Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization.

Area of Science:

• Oncology
• Medical Physics
• Radiation Oncology

Background:

• High-dose-rate (HDR) endobronchial brachytherapy is used for lung cancer treatment, but carries a risk of fatal hemoptysis.
• Up to one-third of patients undergoing this treatment may die from bleeding complications.

Purpose of the Study:

• To analyze the radial dose distribution of an Ir-192 HDR source.
• To evaluate the American Brachytherapy Society (ABS) recommendations for dose and prescription points.
• To perform a radiobiological analysis to minimize hemoptysis risk.

Main Methods:

• Monte Carlo simulation was used to calculate the radial dose rate of an Ir-192 HDR source.
• The linear quadratic model was applied to estimate palliative, curative, and blood vessel rupture radii.
• Analysis included ABS recommendations and customized HDR prescriptions.

Main Results:

• The estimated radius for blood vessel perforation with ABS recommendations is 7-9 mm.
• Optimized prescriptions may reduce the blood vessel perforation radius to as low as 4 mm.
• The calculated blood perforation radius is generally smaller than the palliative radius.

Conclusions:

• Individualized endobronchial HDR prescriptions are feasible and can minimize complications like fatal hemoptysis.
• Strategies such as fiducial stents, catheter centering, and CT imaging can enhance the therapeutic index.
• Prospective trials are needed to validate treatment optimization algorithms.