Biomedical subjects

S Ranka

Publications and source records attributed to S Ranka.

4 recordsLinked to original sources

PubMed2001

An algorithm for automatic, computed-tomography-based source localization after prostate implant.

Permanent implant of the prostate using I-125 and Pd-103 seeds is a popular choice of treatment for early-stage prostate cancer in the United States. Evaluation of the quality of the implant is best based on the calculated dose distribution from postimplant computed tomography (CT) images. This task, however, has been time-consuming and inaccurate. We have developed an algorithm for automatic source localization from postimplant CT images. The only requirement of this algorithm is knowledge of the number of seeds present in the prostate, thus minimizing the need for human intervention. The algorithm processes volumetric CT data from the patient, and pixels of higher CT numbers are categorized into classes of definite and potential source pixels. A multithresholding technique is used to further determine the number of seeds and their precise locations in the CT volume data. A graphic user interface was developed to facilitate operator review of and intervention in the calculation and the results of the algorithm. This algorithm was tested on two phantoms containing nonradioactive seeds, one with 20 seeds in discrete locations and another with 100 seeds with small distances between seeds. The tests showed that the algorithm was able to identify the seed locations to within 1 mm of their physical locations for discrete seed locations. It was further able to separate seeds at close proximity to each other while maintaining an average seed localization error of less than 2 mm, with no operator intervention required.

Algorithms↗

PubMed1992

Prediction criteria for successful weaning from respiratory support: statistical and connectionist analyses.

OBJECTIVE: To develop predictive criteria for successful weaning of patients from mechanical assistance to ventilation, based on simple clinical tests using discriminant analyses and neural network systems. DESIGN: Retrospective development of predictive criteria and subsequent prospective testing of the same predictive criteria. SETTING: Medical ICU of a 300-bed teaching Veterans Administration Hospital. PATIENTS: Twenty-five ventilator-dependent elderly patients with acute respiratory failure. INTERVENTIONS: Routine measurements of negative inspiratory force, tidal volume, minute ventilation, respiratory rate, vital capacity, and maximum voluntary ventilation, followed by a weaning trial. Success or failure in 21 efforts was analyzed by a linear and quadratic discriminant model and neural network formulas to develop prediction criteria. The criteria developed were tested for predictive power prospectively in nine trials in six patients. RESULTS: The statistical and neural network analyses predicted the success or failure of weaning within 90% to 100% accuracy. CONCLUSION: Use of quadratic discriminant and neural network analyses could be useful in developing accurate predictive criteria for successful weaning based on simple bedside measurements.

Aged↗

PubMedDate not supplied

Modified mesh rectopexy: a study.

AIM: To evaluate the efficacy of modified mesh rectopexy for complete rectal prolapse. SUBJECT AND METHODS: In a prospective study between 1989-1998, 47 patients (25 males and 22 females) underwent modified mesh rectopexy using a "Cross-shaped" knitted monofilament polypropylene. They were followed up for a period of four years postoperatively. RESULTS: Anatomical repair was achieved in all patients. Preoperative constipation, a complaint in 22 patients, was relieved in 13 patients and need for laxatives decreased in another four. There were no new cases of constipation. Sexual functions were not hampered irrespective of gender. The complications included prolonged ileus (4 patients), faecal impaction (1), partial mucosal prolapse (2) and post-operative obstruction (2). There was no recurrence. CONCLUSION: This technique aligns the rectum, avoids excessive mobilisation and division of lateral ligaments thus preventing constipation and preserving potency. We recommend this technique for patients with complete rectal prolapse with up to grade 1, 2 and 3 incontinence based on Browning and Parks classification.

Adult↗

PubMedDate not supplied

Self-bougienage: long-term relief of corrosive esophageal strictures.

BACKGROUND: Corrosive esophageal strictures require dilatation at frequent intervals. OBJECTIVE: To determine the efficacy of self-dilatation in treatment of corrosive esophageal strictures. METHODS: Retrospective analysis of data from 51 patients with corrosive esophageal strictures seen in a surgical unit. Eighteen patients underwent per-oral antegrade dilatation of stricture using gum elastic bougies (Group I); 15 patients underwent retrograde dilatation with endless string using an India rubber dilator devised at the authors' institution, followed by per-oral antegrade dilatation (Group II); 15 patients underwent retrograde dilatation followed by antegrade dilatation with endless string through esophagostomy (Group III). In three patients with stricture of the entire esophagus, endless string could not be passed; they were subjected to esophagocoloplasty. All patients were taught self-dilatation with gum elastic bougies as the final step, and were put on a progressive, domiciliary, self-dilatation program. Quarterly follow up was done for one year, to ascertain whether self-bougienage was being performed properly. RESULTS: All patients responded well to treatment, with significant relief of dysphagia and improvement in health and barium study findings. Six patients developed mediastinitis (3, 2 and 1 in Groups I, II and III, respectively) during initial dilatation; all improved with conservative management. Only one patient who failed to carry out self-bougienage had to be readmitted and retrained in the procedure, after which he remained asymptomatic. CONCLUSIONS: Patients with corrosive esophageal strictures can be treated with a long-term self-bougienage program, which avoids the need for frequent hospital admissions for esophageal dilatation.

Adolescent↗