randomised trials which have shown a disease specific mortality reduction of 15-33 % over a period of 8-13 years. But it must be clear that the economic resources must be mobilised individually or by insurance: offering the testing of only FOBT for ten years to one thousand persons can save one life.

Adult↗

PubMed1994

Serum screening for Down's syndrome: experiences of obstetricians in England and Wales.

OBJECTIVES: To assess the experiences of obstetricians in England and Wales of serum screening for Down's syndrome. DESIGN: Postal questionnaire survey. SUBJECTS: Questionnaires were sent to all practising obstetricians in England and Wales with nonacademic appointments who had not participated in an earlier (randomly sampled) survey of obstetricians' attitudes (n = 555). Responses were received from 393 (71%), of which 351 were analysed. The data represent about one third of obstetric consultants in England and Wales. MAIN OUTCOME MEASURES: The extent of use of serum screening for Down's syndrome, and the problems encountered. RESULTS: Serum screening for Down's syndrome was being offered on some basis by virtually all obstetricians in the survey. Nearly half the sample said that they did not have adequate resources for counselling all the women to whom screening was offered. Many problems were reported, which in all cases were more common than equivalent problems encountered with serum screening for neural tube defects. Over 80% (289) said that women not understanding the test was a problem. CONCLUSIONS: There is considerable confusion associated with serum screening for Down's syndrome. The precedent of serum screening for neural tube defects does not seem to have lessened the problems experienced, rather the contrary. Many obstetricians report inadequate resources for counselling, which is consistent with the high prevalence of problems associated with women not understanding the test. There is an urgent need to consider what counselling should consist of and who should undertake it and to ensure that necessary resources are available.

Anxiety↗

PubMed2002

Colorectal cancer screening: a challenge for magnetic resonance colonography.

The high incidence of colorectal carcinoma and the fact that colorectal cancer mostly arises from benign adenomas have led to recommendations for screening programs. The introduction of ultrafast three-dimensional datasets acquired by cross-sectional imaging modalities (computed tomography or magnetic resonance imaging) in combination with new postprocessing modes, known as virtual endoscopy, has led to new discussion on the recommendation of screening tests for colorectal cancer. Published results have indicated a high sensitivity for computed tomographic colonography and magnetic resonance-based colonography. Both techniques currently must be combined with colon cleansing. Three-dimensional data acquisition for magnetic resonance-based colonography is less than 1 minute using three-dimensional gradient-echo sequences. The lack of ionizing radiation, the low risk and discomfort to patients, and new techniques of minimized patient preparation make this magnetic resonance technique an attractive diagnostic procedure for colorectal lesions, with many aspects for use as a screening method.

Colonoscopy↗

PubMed2006

Mycoplasma genitalium as a sexually transmitted infection: implications for screening, testing, and treatment.

The evidence that Mycoplasma genitalium is a sexually transmitted pathogen is virtually incontrovertible based on both the concordance rates among partners and on DNA typing showing the same sequence type among partners in contrast to unrelated M genitalium positive patients. The implications that this has for the screening, testing, and treatment of patients is less certain however. Which tests are the most sensitive and specific, what samples are most appropriate, who should be tested, what treatment is best and how should partners be managed?

Animals↗

PubMed2005

Computer-aided detection (CAD) for CT colonography: a tool to address a growing need.

Colorectal cancer is the third most common cancer in both men and women. It is estimated that in 2004, nearly 147,000 cases of colon and rectal cancer will be diagnosed in the USA, and approximately 57,000 people would die from the disease; however, only 44% of the eligible population undergoes any type of colorectal cancer screening. Many reasons have been identified for non-compliance, with key ones being patient comfort, bowel preparation and cost. Virtual colonoscopy derived from computed tomography (CT) images is gaining broader acceptance as a screening method for colorectal neoplasia. Our research suggests that computer-aided detection (CAD) as a second reader has great potential in improving polyp detection. The ColonCAD prototype presented in this paper was developed and tested on cases representative of the variability and quality in true clinical practice. Results of this study with 150 patients demonstrate that: the developed algorithm generalises well: the sensitivity for polyps > or = 6 mm is on average 90%; and the median false positive rate is a manageable 3 per volume.

Algorithms↗

PubMed2006

Virtual imprinting as a tool to design efficient MIPs for photosynthesis-inhibiting herbicides.

Molecular modelling and computational screening were used to identify functional monomers capable of interacting with several different photosynthesis-inhibiting herbicides. The process involved the design of a virtual library of molecular models of functional monomers containing polymerizable residues and residues able to interact with the template through electrostatic, hydrophobic, Van der Waals forces and dipole-dipole interactions. Each of the entries in the virtual library was probed for its possible interactions with molecular models of the template molecules. It was anticipated that the monomers giving the highest binding score would represent good candidates for the preparation of affinity polymers. Strong interactions were computationally determined between acidic functional monomers like methacrylic acid (MAA) or itaconic acid (IA) with triazines, and between vinylimidazole with bentazone and bromoxynil. Nevertheless, weaker interactions were seen with phenylureas. The corresponding blank polymers were prepared using the selected monomers and tested in the solid phase extraction (SPE) of herbicides from chloroform solutions. A good correlation was found between the binding score of the monomers and the affinities of the corresponding polymers. The use of computationally designed blanks can potentially eliminate the need for molecular imprinting, (adding a template to the monomer mixture to create specific binding sites). Data also showed that some monomers have a natural selectivity for some herbicides, which can be further enhanced by imprinting. Thus, in regard to retention on the blank polymer, we can estimate if the resulting imprinted polymer will be effective or not.

Drug Design↗

PubMed2001

Virtual colonoscopy: the endoscopist's point of view.

The major advantage of virtual colonoscopy is that it might increase acceptance of colorectal cancer (CRC) screening. Its disadvantages are high costs and unknown sensitivity and specificity if widely applied. It might replace colonoscopy to a substantial degree only if no bowel preparation is necessary. Gastroenterologists have to include virtual colonoscopy as a complementary method to colonoscopy. Virtual colonoscopy may increase the ratio of therapeutic colonoscopies compared with simple "diagnostic" procedures.

Attitude of Health Personnel↗

PubMed2000

[Virtual reality in neurosurgery].

DEFINITION: Virtual reality enables users to immerse themselves in a virtual three-dimensional world and to interact in this world. The simulation is different from the kind in computer games, in which the viewer is active but acts in a nonrealistic world, or on the TV screen, where we are passively driven in an active world. In virtual reality elements look realistic, they change their characteristics and have almost real-world unpredictability. USE OF VIRTUAL REALITY: Virtual reality is not only implemented in gambling dens and the entertainment industry but also in manufacturing processes (cars, furniture etc.), military applications and medicine. Especially the last two areas are strongly correlated, because telemedicine or telesurgery was originated for military reasons to operate on war victims from a secure distance or to perform surgery on astronauts in an orbiting space station. In medicine and especially neurosurgery virtual-reality methods are used for education, surgical planning and simulation on a virtual patient.

Endoscopes↗

PubMed2002

Epidemiology and survival analysis of cystic fibrosis in an area of intense neonatal screening over 30 years.

This population-based study was conducted in Veneto and Trentino (northwestern Italy, population 5 million). In this area, neonatal screening for cystic fibrosis started in 1973 and has been virtually universal since the early 1980s. During this study, the estimated incidence of cystic fibrosis in this region was 1/2,650 livebirths per year. The authors analyzed data on 593 patients born in 1938-2000 and living in the region who were followed by a single referral center. Median time from birth to confirmation of diagnosis after screening was 32 days (range, 0-1,531). For patients whose disease was recognized after symptoms occurred, median age at diagnosis was always less than 1 year. Median survival age was 37.7 years. Long-term survival (to age 20-30 years) was not significantly influenced by mode of diagnosis (screened or unscreened), sex, or age at diagnosis for unscreened patients (<1, 1-5, >5 years). Current survival analysis of three consecutive decades showed that improving survival tended to vanish in the last years of the study. The authors concluded that a regional neonatal screening program allows very early recognition of cystic fibrosis. They could not conclude that neonatal screening improves long-term survival if compared with diagnosis by symptoms in early infancy.

Age Distribution↗

PubMed1988

Dipstick screening for urinary tract infection.

In screening for urinary tract infection the leucocyte esterase test will detect almost all samples with significant pyuria and bacteriuria, but is relatively nonspecific. The nitrite test is more specific but less sensitive and about one-third of the urinary tract infections in a large group of children were missed. The combination of screening tests results in greater overall accuracy both in the diagnosis and exclusion of urinary tract infection. Almost all cases of urinary tract infection were detected when either the leucocyte esterase or the nitrite screening test or both were positive. If both tests are negative, urinary tract infection is virtually excluded and unless the child is symptomatic, further urinalysis is unnecessary. Laboratory urinalysis is, however, necessary if any one screening test for leucocyte esterase or nitrite (or protein or haemoglobin) is positive. Combined biochemical screening for urinary tract infection with dipstick test strips is reliable and allows early diagnosis and management. By avoiding unnecessary urinalysis it is cost-effective for the patient and will significantly reduce the laboratory workload.

Adolescent↗

PubMed2002

A review of the case for neonatal thyrotropin screening in developing countries: the example of India.

BACKGROUND: Infantile hypothyroidism, either caused by iodine-deficiency disorder (IDD) or congenital hypothyroidism (CH), is the world's leading cause of preventable mental retardation. Such hypothyroidism has virtually been eliminated in the developed world by salt iodization and neonatal thyroid screening. However, most developing countries do not have neonatal thyroid screening programs. Using India as an example, we review the case for newborn screening in the developing world. METHODS: A literature review on infantile hypothyroidism in India was conducted and three Indian thyroid experts were queried about their views on neonatal screening in India. RESULTS: Iodine nutrition improved markedly in India during the 1990s; 49% of the households are now using adequately iodized salt. The control of IDD is still insufficient in India. Nationally representative data on neonatal screening in India are not available, but two regional studies have been published. One study (n = 12,407) measured cord blood thyrotropin and the other (n = 25,244) measured filter paper thyroxine. These studies reported difficult socioeconomic and organizational barriers to the implementation of neonatal screening in India. DISCUSSION: It is time for India to make neonatal thyroid screening and mandatory iodization of salt a priority and develop a comprehensive infantile hypothyroidism policy. Prioritization of infantile hypothyroidism prevention is justified by its high frequency, sensitivity of screening in detecting both IDD and CH, adverse consequences of missing diagnosis at birth, high effectiveness of prevention, severity of disability from hypothyroidism, cost effectiveness of prevention, and lack of a clinical method of diagnosis near birth.

Congenital Hypothyroidism↗

PubMed1979

Single injection thallium-201 stress and redistribution myocardial perfusion imaging: comparison with stress electrocardiography and coronary arteriography.

The efficacy of single injection thallium-201 exercise stress and rest redistribution imaging in the evaluation of myocardiacl ischemia was compared with stress electrocardiography and coronary arteriography. Thallium-201 imaging was interpreted at two levels of sensitivity in order to define the circumstances under which it best serves as a screening modality for coronary arteriography. With the prevalence of coronary disease usually found in patients referred for coronary arteriography (75%), unprocessed thallium-201 imaging is as good as stress electrocardiography in identifying patients apt to show coronary artery abnormalities, but not much better than stress electrocardiography in delineating those patients unlikely to show coronary artery disease. In contrast, processed lesion enhanced images showing normal results virtually eliminate the possibility of significant arteriographic findings. With this screening technique, many patients may be spared unnecessary coronary arteriography.

Adult↗

PubMed2000

Virtual placement of frontal ventricular catheters using frameless neuronavigation: an "unbloody training" for young neurosurgeons.

OBJECTIVE: To evaluate virtually the reliability of freehand puncture of the anterior horn of the lateral ventricle and to provide realistic, but unbloody training for young neurosurgeons. METHODS: Virtual placement of ventricular catheters was performed repeatedly by neurosurgical doctors and thereafter controlled by neuronavigation. With the help of a frameless stereotactic navigation device they virtually had to hit the anterior horn of the lateral ventricle on the MRI of 29 brains with normal ventricular sizes and 60 pathological ventricles, respectively. The catheter placement was simulated using the pointer of the navigation system (EasyGuide Neuro). The monitor screen was blinded, so that on-line control was impossible. Virtual elongation of the pointer tip was performed on the workstation and the position of the virtual catheter was evaluated on a printout. RESULTS: Virtual freehand catheter placement was performed 145 times into the MRIs of the normal brains. In 66 cases (45%) the site of the catheter tip was judged as accurate as shown by the navigation system. No difference concerning the number of correctly placed catheters was observed when comparing more and less experienced doctors. The results in the 60 pathological MRIs of patients differed with respect to the size of the ventricles: in narrow ventricles an accurate placement succeeded in 7 of 22 cases (32%), moderately enlarged ventricles were accurately hit in 15 out of 32 cases (46%) and wide ventricles in 5 of 6 attempts (83%), respectively. CONCLUSION: This setup is a simple, practicable tool for neurosurgical education. The virtual freehand placement of ventricular drains controlled by neuronavigation provides an unbloody training of a routine neurosurgical procedure in a realistic setting without the risk of injuring a patient. Neuronavigation systems can serve therefore as a link between learning from observation and handling the real situation.

Adolescent↗

PubMed2001

A review of technical advances in virtual colonoscopy.

Early detection of polyps has proven to lead to a decrease in incidence of colon cancer. In the past few years, virtual colonoscopy has been developed as a patient-friendly screen-ing technique. The procedure comprises the following steps. First, the patient's colon is cleansed and transanally inflated with air. Subsequently, a 3D image volume is acquired of the abdomen by CT or MRI. Finally, the bowel surface is extracted and visualized, after which the physician virtually navigates through the colon and examines the surface for abnormalities. This paper describes the progress in research for virtual colonoscopy.

Colonography, Computed Tomographic↗

PubMed2003

Genetic testing for hereditary colorectal cancer in children: long-term psychological effects.

Children who carry a gene mutation for familial adenomatous polyposis are virtually certain to develop colorectal cancer without annual endoscopic screening and a colectomy when polyps appear. Predictive genetic testing can identify children who need regular surveillance. While the medical benefits of genetic testing are clear, the psychological effects have not been well studied. We evaluated the long-term psychological effects of genetic testing in 48 children and their parents. In each family, one parent was a known APC gene mutation carrier. Before genetic testing, and three times afterward, participants completed measures of psychological functioning, which, for children, included depression and anxiety symptoms, and behavior problems and competencies. Parents completed a measure of depression symptoms. Data were collected at 3-, 12-, and 23-55 months after disclosure. Twenty-two children tested positive; 26 children tested negative. Mean length of follow-up was 38 months. There were no clinically significant changes in mean psychological test scores in children or parents, regardless of the children's test results or the sex of the affected parent. However, the group of children who tested positive and had a mutation-positive sibling showed significant, but subclinical, increases in depression symptoms. Furthermore, several individual mutation-negative children with a positive sibling had clinical elevations in anxiety symptoms at one or more follow-up. Behavior problems declined for all groups, and behavior competence scores remained unchanged. We conclude that most children do not suffer clinically significant psychological distress after testing. However, because some children showed clinically significant anxiety symptoms, long-term psychological support should be available to those families with both mutation-positive and mutation-negative children, and with multiple mutation-positive children. Our findings should call for a multidisciplinary approach to genetic testing for children.

Anxiety↗