CN2242521Y

CN2242521Y - Medical X-ray tube of fluorescent-enhancement type

Info

Publication number: CN2242521Y
Application number: CN 95232718
Authority: CN
Inventors: 谭大刚
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-11-16
Filing date: 1995-11-16
Publication date: 1996-12-11
Anticipated expiration: 2005-11-16

Abstract

The utility model relates to an improved medical X-ray tube of K fluorescent-enhancement type. The target layer of the fixed K fluorescence-enhancement anode of the X-ray tube is formed by that tungsten or gold is deposed on the membrane piece of a diamond or graphite heat conducting layer, a K fluorescent layer made of rare earth elements is positioned under the transmission heat conducting layer, the composite target piece is pressed on the anode body through a target pressing plate (column), an electronic beam inlet hole and an X-ray outlet hole are processed on the target pressing plate (column), the anode body is sealed with a tube casing, a heat radiating piece is arranged at the back of the anode body, and a water-cooling cover is arranged at the back of the anode body. The target membrane of the rotary K fluorescence-enhancement anode of the X-ray tube, the transmission heat conducting layer and the K fluorescent layer are all annular. Because strong K fluorescence radiation can be produced and the energy is the optimal energy for medical diagnosis, the utility model has the advantages of high image efficiency, low radiant quantity for person being X-ray examined, etc.

Description

Medical K fluorescence enhancement mode X spool

The utility model relates to a kind of improvement of medical x-ray tube.

The X line is from find to be used in the medical diagnostic image technology over 100 years always.Because the X line has certain biological effect to human body, before guaranteeing the quality of image, how to reduce under the topic and checked that exposure is the important topic of medical physics always.Along with the development of digitized image technology, signal noise ratio (snr) of image has been acknowledged as the objective indicator of weighing the quality of image in recent years.Studies show that to any diagnosis object-receiving system, its signal noise ratio (snr) of image all is proportional to the roentgen radiation x amount, change with incident photon energy is different and obtain the required exposure of same signal to noise ratio.For common trouble body structure-receiving system commonly used, (to breast disease diagnosis 22-35keV) required exposure minimum when incident photon energy is 37.5 to 50keV.And being below or above the photon of above-mentioned numerical value for energy, required exposure all can significantly increase.For example, when making the barium meal transillumination with calcium tungstate screen, the exposure that obtain the required 30keV photon of same signal noise ratio (snr) of image, 60keV photon is respectively 44 and 4 times of 40keV photon irradiation amount.And when making the iodine radiography, above-mentioned multiple is respectively 75 and 4.6 times.Mammary gland is taken pictures, and required 17keV and 50keV photon irradiation amount are respectively 8.7 and 5.7 times of 25keV photon irradiation amount.

The medical diagnostic X-ray spool is all used the tungsten target anode at present, produces the continuum photon.The special-purpose X spool of some mammary gland adopts molybdenum target, produces K feature photon.But its energy (17.5keV) is too low, so this kind pipe is seldom used abroad.The optimization study done of medical physics circle all is based on the output of tube with W target,x-ray so far, seeks optimized tube voltage and filtercondition and changes spectral shape to improve signal noise ratio (snr) of image and to reduce exposure.Result as Zammenhof shows that to fat, calcification and iodine radiography-CsI screen system, optimal condition is: tube voltage 60-70keV and thick as far as possible aluminium filter.And in practicality, limit because of pipe power, people can't adopt above-mentioned optimal condition, often need more high voltage.Cause exposure far above theoretical optimal value.

The utility model purpose is, overcoming conventional medical diagnostic X-ray spool is increasing signal noise ratio (snr) of image and is avoiding improving the difficulty that patient's exposure and tube power load are faced, a kind of certain very strong K fluorescence composition that has in spectrum is provided, its energy by chance is the optimum capacity of medical diagnosis, can provide higher signal noise ratio (snr) of image and medical K fluorescence enhancement mode X spool under less exposure and tube power load.

The utility model is by insulator, the negative electrode assembly, the anode assembly, shell, cooling device is formed, the target layer that the fixed K fluorescence of X spool strengthens anode is the metal material tungsten of 3 μ m to 15 μ m or deposition of gold at thickness by thickness is on the diaphragm of the diamond of 80 μ m to 250 μ m or graphite heat conducting layer, the K fluorescence coating of making by rare earth element be positioned at the transmission heat-conducting layer below, above-mentioned composite target sheet is pressed on the anode bodies by target pressing plate (post), be processed with electron beam incident hole and X line perforation hole on the target pressing plate (post), this anode bodies and package closure, the anode bodies back side is provided with fin, and the anode bodies back side also is provided with water-cooled cap; The target layer that the rotary K fluorescence of X spool strengthens anode is deposited on the target surface of rotarting anode body by tungsten, it wherein below the portion graphite transmission heat-conducting layer ring of 50 μ m to 200 μ m, the focus ring position is provided with K fluorescence coating ring in its lower section, and K fluorescence coating ring is made by rare earth element or its high melting compound; X line exit direction and electron beam incident angular separation are 105 ° to 125 °; The X line is 15 ° to 25 ° to the target surface angle of emergence.

The utlity model has by changing the photons spectrum that anode construction and material change generation, it is strengthened especially at the optimum capacity place, image efficient significantly improves, to characteristics such as the remarkable reductions of person under inspection's exposure.

Accompanying drawing 1 is that the fixed K fluorescence of the utility model strengthens anode X spool structural representation.

Accompanying drawing 2 is that the rotary K fluorescence of the utility model strengthens anode X spool structural representation.

Accompanying drawing 3 is the anode amplification profile diagram that the rotary K fluorescence of the utility model strengthens anode X spool.

Below in conjunction with accompanying drawing the utility model is further described, target layer 1 is the metal material thin layer (gold or tungsten) of 3 μ m to 15 μ m by thickness, being deposited on thickness is on the diamond or graphite film transmission heat-conducting layer 2 of 80 μ m to 250 μ m, the material of transmission heat-conducting layer is by low atomic number, high conductivity material, but its molten point or working temperature should be complementary with the molten point of target layer material, best material is a diamond, secondly be graphite, the thickness of transmission heat-conducting layer should be 5 to 10 times of target layer thickness, the Temperature Distribution of its back can be reduced to the degree that the fluorescence coating material can tolerate, because 4 to 5 times and 12 to 15 times of tungsten for gold are given birth in adamantine heat conduction, combinations thereof can make effective heat conduction give birth to (when focal spot size during much larger than target layer thickness) 2 to 6 times and 6 to 10 times of tungsten for gold.The material of K fluorescence coating 3, select certain metallic element or rare earth element according to the K fluorescence photon energy that will strengthen, target pressing plate (post) 4 and anode water-cooled radiator structure, for fixed anode K image intensifier, the anode assembly must adopt direct water-cooling, in order to improve water-cooled efficient, the composite target sheet tightly is pressed on the copper anode bodies 5 by a special target pressing plate (post), target pressing plate (post) itself also is a copper, can be gold-plated at electron impact hole 6 inwalls to improve atomic number, increase also is processed with X line perforation hole 7 to the electron scattering rate on the target pressing plate (post), anode bodies and shell 8 seal welds are one, in combination target sheet pressing position, its very thin thickness, the anode bodies back side is provided with fin 9, and the anode bodies back side also is provided with water-cooled cap 10.Rotation for the X spool strengthens anode, because of its target film, transmission heat-conducting layer and K fluorescence coating are difficult to be assembled with modes such as mechanical compactions, the comprehensive employing of above-mentioned each layer needs electroplated, technologies such as vacuum moulding machine successively process, rotarting anode is provided with water-cooled mechanism, whole anode need tolerate higher temperature, so have only tungsten film to be suitable as target layer material, graphite film is suitable as transmission heat-conducting layer ring material, is fit to K fluorescence coating ring, material is Gd, Tb, etc., the rotarting anode body can be by tungsten or molybdenum, or graphite is formed by combining, the utility model adopts the radiation angle (pointing out ray and incident beam angle) greater than 90 °, about 120 ° of best radiation angle, and the ray angle (the X line is to the target surface angle of emergence) that goes out to shoot at the target is about 15 °.Bigger radiation angle can reduce hard photon composition in the output radiation, helps reducing person under inspection's dosage.

Operation principle of the present utility model is such, quicken through high voltage electric field from the electron beam of cathode emission, the bombardment plate target, all electron beam will be stoped and produce radiation X line by the target film, this radiation X line is except that penetrating into through exit portal the useful ray, its intensity and orthovoltage x-ray pipe about equally, the strongest x-ray radiation for forwards to, see through on the heat insulation transmission layer irradiation K fluorescence enhancement layer, and on K fluorescence enhancement layer, produce strong K fluorescent x-ray radiation.The K fluorescence of isotropic emission sees through transmission layer and target film through necessarily weakening, but still can increase extremely strong K fluorescence composition in total X line power spectrum of exit portal outgoing.The utility model is compared with the orthovoltage x-ray pipe, under same tube power load, can give birth to extremely strong K fluorescent radiation by fecund, its energy is the optimum capacity of medical diagnosis, makes X spool composition when making medical diagnosis, produces the required exposure of same signal noise ratio (snr) of image and greatly reduces.

Claims

1. medical K fluorescence enhancement mode X spool, be by insulator, the negative electrode assembly, the anode assembly, shell, cooling device is formed, be divided into two kinds of fixed anode tube and rotatable anode pipes, the target layer 1 that the fixed K fluorescence that it is characterized in that the X spool strengthens anode is the metal material tungsten of 3 μ m to 15 μ m or deposition of gold at thickness by thickness is on the diaphragm of the diamond of 80 μ m to 250 μ m or graphite heat conducting layer 2, the K fluorescence coating of making by rare earth element 3 be positioned at the transmission heat-conducting layer below, above-mentioned composite target sheet is pressed on the anode bodies 5 by target pressing plate (post) 4, be processed with electron beam incident hole 6 and X line perforation hole 7 on the target pressing plate (post), this anode bodies and shell 8 sealings, the anode bodies back side is provided with fin 9, and the anode bodies back side also is provided with water-cooled cap 10.

2. according to the described medical K fluorescence enhancement mode X spool of claim 1, the target layer that it is characterized in that the rotary K fluorescence enhancing anode of X spool is deposited on the target surface of rotarting anode body by tungsten, it wherein below the portion graphite transmission heat-conducting layer ring of 50 μ m to 200 μ m, the focus ring position is provided with K fluorescence coating ring in its lower section, and K fluorescence coating ring is made by rare earth element or its high melting compound.

3. according to the described medical fixed anode K fluorescence enhancement mode X spool of claim 1, it is characterized in that pressing target plate (post) that each layer target sheet is pressed on the anode bodies, be processed with the heat radiation flow deflector at the copper anode body back side.

4. according to the described medical K fluorescence enhancement mode X spool of claim 1 (comprising fixed anode pipe or rotating-anode tube), it is characterized in that X line exit direction and electron beam incident angular separation are 105 ° to 125 °.

5. according to the described medical K fluorescence enhancement mode X spool of claim 1 (comprising fixed anode pipe or rotating-anode tube), it is characterized in that the X line is 15 ° to 25 ° to the target surface angle of emergence.