Magnetic Resonance Imaging-Guided Online Adaptive Lattice Stereotactic Body Radiotherapy in Voluminous Liver Metastasis: Two Case Reports

Abstract

Lattice Radiotherapy (LRT) is a technique in which heterogeneous doses are delivered to the target so large tumors can have optimal doses of radiation without compromising healthy tissue sparing. To date, case reports and case series documented its application for bulky tumors mainly in the pelvic region. LRT not only provides dosimetric advantages but also promotes tumor control by triggering some radiobiological and immunological pathways. We report two cases of giant liver metastases for whom other treatment options were not suitable. We treated both patients with Magnetic Resonance Image-Guided Radiotherapy (MRgRT) with online adaptive LRT (OALRT) technique. Adaptive plans were generated before each fraction. Tumors were observed to have regressed interfractionally so the location and number of spheres were adapted to tumor size and daily anatomy of the surrounding organs at risk (OAR). Both patients had good treatment compliance without any Grade 3+ side effects. They are both under follow-up and report improvement. By reporting the first application of OALRT by using MRgRT in liver metastases, we show that MRgRT is a promising modality for LRT technique with better target and OAR visualization as well as online adaptive planning before each fraction according to the daily anatomy of the patient.

Impressive Results after “Metabolism-Guided” Lattice Irradiation in Patients Submitted to Palliative Radiation Therapy: Preliminary Results of LATTICE_01 Multicenter Study

“…Actually, we reported a symptomatic response in 100% of patients, maintaining long-lasting symptom control in 28/30 patients. These results confirm both the low toxicity profile and clinical response observed in other published case series and case reports [ 19 , 20 , 21 , 22 ]. It is noteworthy to underline that in our patients, we observed a rapid symptomatic response after the first day of irradiation (radiotherapy to the vertices) in 3/30 patients, while a symptomatic benefit with a reduction in VAS score was reported within 8 days from the end of irradiation in all treated patients.…”

Spatially fractionated radiation therapy: a critical review on current status of clinical and preclinical studies and knowledge gaps

“…On the other hand, in LRT (Wu et al 2020) the spatial fractionation is only present in the target, where multiple localized high-dose spherical regions (1-2 cm size) called vertices are produced within the tumor, as represented in figure 2. Some techniques for delivering LRT include volumetric modulated arc therapy (VMAT) (Grams et al 2021), intensity-modulated radiation therapy (IMRT) (Dincer et al 2022), and proton/heavy ion beams with spot scanning nozzles (Wu et al 2020). The placement of vertices is optimized during planning to meet the dose criteria (the dose to the tumor periphery is kept to a level deemed tolerable by the surrounding normal tissues and critical organs).…”

Neoadjuvant Radiation Therapy with Interdigitated High-Dose LRT for Voluminous High-Grade Soft-Tissue Sarcoma

“…75,76 Keeping the essence of its 3D characteristics, LRT could be applied in various forms, from being the sole treatment, field-in-field simultaneous boost, integration with conventional RT, to having the vertices selectively placed in regions of differential biological significance. [77][78][79][80][81][82][83][84][85][86][87][88] Given the unique advantage of LRT over GRID in avoiding high doses to the surrounding normal tissues, it is a logical choice to use LRT for escalating boost dose further.…”