| 摘要 |
<p>An improved cryosurgical system includes means for cooling the cryoprobe instrument (300) to temperatures below the normal boiling point of liquid nitrogen as well as means for recovering the sub-cooled liquid coolant. A unique cryoprobe instrument (300) of simplified construction uses an active vacuum (11) for thermal insulation. Means are provided for controllably adjusting the length (L) of the freezing zone of the cryoprobe (300) to allow the freezing zone to be adjusted for different sizes and shapes of tumors which may be ''observed'' before surgery by ultrasound imaging. Multiple, disposable cryoprobe instruments (300) can be individually controlled for both operating temperature and freeze zone length (L). A preferred refrigeration system (10) for sub-cooling liquid nitrogen refrigerant or other cryogenic liquid refrigerant is based on the principles of evaporative cooling.</p> |
