Use of computerized tomography in dose calculations for radiation treatment planning

The detailed anatomic information provided by CT scanners can be used to improve the accuracy of dose distribution calculations for radiation treatment planning. Commonly used methods for dose computations are described, with emphasis on their use with CT data, and measured data are presented to illustrate their relative merits. Modification of CT numbers to account for the difference in energies of diagnostic and therapeutic radiation is discussed. A description of a typical CT-based radiation treatment planning system is presented.

Electrokinetic properties of (Na+, K+)-ATPase vesicles as studied by laser Doppler spectroscopy

The technique of laser Doppler electrophoresis was applied for the study of the surface charge properties of (NA+, K+)-ATPase containing microsomal vesicles derived from guinea-pig kidney. The influence of pH, the screening and binding of uni- and divalent cations and the binding of ATP show: (1) one net negative charge per protein unit with a pK = 3.9; (2) deviation from the Debye relation between surface potential and ionic strength for univalent cations, with no difference in the effect of Na+ and K+; (3) Mg2+ binds with an association constant of Ka = 1.1. 10(2) M-1 while ATP binds with an apparent Ka = 1.1.10(4) M-1 for 1 mM NaCl, 0.2 mM KCI, 0.1 mM MgCl2, 0.1 mM Tris-HCl2, 0.1 mM Tris-HCl (pH 7.3). The binding is weaker at higher Mg2+ concentrations. There is no ATP binding in the absence of Mg2+. In addition, the average vesicle size derived from the linewidth of the quasielastic light scattering spectrum is 203.7 +/- 15.2 nm. In the presence of ATP a reduction in size is observed.

A method of correction for curvature and inhomogeneities in computer aided calculation of external beam radiation dose distributions

This paper deals with the problem of finding the effective pathlength along a ray passing through a patient's outline and internal structure. The pathlength contributes to the correction applied for curvature and inhomogeneities in the computer-aided calculation of external beam radiation dose distributions. The pathlength is found by first determining the intersections of the ray with the contours defining the patient's body and the interior inhomogeneities. From these intersections the geometric length within each contour is obtained. This information is then employed in a treatment planning program for high energy gamma and X-rays and electrons, in which the radiation dose distribution is computed taking into account the actual inhomogeneous tissue structures. Other applications of the techniques described to problems in the field of radiation therapy are briefly discussed.

Oak poisoning of cattle in Ohio

Fourteen cases of oak poisoning were diagnosed at the Ohio Veterinary Diagnostic Laboratory, Reynoldsburg, Oh, in the fall of 1976. The poisoning was attributed to ingestion of oak shrubs, oak leaves, and acorns. Clinical signs included anorexia, rumen atony, hemorrhagic diarrhea, subcutaneous edema, and abnormal renal function. Perirenal edema and hemorrhage, ascites, hydrothorax, and hemorrhagic enteritis were frequently encountered pathologic changes. Histologic examination of the kidney revealed multifocal necrosis of the proximal convoluted tubules, which is a characteristic feature of this type of poisoning.

Computer-compatible patient contour plotter

The use of a compact, mobile, relatively inexpensive electromechanical patient-contouring mechanism is described. The system utilizes a Numonics Model 224 graphics digitizer suspended over the patient. The digital X and Y coordinates of the patient contour in either of multiple, parallel transverse, or sagittal planes are inherently accurate to within +/-0.25 mm over a total reading are of 60X90 cm. Display features include the interface to an analog 11-in.X17-in. X-Y plotter with a variable scale-down factor for those contours which would otherwise be larger than the plotting surface. The system is easy to use and may also be readily interfaced for on-line entry of patient contours to calculator- or minicomputer-based treatment-planning systems.