# Low Radiation Doses to Gross Tumor Volume in Metabolism Guided Lattice Irradiation Based on Lattice-01 Study: Dosimetric Evaluation and Potential Clinical Research Implication

## TL;DR

This study evaluates how much of a tumor receives low radiation doses during a new type of radiation therapy and suggests it could boost the immune system's fight against cancer.

## Contribution

The study introduces a novel dosimetric evaluation of low-dose radiation in metabolism-guided lattice irradiation and its potential to enhance immunotherapy.

## Key findings

- A median of 51.58% of the gross tumor volume received at least 3 Gy of radiation.
- The lattice irradiation technique combines high- and low-dose regions to potentially stimulate the immune system.
- Dosimetric data suggests this approach could be useful in future immunotherapy combination studies.

## Abstract

Purpose: This paper aims to calculate the gross tumor volume (GTV) receiving low radiation doses in patients submitted to “metabolism-guided” lattice radiation therapy and relative possible implications with clinical outcomes. Material and Methods: We reviewed plans for treating voluminous masses via “metabolism-guided” LATTICE-01 irradiation. The aim was to deliver high-dose radiation to spherical deposits (vertices) within a bulky tumor mass. These were placed at tumor areas with differing PET metabolism. We evaluated the relationships between GTV volumes and dose-volumetric histograms (mean, maximum, minimum, and % GTV received 0.5, 1, 2, 3 Gy). Results: Sixty-two plans of treatment met the inclusion criteria as established. The median GTV volume was 315.9 cc (range = 10.54–2605.9 cc). A median of two Vertices was allocated within the GTVs (range 1–9) and were planned to receive a dose of ≥10 Gy/1 fraction (median 12 Gy, range 10–15 Gy). Median V3Gy percentage was 51.58% (range 2–100%), median V2Gy percentage was 67.80% (range 1.60–100%), median V1Gy percentage was 83.70% (range 0.80–100%), and median V0.5Gy percentage was 88.49% (range 17.60–100%). Conclusions: In the present series, we performed a dosimetric evaluation of the GTV’s volume exposed to low doses during the metabolic guided lattice irradiation process. Combining high- and low-dose radiotherapy based on a spatially fractionated (LATTICE) approach could reactivate the immune system against cancer cells. These observations could be useful for planning prospective studies on immunotherapy combined with the lattice technique.