An ablation probe, comprising: an applicator arranged to apply radiation to heat surrounding tissue; a feeding cable arranged to supply electromagnetic energy to the applicator; a first coolant flow path via which coolant is able to flow; a deformable member arranged to move between an insertion configuration in which insertion of the probe is facilitated and a deployed configuration, wherein the deformable member comprises a non-compliant material arranged to fold or unfold in order to move between the insertion and deployed configurations; a second coolant path, via which coolant is able to flow, the second coolant path being provided by the deformable member when in the deployed configuration, wherein a combination of the first and second coolant paths form a coolant circuit arranged to deliver a flow of coolant towards and away from the applicator, wherein coolant is able to flow: towards the applicator via the first coolant path and away from the applicator via the second coolant path; or away from the applicator via the first coolant path and towards the applicator via the second coolant path; and a tube arranged to house a distal portion of the feeding cable, wherein the deformable member surrounds at least part of the tube, wherein the ablation probe comprises: a. a needle portion adapted to be inserted into tissue during use, the needle portion comprising: the deformable member; the applicator; the distal portion of the feeding cable; at least part of the tube housing the distal portion of the feeding cable; and a distal portion of the first coolant path, and b. a catheter portion comprising: a proximal portion of the feeding cable; a proximal portion of the first coolant path; and a non-deformable coolant conduit, wherein the deformable member is fluidly connected to the non-deformable coolant conduit at a boundary between the needle portion and the catheter portion. an applicator arranged to apply radiation to heat surrounding tissue; a feeding cable arranged to supply electromagnetic energy to the applicator; a first coolant flow path via which coolant is able to flow; a deformable member arranged to move between an insertion configuration in which insertion of the probe is facilitated and a deployed configuration, wherein the deformable member comprises a non-compliant material arranged to fold or unfold in order to move between the insertion and deployed configurations; a second coolant path, via which coolant is able to flow, the second coolant path being provided by the deformable member when in the deployed configuration, wherein a combination of the first and second coolant paths form a coolant circuit arranged to deliver a flow of coolant towards and away from the applicator, wherein coolant is able to flow: towards the applicator via the first coolant path and away from the applicator via the second coolant path; or away from the applicator via the first coolant path and towards the applicator via the second coolant path; and a tube arranged to house a distal portion of the feeding cable, wherein the deformable member surrounds at least part of the tube, wherein the ablation probe comprises: a. a needle portion adapted to be inserted into tissue during use, the needle portion comprising: the deformable member; the applicator; the distal portion of the feeding cable; at least part of the tube housing the distal portion of the feeding cable; and a distal portion of the first coolant path, and b. a catheter portion comprising: a proximal portion of the feeding cable; a proximal portion of the first coolant path; and a non-deformable coolant conduit, wherein the deformable member is fluidly connected to the non-deformable coolant conduit at a boundary between the needle portion and the catheter portion. a. a needle portion adapted to be inserted into tissue during use, the needle portion comprising: the deformable member; the applicator; the distal portion of the feeding cable; at least part of the tube housing the distal portion of the feeding cable; and a distal portion of the first coolant path, and b. a catheter portion comprising: a proximal portion of the feeding cable; a proximal portion of the first coolant path; and a non-deformable coolant conduit, wherein the deformable member is fluidly connected to the non-deformable coolant conduit at a boundary between the needle portion and the catheter portion.