New device for accurate measurement of the x-ray intensity distribution of x-ray tube focal spots.

A new device has been developed with which the focal spot distribution can be measured accurately. The alignment and localization of the focal spot relative to the device are accomplished by adjustment of three micrometer screws in three orthogonal directions and by comparison of red reference light spots with green fluorescent pinhole images at five locations. The standard deviations for evaluating the reproducibility of the adjustments in the horizontal and vertical directions were 0.2 and 0.5 mm, respectively. Measurements were made of the pinhole images as well as of the line-spread functions (LSFs) and modulation transfer functions (MTFs) for an x-ray tube with focal spots of 1-mm and 50-mum nominal size. The standard deviations for the LSF and MTF of the 1-mm focal spot were 0.017 and 0.010, respectively.

Relief of pressure damping during coronary angioplasty: a device for creating side holes in PTCA guiding catheters.

Percutaneous coronary angioplasty guiding catheters occasionally wedge in the coronary orifice and obstruct blood flow, making completion of the balloon dilatation difficult. Side holes may be made in the catheter, but when created free-hand may not be ideal. This report describes a device for creating side holes of small size, with uniform shape, and without rough edges. The disadvantages of dye extravasation and loss of strength in the catheter are minimized.