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J Doll

Publications and source records attributed to J Doll.

At least 37 records · Page 2Linked to original sources
PubMed1997

Performance evaluation of a whole-body PET scanner using the NEMA protocol. National Electrical Manufacturers Association.

UNLABELLED: This study evaluates the performance of the newly developed high-resolution whole-body PET scanner ECAT EXACT HR+. METHODS: The scanner consists of four rings of 72 bismuth germanate block detectors each, covering an axial field of view of 15.5 cm with a patient port of 56.2 cm. A single block detector is divided into an 8 x 8 matrix, giving a total of 32 rings with 576 detectors each. The dimensions of a single detector element are 4.39 x 4.05 x 30 mm3. The scanner is equipped with extendable tungsten septa for two-dimensional two-dimensional measurements, as well as with three 68Ge line sources for transmission scans and daily quality control. The spatial resolution, scatter fraction, count rate, sensitivity, uniformity and accuracy of the implemented correction algorithms were evaluated after the National Electrical Manufacturers Association protocol using the standard acquisition parameters. RESULTS: The transaxial resolution in the two-dimensional mode is 4.3 mm (4.4 mm) in the center and increases to 4.7 mm (4.8 mm) tangential and to 8.3 mm (8.0 mm) radial at a distance of r = 20 cm from the center. The axial slice width measured in the two-dimensional mode varies between 4.2 and 6.6 mm FWHM over the transaxial field of view. In the three-dimensional mode the average axial resolution varies between 4.1 mm FWHM in the center and 7.8 mm at r = 20 cm. The scatter fraction is 17.1% (32.5%) for a lower energy discriminator level of 350 keV. The maximum true event count rate of 263 (345) kcps was measured at an activity concentration of 142 (26.9) kBq/ml. The total system sensitivity for true events is 5.7 (27.7) cps/Bq/ml. From the uniformity measurements, we obtained a volume variance of 3.9% (5.0%) and a system variance of 1.6% (1.7%). The implemented three-dimensional scatter correction algorithm reveals very favorable properties, whereas the three-dimensional attenuation correction yields slightly inaccurate results in low- and high-density regions. CONCLUSION: The ECAT EXACT HR+ has an excellent, nearly isotropic spatial resolution, which is advantageous for brain and small animal studies. While the relatively low slice sensitivity may hamper the capability for performing fast dynamic two-dimensional studies, the scanner offers a sufficient sensitivity and count rate capacity for fully three-dimensional whole-body imaging.

Adenocarcinoma, Follicular↗
PubMed1996

[PET studies with C-11 ethanol in intratumoral therapy of hepatocellular carcinomas].

Positron emission tomography (PET) is a noninvasive functional method for the study of solid tumor perfusion, metabolism and interaction with different therapeutic agents. The aim of the study was the investigation of the metabolism of hepatocellular carcinomas (HCC) and the kinetics during a treatment with intratumoral ethanol by PET. The ongoing study includes seven patients with child. A cirrhosis and HCC (UICC stage III-IVA; tumor size 3-6 cm). Dynamic PET studies (60 min) with 18F-fluordeoxyglucose (FDG) were performed prior to therapy to assess tumor viability. The evaluation of the FDG data demonstrated a liver-equivalent uptake in six of the tumors (well and moderately differentiated HCC), which were poorly delineated against the normal liver parenchyma. One moderately differentiated HCC showed an increased FDG metabolism, indicating no correlation between histology and metabolism. A dose of 37-80 MBq 11C-ethanol was applied together with a nonlabelled therapeutic dose of the drug via a puncture needle positioned under sonography. Five out of seven tumors demonstrated a high 11C uptake shortly after the end of the ethanol injection followed by constant 11C-ethanol concentration during the whole study period of 45 min. The PET data demonstrated no significant elimination of the 11C-ethanol from the tumor and no accumulation in the surrounding liver tissue. One case showed a decrease of the intra-tumoral 11C-ethanol concentration due to a punkture of a tumor vein, and in another case the surrounding liver parenchyma demonstrated significant 11C uptake in the early phase following paratumoral injection of the drug. In conclusion, PET is a useful tool for the study of the mechanism and the kinetics of percutaneous intratumoral ethanol injection of HCC.

Aged↗
PubMed1996

[Predictive value of a rapid negativity of serum virus C viremia during treatment with interferon alpha in patients with chronic hepatitis C].

Interferon alpha (INF) used for chronic hepatitis C treatment induces a response in less than 25% of patients. The aim of this study was to appreciate the predictive value of the delay of clearance of hepatitis C virus (HCV) viremia after onset therapy and to compare it with other virological markers such as viral load before treatment and viral type. Thirty one patients with chronic hepatitis C, treated with 3 MU Interferon, 3 times a week for 6 months, were followed until 6 months post-treatment. Response was defined according to the normalisation of transaminases levels and loss of HCV viremia. Five patients were long term responder, eleven patients were complete to relapse responder and fifteen patients were non responder. Serum HCV RNA level, HCV type and serial detection of serum HCV RNA were determined and correlated with the long term response to INF. Patients with long term response had lower pre-INF viral load compared to the complete to relapse responder or to the non responder (p < 0.001). A rapid clearance of serum HCV RNA (1 month) is observed for all the long term responder (p < 0.001). The lowest viral load is also observed in these patients (p < 0 05). By contrast, although the number of patient is low, we were not able to observe a relation between the viral type and the response to treatment. In conclusion this data indicate that the delay of clearance of HCV RNA is also a good predictor of response to INF therapy. Furthermore a rapid clearance of HCV RNA in patients with a very weak pre-INF viral load is strongly associated with long term response (positive predictive value: 100%).

Antiviral Agents↗
PubMed1995

Multistep tumor targeting in nude mice using bispecific antibodies and a gallium chelate suitable for immunoscintigraphy with positron emission tomography.

To improve tumor:tissue ratios in immunoscintigraphy, a three-step targeting method has been developed. The reagents used were (a) a radioactive, low molecular weight chelate prepared from ionic gallium and a phenolic polyaminocarboxylic acid, which can be labeled either with the single-photon emitter 67Ga or with the short-lived positron emitter 68Ga (t1/2 = 68 min); (b) a bispecific monoclonal antibody (bs-mAb) synthesized from the F(ab)2 fragment of the 1.1ASML antibody specific for the glycoprotein CD44v associated with a rat pancreas carcinoma cell line and the F(ab') fragment of an antibody specific for the gallium chelate; and (c) the nonradioactive gallium chelate covalently coupled to transferrin, which served as a high molecular weight blocker to prevent binding of the radioactive gallium chelate to bs-mAbs in the circulation. Targeting experiments in tumor-bearing nude mice with different doses of bs-mAbs, blocker, and 67Ga chelate were adjusted to maximize tumor to tissue contrasts and tumor uptake. Compared with the biodistribution of the 131I-labeled, native 1.1ASML antibody 24 h postinjection, a schedule using 100 pmol bs-mab 24 h later 100 pmol blocker, 15 min later 16 pmol 67Ga chelate, 1 h later examination, increased tumor:blood and tumor: liver ratios by a factor of 5 while keeping the localization of radioactivity in the tumor constant (10.1% injected dose/g). High-contrast images using either 67Ga or 68Ga were obtained within 1 h. The targeting method described enables the use of the short-lived positron emitter 68Ga and thus allows the combination of an improved immunoscintigraphy and positron emission tomography.

Animals↗
PubMed1994

[Psoas abscess exteriorized in the groin revealed late after acute pancreatitis].

Two cases of psoas abscess complicating acute necrotizing pancreatitis are reported. These cases were particular because the abscesses exteriorized in the groin and symptoms were misleading. The abscesses were detected late, three and five months after the beginning of the pancreatitis respectively. The difficulties in diagnosis and the long delay to diagnosis are emphasized as possible sources of superinfection.

Acute Disease↗
PubMed1993

Child care centers: a community resource for injury prevention.

Child passenger safety, a major public health concern, has been addressed by state laws mandating use of child restraint devices. Usage rates in poor and minority communities are disproportionately low. To determine the influence of the child care center within these communities to improve routine use, an educational clinical trial, based on social learning theory was designed. Two urban child care centers enrolling high-risk 2- through 6-year-old children were monitored for correct child restraint use during a 5-month educational intervention at one center. Key features of intervention programming included weekly, developmentally appropriate presentations by the staff to the children and documented parental awareness of the child care center's policy advisory regarding child restraint use. Results demonstrate statistically significant (p < .01) increases in use at the intervention center. This study finds that child care center policy and programming can be effective in promoting child passenger safety.

Accidents, Traffic↗
PubMed1993

Fluorodeoxyglucose imaging of advanced head and neck cancer after chemotherapy.

Positron emission tomography (PET) was applied to evaluate therapeutic effects in patients with advanced head and neck cancer for use in monitoring therapy. In 18 patients with histologically proven head and neck cancer, PET studies with 330-440 MBq 18F-fluorodeoxyglucose (FDG) were performed prior to the first chemotherapeutic cycle with cisplatin and 5-FU. A second examination after the first chemotherapeutic cycle was performed in 11 patients. Tumor or lymph node volumes were determined from CT slices and the growth rate was calculated assuming an exponential function. Uptake in a region of interest was used for the quantitative evaluation of the PET images after standardization to injected dose and body weight. FDG data were available for 6 tumors and 10 metastases, volumetric data for 5 tumors and 7 metastases. One lesion showed an increase, seven a decrease in FDG uptake and eight lesions remained unchanged. Multiple lymph nodes in the same patient showed different baseline metabolisms and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included for treatment planning in patients undergoing systemic chemotherapy.

Adult↗
PubMed1991

Modification of a three-dimensional treatment planning system for the use of multi-leaf collimators in conformation radiotherapy.

The multi-leaf collimator of the DKFZ is designed as a low cost add-on device for conventional linear accelerators for radiotherapy. The technical specification of the computer controlled collimator is described briefly. A major limitation in the use of the wide capabilities of multi-leaf collimators in the clinic is still an appropriate treatment planning system. This paper describes treatment planning and dose calculation techniques for multi-leaf collimators and shows examples where the capabilities of the collimator are used extensively.

Dose-Response Relationship, Radiation↗
PubMed1991

Pharmacokinetics of molsidomine and its active metabolite, linsidomine, in patients with liver cirrhosis.

The pharmacokinetics of molsidomine were investigated in six healthy volunteers and in seven patients with alcoholic cirrhosis. After a 2 mg oral dose, molsidomine elimination half-life was prolonged in cirrhotic patients (13.1 +/- 10.0 h vs 1.2 +/- 0.2 h, P less than 0.01) because of a decrease in its apparent plasma clearance (CL/F) (39.8 +/- 31.9 ml h-1 kg-1 in patients with cirrhosis vs 590 +/- 73 ml h-1 kg-1 in volunteers). The elimination half-life of the active metabolite, linsidomine (SIN-1) was also prolonged in cirrhotic patients (7.5 +/- 5.4 h vs 1.0 +/- 0.19 h, P less than 0.05). The AUC values of both molsidomine and linsidomine were increased in the cirrhotic group, but the increase in the former was considerably greater than in the latter as shown by the significant decrease of the ratio AUClinsidomine/AUCmolsidomine x 100 (4.5 +/- 6.1 in cirrhotic patients vs 23.5 +/- 3.4 in healthy volunteers, P less than 0.001). These results suggest that liver cirrhosis profoundly alters the pharmacokinetics and metabolism of molsidomine.

Adult↗
PubMed1991

[Prediction of goal-directed behavior: attitude, subjective behavioral competence and emotions].

Ajzen's (1985) theory of planned behavior explaining and predicting goal-directed behavior is extended by an emotional component. The extended theory of planned behavior is tested experimentally. N = 64 subjects play with two video games (a speed- and a problem-oriented game) under an achievement-motivational orientation. One half of the subjects plays both games in an easy version, the other half in a difficult version. The verbal emotional reactions to playing video games are grouped factor-analytically into an "activity emotion" and a "security emotion". Subjects playing video games in the difficult condition feel significantly more insecure, and perceive their behavioral control as significantly lower than subjects playing in the easy condition. Tests of the extended theory of planned behavior lead to significant squared multiple correlations for the dependent variables within the range of R2 = .20 to .58. The activity emotion accounts predominantly for a significant part of the variance of the attitude and the security emotion accounts for a significant part of the variance of the perceived behavioral control. No predictive power was found for the intention to play the games successfully.

Achievement↗
PubMed1991

Non-uniformity measurements in PET.

To gain practical experience with the procedures suggested by the EEC task group on performance evaluation of positron tomographs, the non-uniformity of the Scanditronix PC 2048-7WB positron tomograph was measured. The test was performed using both a cylindrical head phantom and the EEC body phantom. According to the recommendation of the task group, 2 million counts were collected in each emission scan as a standard. As to be expected, non-uniformity decreased when more counts were collected or a wider reconstruction filter was used. Non-uniformity increased when going from the head phantom to the body phantom leaving all parameters unchanged. It was concluded that this effect was caused by increased noise due to the larger attenuation lengths but not to attenuation correction. The preliminary results of this study show that counting statistics dominates non-uniformity in the count range of about 2 million counts per image. Measured non-uniformity values are in the range of +/- 30%.

Equipment Design↗
PubMed1990

Three-dimensional photon radiotherapy planning for laryngeal and hypopharyngeal tumours.

Three-dimensional absorbed dose distributions have been computed for high-energy photon radiation therapy of laryngeal and hypopharyngeal cancers, using a coaxial pair of opposing lateral beams in fixed positions. Treatment plans obtained under various conditions of irradiation are analyzed and compared for a cobalt-60 gamma unit (GAMMATRON S80, Siemens), photon beams from a 6 MV (CLINAC 1800, VARIAN), an 8 MV (SATURNE, CGR) and a 15 MV (MEVATRON 77, Siemens) linear accelerator. Using open fields a somewhat non-uniform and partly insufficient dose in target volume of interest is obtained with all treatment units if sufficient protection of the spinal cord is provided. The x-ray plans are somewhat superior to the cobalt-60 ones. Depending on the quantum energy and wedge isodose angle, wedging only slightly improves or sometimes moderately decreases the homogeneity of the dose in the target volume. According to these small and/or controversial effects of wedges their application seems unnecessary and/or non-convenient. Simulations show that extreme care is needed in positioning the isocentre: an accuracy of +/- 3 mm is required in the median sagittal plane.

Cobalt Radioisotopes↗
PubMed1990

[Psychosocial factors of participation in HIV testing].

The relevance of the attitude toward the HIV test, the subjectively perceived infection risk, the expected consequences of testing, and the perceived reference group influences for HIV antibody testing is studied. 211 persons, who were tested for AIDS in an AIDS consulting institution, and 86 controls, who had not been tested, participated in the study. The significance of the results for AIDS prevention is discussed.

AIDS Serodiagnosis↗
PubMed1989

Measured attenuation correction methods.

Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4-5 in brain studies to 50-100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide 68Ge/68Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible.

Humans↗