Dosimetrical and geometrical parameters in single-fraction lattice radiotherapy for the treatment of bulky tumors: Insights from initial clinical experience.

PURPOSE: This study aims to investigate lattice radiotherapy (LRT) for bulky tumor in 10 patients, analyzing geometrical and dosimetrical parameters and correlations among variables. METHODS: Patients were prescribed a single-fraction of 18 Gy to 50 % of each spherical vertex (1.5 cm diameter). Vertices were arranged in equidistant planes forming a triangular pattern. Center-to-center distance (Dc-c) between vertices was varied from 4 to 5 cm. A new method for calculating the valley-to-peak dose ratio (VPDR) was proposed and compared to other two from existing literature. GTV volumes (VGTV), vertex number (Nvert), low-dose related parameters and vertex D99%, D50%, and D1% were recorded. Beam-on time and Monitor Units (MU) were also evaluated. Correlations were assessed using Spearman's coefficient, with significant differences analyzed using Mann-Whitney U test. RESULTS: Tumor volumes ranged from 417 to 3615 cm3. Median vertex number was 14.5 (IQR:11.3-17.8). VPDR ranged from 0.16 to 0.28. Median D99% spanned from 10.0 to 13.7 Gy, median D50% exceeded 18.0 Gy, and median D1% surpassed 23.3 Gy. Periphery dose remained under 4.0 Gy. Plans exhibited high modulation, with median beam-on time and MU of 8.8 min (IQR:8.2-10.1) and 13,069 MU (IQR:11574-13639). Significant correlations were found between Nvert and VGTV (p < 0.01), MU (p < 0.02) and beam-on time (p < 0.01) and between Dc-c and two VPDR definitions (p < 0.02) and periphery dose (p < 0.01). Significant differences were observed among the three valley dose definitions (p < 0.01) and the three peak dose definitions (p < 0.01). CONCLUSIONS: Reporting geometrical and dosimetrical parameters in LRT is crucial, alongside the need for unified definitions of valley and peak doses.

Radiotherapy for ostheoarticular degenerative disorders: When nothing else works.

Objectives: Show the results in pain and functionality, using low-dose radiotherapy in osteoarticular degenerative disorders (OADD). Review of the evidence. Material and methods: Patients suffering from OADD with no response to other treatments, receive 6Gy in 6 fractions of 1 Gy, each other day, repeating the scheme if necessary. Evaluation of pain based on Visual Analogic Scale, analgesia intake and VonPannewitz score. Results: Results observed in our series of patients treated with low doses of radiotherapy are similar to those previously published and reinforce the consideration of radiotherapy as an useful option for degenerative musculoskeletal disorders. Conclusion: Low dose radiotherapy seems to be a good alternative for aged patients suffering from OADD.