Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
  • B01J19/122—Incoherent waves
  • B01J19/126—Microwaves

Definitions

• the present invention relates to a microwave device intended for the treatment of process liquids, prefer ⁇ ably the labelling of precursors to radiopharmaceuti- cals.
• the invention also relates to a method for treat ⁇ ing process liquids, preferably when labelling precur ⁇ sors to radiopharmaceuticals with the aid of microwave radiation.
• microwaves In certain cases, treatment with microwaves is able to increase drastically the rates of organic reactions. See in this respect R. Gedye et al, Tetrahedron Letters, 22279 (1986). Microwaves have also been earlier used for the preparation of positron-emitting precursors that are intended for labelling purposes; see R.a. Ferrieri et al, Int. J. Appl. Radiat. Isot.
• Microwaves have also been used in the preparation of radiopharmaceuticals labelled with 11C and 18F. Such microwave treatment processes result in short reaction times and higher yields of the radio- labelled product.
• the microwave device used in the aforesaid liquid reactions is a conventional domestic microwave oven. An oven of this kind normally has a microwave frequency of 2450 MHz.
• an accelerator for the preparation of radioactive isotopes which are formed into larger molecules in a subsequent radiochemical process and later administered to the patient, who is subsequently examined with a positron camera.
• the normal half-life of the isotopes is from 2 minutes to about 110 minutes. It will be realized that the radiochemical process must be capable of being carried out quickly, in view of the short half-life of the isotopes.
• the microwave field can be described as a periodically reversed electromagnetic field. The electrons in the polar molecules follow the field direction and are placed in periodic motion, which in turn results in the generation of heat, among other things.
• the drawbacks with the use of the aforesaid microwave oven when treating precursors to radiopharmaceuticals are that the microwave field cannot be adapted either to the type or to the quantity of the process liquid to be treated.
• the geometry of the oven is determined once and for all, and the microwave field can neither be concentrated nor varied with respect to strength and frequenc .
• the object of the present invention is to provide a method and a microwave device of the kind defined in the introduction which will enable a microwave cavity to be adapted geometrically to the amount and to the type of process liquid used, with the intention of shortening the process-liquid treatment time and of increasing the yield in which labelling substances are incorporated in a larger molecule.
• Figure 1 illustrates schematically a microwave device constructed in accordance with the invent- ion
• Figure 2 is a cross-sectional view of an alternative embodiment of the microwave cavity of the microwave device
• Figure 3 is a diagramme which illustrates the effect of the microwave cavity geometry on solvent boiling times
• Figure 4 is a diagramme which illustrates the effect of using salt in the process liquid to re ⁇ cute the boiling time of different solvents
• Figure 5 is a diagramme which illustrates the rela ⁇ tionship between the intensity of the micro ⁇ wave field and the boiling time of given, different solvents with a given microwave cavity geometry
• Figure 7 is a diagramme which illustrates the yield obtained when incorporating 18F with the aid of conventional heating processes in the absence of microwave treatment;
• Figure 8 is a diagramme corresponding to the dia ⁇ gramme of Figure 7 and illustrating the use of microwave treatment in a microwave device constructed in accordance with the invent ⁇ ion;
• Figure 9 is finally a diagramme which illustrates the effect of the microwave cavity geometry on tthhee iinnccoorrppoorraattiioonn of 18F in the reaction shown in Figure 6.
• Figure 1 illustrates a microwave device constructed in accordance with the present invention.
• the device includes an antenna 1 for radiating a microwave field.
• a microwave generator (not shown), which preferably has a variable power output, supplies the generated micro ⁇ wave signal through a coaxial cable connected to the antenna 1.
• the antenna 1 is illustrated purely schema ⁇ tically and may, for example, be of the horn type.
• the antenna is arranged in a microwave cavity 2 formed by a tube 3 having two end-walls 4 and 5.
• a first opening 6 penetrates the tube wall and is disposed substantially midway along the elongated tube.
• a second opening 7 is located opposite the first opening 6 and also pene ⁇ trates the tube wall.
• Each of two coaxial bars 8, 9 extend from a respective end-wall inwardly towards the centre of the tube. Both of the bars are arranged centrally within the tube and present two mutually opposing end surfaces 10, 11.
• Each of the bars extends through a respective end-wall and is carried for axial movement by a respective holder device 12, 13.
• Each holder device includes a plurality of spacers in the form of rods 14 which are arranged concentrically at the end-wall and which are anchored to respective end- walls 4, 5.
• the rods 14 carry a plate 15 which is provided with an opening 16 in which respective bars 7, 8 are mounted for axial movement.
• the end-walls 4, 5, which define the resonance chamber in the cavity, are mounted for axial movement in the tube 3 and the position of respective end-walls can be adjusted by manipulating a respective, schematically illustrated setting rods 17 and 18.
• the length of the cavity, i.e. the distance between the end-walls 4, 5 is related to the wavelength of the microwave field, in a known manner.
• a schematically illustrated sample container 19 filled with process liquid 20 to be treated with microwave radiation is inserted through the openings 6, 7.
• the positions of the bars 8, 9 are adjusted so that the microwave field will be con- centrated on the process liquid 20, this adjustment being contingent on the geometry of the container 19.
• the end surfaces 10, 11 of the bars must not be placed so close to the container so as to cause electric sparking between the end surfaces. Neither should the energy of the microwave field be so high as to result in electric sparking.
• the process liquid 20 is subjected to the microwave field concentrated by the bars 8, 9. Treatment time will vary according to the type of liquid concerned and the quantity of said liquid.
• the microwave container 19 shall be made of a non- metallic material which will not be polarized by the microwave field. Quartz is a preferred material, in this respect, although Teflon or Pyrex can also be used.
• the liquid treatment time can be shortened and the yield of the chemical reaction in said liquid can be increased by adjusting the distance between the mutually opposing end surfaces 10, 11 of the bars proportionally to the geometric shape of the container 19 located between said end surfaces, in other words by varying the geometry of the microwave cavity 2.
• the reaction time is shortened and the yield produced by said chemical reaction is increased in comparison to the case when a larger volume of process liquid and a correspondingly larger mutual distance between the end surfaces 10, 11 is used.
• Figure 2 illustrates a preferred embodiment of the microwave cavity in the area of the openings 6, 7.
• Two openings 21, 22 are provided opposite one another in the tube wall.
• the openings 21, 22 are displaced through an angle of 90° in relation to the openings 6, 7, as shown in Figure 2.
• the intensity of the microwave field can also be varied. This inten ⁇ sity, i.e. the field strength, may not be increased to unpermitted values at which electric sparking will occur between the bars 8, 9 or at which the process liquid will be destroyed.
• reaction time can also be shortened and the reac ⁇ tion yield also increased by adding salts to the pro ⁇ cess liquid with the intention of increasing the number of ions in the process liquid, therewith also increas- ing the dielectric constant of the liquid and improving the correlationship between the alternating microwave field and the movement of the molecules in the process liquid.
• Figure 4 illustrates the reduction in solvent boiling times when salt is added to the solvents.
• Figure 5 illustrates the correlationship between micro- wave intensity and the boiling time of different sol ⁇ vents with a microwave cavity and container of prede ⁇ termined geometry.
• Figure 6 illustrates the reaction of 18F with 4-nitro- 4'-fluorobenzophenone. Figure 6 also illustrates the reaction of 18F with 4-nitro- 4'-fluorobenzophenone. Figure 6 also illustrates the reaction of 18F with 4-nitro- 4'-fluorobenzophenone. Figure 6 also illustrates the reaction of 18F with 4-nitro- 4'-fluorobenzophenone. Figure 6 also illustrates the reaction of 18F with 4-nitro- 4'-fluorobenzophenone. Figure 6 also illustrates the
• Figure 9 illustrates how incorporation of 18F is influenced by the geometry of the container and the geometry of the microwave cavity.
• the incorporation of F increases from about 8% in the case of a tube diameter of 6 mm, to about 20% in the case of a tube diameter of 4 mm, when the sample is subjected in both instances to a microwave power of 35 watts for 2.5 minutes.
• it is not only the total incorporation of the products (A) and (B) in Figure 5 that is influenced by the geometry and field strength respectively, but also the distribution of the products.
• the microwave field can be con ⁇ centrated with the aid of lenses.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Drying Of Semiconductors (AREA)
• Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20379767

Family Applications (1)

Country Status (9)

Families Citing this family (19)

Citations (1)

Family Cites Families (8)

• 1990
  • 1990-06-14 SE SE9002117A patent/SE9002117L/sv not_active IP Right Cessation
• 1991
  • 1991-06-12 AU AU80727/91A patent/AU644193B2/en not_active Ceased
  • 1991-06-12 US US07/952,542 patent/US5308944A/en not_active Expired - Lifetime
  • 1991-06-12 JP JP03511166A patent/JP3126142B2/ja not_active Expired - Fee Related
  • 1991-06-12 DE DE69117290T patent/DE69117290T2/de not_active Expired - Fee Related
  • 1991-06-12 EP EP91912020A patent/EP0533814B1/en not_active Expired - Lifetime
  • 1991-06-12 WO PCT/SE1991/000426 patent/WO1991020169A1/en active IP Right Grant
  • 1991-06-12 AT AT91912020T patent/ATE134471T1/de not_active IP Right Cessation
  • 1991-06-12 CA CA002084754A patent/CA2084754C/en not_active Expired - Fee Related

Patent Citations (1)

Also Published As

Similar Documents

Legal Events