Cryosurgical apparatus and methods

#This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in UK Patent Application No. 0111986.6 filed on May 16, 2001.

#This application relates to apparatus for and methods of performing cryosurgery and in particular to the prevention of damage to tissue surrounding that which is being treated.

#Cryosurgery is a modality utilising freezing for ablation of unwanted tissue—e.g. that of a tumour. Clinical experience indicates that for the best results and to ensure proper ablation of the necessary tissue, the tissue should be cooled below about −40° C. The effectiveness may be further enhanced by thereafter allowing the tissue to thaw and repeating the freezing process.

#Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

#FIG. 1 is a schematic block diagram of a thermal dosimetry system in accordance with the invention;

#FIG. 2 is an enlarged, schematic cross-sectional view of an embodiment of the invention being used in the cryotreatment of a prostate;

#Turning to FIG. 1 there may be seen a schematic block diagram of a thermal dosimetry system in accordance with the invention. A schematic representation of a patient's prostate gland is indicated by the reference numeral 2. A series of cryoapplicators 4 are inserted into the organ 2. These may be any commercially available applicators of the sort well known in the art. These function by allowing the expansion of highly pressurised argon gas from a gas source 6. Also inserted into the organ 2 are a series of fibre optic temperature probes 8 for monitoring temperature within the organ 2. These probes are described in greater detail in WO 01/18513 to which reference should be made for further information.

#The fibre optic thermal probes 8 are interrogated by a thermal data acquisition unit 10 the output of which is fed into a computer 12 on which the thermal properties of the organ 2 are modelled mathematically.

#Also provided in the proximity of the organ 2 is an ultrasound probe 14 of known type which is driven by a scanning unit 16 which feeds the resulting image data both to the thermal model 12 and an integration unit 18. The integration unit 18 integrates the thermal information received from the dosimetry model 12 and the ultrasound image information from the ultrasound scanner 16 and uses these to produce a visible image on a screen 20 showing the pattern of isotherms overlaid on the actual image of the organ 2. This image may be recorded on a video cassette recorder 22. The integration unit 18 is also connected to the cryoapplicator driving unit 6 which makes it possible for the integration unit 18 to control the cryoapplicators 4.