Dosimetry and techniques for simultaneous hyperthermia and external beam radiation therapy

Area of Science:

• Oncology
• Medical Physics
• Radiation Oncology

Background:

• Combining hyperthermia with radiation therapy significantly increases biological effect for cancer treatment.
• Advancements in technology allow for simultaneous delivery of hyperthermia (ultrasound or microwave) and photon radiation therapy.
• Two clinical techniques, orthogonal and en face, have been developed for concomitant thermoradiotherapy.

Purpose of the Study:

• To detail the dosimetry and logistics of simultaneous thermoradiotherapy techniques.
• To present findings based on 7 years of clinical experience with over 50 patients.
• To provide insights into the practical implementation of combined hyperthermia and radiation therapy.

Main Methods:

• Description of the orthogonal technique (beams are perpendicular).
• Description of the en face technique (beams share the same path), including necessary specialized attachments for linear accelerators.
• Discussion of unique simulation, dosimetry, and operational requirements for each technique, including hyperthermia physicist involvement and consideration of applicator/reflector attenuation.

Main Results:

• The en face technique requires specialized attachments for mounting hyperthermia devices to the linear accelerator.
• Both techniques necessitate close collaboration between hyperthermia and radiation therapy personnel.
• Dosimetric considerations, including attenuation of microwave applicators and ultrasound reflectors, are crucial for the en face technique.

Conclusions:

• Simultaneous thermoradiotherapy, using either the orthogonal or en face technique, is clinically feasible.
• Careful planning of dosimetry and logistics is essential for successful implementation.
• Experience with over 50 patients over 7 years demonstrates the practical application of these combined treatment modalities.