Experimental And Clinical Study Of Intracavitary Thermotherapy Applicator For Nasopharyngeal Carcinoma

Purpose: To study thermal distribution of the manufactured applicator for intracavitary thermotherapy of nasopharyngeal carcinoma (NPC) in simulated nasopharyngeal cavity of muscle phantom and rabbit thigh. According to experimental results, to regulate frame and length of the manufactured applicator and optimize the thermal distribution. To evaluate the clinical efficacy, thermal enhancement ratio(TER) and toxicity of combination of intracavitary thermotherapy and radiotherapy for nasopharyngeal carcinoma, then to provide experimental data for clinical use of the manufactured applicator in the future.Methods: This test was divided two parts. The first part: muscle phantom was made and the thermal distribution was showed by using liquid crystal membrane; A cavity as the simulated nasopharyngeal cavity was made in muscle phantom, then applicator and thermoscope probes were put into the cavity, the temperature of para—applicator and bilateral and basilar wall of the simulated nasopharyngeal cavity were determined respectively; Cavities as the simulated nasopharyngeal cavity were made in 6 healthy Zelanian rabbits' thigh, then the temperature of para—applicator and bilateral , parietal and basilar wall of the simulated nasopharyngeal cavity were determined respectively; The temperature in muscle, that the distance from the thermoscope probes in muscle to the applicator were 0.5 , 1.0cm, were determined respectively; The temperature outside the parietal wall which was made of bone of the simulated nasopharyngeal cavity were determined. The second part: Seventy untreated NPC patients were divided into combined group(intracavitary thermotherapy plus radiotherapy) and controlled group(radiotherapy alone) based on treatmental methods. The combined group was given intracavitary hyperthermia with a 915MHz microwavehyperthermia unit. The surface temperature of nasopharyngeal tumor ranged from 42 °C to 43 °C .The time was 40 minutes, once or twice per week, 4 weeks in all. Radiotherapy were delivered by 6MVX and lOMEVp in all patients. The total dose of nasopharyngeal primary tumor and cervical metastatic cancer were 70-80GY^ 60-70Gy- Fraction of 2Gy/fraction/day was delivered, 10/5Gy fractions/week. The clinical efficacy , thermal enhancement ratio and toxicity were compared in two groups respectively. The data were analyzed by using SPSS12.0 software.Results: The first part: Liquid crystal membrane showed that the thermal distribution of the fields which corresponded to parietal and lateroposterior wall of nasopharyngeal cavity and posterior naris was well. The sequence of the temperature ranged from top to low of all determined points in muscle phantom was para-radiator >. ipsilateral n contralateral and basilar wall of the simulated nasopharyngeal cavity; The sequence of the average temperature ranged from top to low of all determined points in rabbit thigh was para-radiator> ipsilateral> parietal n contralateral and basilar wall of the simulated nasopharyngeal cavity(F = 673. 38 P<0. 01). The depth where effective penetrated temperature attained in live animal tissue was lcm, The temperature outside the parietal wall was lower than that in the simulated nasopharyngeal cavity by 3°C average. The second part: The complete response rate (CRR) and overall response rate (ORR) of nasopharyngeal primary tumor were 65. 7% ^ 97.1% in combined group, compared to 31.4 % -. 77.1% in controlled group. The difference between the two groups was statistically significant (P<0. 01); The complete response rate (CRR) and overall response rate (ORR) of cervical metastatic cancer were 87. 5% ^ 100.0% in...