ON MODERN TECHNICAL APPROACHES OF THREE-DIMENSIONAL HIGH-DOSE LATTICE RADIOTHERAPY (LRT)

Purpose: Two-dimensional (2D) high-dose GRID radiotherapy has shown effective tumor control in the clinical setting, and radiobiological data suggest potent bystander/abscopal effects with this technique. We present a new technical concept using modern radiation therapy instrumentation to advance traditional GRID treatment to modern three-dimensional (3D) high-dose LATTICE radiotherapy (LRT). Materials and Methods: An array of focused high-dose volumes, in essence a lattice of doses in 3D, can be generated through modern techniques resulting in highly heterogeneous dose distributions within the tumor volume, leaving adjacent and peripheral normal tissue minimally exposed. Two technical approaches were investigated for this novel concept: non-coplanar focused beams and MLC-based or aperture-modulated arc. Results: High magnitude dose oscillation is essential in traditional GRID therapy. The 3D “peak-to-valley” dose fall-off (100% to 20-30%) characteristic was attainable in test LRT cases, with a greater ability to place dose peaks within the radiation target volume and minimal dose to surrounding normal tissue. Conclusion: Modern radiotherapy methods are readily available to deliver 3D high-dose LATTICE radiotherapy with superior dosimetry compared to the 2D GRID technique. This is an easily accessible therapeutic modality that could potentially result in comparable or superior treatment outcomes than traditional 2D GRID therapy when implemented in the clinical setting.