| Objective:Curretage is a method of treating benign bone tumor or tumor-like lesion .In clinically,it is applicated widly.In the process of operation,for example,the cavity wall of tumor tissue would usually be cauterized after tumor tissue was finished scoraping in order to preventing tumor from recurring.How long is the longest distance of destroying latent tumor tissue through heat conduction in the process of thermotherapy?The purpose of the experiment is to determine the longest distance through this way that normal bone tissue is radiated by thermotherapy machine with different time and different power .Theory base will be provided for destroying latent tumor cell through the experiment.Method:Collection of 60femur tissue specimens with freshly and immediately.These specimens were from those patient with malignant bone tumor who performed amputation surgery or mutilation operation . The tissue of bone with normally and freshly is taked and then removaled periosteum after operation. The specimens of bone is drilled every 3mm interval and it is drilled 8 hole in all. Eight point instrument of measuring temperature is connected with the CPU of measuring temperature computer and thermotherapy machine . Eight thread point in the instrument of measuring temperature is placed in the hole and is fixed.The time that the femurs are radiated with different power of 40±3W.60±3W.90±3W is 40 min,30min, 10min,20min. Measure the temperature of cortical bone every 3mm interval out of radiation point ,serial number from 1 to 8.Among these points,two points must be found,one point's temperature is lager than 50℃,another is less than 50℃. Determination of the distance of destroying bone tissue through heat conduction on the basis of 50℃and 10min are the temperature and the time of bone necrosis and of relation between distance,time and temperature.Result:1.The more bigger the power is ,the more longer time Is the more longer the distance of radiation is. Begin from radia- tion point, the temperature degrade gradually and the distrbution of it is of gradient.There is the larger temperature change in NO. 1to NO.4,however,there is the less temperature change in NO.5 to NO.8. under certain power,Give different actiontime,the more longer is away from radiation point,the more less is temperature change.The distance of destroying bone tissue tends to increase as the power is more and more larger and the time is more and more longer.Under 40±3W and 60±3W,The distance of destroyi- ng bone tissue increase obviously.However,under90±3W,heati- ng 20min.30min.40min.we find The distance of destroying bone tissue does not enlarge obviously.2.Make use of statistics software SAS,Kruskal-Wallis H testχ=9.780,10.82,12.50,9.50, P<0.05,That is to say, there is manifest difference in the distance of destroying bone tissue among 40±3W,60±3W and 90±3W.Then according to Bonferroni'test F=12.67,P<0.05.That is to say,there is manifest difference in the distance of destroying bone tissue between 40±3W and 60±3W or 40±3W and 90±3W.but there is not manifest difference between 60±3W and 90±3W.Conclusion: according to experimental data,the distance of heat transfering for bone cortical is very short.The distance is only 2.4cm in the power of 90W and the time of 40min. So thermotherapy is a kind of safe method after curretage. and it is fairly poor to bone cortical for its efficiency of heat conduction.The distance of destroying bone tissue was fairly short. It is only 1.708±0.080cm long in 90W and 40min.According to statistical result, heating 40min. for femurs in different power , there is not manifest difference between 60±3Wand 90±3W.That is to say,the distance of destroying bone tissue will tend to certain limit as the power is more and more larger and the time is more and more longer. Apprantly,if we make the power large,the distance of destroying bone tissue would not increase.In the power of 90±3W.heating femur tissue 20min.30min.40min.we find 50℃is all between point 5to point 6.Obviously,if we lenghthen time, the distance of destroying bone tissue would not increase but it can caused heat injury to nomal tissue around tumor cavity.For us,we should use the longer time and the larger power to heat cavity wall of tumor tissue after we perform the operation of curettage.In order to destroy latent tumor cell,We advise to use 60±3W and the time of heating 20min to 30min.to heat cure and the distance among radiation point is not larger than 1.708±0.080cm.
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