Biomedical subjects

S Quint

Publications and source records attributed to S Quint.

14 recordsLinked to original sources

PubMed2006

[Fear Avoidance Beliefs and physical function in elderly individuals with chronic low back pain].

Fear Avoidance Beliefs and physical function in elderly individuals with chronic low back pain This analysis assessed how fear avoidance beliefs (FABs) affected subjective and objective functional parameters as well as pain in elderly individuals. The study comprised 152 elderly patients with low back pain, which was attributed to spondylosis in almost half of the cases. Their average age was 70.1 years (SD=4.3, range 65-84). All of the patients participated in a physiotherapeutic program including data acquisition before treatment (t1), immediately after its completion (t2), and 6 months later (t3). FABs were assessed by a five-item scale with satisfying psychometric properties. The primary outcome criterion was function, which was evaluated as a subjective measure using the Hannover functional disability scale and as an objective measure based on the anteflexion determined by ultrasound topometry. Secondary outcome criteria were pain parameters. At the time o the first measurement (t1), the patients were classified into three groups with strong, intermediate, or weak FABs. Analyses of variance reveal an improvement of subjective functional capacity in every FAB group between t1 and t2. At t3, there is a decline of these values only in the group of the high fear avoiders. High fear avoiders also show lower values in the objective measure at all three measurement points. No influence of the FABs on the pain parameters could be determined. It would be expected that the efficacy of physiotherapy could be improved if the patients' FABs are taken into consideration when planning the treatment regimen.

Activities of Daily Living↗

PubMed2001

Reduction of irradiated small bowel volume and accurate patient positioning by use of a bellyboard device in pelvic radiotherapy of gynecological cancer patients.

PURPOSE: To reduce the volume of small bowel within pelvic treatment fields for gynecological cancer using a bellyboard device and to determine the accuracy of the prone treatment position. MATERIALS AND METHODS: Fifteen consecutive patients with a gynecologic malignancy who were treated with postoperative pelvic radiotherapy were selected for this study. The volume of small bowel within the treatment fields was calculated for both the supine and prone treatment positions. The patients were treated in the prone position in a so-called bellyboard device. During treatment sessions electronic portal images were obtained. An off-line setup verification and correction protocol was used and the setup accuracy of the positioning in the bellyboard was determined. RESULTS: The average volume of small bowel within the treatment fields was 229 cm(3) and 66 cm(3) in the supine and prone treatment, respectively, which means an average volume reduction in the prone position of 64% (95% CI 56-72%), as compared with the supine position. For the position of the patient in the field, the systematic error defined by the standard deviation (SD) of the mean difference per patient between simulation and treatment images was 1.7 mm in the lateral direction, 2.1 mm in the craniocaudal direction and 1.7 mm in the ventrodorsal direction. On average, only 0.4 setup correction per patient was required to achieve this accuracy. The random day-to-day variations were 1.9 (1SD), 2.6 and 2.3 mm, respectively. Standard deviations of the systematic differences between patient positioning relative to the bellyboard were 6.2 mm in lateral direction and 9.1 mm in craniocaudal direction. CONCLUSIONS: Treatment of gynecological cancer patients in the prone position using a bellyboard reduces the volume of irradiated small bowel. An off-line verification and correction protocol ensures accurate patient positioning. Daily setup variations using the bellyboard were small (1 SD<3 mm). Therefore for pelvic radiotherapy in patients with a gynecological malignancy, the use of a bellyboard is recommended.

Aged↗

PubMed2001

Set-up verification of cervix cancer patients treated with long treatment fields; implications of a non-rigid bony anatomy.

BACKGROUND AND PURPOSE: For cervix cancer patients, treatment fields may extend up to vertebra L1. In clinical practice, set-up verification is based on measured displacements of the pelvic rim as visible in the caudal part of the treatment fields. The implications of this procedure for the positions of bony structures in the cranial part of the fields were investigated. MATERIALS AND METHODS: Twelve patients had four repeat simulator sessions. Both during treatment simulation (the reference) and the repeat sessions, anterior radiographs were acquired covering the whole treatment field. The films were used to investigate differences between the cranial and the caudal parts of the treatment field in day-to-day bony anatomy displacements. RESULTS: Both in the transversal and the longitudinal directions, these differences were significant (3.5 mm, 1 SD). Indications were found that large differences in the cranio-caudal direction may be correlated with (non-rigid) internal pelvic rim rotations around a lateral axis. In the longitudinal direction, the position of L1 correlated much better with the position of vertebra S1 than with the position of the pelvic rim, which is usually used for set-up verification. CONCLUSIONS: Due to the non-rigid bony anatomy of the studied patients, the usual set-up verification and correction procedure can result in set-up errors of 10 mm and more for structures in the cranial part of the treatment field, even in the case of a perfect set-up of the pelvic rim. Possibly, other patient set-up and immobilization procedures may result in a better day-to-day reproducibility of the 3D bony anatomy shape. (Remaining) Differences in anatomy position changes between the caudal and cranial field ends may be accounted for by using non-uniform clinical target volume-to-planning target volume margins, or by an adapted patient set-up verification and correction protocol.

Electronics, Medical↗

PubMed2000

On-line set-up corrections during radiotherapy of patients with gynecologic tumors.

PURPOSE: Positioning of patients with gynecologic tumors for radiotherapy has proven to be relatively inaccurate. To improve the accuracy and reduce the margins from clinical target volume (CTV) to planning target volume (PTV), on-line set-up corrections were investigated. METHODS AND MATERIALS: Anterior-posterior portal images of 14 patients were acquired using the first six monitor units (MU) of each irradiation fraction. The set-up deviation was established by matching three user-defined landmarks in portal and simulator image. If the two-dimensional deviation exceeded 4 mm, the table position was corrected. A second portal image was acquired using 30 MU of the remaining dose. This image was analyzed off-line using a semiautomatic contour match to obtain the final set-up accuracy. To verify the landmark match accuracy, the contour match was retrospectively performed on the six MU images as well. RESULTS: The standard deviation (SD) of the distribution of systematic set-up deviations after correction was < 1 mm in left-right and cranio-caudal directions. The average random deviation was < 2 mm in these directions (1 SD). Before correction, all standard deviations were 2 to 3 mm. The landmark match procedure was sufficiently accurate and added on average 3 min to the treatment time. The application of on-line corrections justifies a CTV-to-PTV margin reduction to about 5 mm. CONCLUSIONS: On-line set-up corrections significantly improve the positioning accuracy. The procedure increases treatment time but might be used effectively in combination with off-line corrections.

Female↗

PubMed2000

Definition and validation of a reference target volume in early stage node-positive cervical carcinoma, based on lymphangiograms and CT-scans.

PURPOSE: To establish a reference planning target volume for postoperative radiotherapy in stage Ib and IIa N+ cervical carcinoma, based on 47 lymphangiograms and 15 CT-scans. METHODS: Radiation oncologists (n=17) from all radiotherapy institutes in The Netherlands were asked to define the clinical target volume (CTV) and planning target volume (PTV), and to delineate (on simulation films) the radiotherapy treatment portals following a radical hysterectomy with lymph node dissection for an early stage cervical carcinoma with positive iliac lymph nodes. A reference PTV was defined by using 47 normal lymphangiograms and CT-data of the pelvis from 15 patients who underwent surgery for cervical carcinoma. The simulation films were digitized and evaluated for adequacy in covering the PTV, previously individually determined by the radiation oncologists. Subsequently, the simulation films were also evaluated for adequacy in covering the reference PTV. RESULTS: Large variations were observed in the portals used and in treatment techniques. From the digitized films, it appeared that in 50% of the cases the defined PTV was not covered adequately. Furthermore, 71% of the treatment plans would not cover the lateral borders of the reference PTV sufficiently. CONCLUSIONS: There appears to be no consensus on the target volumes to be irradiated in postoperative radiotherapy of early stage cervical carcinoma. When a PTV defined on the basis of lymphangiograms and CT-data is taken as a reference, 71% of the treatment plans would not cover this PTV adequately. These findings indicate the need for a consensus in the design of standardized treatment volumes.

Carcinoma, Squamous Cell↗

PubMed1999

Transit dosimetry with an electronic portal imaging device (EPID) for 115 prostate cancer patients.

PURPOSE: Comparison of predicted portal dose images (PDIs) with PDIs measured with an electronic portal imaging device (EPID) may be used to detect errors in the dose delivery to patients. However, these comparisons cannot reveal errors in the MU calculation of a beam, since the calculated number of MU is used both for treatment (and thus affects the PDI measurement) and for PDI prediction. In this paper a method is presented that enables "in vivo" verification of the MU calculation of the treatment beams. The method is based on comparison of the intended on-axis patient dose at 5 cm depth for each treatment beam, D5, with D5 as derived from the portal dose Dp measured with an EPID. The developed method has been evaluated clinically for a group of 115 prostate cancer patients. METHODS AND MATERIALS: The patient dose D5 was derived from the portal dose measured with a fluoroscopic EPID using (i) the predicted beam transmission (i.e., the ratio of the portal dose with and without the patient in the beam) calculated with the planning CT data of the patient, and (ii) an empirical relation between portal doses Dp and patient doses D5. For each beam separately, the derived patient dose D5 was compared with the intended dose as determined from the relative dose distribution as calculated by the treatment planning system and the prescribed isocenter dose (2 Gy). For interpretation of observed deviating patient doses D5, the corresponding on-axis measured portal doses Dp were also compared with predicted portal doses. RESULTS: For three beams, a total of 7828 images were analyzed. The mean difference between the predicted patient dose and the patient dose derived from the average measured portal dose was: 0.4+/-3.4% (1 SD) for the anterior-posterior (AP) beam and -1.5+/-2.4% (1 SD) for the lateral beams. For 7 patients the difference between the predicted portal dose and the average measured portal dose for the AP beam and the corresponding difference in patient dose were both greater than 5%. All these patients had relatively large gas pockets (3-3.5 cm in AP direction) in the rectum during acquisition of the planning CT, which were not present during (most) treatments. CONCLUSIONS: An accurate method for verification of the MU calculation of an x-ray beam using EPID measurements has been developed. The method allows the discrimination of errors that are due to changes in patient anatomy related to appearance or disappearance of gas pockets in the rectum and errors due to a deviating cGy/MU-value.

Electronics, Medical↗

PubMed1999

Three-dimensional treatment planning for postoperative radiotherapy in patients with node-positive cervical cancer. Comparison between a conventional and a conformal technique.

PURPOSE: Reduction of irradiated small bowel volume, using a conformal three-dimensional treatment planning technique in postoperative radiotherapy of cervical cancer patients. PATIENTS AND METHODS: Large gynecological treatment fields including the para-aortic nodes were analyzed in 15 patients. A conventional treatment plan with anterior and posterior (AP-PA) parallel opposed fields and a 3D 4-field conformal radiotherapy plan with a central blocking of small bowel were compared for each patient. Dose-volume histograms and dose parameters were established. Because of the tolerance constraints of the small bowel, the cumulative dose applied to the target was 48.6 Gy. RESULTS: The mean Tumor Control Probability (TCP) values for both the conventional and the conformal technique were 0.60 and 0.61, respectively, with ranges of 0.56 to 0.67 and 0.57 to 0.66, respectively. The mean volume receiving 95% or more of the prescribed dose (V95) of the small bowel was 47.6% (32.5 to 66.3%) in the AP-PA technique and 14.9% (7.0 to 22.5%) in the conformal technique (p < 0.001), indicating a significant reduction in irradiated volume of small bowel in the higher dose range. The mean Normal Tissue Complication Probability (NTCP) decreased from 0.11 to 0.03 with the conformal plan. In patients who received a pedicled omentoplasty during surgery, the mean V95 for small bowel could be reduced to 8.5% (7.0 to 9.9%). The mean median dose to the kidneys was only slightly elevated in the conformal treatment. Especially the mean dose to the right kidney in conventional vs conformal treatment was 3.3 vs 7.9 Gy. The mean near-minimum dose (D95) to the rectosigmoid decreased from 48.4 to 30.1 Gy in the conformal plan compared to the conventional plan. CONCLUSION: The small bowel dose can be significantly reduced with 3D treatment planning, particularly if a pedicled omentoplasty is performed. This allows dose escalation to the tumor region without unacceptable toxicity for the small bowel.

Adenocarcinoma↗

PubMed1998

In vivo dosimetry for prostate cancer patients using an electronic portal imaging device (EPID); demonstration of internal organ motion.

PURPOSE: To investigate the use of a commercially available video-based EPID for in vivo dosimetry during treatment of prostate cancer patients. METHODS: For 10 prostate cancer patients, the inter-fraction variation within measured portal dose images (PDIs) was assessed and measured PDIs were compared with corresponding predicted PDIs based on the planning CT scan of the patient. RESULTS: For the lateral fields, the average standard deviation in the measured on-axis portal doses during the course of a treatment was 0.9%; for the anterior fields this standard deviation was 2.2%. The difference between the average on-axis measured portal dose and the predicted portal dose was 0.3+/-2.1% (1 SD) for the lateral fields and 0.7+/-3.4% (1 SD) for the anterior fields. Off-axis differences between measured and predicted portal doses were regularly much larger (up to 15%) and were caused by frequently occurring gas pockets inside the rectum of the patients during treatment or during acquisition of the planning CT scan. The detected gas pockets did sometimes extend into the gross tumour volume (GTV) area as outlined in the planning CT scans, implying a shift of the anterior rectum wall and prostate in the anterior direction (internal organ motion). CONCLUSIONS: The developed procedures for measurement and prediction of PDIs allow accurate dosimetric quality control of the treatment of prostate cancer patients. Comparing measured PDIs with predicted PDIs can reveal internal organ motion.

Follow-Up Studies↗

PubMed1996

Picture confrontation oral naming: performance differences between aphasics and normals.

Oral confrontation naming was compared in 108 normal subjects controlled for education, age, and gender and in 18 aphasic patients for the same set of 115 pictures. Demographic variables influenced both normals' and aphasics' performance. However, the nature of aphasics' misnamings on the one hand and the differential effects of characteristics of pictures and words on normals' and aphasics' responses on the other indicated specific deficits in patients. The classical hypothesis that aphasics' misnamings and the production of word associations by normals should rely on similar mechanisms (Rinnert & Whitaker, 1973) is questioned. Nondominant responses observed in normals accounted for a larger proportion of verbal errors than associates to target words.

Adult↗

PubMed1990

[Correlation of thalamic aphasia and cerebral blood flow].

Relations between linguistic deficits and cerebral blood flow (CBF) were studied in 20 cases of thalamic aphasia due to hemorrhage. Language analysis was based on BDAE, verbal intelligence quotient and verbal subtest of the memory quotient (Wechsler). CBF analysis (and of asymmetry index: AI) was done with 133 Xenon by SPECT technique in tomographic slices and in 15 areas of interest, i.e. cortical and deep areas. Relationships were analyzed by multiple correlations procedure and stepwise regression. Significant correlations were observed between linguistic results and AI of cortical but also deep areas (lenticular). Dynamic anomalies (fluency) were correlated with the IA and/or CBF of the frontal cortex. Verbal comprehension, naming and paraphasia were related to the AI of deep structures (insula and lenticular nucleus) and the AI of posterior cortex (temporo-occipital). Several correlations were found significant between results on verbal IQ of the WAIS and IA of the insula and lenticular nucleus.

Aged↗

PubMed1990

[Clinical course after surgery of aneurysms of the anterior communicating artery].

The evolution and correlations between initial state and outcome (one year) are analysed in 81 patients with anterior cerebral artery aneurysm. The age and initial evaluations are seldomly correlated with late evaluations, Jennett and Holbook scales, frontal syndrome, amnesia. The evaluations at one month are very significantly correlated to the late evaluations.

Adolescent↗

PubMed1987

Unilateral pseudobulbar syndrome with limited capsulothalamic infarction.

A unilateral pseudobulbar syndrome consequent to unilateral capsulothalamic infarction is described. Motor deficit of the face was associated with marked velar and pharyngeal unilateral palsy; paresis of limbs was mild. ACT scan revealed a circumscribed infarction of the genu of the internal capsule. This raised the problem of unilateral supranuclear pharyngeal palsies and of the precise anatomy of the genicular tract in the genu of the internal capsule.

Aged↗

PubMed1986

[Balint syndrome as a result of a biparietal infarct. Neuropsychological analysis].

A case of Balint syndrome with bilateral parietal infarction is presented. Analysis shows the tight intrication of visual inattention and psychic gaze palsy. The deficit of visuo-manual adjustment is characterized by a fixed divergence between the target and the point where the patient places his hand, either in ballistic movements (classical optic ataxia), either in pursuit movements; for this reason, a simple disconnexion should not explain the classic optic ataxia. The discretion of aphasia allows the individualization of an anterograde and partially retrograde amnesia.

Agnosia↗

PubMedDate not supplied

Diversity of patterns of improvement in confrontation naming rehabilitation: some tentative hypotheses.

A previous group analysis of the effects of a computerized written naming rehabilitation program revealed global improvement with generalization of benefits to untrained items and to untreated oral naming (Deloche et al., 1992). The present multiple single-case analysis of the data indicates a variety of patterns of improvement and of generalization effects among individual patients. Patterns of relationships between written and oral naming behaviors help to explain the type of improvement that was observed.

Adult↗