Biomedical subjects

T D Kampp

Publications and source records attributed to T D Kampp.

5 recordsLinked to original sources

PubMed1990

An interactive treatment planning system for ophthalmic plaque radiotherapy.

Brachytherapy using removable episcleral plaques containing sealed radioisotope sources is being studied as an alternative to enucleation in the treatment of choroidal melanoma and other tumors of the eye. Encouraging early results have been reported, but late complications which lead to loss of vision continue to be a problem. A randomized national study, the Collaborative Ocular Melanoma Study (COMS) is currently in progress to evaluate the procedure. The COMS specified isotope is 125I. Precise dosimetric calculations near the plaque may correlate strongly with complications and could also be used to optimize isotope loading patterns in the plaques. A microcomputer based treatment planning system has been developed for ophthalmic plaque brachytherapy. The program incorporates an interactive, 3-dimensional, solid-surface, color-graphic interface. The program currently supports 125I and 192Ir seeds which are treated as anisotropic line sources. Collimation effects related to plaque structure are accounted for, permitting detailed study of shielding effectiveness near the lip of a plaque. A dose distribution matrix may be calculated in any subregion of a transverse, sagittal, or coronal planar cross section of the eye, in any plane transecting the plaque and crossing the eye diametrically, or on a spherical surface within or surrounding the eye. Spherical surfaces may be displayed as 3-dimensional perspective projections or as funduscopic diagrams. Isodose contours are interpolated from the dose matrix. A pointer is also available to explicitly calculate and display dose at any location on the dosimetry surface. An interactive editing capability allows new plaque designs to be rapidly added to the system.

Brachytherapy↗

PubMed1990

Passive elastic properties of the rat aorta.

The passive anisotropic elastic properties of rat's aorta were studied in vitro by subjecting cylindrical segments of thoracic and abdominal aorta to a wide range of deformations. Using data on pressure, axial stretch, outer diameter, axial force and wall thickness, incremental moduli of elasticity in the circumferential, axial and radial directions were computed. Results indicate that while the elastic behavior of the aortic wall is globally anisotropic, there exists a state of deformation at which the vessel displays incremental isotropy. This state of deformation corresponds approximately to the loading conditions to which the aorta is exposed in situ. Values of the moduli, analyzed as a function of transmural pressure, show that the stiffness of the aortic wall is fairly constant at low pressures but raises steeply for pressures higher than physiological. For axial stretches as occurring in situ, the magnitudes of the circumferential and radial moduli do not differ significantly for the thoracic aorta; hence this vessel can be regarded as transversely isotropic over a wide range of pressures. The same observation is valid also for the abdominal aorta when pressures equal or smaller than physiological are considered. For both the thoracic and abdominal segments of the aorta, the circumferential and radial moduli are smaller than the axial modulus at low pressures, while the reverse is true for large pressures.

Animals↗

PubMedDate not supplied

The backprojection method applied to classical tomography.

A method based upon backprojection of projection images which allows six degrees of freedom in the selection of the plane to be tomosynthesized is described. Data can be collected with any type of classical tomographic apparatus, including linear, circular, or other complex motion unit, which has been modified by the addition of a digital imaging chain. A set of projection images can be acquired in a single sweep, although, in principle, they could be acquired simultaneously. In addition, C-arms can also be used with no limitations of the selection of tomosynthesized planes.

Biometry↗

PubMedDate not supplied

A technique for combining microwave hyperthermia with intraluminal brachytherapy of the oesophagus.

A technique for combining microwave hyperthermia with 192Ir brachytherapy for the treatment of oesophageal carcinoma is described. This approach uses an intraluminal afterloading applicator and up to six microwave antennae to deliver both hyperthermia and brachytherapy, with minimal modification of the existing procedure for brachytherapy alone. Each microwave antenna includes a built-in thermistor to control temperature and balance power. Longitudinal temperature distributions were measured in situ from within the applicator, and at the applicator-tissue interface in vivo. Two-dimensional SAR and steady-state temperature distributions measured in muscle-equivalent phantom are presented and discussed. The technique appears to be capable of elevating tissue temperature to greater than 42 degrees C in a radially symmetric volume of length greater than 5 cm, with radial penetration of 0.5 cm. The clinical technique is relatively simple and well tolerated.

Brachytherapy↗

PubMedDate not supplied

Microwave applicator for transurethral hyperthermia of benign prostatic hyperplasia.

An applicator for heating the prostate gland using a transurethral approach is described. This technique uses three microwave antennas and a thermometry sensor attached to the outer surface of a balloon (Foley) type urological catheter. Each microwave antenna also includes a built-in thermistor to control temperature and balance power. The balloon catheter assures rapid and reproducible localization of the antennas in the prostatic urethra. The two-dimensional SAR and steady-state temperature distributions surrounding the applicator in tissue equivalent phantom are reported. Longitudinal temperature distributions measured in situ at the applicator-urethral interface and the longitudinal and radial temperature distributions measured in normal canine prostate are presented and discussed. The technique appears to be capable of elevating temperature to greater than 42 degrees C in a cylindrically symmetrical volume up to 5 cm length and 0.5 cm radial penetration surrounding the applicator.

Hot Temperature↗