Dosimetrical and geometrical parameters in single-fraction lattice radiotherapy for the treatment of bulky tumors: Insights from initial clinical experience.
Phys Med
; 123: 103408, 2024 Jul.
Article
em En
| MEDLINE
| ID: mdl-38889590
ABSTRACT
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 (IQR11.3-17.8). 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 (IQR8.2-10.1) and 13,069 MU (IQR11574-13639). 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.Palavras-chave
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Radiometria
Limite:
Aged
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Phys Med
/
Phys. medica (Testo stamp.)
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Physica medica
Assunto da revista:
BIOFISICA
/
BIOLOGIA
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MEDICINA
Ano de publicação:
2024
Tipo de documento:
Article