title: Gel phantom study of a cryosurgical probe with a thermosiphon effect and liquid nitrogen-cooled aluminum thermal storage blocks.
abstract: Cryosurgery is a minimally invasive treatment for certain types of cancers. Argon-based cryosurgical devices are available at present, however a large compressed gas cylinder with the pressure of 300 atmospheres is needed. To overcome these drawbacks, we developed a new cryosurgical probe measuring about 50 cm in length with separate lumens inside for liquid and gaseous ethylene to be used as a thermosiphon and liquid nitrogen-cooled aluminum thermal storage blocks. The probe needle was 8 cm in length and 3 mm in outer diameter. To investigate the freezing capabilities of our new cryosurgical system we inserted the needle 5cm into a poly-acrylamide gel phantom warmed to 36.5 ℃. Thermal storage blocks made of aluminum, cooled at -196 ℃ in liquid nitrogen, were attached to the condenser of the probe and replaced with thermal storage blocks every 4 to 5 minutes to compensate for warming. We took digital camera images of the ice ball at the needle and measured the temperature in certain locations of the cryoprobe. Ice ball formation started at one minute after cooling. The sizes (longest diameter × minimum diameter) at 10, 20 and 30 minutes after the start of the procedure were 4.5×2.1, 4.5×3.1 and 4.6×3.7 cm, respectively. During the procedure the minimum temperature of the condenser was -85 ℃ and the needle was -65 ℃. This newly developed compact cryosurgical probe with thermosiphon effect and cooled thermal storage blocks created an ice ball that can be used for cryosurgery within 20 minutes.
authors.affiliation: Brain & Mind Research Center, Nagoya University, Nagoya, Japan ; Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Isoda
authors.affiliation: Department of Radiology, Hamamatsu University Hospital, Hamamatsu, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Takehara
authors.affiliation: Twinbird Corporation, Tsubame, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Fujino
authors.affiliation: Twinbird Corporation, Tsubame, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Sone
authors.affiliation: Twinbird Corporation, Tsubame, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Zeon Medical Inc., Tokyo, Japan.
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Tsuzaki
authors.affiliation: Zeon Corporation, Tokyo, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Miyazaki
authors.affiliation: Research Equipment Center, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Fujie
authors.affiliation: Research Equipment Center, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Sakahara
authors.affiliation: JST Innovation Satellite Shizuoka, Japan Science and Technology Agency, Hamamatsu, Japan ; Strategic Innovation Division, Hamamatsu Agency for Innovation, Hamamatsu, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Maekawa
keywords: cryoablation; cryosurgery; cryotherapy; phantom study; thermosiphon