Abstract: A computer graphics interface for producing an enhanced gray scale image on a monitor having a plurality of separate color inputs. The graphics interface converts at least a first and a second analog signal corresponding to two n-bit digital bytes into a single enhanced signal representative of an x-bit digital byte (where x is greater than n). The interface has an interface input for receiving the analog signals from the computer, a divider for reducing the amplitude of the second analog signal by 2.sup.n to produce an augmented signal, a summer for adding a first of the analog signals and the augmented signal to produce an enhanced signal, and means for conveying the enhanced signal to each of the monitor inputs. This interface is especially useful with a color VGA graphics board where n is 6.

Abstract: A radiation detector has a number of ionization chambers. Each ionization chamber is connected to an accumulating capacitor which in turn is sequentially read by a multiplexed charge-counter. The charge-counter eliminates the effect of variations of the capacitance values of the accumulating capacitors associated with each ionization chamber cell and provides a consistency of measurement among the ionization chamber cells unlike a design employing multiple measurement circuits dedicated to each ionization chamber cell.

Abstract: A method of producing highly homogeneous material, for constructing bone density phantoms used in calibrating CT machines and the like, dehumidifies the x-ray absorbing constituents of the material and combines them under vacuum to reduce the effects of absorbed atmospheric moisture and of air entrained by the mixing process. The binding polymer into which the x-ray absorbing materials are added is predoped with hardener to increase its viscosity to a point that prevents the migration of the components during the hardening process but that does not prevent their adequate dispersion throughout the mixture. Molds are filled by transferring the unhardened material through a tube connected to the bottom of the mixing vessel and to the bottom of the mold to further prevent the entrainment of air.

Abstract: An ion chamber for use with analysis and alignment of radiation therapy equipment is disclosed which includes a one millimeter deep ion chamber formed by a cavity in the front of a core member which is closed at its upper end by a thin electrode stretched and held in place over the cavity. A guard ring around the collecting electrode is maintained by a coated layer formed on the surface of the core inside of the cavity. Suitable conductive layers applied to the core connect to the various conductors of a triaxial cable so that the front electrode, the ion collecting electrode, and the guard ring electrode, can all be relatively easily connected to the single triaxial cable connected to the ion chamber. Components of the ion chamber are all, with the exception of the front electrode and the ion collecting electrode, fabricated of a single uniform material having known and defined radiation transmission properties so that radiation field discontinuities and perturbations are not generated within the instrument.

Abstract: A probe (10) employs a scintillator (18) as a detector for high-energy beam dosimetry. The scintillator (18) is positioned in an ionizing radiation beam (52) which creates a light output that is proportional to the radiation dose-rate incident upon the scintillator (18). The light is conducted from the scintillator (18) through a light pipe (16) to a photomultiplier tube (28), which converts the light to an electric current. The scintillator (18), the light pipe (16), the photomultiplier (28), and associated optical connections have opaque coverings or sheaths to prevent extraneous light from being introduced into the probe (10). The electric current produced by the photomultiplier tube (28) is proportional to the radiation dose-rate incident upon the scintillator (18). The radiation dose-rate may then be displayed or recorded by a measurement of the electric current.

Abstract: An instrument for measuring the characteristics of an x-ray unit includes two pairs of photo detectors to measure the kVp of the x-ray beam, a single photo detector to measure the relative film exposure produced by the beam and another single photo detector used to measure the relative current in milliamps (mA) of the x-ray unit. The instrument multiplexes the signals and converts them to digital form for storage and analysis by a microprocessor. The output is a display the contents of which is user selectable either by a switch panel or through use of a remote control unit.

Abstract: A measuring tool (10) for determining the thickness and position of the X-ray beam of a computer is disclosed which allows the information about the X-ray beam to be derived by analysis of a tomographic image taken of the measuring tool. The measuring tool (10) includes a phantom (12) which has formed therein a plurality of receptacles (14) which receive inserts (16). At least two of the inserts (16) each include therein an image creating pattern (20) including a helical pattern (22) and a center indicator (24) so that both thickness and positioning information can be obtained from the computer-generated tomographic image taken of the tool by examining the images created of the helical patterns (22) and center indicators (24) in the inserts (16).