Dosimetry for tangential chest wall irradiation

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Dosimetry

Background:

• Megavoltage photon beams offer skin-sparing benefits in radiation therapy.
• Tangential beam techniques for chest wall irradiation can compromise this skin-sparing effect.
• Accurate skin dose assessment is crucial for optimizing radiotherapy planning and minimizing side effects.

Purpose of the Study:

• To investigate the skin dose distribution when using tangential beams for chest wall irradiation with 4- and 6-MV photons.
• To evaluate the impact of bolus application, including metal/tissue interface effects, on skin dose.
• To compare different dosimetry methods for measuring skin dose in this clinical scenario.

Main Methods:

• Utilized 4- and 6-MV photon beams for tangential chest wall irradiation.
• Employed film dosimetry, thermoluminescent dosimeters, and ionization chambers for dose measurements.
• Investigated the use of a flexible brass fabric bolus and assessed metal/tissue interface effects.

Main Results:

• The skin-sparing effect of megavoltage photons was diminished with tangential beam techniques.
• The application of a bolus significantly influenced the skin dose, with notable variations observed.
• Metal/tissue interface effects were identified when using a brass fabric bolus, indicating potential dose perturbations.

Conclusions:

• Tangential beam irradiation for chest wall treatment necessitates careful consideration of skin dose due to reduced skin-sparing.
• Bolus selection and material composition (e.g., metal/tissue interfaces) critically affect surface dose and require thorough dosimetric evaluation.
• Accurate skin dose measurement using multiple dosimetry techniques is essential for safe and effective radiotherapy of the chest wall.