Dataset Information

Evaluation of the correlation between dosimetric, geometric, and technical parameters of radiosurgery planning for multiple brain metastases.

ABSTRACT:

Purpose

To evaluate the correlation between dosimetric, geometric, and technical parameters for radiosurgery planning of multiple brain metastasis treatments treated with a linear accelerator with volumetric modulated arc therapy (VMAT) technique.

Materials and methods

Data were collected retrospectively from 55 patients who underwent radiosurgery in a single institution from August 2017 to February 2020. Patients presented 4-21 brain metastases were treated with a single fraction with doses between 18 and 20 Gy. Dosimetric variables were collected including V5Gy, V8Gy, V10Gy, V12Gy, V14Gy, conformity index (CI), heterogeneity index (HI), maximum dose (Dmax), and the CI_R50. Geometric variables including the number of lesions, target volumes, the smallest target volume, the largest target volume, and the distance between the isocenter and the most distant lesion (DIL) and technical variables such as the numbers of total arcs, noncoplanar arcs, and isocenters were collected for analysis.

Results

The number of lesions had a moderate positive correlation with V5Gy, V8Gy, V10Gy, V12Gy, V14Gy, HI, Dmax, and with the number of total arcs. The target volumes had a positive medium-high correlation with V5Gy, V8Gy, V10Gy, V12Gy, V14Gy, and moderate positive correlation with HI, Dmax, number of arcs and noncoplanar arcs. The CI and CI_R50 had a negative correlation with all volumes related to the target: the target volumes, the smallest, and the largest lesion. A positive correlation was observed between the distance of the isocenter and the most DIL with V5Gy, V8Gy, V10Gy, V12Gy, V14Gy, HI, Dmax, and the number of isocenters.

Conclusion

It was found that the number of lesions and the target volumes are good predictors of dosimetric indexes of plan evaluation and that the distance between the isocenter and the most DIL harms them.

SUBMITTER: de Camargo AV

PROVIDER: S-EPMC8364278 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Introduction:Due to the neurocognitive side effects of whole brain radiation therapy (WBRT), stereotactic radiosurgery (SRS) is being used with increasing frequency. The use of SRS is expanding for patients with multiple (>4) brain metastases (BM). This study summarizes our institutional experience with single-fraction, linear-accelerator-based SRS for multiple BM. Methods and materials:All patients who were treated between January 1, 2013, and September 30, 2015, with single-fraction SRS for ?4 BM were included in this institutional review board-approved, retrospective, single-institution study. Patients were treated with linear accelerator-based image guided SRS. Results:A total of 59 patients with ?4 BM were treated with single-fraction SRS. The median follow-up was 15.2 months, and the median overall survival for the entire cohort was 5.8 months. The median number of treated lesions per patient was 5 (range, 4-23). Per patient, the median planning target volume (PTV) was 4.8?cc (range, 0.7-28.8?cc). The prescribed dose across all 380 BM for the 59 patients ranged from 7 to 20?Gy. The median of the mean dose to the total PTV was 19.5?Gy. Although the number of treated lesions (4-5 vs ?6) did not influence survival, better survival was noted for a total PTV <10?cc versus ?10?cc (7.1 vs 4.2 months, respectively; P?=?.0001). A mean dose of ?19?Gy to the entire PTV was also associated with increased survival (6.6 vs 5.0 months, respectively; P?=?.0172). Patients receiving a dose of >12?Gy to ?10?cc of normal brain had worse survival (5.1 vs 8.6 months, respectively; P?=?.0028). Conclusion:In single-fraction SRS for patients with multiple BM, smaller total tumor volume, higher total dose, and lower volume of normal brain receiving >12?Gy were associated with increased survival. These data suggest that using SRS for the treatment of multiple BM is efficacious and that outcomes may be affected more by total tumor volume than by the number of lesions.

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