Deep local hyperthermia for cancer therapy: external electromagnetic and ultrasound techniques.

External heating techniques for delivery of localized hyperthermia in patients are reviewed. This paper covers microwaves, radiofrequency, and ultrasound methods. Fundamental principles governing tissue absorption, guidelines for applicator selection and design, and restrictions of each heating approach are discussed. Innovative techniques utilizing multiple applicators to achieve better heating uniformity are also presented. The advantages and disadvantages of electromagnetic versus ultrasound heating techniques are compared as a conclusion to this review.

Cheung AY ，Neyzari A 《CANCER RESEARCH》

Applications of microwave, ultrasound, and radiofrequency heating.

Different needs must be considered in the control of localized tumors or disseminated disease when deep heating techniques are used. For localized disease, various electromagnetic microwaves, radiofrequency currents and high-powered ultrasound sources are being used. At the present time, each approach has its own strengths and limitations. Microwave and inductive approaches appear to be useful only for surface lesions. Radiofrequency currents, generated by pairs of plates, give more deeper heating in the body, but excessive heating occurs in fatty layers related to high resistivity of the tissue and sometimes near the edge of the applicators. In an invasive approach, needles are implanted into the tumor and excited by a radiofrequency source. Considerable clinical successes are claimed for local heating of the lesion with this approach, but it is only useful for specific sites of the body. Ultrasound has special advantages for both surface or deep-seated soft tissues due to its flexibility and its ability to focus the beam onto the lesion. However, ultrasound cannot be used in the chest cavity or near bone, and the dosimetry is not defined at present. For disseminated disease, much larger regions, particularly in the chest cavity, can be heated, with the hope that the reduced blood circulation in some tumors can achieve a preferential heating in the lesion. Several microwave and inductive heating approaches are being used or considered in the achievement of this goal.

Hunt JW 《-》

Hyperthermia in the treatment of cancer.

The clinical use of hyperthermia for the treatment of cancer continues to be hampered by technical difficulties. Current methods of local heating do not give satisfactory heat profiles. The biological concepts behind the potentially successful use of this treatment modality are discussed together with a review of the advantages and disadvantages of the various techniques employed. Some clinical studies using microwaves and radiofrequency heating are reviewed.

Bleehen NM 《-》

An edge-element based finite element model of microwave heating in hyperthermia: application to a bolus design.

Heating of superficial tumours with microwave waveguide applicators has been shown in phase III trials to significantly improve the local control of small lesions when combined with radiation therapy. This success has not yet translated to the treatment of larger tumours, due to difficulty in adequately heating the entire tumour region. Several modifications to the water bolus used with external waveguide applicators have been made in the past in order to increase the heating area. One such modification consisted of a large, microwave-absorbing patch placed inside the bolus, which flattens out the beam profile produced by the applicator. Using this bolus instead of a conventional one resulted in a 30% increase in the effective heating volume produced by the BSD MA120 applicator. This paper describes an optimization procedure for this bolus design which utilises a new finite element model of microwave heating described in an accompanying paper. The optimization procedure resulted in a further 28% increase in the effective heating volume.

Kumaradas JC ，Sherar MD 《INTERNATIONAL JOURNAL OF HYPERTHERMIA》

Hyperthermia and cancer therapy: a review of biomedical engineering contributions and challenges.

Strohbehn JW ，Douple EB 《IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING》