Brown S L, Li X L, Pai H H, Worthington A E, Hill R P, Hunt J W
Ontario Cancer Institute, Toronto, Canada.
Int J Hyperthermia. 1992 Mar-Apr;8(2):275-87. doi: 10.3109/02656739209021782.
Actual thermal gradients in perfused tissues are difficult to observe using thermocouples because of thermal conduction along the probes. We have used fine type-K (chromel-alumel) probes, which have a much lower thermal conductivity than equivalent-sized type-T (copper-constantan) thermocouples, to examine thermal gradients in two mouse tumour systems during water bath heating. The results indicate substantial heterogeneity in temperature distribution even in tumours transplanted in the foot and immersed to a depth of 2 cm in a 44 degrees C water bath for 20 min, i.e. thermal gradients greater than 1 degree C/mm were observed in KHT fibrosarcomas. The temperature heterogeneity for water bath heating is primarily a result of blood flow and appears to be tumour-specific. Temperature measurements using an excised perfused canine kidney demonstrate that increased perfusate volume flow increases the range of tissue temperatures. Consistent with theory, an artifactual improvement in temperature homogeneity resulted when temperature was measured using type-T thermocouples instead of type-K probes. These results emphasize the difficulties in obtaining accurate temperature measurements during experimental and clinical hyperthermia. Even extensive measurements of temperature in tissues may underestimate the true range of heterogeneity unless factors such as thermal smearing are controlled.
由于沿着探针的热传导，使用热电偶很难观察到灌注组织中的实际热梯度。我们使用了精细的K型（镍铬-镍硅）探针，其热导率比同等尺寸的T型（铜-康铜）热电偶低得多，以研究在水浴加热过程中两个小鼠肿瘤系统中的热梯度。结果表明，即使在移植到足部并浸入44℃水浴中2厘米深度20分钟的肿瘤中，温度分布也存在显著的异质性，即在KHT纤维肉瘤中观察到大于1℃/毫米的热梯度。水浴加热的温度异质性主要是血流的结果，并且似乎是肿瘤特异性的。使用切除的灌注犬肾进行温度测量表明，灌注液体积流量增加会增加组织温度范围。与理论一致，当使用T型热电偶而不是K型探针测量温度时，温度均匀性出现了人为的改善。这些结果强调了在实验性和临床热疗期间获得准确温度测量的困难。除非控制热涂抹等因素，否则即使对组织进行广泛的温度测量也可能低估异质性的真实范围。
