Spatially fractionated stereotactic body radiation therapy (Lattice) for large tumors

Abstract

Purpose Stereotactic body radiation therapy (SBRT) has demonstrated clinical benefits for patients with metastatic and/or unresectable cancer. Technical considerations of treatment delivery and nearby organs at risk can limit the use of SBRT in large tumors or those in unfavorable locations. Spatially fractionated radiation therapy (SFRT) may address this limitation because this technique can deliver high-dose radiation to discrete subvolume vertices inside a tumor target while restricting the remainder of the target to a safer lower dose. Indeed, SFRT, such as GRID, has been used to treat large tumors with reported dramatic tumor response and minimal side effects. Lattice is a modern approach to SFRT delivered with arc-based therapy, which may allow for safe, high-quality SBRT for large and/or deep tumors. Methods and Materials Herein, we report the results of a dosimetry and quality assurance feasibility study of Lattice SBRT in 11 patients with 12 tumor targets, each ≥10 cm in an axial dimension. Prior computed tomography simulation scans were used to generate volumetric modulated arc therapy Lattice SBRT plans that were then delivered on clinically available Linacs. Quality assurance testing included external portal imaging device and ion chamber analyses. Results All generated plans met the standard SBRT dose constraints, such as those from the American Association of Physicists in Medicine Task Group 101. Additionally, we provide a step-by-step approach to generate and deliver Lattice SBRT plans using commercially available treatment technology. Conclusions Lattice SBRT is currently being tested in a prospective trial for patients with metastatic cancer who need palliation of large tumors ( NCT04553471 , NCT04133415 ).

LITE SABR M1: a Phase I Trial of Lattice Stereotactic Body Radiotherapy for Large Tumors

“…Our treatment planning and quality assurance (QA) process has been detailed previously, and a guide of the treatment planning process is available. 16 Computed tomography (CT) simulation was completed with 3 mm slices and four-dimensional (4D) CT was used to assess tumor motion for all patients with thoracic and abdominal tumors above the iliac crest. Gated radiotherapy was used if tumor motion was more than 5 mm in a single direction.…”

“…We previously described a novel spatially fractionated SBRT technique – Lattice SBRT – that delivers 20 Gy in 5 fractions with a 66.7 Gy simultaneous integrated Lattice boost using volumetric modulated arc therapy (VMAT). 16 Here we present the results of the first prospective study of Lattice SBRT, LITE SABR M1: a single-arm phase I study of Lattice SBRT for large tumors (NCT04133415).…”

Divide and conquer: spatially fractionated radiation therapy

“…The dose is diminished in the surrounding normal tissues (Ref. 21) with respect to conventional irradiations (see Fig. 5).…”

Lattice or Oxygen-Guided Radiotherapy: What If They Converge? Possible Future Directions in the Era of Immunotherapy

“…Globally, no patient experienced severe lattice RT-related toxicities or death. The feasibility of lattice RT delivery in an SRT-like manner that also incorporates the SBRT dose constraints suggested by AAPM task group 101 [20] was demonstrated for eleven patients with large tumors (up to 4440 ccs) of various histologies and locations [21]. All above lattice treatments were planned with VMAT and commercially available technology equipment.…”