Patent Number: 047019425
Section: claims

1. The method, in radiology, of using a printer to prepare an individual X-ray attenuation compensation mask for each patient by placing ink on a substrate, comprising the steps of: determining the desired X-ray attenuation of each area of the mask by operating an X-ray source to produce a first X-ray exposure of the patient,  analyzing the X-ray intensity at each location of the receiving field to provide intensity information,  using computer means to convert the intensity information into digital data corresponding thereto, and using the digital data to control a printer to print ink on a substrate with the location of the ink being determined by the said digital data to provide an X-ray attenuation mask which is selectly printed with the ink in certain areas,  positioning the X-ray attenuation mask between the X-ray source and receiving field to attenuate the X-rays by the mask and produce an even intensity of the X-rays at the receiving field and taking a second X-ray exposure of the patient;  characterized in that the printer is an ink jet printer which deposits ink jet droplets on said substrate, the jet printer deposits a plurality of droplets on certain areas of the substrate with the number of droplets at each area being controlled by said digital data, said substrate is an ink absorbent sheet and said ink jet droplets consist of a dispersant of a finely powered metal in a liquid carrier.  determining the desired X-ray attenuation of each area of the mask by operating an X-ray source to produce a first X-ray exposure of the patient,  analyzing the X-ray intensity at each location of the receiving field to provide intensity information,  using computer means to convert the intensity information into digital data corresponding thereto, and using the digital data to control a printer to print on a substrate with the location of the ink being determined by the said digital data to provide an X-ray attenuation mask which is selectly printed with the ink in certain areas,  positioning the X-ray attenuation mask between the X-ray source and the receiving field to attenuate the X-rays by the mask and produce an even intensity of the X-rays at the receiving field and taking a second X-ray exposure of the patient;  characterized in that the printer is an ink jet printer which deposits droplets of ink on said substrate, the jet printer deposits a plurality of droplets at each area being controlled by said digital data, said substrate is an ink absorbent sheet and the ink consists of a solution of a metallic compound as the solute. 2. The method of using an ink jet printer as in claim 1 wherein the powdered metal is selected from the group consisting of lead, barium, cesium, calcium, cadmium, cobalt and lithium. 3. The method of using an ink jet printer as in claim 1 wherein said printer uses a multi-orifice head to reduce the required number of passes of the head over the substrate. 4. The method of using an ink jet printer as in claim 1 wherein said substrate is divided into a field of at least 32.times.32 pixels. 5. The method of using an ink jet printer as in claim 1 wherein said substrate is absorbent blotting paper of at least 1/8-inch in thickness. 6. The method of using an ink jet printer as in claim 1 wherein said substrate is a multi-cell honeycomb capillary tube structure whose tubes are perpendicular to the plane of the substrate. 7. The method of using an ink jet printer as in claim 1 wherein the printer has an ink jet head which makes at least 20 passes over the substrate to deposit at least 20 droplets in selected areas. 8. The method of using an ink jet printer as in claim 1 wherein the mask is produced in less than 40 seconds and the entire X-ray procedure measured from the first exposure to the second exposure occurs in less than one minute. 9. The method of using an ink jet printer as in claim 1 wherein the printer operates at a high rate of over 50,000 Hertz to produce the mask within 40 seconds. 10. The method of using an ink jet printer as in claim 1 wherein the attenuation of a single layer of said ink on said substrate is at least 10%. 11. The method, in radiology, of using an ink printer to prepare an individual X-ray attenuation compensation mask for each patient by placing ink on a substrate, comprising the steps of: 12. The method of using an ink jet printer as in claim 11 wherein the metallic compound is selected from the group consisting of calcium, cesium, cadmium, cobalt, lithium and barium, and the solvent is an organic solvent. 13. The method of using an ink jet printer as in claim 11 wherein said printer uses a multi-orifice head to reduce the required number of passes of the head over the substrate. 14. The method of using an ink jet printer as in claim 11 wherein said substrate is divided into a field of at least 32.times.32 pixels. 15. The method of using an ink jet printer as in claim 11 wherein said substrate is absorbent blotting paper of at least 1/8-inch in thickness. 16. The method of using an ink jet printer as in claim 11 wherein said substrate is a multi-cell honeycomb capillary tube structure whose tubes are perpendicular to the plane of the substrate. 17. The method of using an ink jet printer as in claim 11 wherein the printer has an ink jet head which makes at least 20 passes over the substrate to deposit at least 20 droplets in selected areas. 18. The method of using an ink jet printer as in claim 11 wherein the mask is produced in less than 40 seconds and the entire X-ray procedure measured from the first exposure to the second exposure occurs in less than one minute. 19. The method of using an ink jet printer as in claim 11 wherein the printer operates at a high rate of over 50,000 Hertz to produce the mask within 40 seconds. 20. The method of using an ink jet printer as in claim 11 wherein the attenuation of a single layer of said ink on said substrate is at least 1%.