Prog Med Phys.  2023 Dec;34(4):48-54. 10.14316/pmp.2023.34.4.48.

Dosimetric Analysis of Lung Stereotactic Body Radiotherapy Using Halcyon Linear Accelerator

• Cho S
• Cho IJ
• Kim YH
• Jeong JU
• Yoon MS
• Nam TK
• Ahn SJ
• Song JY

• KMID: 2550125
• DOI: http://doi.org/10.14316/pmp.2023.34.4.48

Abstract

Purpose
In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability.
Methods
We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)—Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique.
Results
Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans.
Conclusions
Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.

Keyword

Lung SBRT; HD-MLC; Halcyon; PTV dose coverage; OAR dose constraint