Benefit of dosimetry distribution for patients with multiple brain metastases from non-small cell lung cancer by a Cyberknife stereotactic radiosurgery (SRS) system

Abstract

Background In order to obtain a high dose conformal index of tumor and steep dose fall-off in healthy tissues for brain metastasis stereotactic radiosurgery (SRS), the aim of this study was to investigate SRS planning optimization by comparing one multiple-lesions plan (MLP) with multiple single-lesion plans (SLPs) for patients with multiple brain metastases using the Cyberknife (CK) system. Methods Fifty non-small cell lung cancer (NSCLC) patients (28 males and 22 females) with 2–4 brain metastases, inter-tumour distances less than 3 cm, were retrospectively replanned with the original prescription dose (12–32 Gy) in the original fractions (1–3). Two different clinical CK SRS plans (SLPs and MLP) were generated for the same patients with the same collimator and prescription isodose line (62–68%) by the CK Multiplan System. Both SLPs and MLP were able to achieve > 95% PTV volume covered prescription dose and met the Timmerman 2011 organs at risk (brainstem, optic nerve and pituitary) constraints. Results Compared with those in the SLPs, the maximum dose (Dmax) and mean dose (Dmean) of brainstem in the MLP were reduced 0.22–3.13% (2.62%) and 2.71–12.56% (5.57%), respectively, all P < 0.05. Meanwhile, the volumes of the whole brain minus the tumors that received a single dose equivalent of 8–16 Gy (V8Gy-V16Gy) were effectively reduced in the MLP. The treatment time parameters, the total number of beams and monitor units, of the MLP were reduced by 3.31 and 1.47% (P < 0.05), respectively. Although there were a few differences in the conformity index (CI) and homogeneity index (HI) between the two treatment plans, the differences were not statistically significant (P = 2.94 and 1.08 > 0.05). Conclusion One multiple-lesions plan for brain metastases could achieve higher precision in the target and lower doses in healthy tissue while shortening the treatment time and improving the treatment efficiency over multiple single-lesion plans.

Comparison of Single and Multiple Treatment Plans Made in CyberKnife® Radiosurgery System on Phantom

“…Yu et al, while finding the CI value similar for both plans, Uzel reported that the plan made separately for each metastasis is more advantageous in terms of CI. In our result, it was found that separately treatment planning was more advantageous in terms of CI, in line with Uzel [19,20]. In our result, it was found that separately treatment planning was more advantageous in terms of CI, in line with Uzel Likewise, it was concluded that it was more appropriate to plan separately according to the nCI values.…”

Dosimetric evaluation of LINAC-based single-isocenter multi-target multi-fraction stereotactic radiosurgery with more than 20 targets: comparing MME, HyperArc, and RapidArc

“…This fractionated approach allows for the delivery of effective doses to the multiple-target while minimizing damage to surrounding healthy brain tissue [ 5 , 6 ]. Various techniques, including the use of conventional linear accelerator (LINAC), Gamma Knife (Elekta AB, Stockholm, Sweden), and CyberKnife (Accuray, Sunnyvale, CA), have been employed for SRS/fSRS [ 7 – 10 ].…”

Influence of Using a Contrast-Enhanced CT Image as the Primary Image on CyberKnife Brain Radiosurgery Treatment Plans

“…Stereotactic radiosurgery (SRS), such as single-fraction or hypofractionated (two to five fractions) cranial radiosurgery, is commonly used to treat various primary and metastatic brain tumors ( 1 ). Compared with other modern SRS treatment equipment, including different types of linear accelerators and Gamma Knife, the frameless image-guided radiosurgery system CyberKnife (CK) can deliver a high conformal dose to the tumor accurately and spare normal brain tissue ( 2 – 6 ). To make it easier and more convenient to contour the target, the patient is often injected with a contrast agent (CA) when CT scanning is performed ( 7 ).…”