Radiofrequency capacitive hyperthermia for deep-seated tumors. I. Studies on thermometry

The thermometry results of radiofrequency (RF) capacitive hyperthermia for 60 deep-seated tumors in 59 patients are reported. Hyperthermia was administered regionally using two RF capacitive heating equipments which the authors have developed in cooperation with Yamamoto Vinyter Company Ltd., (Osaka, Japan). Intratumor temperatures were measured by thermocouples inserted through angiocatheters which were placed 5 cm to 12 cm deep into the tissues. Tumor center temperatures were measured for 307 treatments in all tumors; thermal distributions within tumors and surrounding normal tissues were obtained for 266 treatments of 53 tumors by microthermocouples. Thermometry results obtained were summarized as follows. A maximum tumor center temperature greater than 43 degrees C and 42 degrees C to 43 degrees C was obtained in 23 (38%) and 14 (23%) of the 60 tumors respectively. The time required to reach 43 degrees C in the tumor center was within 20 minutes after the start of hyperthermia in 87% of tumors heated to more than 43 degrees C. Temperature variations within a tumor exceeded 2 degrees C in 81% of tumors heated to more than 43 degrees C. The lowest tumor temperature greater than 42 degrees C was achieved in six of the 53 tumors (11%). Of 42 tumors in which temperatures of the subcutaneous fat, surrounding normal tissues, and the tumor center were compared, 24 (57%) showed the highest temperature in the tumor center and ten (24%) in the subcutaneous fat. When the heating efficacy was assessed in terms of a maximum tumor center, it great deal depended on the treatment site, tumor size, thickness of subcutaneous fat, and tumor type. Tumors in the head and neck, thorax, lower abdomen, and pelvis could be heated better than tumors in the upper abdomen. Greater heating efficacy was shown in patients with large, hypovascular tumors, and with the subcutaneous fat measuring less than 15 mm thick. The predominant limiting factor for power elevation was pain associated with heating. Systemic signs including increases in pulse rate and body temperature were not serious and seldom became limiting factors for power elevation. Our thermometry results indicate that the advantages of deep RF capacitive heating are its applicability to various anatomic sites and negligible systemic effects. The disadvantages are that its primary usefulness is limited to patients with thin subcutaneous fat and with large or hypovascular tumors.     

Clinical results of radiofrequency capacitive hyperthermia in deep-seated tumors

The advantages of deep radiofrequency (RF) capacitive heating are its applicability to various anatomical sites and negligible systemic effects. The disadvantages are on the other hand, that its primary usefulness is limited to patients with thin subcutaneous fat and with large or hypovascular tumors. Clinical benefits of RF hyperthermia combined with radiotherapy are strongly suggested for deep-seated tumors. Intratumor low density areas on post-treatment CT and histopathological examinations are considered important parameters to assess the tumor response to thermoradiotherapy.     

Radiofrequency (RF) capacitive hyperthermia combined with radiotherapy in the treatment of abdominal and pelvic deep-seated tumors

Thermal parameters and tumor response were determined in 33 abdominal and pelvic deep-seated tumors which were treated with hyperthermia in combination with radiation therapy. Hyperthermia was applied regionally for a total of 3-14 sessions (mean; 6.4 sessions), using an 8 MHz radiofrequency (RF) capacitive heating device. An average tumor temperature (Tav) of more than 42 degrees C was achieved in 17 (52%) tumors, and intratumor temperatures above 42 degrees C could be maintained for more than 20 min (effective heat session) in 103 (52%) of the 198 heat sessions. Of the 33 tumors, 4 tumors exhibited complete regression (CR), 7 PRa (80-99% regression), 7 PRb (50-79% regression) and 15 NR (less than 50% regression). Tumor response (CR + PRa) was apparently dependent on the thermal parameters. Tumors with Tav of more than 42 degrees C or those receiving more than three effective heat sessions showed a significantly higher response rate than those heated less effectively. This trend was also noted in minimum tumor temperature. As to radiation dose, most of the responders received a total of 60-70 Gy irradiation. The two characteristic features in tumor response in effectively heated tumors, were slow tumor regression and appearance of an intratumor low density area on post-treatment computed tomography.     

Radiofrequency capacitive hyperthermia for superficial malignant-tumors

Eighteen patients with inoperable head, neck and upper chest wall cancers underwent radiofrequency hyperthermia in combination with chemotherapy and radiotherapy (HCR therapy). Of the eighteen patients, three showed complete response (CR); eight, partial response (PR); four, no change (NC); and three. progressive disease (PD). The overall efficacy (%CR+PR) was 61.1%. The efficacy tended to be higher in the patients treated with a maximal intratumoral temperature over or equal to 43-degrees-C (71%) than that in patients treated with under 43-degrees-C (25%). As the local control of the tumors was not related with their prognosis it is important that the patients should undergo not only regional hyperthermia but also systemic chemotherapy. Eight patients, who had suffered from heat burns, have all been cured by conservative therapy. These results suggested that HCR therapy might be useful in treating inoperable superficial malignant tumors, and be well tolerated under protection from skin bums.     

Heating efficiency of radiofrequency capacitive hyperthermia for treatment of deep-seated tumors in the peritoneal cavity

We analyzed heating profiles from 318 hyperthermic treatments of 39 patients with recurrent or inoperable cancers of the digestive organs whose deep-seated tumors were treated by radiofrequency (RF) capacitive heating of the abdominal region, and we investigated the heating efficiency and antitumor effect of such treatment. It was apparent that heating with a mean maximum RF output of 1,000 watts (700 watts at least), repeated four times or more, was necessary for a high rate of response by the tumor. Although it was difficult to heat tumors of the bile duct/pancreas to 42 degrees C or more, there was a strong positive correlation between maximum output of RF energy and maximum temperature of tumors (r = 0.839, P less than 0.001). The antitumor effect of RF hyperthermia was augmented with increasing output of RF energy. Therefore, the maximum level of RF output may be a useful index for expressing the heating efficiency with respect to intra-abdominal deep-seated tumors.     

Radiofrequency capacitive hyperthermia combined with irradiation or chemotherapy for patients with invasive bladder-cancer

The immediate therapeutic clinical efficacy and long-term outcome of hyperthermia in combination with irradiation or chemotherapeutic agent was evaluated in 46 patients with invasive bladder cancer. Radiohyperthermia was performed in 19 cases and chemohyperthermia in 27 cases. Complete response (CR) was obtained in 5 and partial response (PR) in 15 of the 46 cases. Five-year survival rates by the Kaplan-Meier method were 43.8% in the CR/PR group and 18.3% in the no change (NC)/progressive disease (PD) group, showing no difference of survival rate between the CR/PR group and the NC/PD group. The overall median survival period for the CR/PR group without metastasis was 61.6 months compared to 32.3 months for the NC/PD group without metastasis (P<0.05).     

Treatment planning for capacitive regional hyperthermia.

Capacitively coupled hyperthermia devices are widely in use, mainly in Asian countries. In this paper, a comprehensive treatment planning system, including a Specific Absorption Rate (SAR) and thermal model for capacitively coupled hyperthermia, is described and demonstrated using a heterogeneous patient model. In order to accurately model a hyperthermia treatment, simulation at high resolution is mandatory. Using the quasi-static approximation, the electromagnetic problem can be solved at high resolution with acceptable computational effort. The validity of the quasi-static approximation is demonstrated by comparing the Maxwell solution of a phantom problem to the quasi-static approximation. Modelling of capacitive hyperthermia of the prostate reveals the difficulty of heating deep-seated tumours in the pelvic area. Comparison of the SAR distribution in the heterogeneous patient model and a patient shaped agar phantom shows a shielding effect of the pelvic bone and the influence of the fat-muscle distribution. It is shown that evaluation of capacitive hyperthermia with agar phantoms leads to overly optimistic conclusions. Therapeutic relevant tumour temperatures can only be obtained by permitting temperature extrema in normal tissue. This concurs with clinical practice, where treatment-limiting hot spots restrict the tumour temperature. It is demonstrated that the use of very cold overlay bolus bags has only a very superficial effect. The presented model can be used for individual treatment planning and optimization, for the evaluation of capacitive applicator modifications and comparison with other devices.     

Locoregional hyperthermia of deep-seated tumours applied with capacitive and radiative systems: a simulation study

Background: Locoregional hyperthermia is applied to deep-seated tumours in the pelvic region. Two very different heating techniques are often applied: capacitive and radiative heating. In this paper, numerical simulations are applied to compare the performance of both techniques in heating of deep-seated tumours.

Methods: Phantom simulations were performed for small (30?×?20?×?50?cm³) and large (45?×?30?×?50?cm³), homogeneous fatless and inhomogeneous fat-muscle, tissue-equivalent phantoms with a central or eccentric target region. Radiative heating was simulated with the 70?MHz AMC-4 system and capacitive heating was simulated at 13.56?MHz. Simulations were performed for small fatless, small (i.e. fat layer typically <2?cm) and large (i.e. fat layer typically >3?cm) patients with cervix, prostate, bladder and rectum cancer. Temperature distributions were simulated using constant hyperthermic-level perfusion values with tissue constraints of 44?°C and compared for both heating techniques.

Results: For the small homogeneous phantom, similar target heating was predicted with radiative and capacitive heating. For the large homogeneous phantom, most effective target heating was predicted with capacitive heating. For inhomogeneous phantoms, hot spots in the fat layer limit adequate capacitive heating, and simulated target temperatures with radiative heating were 2–4?°C higher. Patient simulations predicted therapeutic target temperatures with capacitive heating for fatless patients, but radiative heating was more robust for all tumour sites and patient sizes, yielding target temperatures 1–3?°C higher than those predicted for capacitive heating.

Conclusion: Generally, radiative locoregional heating yields more favourable simulated temperature distributions for deep-seated pelvic tumours, compared with capacitive heating. Therapeutic temperatures are predicted for capacitive heating in patients with (almost) no fat.     

Radiofrequency capacitive heating of deep-seated tumours using pre-cooling of the subcutaneous tissues: results on thermometry in Dutch patients.

The capacity of a radiofrequency, 13.56 MHz, capacitive hyperthermia system using extensive pre-cooling of the subcutaneous tissue to induce locoregional deep heating has been investigated in 11 patients. Tumour location was presacral in nine--and eccentric towards the lateral side of the pelvis in two patients. For thermometry multiple catheters (mean 2.7) were inserted into the treatment volume. The mean numbers of temperature measuring points per treatment were 9.4 in tumour, 5.5 in muscle and 7.2 in subcutaneous fat. RF energy was applied after 30 min of cooling through two flexible boli perfused with saline water at 5-10 degrees C. Patient tolerance to pre-cooling was very good and after some initial discomfort the patient became rapidly accustomed to the cold water boli. For some patients better temperatures were achieved when the conventional anterior-posterior applicator set-up was replaced by a set-up with an applicator on each lateral side of the patient. As patients can tolerate temperatures within the fat tissue as high as 45.5 degrees C without complaining it appears important to monitor the temperature at the transition of fat to muscle tissue to prevent subcutaneous burns. The study shows that pre-cooling cannot avoid preferential heating at the interface from fat to muscle tissue. In this patient group the quality of the hyperthermia treatment appeared to be rather poor: 60% of the measured tumour temperatures were below 40 degrees D.     

Treatment planning for capacitive regional hyperthermia

Capacitively coupled hyperthermia devices are widely in use, mainly in Asian countries. In this paper, a comprehensive treatment planning system, including a Specific Absorption Rate (SAR) and thermal model for capacitively coupled hyperthermia, is described and demonstrated using a heterogeneous patient model. In order to accurately model a hyperthermia treatment, simulation at high resolution is mandatory. Using the quasi-static approximation, the electromagnetic problem can be solved at high resolution with acceptable computational effort. The validity of the quasi-static approximation is demonstrated by comparing the Maxwell solution of a phantom problem to the quasi-static approximation. Modelling of capacitive hyperthermia of the prostate reveals the difficulty of heating deep-seated tumours in the pelvic area. Comparison of the SAR distribution in the heterogeneous patient model and a patient shaped agar phantom shows a shielding effect of the pelvic bone and the influence of the fat-muscle distribution. It is shown that evaluation of capacitive hyperthermia with agar phantoms leads to overly optimistic conclusions. Therapeutic relevant tumour temperatures can only be obtained by permitting temperature extrema in normal tissue. This concurs with clinical practice, where treatment-limiting hot spots restrict the tumour temperature. It is demonstrated that the use of very cold overlay bolus bags has only a very superficial effect. The presented model can be used for individual treatment planning and optimization, for the evaluation of capacitive applicator modifications and comparison with other devices.     

Regional hyperthermia for clinically advanced deep-seated pelvic malignancy

Forty-three patients with deep-seated pelvic malignancy have been treated at the University of Utah on a pilot protocol involving regional hyperthermia (HT) produced by the BSD-1000 HT system and the annular phased array applicator (AA) usually driven at 60 MHz. Acute toxicity consisted primarily of pain within the AA aperture (74%), pain outside the aperture (33%), and bladder spasm (26%) or systemic stress (25%). Systemic stress only infrequently was power limiting. The most common power-limiting factors were pain (33%) and excessive heating of normal tissues (23%). In 9 patients (21%), there was no power-limiting factor. Treatment-related complications were uncommon and consisted of superficial second degree burns (3 patients), small bowel obstruction (1 patient), and rectal fistula (1 patient), all of which resolved with supportive nonsurgical therapy. Detailed thermal mapping and thermal dosimetry were performed on 36 patients. Thermal dosimetry parameters were all rather disappointing; however, the protocol prioritized the prevention of complications, and patients with acute toxicity or other power-limiting factors were not pushed to achieve high thermal doses. A logistic regression analysis was performed to determine if any factors were correlated with response (PR + CR). "Concurrent radiation dose" and "number of satisfactory heat treatments" were highly and independently correlated with response (p = 0.002). Responders (median survival = 10 months) survived significantly longer (p = 0.0014) than nonresponders (median survival = 4 months). Four of the responders are alive and currently without evidence of disease.     

Radiofrequency capacitive heating of deep-seated tumours using pre-cooling of the subcutaneous tissues: Results on thermometry in Dutch patients

The capability of a radiofrequency, 13.56 MHz, capacitive hyperthermia system using extensive pre-cooling of the subcutaneous tissue to induce locoregional deep heating has been investigated in 11 patients. Tumour location was presacral in nine—and eccentric towards the lateral side of the pelvis in two patients. For thermometry multiple catheters (mean 2.7) were inserted into the treatment volume. The mean numbers of temperature measuring points per treatment were 9.4 in tumour, 5.5 in muscle and 7.2 in subcutaneous fat. RF energy was applied after 30 min of cooling through two flexible boli perfused with saline water at 5–10°. Patient tolerance to pre-cooling was very good and after some initial discomfort the patient became rapidly accustomed to the cold water boli. For some patients better temperatures were achieved when the conventional anterior-posterior applicator set-up was replaced by a set-up with an applicator on each lateral side of the patient. As patients can tolerate temperatures within the fat tissue as high as 45.5° without complaining it appears important to monitor the temperature at the transition of fat to muscle tissue to prevent subcutaneous burns. The study shows that pre-cooling cannot avoid preferential heating at the interface from fat to muscle tissue. In this patient group the quality of the hyperthermia treatment appeared to be rather poor: 60% of the measured tumour temperatures were below 40°.     

Initial results of phase I/II interstitial thermoradiotherapy for primary advanced and local recurrent tumors

Since January 1986 in a phase I/II study, 45 lesions (30 head and neck, 11 pelvic, and 4 other lesions) in 44 patients (24 men, 20 women; age 18-81 years) received a combination of interstitial Ir-192 radiotherapy (IRT) and interstitial 915 MHz MW hyperthermia (IHT) supplemented by external radiation (ERT). In June 1989, evaluation was performed for lesions with minimum follow-up (FU) of 6 months and FU periods between 6 and 39 months (mean: 16 months, SD +/- 9). The tumors comprised 21 advanced primary (AP) lesions without prior ERT, 18 local recurrent (LR) and 6 local metastatic (LM) lesions with variable prior treatment modes; 24 lesions had received prior ERT between 40 and 70 Gy, 23 chemotherapy and 30 prior surgery. The mean dimensions of 42 lesions were 4.5 X 4.0 X 3.0 (cm3) with tumor volumes ranging from 12 to 135 cm3 (mean: 54 cm3, SD +/- 35); 3 lesions had extensive tumor volumes greater than 225 cm3. IHT was applied immediately prior to and/or after low-dose Ir-192 IRT (20-30 Gy) for 60 min at temperatures between 41 and 44 degrees C. ERT (40-50 Gy) was always given for AP and LM lesions, but variably applied for previously irradiated LR lesions, thereby avoiding the cumulative radiation dose exceeding 110 Gy per site. IRT doses ranged from 17-48 Gy (mean: 26.8 Gy, SD +/- 8) at a dose rate of 25-70 cGy/h (mean: 42 cGy/h, SD +/- 12). Thirty-three lesions received additional ERT of 30-56 Gy (mean: 46.5 Gy, SD +/- 9). Total radiation dose (IRT + ERT dose) ranged from 31 to 82 Gy (mean: 61 Gy, SD +/- 18). The hyperthermia systems of Lund/Buchler 4010 and Clini-Therm Mark VI/IX with thermistor or fiber-optic thermometry devices were employed. Initial response at 3 months FU showed 31 (69%) lesions complete response (CR), 10 (22%) partial response (PR), and 4 (9%) no change (NC). Long-term response of 30 lesions at 12 months FU revealed a total of 27 (90%) with local control (LC) and 3 (10%) in-field recurrences. Six patients died prior to 12 months FU, three with LC and three with progressive disease. So far 10 (22%) patients have developed distant metastases. Acute side-effects occurred in 15 lesions (33%) resulting in 12 (27%) long-term complications with 3 lesions (7%) requiring surgery.(ABSTRACT TRUNCATED AT 400 WORDS)     

Histopathological changes of human tumors following thermoradiotherapy

Twenty human malignant tumors treated with thermoradiotherapy were examined histopathologically. Hyperthermia was administered regionally with a 13.56-MHz or 8-MHz RF heating device, once or twice a week after irradiation, 2 to 12 sessions in total. Fifteen tumors received a total radiation dose of 26 to 70 Gy in fractions of 1.8 Gy to 2.0 Gy a day, 5 days a week, whereas five tumors received a total dose of 20 to 60 Gy in fractions of 4 Gy each, twice a week. Microscopic examination of 4 of the 20 tumors revealed complete necrosis throughout the cross-section of the entire tumor. All the four tumors had received a total dose of over 60 Gy and a tumor center temperature of over 42 degrees C. In 10 tumors, more than 50% but less than 99% of the cross-section of the entire tumor had massive coagulation necrosis. The remaining six tumors showed relatively little change; the area of intratumor necrosis was less than 50%. The grade of tumor necrosis was dependent on both the temperatures of tumor center and periphery, and a total radiation dose. The small blood vessels and capillaries in the tumor parenchyma were markedly damaged in 16 of the 20 tumors, while the blood vessels in the tumor stroma were damaged in only 2 tumors. Condensation of the destroyed nucleus observed in 15 tumors was considered to be a typical change induced by thermoradiotherapy. Viable tumor cells remained in the tumor central area in only four tumors and around the blood vessels in only three tumors. However, in the tumor peripheral area, viable tumor cells were observed in 16 out of the 20 tumors. These results indicate that histopathological changes induced by thermoradiotherapy are greater in the tumor central area than in the tumor peripheral area, and provide strong rationale for utilizing full dose radiation therapy in combination with hyperthermia as opposed to lower doses for cancer therapy.     

Regional hyperthermia for deep-seated malignancies using the BSD annular array

Forty-four patients were treated using the BSD-1000 Annular Phased Array between April 1983 and December 1986. There were 32 pelvic, nine abdominal, two extremity, and one thoracic sites treated. Mean tumour volume was 646 cc. Thirty-nine patients had concurrent radiation therapy, receiving a mean dose of 38 Gy. Mean average temperature was 41.0 +/- 1.4 degrees C. Most patients experienced local or systemic toxicity, requiring temporary treatment interruption in 33 patients, and termination of treatment in eight. Chronic complications were seen in four, but these were in patients receiving high total radiation doses as well. There were six complete and five partial responses. Among the 32 patients with pelvic tumours, mean tumour volume was 317 cc, mean radiation dose was 42 Gy, and mean average temperature was 41.3 +/- 1.2 degrees C. There were five complete and four partial responses. Achieving tumour temperatures greater than or equal to 42 degrees C with the annular array is difficult, due to both systemic and local toxicity. To improve clinical hyperthermia for thoracic, abdominal, and pelvic tumours, new technologies such as steerable phased array microwave systems; scanned, focused ultrasound; and permanently implantable thermoregulating ferromagnetic seeds, or new approaches such as using drugs to alter blood flow, or combining hyperthermia with antineoplastic drugs or biological agents, will be necessary.     

射频透热治疗恶性肿瘤56例疗效分析

目的报告应用国产ＳＲ１０００型射频热疗机治疗５６例深部恶性肿瘤的初步结果。方法５６例恶性肿瘤来源于１７种不同器官,均为晚期或手术后复发。其中男性４５例,女性１１例,平均年龄５３．５岁（３３～７３岁）。治疗方案：热疗＋化疗或热疗＋放射治疗。热疗机频率４１ＭＨｚ,功率５００～８００Ｗ,反射功率２０～４０Ｗ,时间６０～９０ｍｉｎ／次,３～８次。结果ＣＲ率７．２％,ＰＲ率６０．７％,ＭＲ率２１．４％,ＮＣ率１０．７％,其中ＣＲ＋ＰＲ率为６７．９％。并发症包括局部疼痛３例,脂肪硬结２例。结论国产ＳＲ１０００型射频热疗机用于治疗深部肿瘤,疗效确切,并发症少。     

Combined treatment of radiofrequency capacitive hyperthermia for urological malignancies

During the period from April 1984 to July 1993, we investigated the clinical efficacy of local hyperthermia used to treat 110 patients with urological malignancies. We investigated the long-term outcome of 40 (36.4%) responders who exhibited an immediate, partial or better response to the therapy. The one-year survival rate was 75% for retroperitoneal tumor, 65% for bladder cancer, 33% for each of renal cell carcinoma and prostatic cancer and 29% for renal pelvic and ureteral cancer. The 5-year survival rate was 48% for bladder cancer, 29% for renal pelvic and ureteral cancer, 25% for retroperitoneal tumor, and 0% for renal cell carcinoma and prostatic cancer. Subsidence of intolerable pain caused by cancer invasion was achieved in 29 of 42 patients (69.0%), indicating an improvement in patient's quality of life through pain relief.     

RTOG quality assurance guidelines for clinical trials using hyperthermia for deep-seated malignancy

Quality assurance has been vague or lacking in many previous hyperthermia trials. Recent publications by the Hyperthermia Physics Center, the Center for Devices and Regulatory Health, and the Radiation Therapy Oncology Group have described general guidelines for quality assurance in equipment reliability and reproducibility, superficial applications, and microwave techniques. The present report details quality assurance factors that are believed to be important for hyperthermia of deep clinical sites, defined as extending at least 3 cm beyond the skin surface. This document will discuss patient and physician factors, as well as thermometric accuracy, assessment of specific absorption rates (SAR), assurance of adequate coverage of tumors by the energy deposition pattern of the treatment device, and recommended documentation of the location, quantity, and frequency of treatment, specifically oriented to deep hyperthermia. The recommendations are structured to facilitate compliance in multiinstitutional trials.     

Experimental thermoradiotherapy of human tumour xenografts in nude mice: design of the hyperthermia system.

An experimental thermoradiotherapy study was started in 1986. For this study a hyperthermia system was developed for the heating of human tumours xenotransplanted into nude mice. Our treatment device was a four-channel computer-controlled hyperthermia system. Temperature was monitored by microwave radiometry at 3 GHz. Specifications of the radiometer were first evaluated under reference conditions, then thermal dosimetry was studied using non-invasive measurement of the brightness temperature TOR. Hyperthermia treatments were simulated in phantom material with radiometric monitor values TR of 40 and 41. In conjunction with the parameters of brightness temperature TOR, surface temperature TO and water bolus temperature TW thermal modelling was performed. Finally, we studied the influence of a perfused phantom to the microwave thermometry.     

Experimental thermoradiotherapy of human tumour xenografts in nude mice; design of the hyperthermia system.

An experimental thermoradiotherapy study was started in 1986. For this study a hyperthermia system was developed for heating human tumours xenotransplanted into nude mice. The treatment device was a four-channel computer-controlled hyperthermia system. Temperature was monitored by microwave radiometry at 3 GHz. Specifications of the radiometer were evaluated first under reference conditions. Subsequently, thermal dosimetry was studied using non-invasive measurement of brightness temperature, TOR. Hyperthermia treatments were simulated in phantom material with radiometric monitor values, TR, of 40 and 41. In conjunction with the parameters of TOR, surface temperature, T0, and water bolus temperature, TW, thermal modelling was performed. Influence of a perfused phantom also was studied on microwave thermometry.