A time-saving system for irradiations of experimental tumors

Area of Science:

• Radiation oncology
• Experimental oncology
• Animal models in cancer research

Background:

• Clinical radiotherapy fractionation schedules are often mimicked in experimental settings.
• Anesthesia reliability and limited access to clinical linear accelerators hinder experimental radiotherapy.
• A need exists for efficient and reliable systems for in vivo tumor irradiation.

Purpose of the Study:

• To develop a reliable, time-saving system for irradiating xenografted tumors in mice.
• To facilitate repeated irradiations at short intervals for experimental radiobiology.
• To enable investigation of dose-modifying effects of gases and acute hypoxia.

Main Methods:

• A novel setup with an acrylic distributor for enflurane anesthesia.
• Simultaneous irradiation of ten mice positioned radially around the distributor.
• Irradiation of xenografted tumors using 15 MeV photons at 2.5 Gy/min.
• Acute hypoxia achieved using an integrated tourniquet; dose modification studies with different carrier gases.

Main Results:

• Minimal animal loss (<2%) due to anesthesia during repeated irradiations (up to 10 fractions).
• Dose variation within the treatment field <4% (TLD dosimetry); effective shielding of the whole body.
• Tourniquet technique effectively induced acute hypoxia, confirmed by 99mTc-albumin studies.
• Steep dose-response curves achieved for neurogenic sarcoma irradiation, indicating high precision.

Conclusions:

• The developed setup significantly saves time due to high dose rate and simultaneous irradiation of ten animals.
• Versatile applicability for investigating various radiobiological parameters, including hypoxia.
• The system is a valuable tool for tumor radiobiology research.