EP0333381A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Thermal seed for treatment of tumors
Assignee: Metcal Inc
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Filing: 1989-03-10
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Granted: —
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Expires: 2009-03-10
Abstract
Abstract A heater (seed) and system for subjecting tumors to closely controlled hypothermia or higher temperatures includes a core of ferromagnetic material having a high resistivity or resistivity of a non-conductor enclosed with a bio-compatible non-magnetic conductive sheath and excited by a coil positioned to establish a magnetic field coupled to the seed. The core is dimensioned so as to reduce demagnetizing effects to acceptable levels. The thickness of the conductive sheath is optimized to achieve a heat generating capacity which is considerably greater than that of the bare ferromagnetic material.
Inventors
- 👤 Philip S. Carter, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 12:52
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/40; A61N1/403; A61N1/406; A61B; A61B18/00; A61F; A61F7/00; A61F2007/009
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
121 words
A heater system for subjecting tumors to hyperthermia or higher temperatures comprising a heater including a core of ferromagnetic material having an elongated dimension, a sheath on and enclosing said core said sheath being of conductive material having a permeability of more than an order of magnitude less than the permeability of said core, a coil structure for producing a varying magnetic field intensity, means for locating said heater relative to said coil structure to have a current induced therein, said means including means for connecting said coil structure across a source of current alternating at a frequency of at least radio frequencies, said core having dimensions transverse to said elongated dimension of at least one-tenth that of the elongated dimension.
Claim 2
Dependent Claim
121 words
A heater system for subjecting tumors to hyperthermia or higher temperatures comprising a heater including a core of ferromagnetic material having an elongated dimension, a sheath on and enclosing said core said sheath being of conductive material having a permeability of more than an order of magnitude less than the permeability of said core, a coil structure for producing a varying magnetic field intensity, means for locating said heater relative to said coil structure to have a current induced therein, said means including means for connecting said coil structure across a source of current alternating at a frequency of at least radio frequencies, said core having dimensions transverse to said elongated dimension of at least one-tenth that of the elongated dimension.
Claim 3
Dependent Claim
18 words
A heater system according to claim 1 wherein the Curie temperature of said core is at least 110°F.
Claim 4
Dependent Claim
20 words
A heater system according to claim 1 further comprising a needle, said heater located at one end of said needle.
Claim 5
Dependent Claim
20 words
A heater system according to claim 1 wherein said core is cylindrical and said sheath covers all of said core.
Claim 6
Dependent Claim
13 words
A heater system according to claim 4 wherein said sheath is chemically inert.
Claim 7
Dependent Claim
15 words
A heater system according to claim 4 wherein the material of said sheath is bio-compatible.
Claim 8
Dependent Claim
16 words
A heater system according to claim 1 wherein said coil structure is a Helmholtz coil system.
Claim 9
Dependent Claim
16 words
A heater system according to claim 1 wherein said coil structure includes three mutually perpendicular coils.
Claim 10
Dependent Claim
21 words
A heater system according to claim 8 further comprising means for sequentially and successively applying said alternating current to said coils.
Claim 11
Dependent Claim
36 words
A heater system according to claim 1 wherein said core has a maximum transverse dimension in a range of one skin depth and less at the frequency of the current to be applied to said coil.
Claim 12
Dependent Claim
22 words
A heater system according to claim 1 wherein said core has a resistivity at least 10 times the resistivity of said sheath.
Claim 13
Dependent Claim
23 words
A heater system according to claim 1 wherein the resistivity of said core is at least 100 times than that of said sheath.
Claim 14
Dependent Claim
14 words
A heater system according to claim 1 wherein said core is a ferromagnetic alloy.
Claim 15
Dependent Claim
39 words
A heater comprising an elongated core of low conductivity high permeability ferromagnetic material, a sheath of high conductivity bio-compatible material surrounding said core, said core having a transverse dimension not more than one sixth the length of said core.
Claim 16
Dependent Claim
39 words
A heater comprising an elongated core of low conductivity high permeability ferromagnetic material, a sheath of high conductivity bio-compatible material surrounding said core, said core having a transverse dimension not more than one sixth the length of said core.
Claim 17
Dependent Claim
17 words
A heater according to claim 14 wherein the Curie temperature of said core is at least 110°F.
Claim 18
Dependent Claim
37 words
A heater according to claim 14 wherein said transverse dimension of said core is in a range of one skin depth and less at the frequency of a energizing magnetic field to be applied to said heater.
Claim 19
Dependent Claim
21 words
A heater according to claim 14 wherein said core has a resistivity at least 10 times the resistivity of said sheath.
Claim 20
Dependent Claim
21 words
A heater according to claim 14 wherein said core has a resistivity of at least 100 times that of said sheath.
Claim 21
Dependent Claim
12 words
A heater system according to claim 1 wherein the sheath is gold.
Claim 22
Dependent Claim
12 words
A heater system according to claim 1 wherein the sheath is silver.
Claim 23
Dependent Claim
31 words
A heater system according to claim 1 wherein the power vs sheath thicknesses for gold and molybdenum are defined by the graph of Figure 9 for current frequencies of one megahertz.
Claim 24
Dependent Claim
23 words
A heater system according to claim 1 wherein the thickness of said sheath is selected to provide maximum power dissipation in said sheath.
Claim 25
Dependent Claim
41 words
A heater system according to claim 1 wherein said sheath thickness is determined approximately by the formula where T is optimum thickness for candidate material T₁ is optimum thickness for gold R is candidate metal resistivity R₁ is resistivity of gold.
Claim 26
Dependent Claim
29 words
A heater system according to claim 1 wherein said coil is shaped to produce a maximum magnetic field parallel to the axis of the maximum length of said core.
References Cited (Backward Citations)
No citation records indexed.
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