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Biomedical subjects

J E Rodgers

Publications and source records attributed to J E Rodgers.

27 records · Page 2Linked to original sources
PubMed1987

Intraoperative single-dose radiotherapy. Observations on staging and interstitial treatment of unresectable liver metastases.

Fourteen patients with a history of colonic cancer were evaluated for metastatic disease and were thought to have unresectable disease confined to the liver. Exploratory surgery revealed that two patients had extensive extrahepatic disease, and the procedure was terminated. In 12 patients, closed-end needles (diameter, 2.1 mm) were introduced into each nodule and connected to a 370-MBq (10-Ci) afterloading iridium source. Radiation doses were dependent on nodule size, providing minimum doses of 20 Gy (2000 rad) to the lesion's periphery with rapid radiation falloff avoiding toxic effects to adjacent normal tissue. The maximum number of nodules treated in one patient was 11. The largest nodule treated measured 9 x 6.5 x 6 cm. Cholecystectomy in four patients allowed precise implantation and obviated biliary fistula. Preoperative computed tomography underestimated the number of hepatic metastases in all cases but one, and treatment-induced computed tomographic alterations further limited its utility. Radiation treatment was well tolerated, and the median hospitalization was eight days. Of ten patients whose preoperative carcinoembryonic antigen values exceeded 10 ng/dL, the values in six patients decreased postoperatively.

Adult↗
PubMed1986

Interstitial radiation therapy for hepatic metastases: sonographic guidance for applicator placement.

A new technique is reported for the treatment of hepatic metastases using sonography-directed percutaneous placement of a 14-gauge needle applicator and a high-intensity "remote afterloading" iridium-192 (Ir-192) source for interstitial radiation therapy. The results with six patients show that the procedure is easily performed, patient tolerance is good, and there is minimal disruption of the patient's lifestyle. Hospitalizations have been less than 24 hr. Partial response or stable disease in the liver was observed in all six patients. Tumoricidal doses up to 5000 rad (cGy) in a single treatment with durations from 7 to 41 min were achieved in small volumes (less than 25 cm3) with no clinically significant toxicity on follow-up evaluations from 2-6 months. The technique appears to ablate discrete metastatic tumor deposits in the liver.

Brachytherapy↗
PubMed1979

Amblyopia in bilateral infantile and juvenile cataract. Relationship to timing of treatment.

Contact lenses were fitted for 51 aphakic infants. From this group data were obtained that support the hypothesis that much of the visual defect in cases of congenital cataract is due to functional amblyopia, and that it is therefore largely preventable and even treatable. The implications of the results for the management of these patients and for human amblyopia are that early treatment and optical correction are essential, since the effects of deprivation start at about 4 months of age and continue to a cumulative but decreasing degree throughout the first decade of life.

Amblyopia↗
PubMedDate not supplied

Digital image processing of radiation therapy portal films.

Digital image processing has the potential to enhance and improve several functions of a modern radiation oncology department. These functions may include improving perception of information for low contrast films, electronic transfer of images to remote facilities and back, and reducing storage space requirements for archiving once treatment is finished. This paper gives an overview of the digitization process and of image processing fundamentals. The clinical evaluation of digitized portal films is also discussed. The authors conclude that digitizing low contrast radiation therapy portal films is feasible with present technology and will produce images acceptable for routine clinical use in most instances. The role of image enhancement is less well established and remains investigational.

Humans↗
PubMedDate not supplied

Analysis of the bremsstrahlung component in 6-18 MeV electron beams.

The magnitude of the bremsstrahlung component in the 6-18 MeV electron beams from a Varian Clinac 18 accelerator was measured directly using a 0.16 T magnetic field to deflect the electron beams. The central axis depth ionization curves were measured at 130- and 197-cm source-surface distances in a Therados RFA-3 water phantom with and without the magnet being placed between the 4 X 4 cm2 electron cone and the water phantom. Results obtained clearly demonstrate that the bremsstrahlung component is primarily (greater than 90%) generated in the electron scattering-foil/collimation system and not in the water phantom. The x-ray central axis depth ionization curves exhibit buildup and attenuation regions characteristic of megavoltage x-ray beams. Ionization profiles of the x-ray component, measured in a plane perpendicular to the central axis, were also examined. Analysis of bremsstrahlung production as a function of photon collimation jaw opening shows a strong dependence, especially for the smaller openings.

Electrons↗
PubMedDate not supplied

A stereotactic brain implant technique with high activity I-125 seeds using a conventional brachytherapy treatment planning system.

A stereotactic brain implant program with removable high-activity I-125 seeds has recently been implemented for the treatment of malignant brain tumors. A Brown-Roberts-Wells (BRW) stereotactic frame with an NIH arc system and a guide template is used to introduce parallel catheters precisely into the tumor volume (Fig. 1). CT scans of patients with the BRW frame in place are used to determine the position of the catheters and the location of seeds in each catheter. The positions of the catheters are determined with respect to a "reference line" which represents the direction of approach in the central plane of the tumor. The seed coordinates are expressed in the catheter coordinate system with the X-axis along the catheter direction and the Y-Z plane parallel to the surface of the guide block. The Y-Z plane is orthogonal to x-axis. An AECL Theratronics Theraplane treatment planning system (SEED program) is used to obtain dose distributions based on seed coordinates. This treatment planning system does not require special purpose software for brachytherapy treatment planning. High-activity I-125 seeds (nominal 10-15 mCi/seed) are after-loaded into the inner catheters of double coaxial silicone (Gutin) catheters according to a preplanned scheme. The physical aspects of the brain implant program, treatment planning technique, and radiation safety measures are described.

Brachytherapy↗