Fiagbedzi, Emmanuel;
Tagoe, Samuel Nii Adu;
Hasford, Francis;
Nisbet, Andrew;
(2025)
Influence of planning target volume margins using various prescription isodoses in gamma knife radiosurgery for single brain metastasis: a phantom study.
Journal of Radiotherapy in Practice
, 24
, Article e4. 10.1017/S1460396925000019.
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Abstract
Objective: The study seeks to evaluate the influence of planning target volume (PTV) margins on plan parameters during inverse planning of brain metastases with the Gamma Knife treatment unit, considering various prescription isodose levels (PIL). // Material & Method: CT scan images of a STEEV anthropomorphic phantom were transferred into the GAMMA PLAN Treatment Planning System. A target measuring a volume of 4·9cc was centrally contoured. Plans with a 0 mm volume margin at five prescription isodose levels from 50% to 70% at 5% increment were created. With 0.5 mm, 1 mm, 1.5 mm and 2 mm PTV margins, identical plans were regenerated. Adjustments were made to each plan when necessary to achieve same target coverage. One-way ANOVA test was used to analyse the influence of PTV margins on parameters including Selectivity[S], Gradient index [GI], V12, Paddick’s conformal index [PCI] and Treatment time [TI]. // Results: Margin addition resulted in PTV volume increase. The findings indicated that the PTV margin of 2.0 mm exhibited the highest mean selectivity of (0.93 ± 0.00), PCI (0.92 ± 0.01), GI (2.50 ± 0.04), V12 (16.17 ± 0.38) and treatment time (118.32 ± 2.91 min). The 0.0 mm PTV margin had the lowest mean value for all the parameters except for the treatment time (105.58 ± 3.48 min) which was slightly higher compared to the 0.5 mm PTV margin (M = 86.36 ± 4.13 min). // Conclusion: Incremental increases in PTV margins for Gamma knife radiosurgery though a relatively controversial concept influence all dosimetric parameters, which may pose potential detrimental effects and thus need to be carefully evaluated for brain metastasis treatment.
| Type: | Article |
|---|---|
| Title: | Influence of planning target volume margins using various prescription isodoses in gamma knife radiosurgery for single brain metastasis: a phantom study |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1017/S1460396925000019 |
| Publisher version: | https://doi.org/10.1017/s1460396925000019 |
| Language: | English |
| Additional information: | Copyright © The Author(s), 2025. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. |
| Keywords: | Gamma knife; margin; parameters; planning target volume; prescription isodose |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10208833 |
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