Recent Technical Developments in Cancer Hyperthermia

Chou, Chung‐Kwang; Luk, Kenneth H.

doi:10.1007/978-1-4612-3386-2_13

Cited by 3 publications

(1 citation statement)

References 44 publications

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“…[6][7][8][9] The problems have been how to effectively deliver heat to deep-seated tumors and how to con- tinuously measure the temperature in these deep-seated tumors during hyperthermia. [10][11][12][13] There are certain problems involved in invasive measurement of intratumoral temperature, especially in deep-seated tumors. In esophageal cancer and rectal cancer, for instance, it is very difficult to insert the catheter into the tumor.…”

Section: Discussionmentioning

confidence: 99%

Biological Cell Survival Mapping for Radiofrequency Intracavitary Hyperthermia Combined with Simultaneous High Dose‐rate Intracavitary Irradiation

Kurosaki

Sakurai

Mitsuhashi

et al. 2001

Japanese Journal of Cancer Research

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We examined the best way to combine recently developed radiofrequency intracavitary hyperthermia with simultaneous high dose-rate intracavitary brachytherapy in an original experimental model. Temperature distribution was measured with an experimental phantom which was immersed in a water bath with the temperature controlled at 37°C. Radiation dose distribution was calculated with a treatment-planning computer. Cell survival was measured by colony assay with HeLa-TG cells in vitro. Radiation dose response at 1-7 Gy and time response with hyperthermia in the range of 40-46°C were estimated. Radiation dose-response curves in simultaneous treatment with hyperthermia for 30 min at 37 to 46°C were estimated and the surviving fractions in combined treatment were plotted against temperature. For intracavitary radiation alone, cell survival rates increased with increasing distance from the source. For intracavitary hyperthermia alone, the maximum temperature was observed at a depth of 13 mm from the surface of the applicator under suitable treatment conditions. Homogeneous cell killing from the surface of the applicator to a tumor depth of 13 mm was observed under a specific treatment condition. Our experimental model is useful for evaluating the best simultaneous combined treatment. Key words: Intracavitary hyperthermia -Intracavitary brachytherapy -High dose-rate irradiationRadiofrequency hyperthermia -Experimental studyThe most effective combination of radiation and hyperthermia is considered to be simultaneous exposure, rather than sequential treatment.1, 2) However, external hyperthermia combined with simultaneous external irradiation for deep-seated tumors is difficult in clinical practice because it requires special devices.3-5) When simultaneous treatment can be applied to deep-seated tumors, an intracavitary or interstitial approach is probably necessary. A combination of recent developed radiofrequency (RF) intracavitary hyperthermia and intracavitary high dose-rate irradiation with iridium-192 sources seems to be a good method for simultaneous exposure to treat deep-seated advanced tumors.Although simultaneous treatment is theoretically attractive, quantitative data on temperature distribution under various heating conditions and on cytotoxicity, including hyperthermic radiosensitization, are not available. The aims of this study were therefore to collect temperature data on radiofrequency intracavitary hyperthermia with an original phantom under various heating conditions and to obtain cell survival maps in the case of simultaneous treatment with an in vitro experimental system. Finally, we investigated the conditions giving the most uniform cytotoxic effect, which should be the best for combined intracavitary hyperthermia and intracavitary radiation treatment. MATERIALS AND METHODSTemperature measurement in RF intracavitary hyperthermia A phantom was used for measuring temperature distribution (Fig. 1). An Endoradiotherm 100A (Olympus, Tokyo) operating at 13.56 MHz was selected as a device for intracavitary...

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Section: Discussionmentioning

confidence: 99%

Biological Cell Survival Mapping for Radiofrequency Intracavitary Hyperthermia Combined with Simultaneous High Dose‐rate Intracavitary Irradiation

Kurosaki

Sakurai

Mitsuhashi

et al. 2001

Japanese Journal of Cancer Research

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Evaluation of microwave hyperthermia applicators

Chou

1992

Bioelectromagnetics

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Hyperthermia has been used in conjunction with radiation and chemotherapy for cancer treatment. When using electromagnetic heating, applicators are critical components in contact with or in proximity to patients and can be the determining factor for effective and safe treatment. Tissue absorption of electromagnetic energy is determined by many factors. Three cases are shown to illustrate the complexity of microwave heating: 1) The BSD MA-151 applicator has good center heating on a muscle-only phantom as shown in the operation manual. When fat slabs of 0.25, 0.5, 1, and 2 cm thick were added, two hot spots near the periphery of the applicator were evident on all fat surfaces, exposed at 631 MHz. At 915 MHz, the heating was elongated on the surface of the models with 0.25- and 2-cm fat, and two hot spots were observed on the 0.5- and 1-cm fat surfaces. 2) Heating patterns of the Clini-Therm applicators on a muscle-only phantom, as indicated in the operations guide, are elliptical with their major axes perpendicular to the electric field. However, when a bolus is used, the elliptical pattern is parallel to the E field. 3) Heating patterns in cylindrical structures were studied with inhomogeneous models of limbs. Arm and thigh models consisting of fat, bone, and muscle material were heated with Clini-Therm L, M, and MS applicators at 915 MHz. In addition to the geometric effect, the results indicated that placing the applicators with E field parallel to the long axis of cylindrical structures can minimize required power, produce less heating of fats and reduce stray radiation. In conclusion, to apply penetrating microwave or other RF fields for tissue heating, one must simulate the clinical exposure conditions as closely as possible to obtain useful heating patterns.

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A Pilot Study of Intracavitary Hyperthermia Combined with Radiation in the Treatment of Oesophageal Carcinoma

Ren

Chou

Vora

et al. 1998

International Journal of Hyperthermia

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Twenty-five patients with primary squamous cell carcinoma of the oesophagus were treated with intracavitary hyperthermia combined with external beam radiation and intraluminal radiation at Nanjing Jinling Hospital, China. External beam radiation was given with a 6-MV X-ray; 1.8-2.0 Gy per fraction and five fractions per week; this brought the total dose to 60 Gy. Two weeks later, hyperthermia was applied with 915 MHz microwave intracavitary applicators, which were designed at the City of Hope. Temperature measurements were obtained while moving fibreoptic temperature sensors at 1.0 cm intervals in each of the six peripheral channels of the applicator. Hyperthermia was applied for 1 h before and after the intraluminal radiation. Intraluminal radiation was provided by low dose-rate iridium-192 ribbons in the same intracavitary applicator, giving 30 Gy at 0.75 cm from the applicator surface. The 3-month post-treatment responses showing complete response, partial response, no change and progressive disease were 60% (15/25), 24% (6/25), 8% (2/25) and 8% (2/25) respectively. The median follow-up time was 17 months (range 4-29 months). The 1- and 2-year overall survival rates were 72% (18/25) and 32% (8/25) respectively, and disease-free survival rates were 47 and 30% respectively. The median overall survival and disease-free survival periods were 17 and 10 months respectively. Fourteen patients had local recurrence (either at the primary site or in the lymph node) or had local progression, and five developed metastases. The median duration of the onset of local recurrence or of local progression was 9.5 months (range 0-20 months); the median of distant metastases was 8 months (range 2-16 months). Seventeen patients died. Of these, 15 died of cancer: six with local recurrence alone, four with local progression primary cancer alone, three with distant metastases alone, and two with both local and distant failure. Two patients with complete response of the primary disease died of other diseases. The toxicity was mild. According to the mucous reaction scoring criteria of the Radiation Therapy Oncology Group, the acute toxicity grades I, II, III and IV were 0% (0/25), 20% (5/25), 48% (12/25) and 32% (8/25) respectively. The major late complication was a mild oesophagus fibrosis and difficult swallowing. No serious side effects (grade IV), fistulas or perforations were seen. These results indicate that this method is safe and feasible for treating oesophageal carcinoma.

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Recent Technical Developments in Cancer Hyperthermia

Cited by 3 publications

References 44 publications

Biological Cell Survival Mapping for Radiofrequency Intracavitary Hyperthermia Combined with Simultaneous High Dose‐rate Intracavitary Irradiation

Biological Cell Survival Mapping for Radiofrequency Intracavitary Hyperthermia Combined with Simultaneous High Dose‐rate Intracavitary Irradiation

Evaluation of microwave hyperthermia applicators

A Pilot Study of Intracavitary Hyperthermia Combined with Radiation in the Treatment of Oesophageal Carcinoma

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