US3778654A - Molybdenum alloy target for mammographic usage in x-ray tubes - Google Patents

Molybdenum alloy target for mammographic usage in x-ray tubes Download PDF

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Publication number
US3778654A
US3778654A US00303015A US3778654DA US3778654A US 3778654 A US3778654 A US 3778654A US 00303015 A US00303015 A US 00303015A US 3778654D A US3778654D A US 3778654DA US 3778654 A US3778654 A US 3778654A
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molybdenum
percent
anode
tungsten
alloy
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Expired - Lifetime
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US00303015A
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English (en)
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R Hueschen
F Bernstein
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General Electric Co
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General Electric Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/04—Alloys based on tungsten or molybdenum

Definitions

  • This invention relates to mammography. More specifically, this invention relates to the X-ray tube and the anode therein employed in mammography.
  • the amount of tissue through which X-rays pass is generally much smaller with respect to the female breast compared to other parts of the body. Since there is no bone in the breast, it is not required, nor is it desirable to employ as high an energy beam to penetrate the breast as compared with the energy requirements for bone tissue. Therefore, in the area of diagnostic mammography, it is generally desirable to employ lower kilovoltages as compared to ordinary diagnostic X-ray techniques. The use of lower energy provides for greater contrast between fat and soft tissue and it is such contrast that is needed in order to obtain an optimum mammogram. I
  • tungsten is an ideal anode target primarily because of its high atomic number and melting point.
  • Ka and KB lines for tungsten requires a minimum of 70 kilovolts.
  • Mammography as a special medical diagnostic technique, requires special techniques in exposure, exposure time and exceptional X-ray film quality and detail.
  • the employment of lower kilovoltages is one means of achieving the fine film quality and details required in mammography.
  • By employing hard X- radiation the diagnostic quality of exposed film is seriously reduced because of a costly reduction in contrast.
  • the continuous and characteristic X-ray spectra for most metals and materials is well known.
  • the characteristic lines of a target material are excited at some minimum kilovoltage.
  • the kilovoltage required to produce the characteristic spectra changes regularly with the atomic number of the metal.
  • the characteristic molybdenum Ka line is excited at a minimum of 20 kilovolts.
  • the mas employed can vary from about several hundred mas to over 1,000 mas.
  • a primary object of the present invention is to provide an X-ray targetsubstantially comprising molybdenum, this target having superior properties with respect to withstanding mechanical stress from high energy impinging electrons. More specifically, it is an object to provide an X-ray anode which is an alloy of molybdenum and tungsten. Upon being subjected to low voltage techniques, the alloy will yield the continuous and characteristic X-ray spectra for molybdenum. The alloy unexpectedly and advantageously has improved properties with respect to low temperature ductility, resistance to thermal fatigue and increased high temperature strength as compared to a pure molybdenum target. I
  • an X-ray anode comprising an alloy of molybdenum and tungsten.
  • the alloy is a solid solution having superior strength compared to molybdenum at room temperatures and at elevated temperatures.
  • the grain size is smaller as compared to pure molybdenum and the atoms of the alloy are in clusters in the solid solution rather than in short range atom order.
  • Solid solution strengthening is important, particularly at elevated temperatures since the exposures required for mammography arerelatively long; This strengthening causes the anode to be more resistant to high thermal fatigue while being subjected to the impinging of high energy electrons.
  • the reduction of grain size results in reduced ductileto-brittle transition temperature thereby providing greater ductility at and above room temperature when the electron beam first strikes the cold anode target.
  • ductile-to-brittle transition temperature see U.S. Pat. No. 3,650,846 issued Mar. 21, 1972.
  • the reduction in ductile-to-brittle transition temperature results in a significant decrease in surface fracturing of the anode and more particularly of the target area.
  • the inhibition of brittle fracture is highly desirable since such fractures cause a marked decrease in X-radiation output intensity.
  • Clustering of atoms is more desirable than short range order since the alloy will evidence increased strength at high temperatures by solute strengthening and by providing improved dislocation mobility, and hence increased ductility at lower temperatures since solute clustering causes removal of interstitial elements from the matrix. That is, the increased ductility is a direct result of decreased interstitial elements within the grains (notably carbon and oxygen) which are known to drastically increase the ductile-to-brittle transition temperature.
  • a further object of this invention is to provide an X-ray tube adapted for mammographic application having a rotary metallic anode body with an exposed target area and electron beam means for producing electrons for impingement on the target area of the anode thereby producing X-ray emission, the anode comprising the alloy described herein.
  • an X-ray anode comprising an alloy of from about 95 to about 65 percent molybdenum and from about 5 to about 35 percent tungsten.
  • the alloy employed in accordance with the invention consists essentially of about 70 percent molybdenum and 30 percent tungsten.
  • the preparation of the alloy is according to standard and art recognized procedures and as such does not constitute a part of the invention.
  • the entire anode need not be made of the molybdenum-tungsten alloy.
  • the target area or the focal track can consist essentially of the alloy whereas the base can comprise other suitable materials such as tungsten, molybdenum and the like.
  • the procedures for making X-ray anodes are well known in the art and need no full elaboration.
  • an X-ray tube adopted for mammography applications comprising a metallic anode body with an exposed target area and electron beam means such as a cathode for producing an electron beam for impingement upon the target area thereby producing suitable X-rays for diagnostic mammography.
  • the anode body or at least the target area of the anode body comprises an alloy of molybdenum and about from 5 to about 35 percent tungsten.
  • the alloy consists essentially of about 70 percent molybdenum and about 30 percent tungsten.
  • FIG. 1 is a plot of X-ray tube output in terms of relative units versus thousands of exposures.
  • FIG. 2 is also a plot of X-ray tube output in terms of relative units versus thousands of exposures.
  • EXAMPLES l A pure molybdenum target is continuously exposed to an electron beam so as to provide X-radiation for mammographic applications under the following conditions: 40 peak kilovolts, 300 milliamperes, 2.5 second exposures. Two exposures are made per minute thereby providing 60,000 heat units per minute inputs. Heat units per minute (H) is defined as the product of the peak kilovoltage applied across the anode and cathode (kvp), the milliamperes (ma), the exposure time (s), and the number of exposures per minute (n) during a life test; H (kvp) (ma) (s) (n).
  • a molybdenum-tungsten alloy target consisting essentially of percent molybdenum and 30 percent tungsten is exposed under the same conditions.
  • the results of the radiation data are plotted in FIG. 1.
  • the X-ray output data is plotted as percent to which it decreased from the initial roentgen per minute value against the number of exposures taken by the tube during a life test. In all instances, the data is obtained using a 0.5 mm aluminum equivalent filter since the filter is generally employed in all mammographic applications.
  • a pure molybdenum target is continuously exposed to an electron beam so as to provide X-radiation for mammographic applications under the following conditions: 40 peak kilovolts, 300 milliamperes, 2.5 second exposures. One exposure is made per minute thereby providing 30,000 heat units per minute inputs.
  • Example 2 As in Example 1, a 0.5 mm aluminum equivalent filter is employed.
  • the molybdenum target output deteriorated rapidly as shown in FIGS. 1 and 2.
  • the pure molybdenum target output degraded to 45 percent (line B) of the original radiation output level after 3,500 exposures whereas the target prepared from the molybdenum-tungsten alloy (line A) evidenced an initial decrease to the 45 percent level after 9,500 exposures.
  • the crack propagation or fracturing of the target material ceased and the alloy target continued to produce useful radiation to 20,000 exposures.
  • the molybdenum target continued to degrade until after 20,000 exposures it retained only 20 percent of the initial radiation output level.
  • FIGS. 1 and 2 It is unexpectedly apparent as illustrated by FIGS. 1 and 2 that the alloying of tungsten to molybdenum enhances low temperature ductility while increasing the high temperature strength thereby enhancing its mammographic applications. This is shown upon comparison of FIGS. 1 and 2.
  • the molybdenum target subjected to 30,000 heat units per minute deteriorated at a more constant rate as compared to the same target subjected to 60,000 heat units per minute.
  • the more constant rate of deterioration of the former is apparently the results of being subjected to greater stresses because of the longer cooling time between exposures.
  • the alloy target subjected to 30,000 heat units per minute initially deteriorated more rapidly than the alloy exposed to 60,000 heat units per minute, however, the rate of deterioration of the former leveled out at a higher percentage output level.
  • An X-ray tube anode wherein at least the target of said anode comprises an alloy of molybdenum and from about 5 to about 35 percent of tungsten.
  • an X-ray tube adopted for mammographic applications having a rotary metallic anode body with an exposed target area and electron beam means for producing an electron beam impinging on said target area thereby producing X-ray emission, the improvement comprising said anode body having at least the target area comprising an alloy of molybdenum and from about 5 to about 35 percent tungsten.
  • the alloy comprises about 70 percent molybdenum and about 30 percent tungsten.
  • anode consists essentially of an alloy of molybdenum with from about 5 to about 35 percent of tungsten.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • X-Ray Techniques (AREA)
  • Radiation-Therapy Devices (AREA)
US00303015A 1972-11-02 1972-11-02 Molybdenum alloy target for mammographic usage in x-ray tubes Expired - Lifetime US3778654A (en)

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US30301572A 1972-11-02 1972-11-02

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US (1) US3778654A (de)
JP (1) JPS581504B2 (de)
AT (1) AT382259B (de)
DE (1) DE2354518C2 (de)
FR (1) FR2205742B1 (de)
GB (1) GB1448488A (de)
NL (1) NL180713C (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004174A (en) * 1973-11-02 1977-01-18 Tokyo Shibaura Electric Co., Ltd. Rotary anode structure for an X-ray tube
JPS55101086U (de) * 1979-01-04 1980-07-14
US4800581A (en) * 1986-10-27 1989-01-24 Kabushiki Kaisha Toshiba X-ray tube
US4993054A (en) * 1989-09-27 1991-02-12 General Electric Company Brazed X-ray tube anode assembly
WO1997013267A2 (de) * 1995-10-04 1997-04-10 Gkss-Forschungszentrum Geesthacht Gmbh Röntgenstrahlungsquelle
US5842700A (en) * 1996-10-08 1998-12-01 Smith International, Inc. Composite rock bit seal
US5913100A (en) * 1993-12-14 1999-06-15 Kabushiki Kaisha Toshiba Mo-W material for formation of wiring, Mo-W target and method for production thereof, and Mo-W wiring thin film
US5930330A (en) * 1995-09-29 1999-07-27 New Mexico Biophysics Method and apparatus for multitaxis scanning system
US20010038087A1 (en) * 1994-06-06 2001-11-08 Hadronic Press, Inc. New chemical species of a magnecule
EP2447710A2 (de) 2010-10-27 2012-05-02 Bruker AXS GmbH Verfahren zur röntgendiffraktometrischen Analyse bei unterschiedlichen Wellenlängen ohne Wechsel der Röntgenquelle

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328626A (en) * 1963-09-02 1967-06-27 Schwarzkopf Dev Co Rotary anodes of x-ray tubes

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT212573B (de) * 1959-07-31 1960-12-27 Plansee Metallwerk Duktile Wolfram- und bzw. oder Molybdänlegierungen
AT231581B (de) * 1962-05-25 1964-02-10 Plansee Metallwerk Drehanode für Röntgenröhren
US3650846A (en) * 1968-11-04 1972-03-21 Gen Electric Process for reconstituting the grain structure of metal surfaces

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328626A (en) * 1963-09-02 1967-06-27 Schwarzkopf Dev Co Rotary anodes of x-ray tubes

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004174A (en) * 1973-11-02 1977-01-18 Tokyo Shibaura Electric Co., Ltd. Rotary anode structure for an X-ray tube
JPS55101086U (de) * 1979-01-04 1980-07-14
JPS598384Y2 (ja) * 1979-01-04 1984-03-15 松下電器産業株式会社 音響機器
US4800581A (en) * 1986-10-27 1989-01-24 Kabushiki Kaisha Toshiba X-ray tube
US4993054A (en) * 1989-09-27 1991-02-12 General Electric Company Brazed X-ray tube anode assembly
US5913100A (en) * 1993-12-14 1999-06-15 Kabushiki Kaisha Toshiba Mo-W material for formation of wiring, Mo-W target and method for production thereof, and Mo-W wiring thin film
EP0947593A3 (de) * 1993-12-14 1999-12-15 Kabushiki Kaisha Toshiba Molybdän-Wolfram Werkstoff für Leitungsdrähte, Molybdän-Wolfram Fangelektrode und ihre Herstellungsverfahren, und Molybdän-Wolfram Legierung für Dünnschichtdrähte
US7153589B1 (en) 1993-12-14 2006-12-26 Kabushiki Kaisha Toshiba Mo-W material for formation of wiring, Mo-W target and method for production thereof, and Mo-W wiring thin film
US6200694B1 (en) 1993-12-14 2001-03-13 Kabushiki Kaisha Toshiba Mo-W material for formation of wiring, Mo-W target and method for production thereof, and Mo-W wiring thin film
EP0947593A2 (de) * 1993-12-14 1999-10-06 Kabushiki Kaisha Toshiba Molybdän-Wolfram Werkstoff für Leitungsdrähte, Molybdän-Wolfram Fangelektrode und ihre Herstellungsverfahren, und Molybdän-Wolfram Legierung für Dünnschichtdrähte
US20010038087A1 (en) * 1994-06-06 2001-11-08 Hadronic Press, Inc. New chemical species of a magnecule
US5930330A (en) * 1995-09-29 1999-07-27 New Mexico Biophysics Method and apparatus for multitaxis scanning system
WO1997013267A3 (de) * 1995-10-04 1997-06-05 Geesthacht Gkss Forschung Röntgenstrahlungsquelle
WO1997013267A2 (de) * 1995-10-04 1997-04-10 Gkss-Forschungszentrum Geesthacht Gmbh Röntgenstrahlungsquelle
US6123337A (en) * 1996-10-08 2000-09-26 Smith International, Inc. Composite earth boring bit seal
US5842700A (en) * 1996-10-08 1998-12-01 Smith International, Inc. Composite rock bit seal
EP2447710A2 (de) 2010-10-27 2012-05-02 Bruker AXS GmbH Verfahren zur röntgendiffraktometrischen Analyse bei unterschiedlichen Wellenlängen ohne Wechsel der Röntgenquelle
DE102010043028A1 (de) 2010-10-27 2012-05-03 Bruker Axs Gmbh Verfahren und Vorrichtung zur röntgendiffraktometrischen Analyse bei unterschiedlichen Wellenlängen ohne Wechsel der Röntgenquelle
US8867704B2 (en) 2010-10-27 2014-10-21 Bruker Axs Gmbh Method for X-ray diffractometry analysis at differing wavelengths without exchanging the X-ray source

Also Published As

Publication number Publication date
JPS581504B2 (ja) 1983-01-11
FR2205742A1 (de) 1974-05-31
NL7313894A (de) 1974-05-06
FR2205742B1 (de) 1979-05-04
NL180713B (nl) 1986-11-03
JPS4996690A (de) 1974-09-12
NL180713C (nl) 1987-04-01
DE2354518C2 (de) 1984-05-03
AT382259B (de) 1987-02-10
GB1448488A (en) 1976-09-08
DE2354518A1 (de) 1974-05-16
ATA926073A (de) 1978-01-15

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