Single-Fraction Stereotactic Radiosurgery vs. Hippocampal-Avoidance Whole-Brain Radiotherapy for Patients with 10-30 Brain Metastases: A Dosimetric Analysis

Nguyen, Timothy; Ruschin, Mark; Detsky, Jay; Soliman, Hany; Myrehaug, Sten; Tseng, C.L.; Husain, Zain; Carty, Adele; Das, Shubhadeep; Yang, Victor XD; Lee, Y.; Sarfehnia, Arman; Chugh, Brige; Yeboah, Collins; Sahgal, Arjun

doi:10.1016/j.ijrobp.2019.06.2352

Cited by 3 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The step‐wise increase in feasibility of SRS alone for increasing number of intracranial lesions has been well documented, initially starting with one to three metastases, eventually increasing to ≤10 16–18 . Case reports and retrospective series have also described the feasibility of SRS for patients with greater than ten metastases 19,20 . SRS in the future will be primarily constrained not by the number of lesions requiring treatment, but rather by the volume of metastatic disease and by the length of time the patient can be on the table undergoing treatment.…”

Section: Discussionmentioning

confidence: 99%

“…[16][17][18] Case reports and retrospective series have also described the feasibility of SRS for patients with greater than ten metastases. 19,20 SRS in the future will be primarily constrained not by the number of lesions requiring treatment, but rather by the volume of metastatic disease and by the length of time the patient can be on the table undergoing treatment. A SIT plan will be able to minimize that time while still minimizing dose to normal brain.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Dosimetric comparison of multiple vs single isocenter technique for linear accelerator‐based stereotactic radiosurgery: The Importance of the six degree couch

Amaya

Shinde

Wohlers

et al. 2021

J Applied Clin Med Phys

View full text Add to dashboard Cite

Purpose Single isocenter technique (SIT) for linear accelerator‐based stereotactic radiosurgery (SRS) is feasible. However, SIT introduces the potential for rotational error which can lead to geographical miss. Additional planning treatment volume (PTV) margin is required when using SIT. With the six degrees of freedom (6DoF) couch, rotational error can be minimized. We sought to evaluate the effect of the 6DoF couch on the dosimetry of patients with multiple brain metastases treated with SIT. Materials and Methods Ten consecutive patients treated with SRS to ≥3 metastases were identified. Original treatments had MIT plans (MITP). The lesions were replanned using SIT. Lesions 5‐10 cm from isocenter had an additional 1mm of margin. Patients were replanned with these additional margins to account for inability to correct rotational error (SITPM). Multiple dosimetric variables and time metrics were evaluated. Dosimetry planning time (DPT) and patient treatment time (PTT) were evaluated. Statistics were calculated using the Wilcoxon signed‐rank test. Results A total of 73 brain metastases receiving SRS, to a median of 6 lesions per patient, were identified. MITPs treated 73 lesions with 63 isocenters. On average, MITPs had a 19.2% higher brain V12 than SITPs (P = 0.017). For creation of SITPM, 30 lesions required 1 mm of additional margin, while none required 2 mm of margin. This increased V12 by 47.8% on average per patient (P = 0.008) from SITP to SITPM. DPT was 5.5 hours for SITP, while median for MITP was 12.5 hours (P = 0.005) PTT was 30 minutes for SITP, while median for MITP was 144 minutes (P = 0.005). Conclusions SITPs are comparable to MITPs if rotational error can be corrected with the use of a 6DoF couch. Increasing margin to account for rotational error leads to a nearly 50% increase in V12, which could result in higher rates of radiation necrosis. Time savings are significant using SIT.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Dosimetric comparison of multiple vs single isocenter technique for linear accelerator‐based stereotactic radiosurgery: The Importance of the six degree couch

Amaya

Shinde

Wohlers

et al. 2021

J Applied Clin Med Phys

View full text Add to dashboard Cite

show abstract

“…Constraints on acceptable hippocampal dosing were obtained from the protocols of NRG CC001 and CC003 and a previous study by Gondi et al [25][26][27] Constraints were converted to a single-fraction scheme using equivalent doses in 2 Gy fractions with an a/b of 2. 20,21,23,28 Hippocampal constraints for single-fraction GK-SRS were D 100 4.21 Gy, D 40 4.50 Gy, and D max 6.65 Gy. Successful hippocampal-sparing was defined as meeting all constraints in both the unilateral and bilateral hippocampi.…”

Section: Methodsmentioning

confidence: 99%

“…18,19 Multiple SRS modalities have previously been shown to be capable of achieving hippocampal dose levels lower than those seen in HA-WBRT in the treatment of extensive brain metastases, often without the need for purposeful hippocampal-avoidance. [20][21][22][23] Additionally, in a comparison of 4 SRS modalities, Zhang et al showed that frame-based technologies such as Gamma Knife (GK-SRS) lead to more dramatic dose fall off and lower hippocampal dosing when treating 3 to 10 brain metastases. 20 Such evidence suggests that GK-SRS is a favorable option for patients with lesions located in close proximity to the hippocampi, the most commonly cited risk factor for excessive hippocampal dosing in SRS.…”

Section: Introductionmentioning

confidence: 99%

“…To date, only 2 studies have evaluated patients with 10 or more brain metastases treated with GK-SRS, neither including cases where lesions were located within 5 mm of the hippocampi (the zone of ineligibility for HA-WBRT). 22,23 Therefore, the goal of this study was to provide the largest and most comprehensive case series to date evaluating hippocampal dosimetry and the role of hippocampal-sparing in single-fraction GK-SRS for the treatment of extensive brain metastases. We evaluated the comparative hippocampal dosimetry of plans for the treatment of 10 and 4 to 9 brain metastases, seeking to characterize risk factors for increased hippocampal dosing and identify patients who may benefit from GK-SRS with purposeful hippocampal-sparing.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hippocampal Dosimetry and the Necessity of Hippocampal-Sparing in Gamma Knife Stereotactic Radiosurgery for Extensive Brain Metastases

Riina

Stambaugh

Huber

2020

Advances in Radiation Oncology

View full text Add to dashboard Cite

To characterize hippocampal dosimetry in Gamma Knife stereotactic radiosurgery (GK-SRS) for extensive brain metastases and evaluate the need for hippocampal-sparing in GK-SRS treatment planning. Methods and Materials: We reviewed 75 GK-SRS plans for the treatment of 4 to 30 brain metastases generated without consideration of the hippocampi. The mean dose, maximum dose to 100% of the volume (D 100 ), maximum dose to 40% of the volume (D 40 ), and maximum point dose (D max , 0.03 cm 3 ) were obtained for the unilateral and bilateral hippocampi and compared between plans with 4 to 9 and 10 lesions. The rate at which plans met hippocampal dose constraints (D 100 4.21 Gy, D 40 4.50 Gy, and D max 6.65 Gy) was compared between groups, and each was examined for risk factors associated with excessive hippocampal dosing. For plans that exceeded constraints, we attempted replanning to spare the hippocampi. Results: Compared with those for the treatment of 4 to 9 brain metastases, GK-SRS plans with 10 lesions were associated with significantly greater median bilateral mean dose (1.0 vs 2.0, P Z .001), D 100 (0.4 vs 0.8, P Z .003), D 40 (0.9 vs 1.9, P Z .001), and D max (2.0 vs 4.9, P Z .0005). These plans also less frequently met hippocampal constraints, with this difference trending toward significance (80% vs 93%; P Z .1382; odds ratio 0.29; 95% CI, 0.06-1.4). Risk factors for exceeding constraints included greater total disease volume and closer approach of the nearest metastasis to the hippocampi, both of which depended upon the number of metastases present. Seven plans failed to meet constraints and were successfully replanned to spare the hippocampi with minimal increases in treatment time and without compromise to target coverage or conformity. Conclusions: Patients with extensive brain metastases treated with GK-SRS are at increased risk for excessive hippocampal dosing when 10 lesions are present or when lesions are in close proximity to the hippocampi and may benefit from hippocampal-avoidant treatment planning.

show abstract

Tumor-dose-rate variations during robotic radiosurgery of oligo and multiple brain metastases

Wilhelm

Chan²,

Abel³

et al. 2020

Strahlenther Onkol

View full text Add to dashboard Cite

Purpose For step-and-shoot robotic stereotactic radiosurgery (SRS) the dose delivered over time, called local tumor-dose-rate (TDR), may strongly vary during treatment of multiple lesions. The authors sought to evaluate technical parameters influencing TDR and correlate TDR to clinical outcome. Material and methods A total of 23 patients with 162 oligo (1–3) and multiple (>3) brain metastases (OBM/MBM) treated in 33 SRS sessions were retrospectively analyzed. Median PTV were 0.11 cc (0.01–6.36 cc) and 0.50 cc (0.12–3.68 cc) for OBM and MBM, respectively. Prescription dose ranged from 16 to 20 Gy prescribed to the median 70% isodose line. The maximum dose-rate for planning target volume (PTV) percentage p in time span s during treatment (TDRs,p) was calculated for various p and s based on treatment log files and in-house software. Results TDR60min,98% was 0.30 Gy/min (0.23–0.87 Gy/min) for OBM and 0.22 Gy/min (0.12–0.63 Gy/min) for MBM, respectively, and increased by 0.03 Gy/min per prescribed Gy. TDR60min,98% strongly correlated with treatment time (ρ = −0.717, p < 0.001), monitor units (MU) (ρ = −0.767, p < 0.001), number of beams (ρ = −0.755, p < 0.001) and beam directions (ρ = −0.685, p < 0.001) as well as lesions treated per collimator (ρ = −0.708, P < 0.001). Median overall survival (OS) was 20 months and 1‑ and 2‑year local control (LC) was 98.8% and 90.3%, respectively. LC did not correlate with any TDR, but tumor response (partial response [PR] or complete response [CR]) correlated with all TDR in univariate analysis (e.g., TDR60min,98%: hazard ration [HR] = 0.974, confidence interval [CI] = 0.952–0.996, p = 0.019). In multivariate analysis only concomitant targeted therapy or immunotherapy and breast cancer tumor histology remained a significant factor for tumor response. Local grade ≥2 radiation-induced tissue reactions were noted in 26.3% (OBM) and 5.2% (MBM), respectively, mainly influenced by tumor volume (p < 0.001). Conclusions Large TDR variations are noted during MBM-SRS which mainly arise from prolonged treatment times. Clinically, low TDR corresponded with decreased local tumor responses, although the main influencing factor was concomitant medication.

show abstract

Single-Fraction Stereotactic Radiosurgery vs. Hippocampal-Avoidance Whole-Brain Radiotherapy for Patients with 10-30 Brain Metastases: A Dosimetric Analysis

Cited by 3 publications

References 0 publications

Dosimetric comparison of multiple vs single isocenter technique for linear accelerator‐based stereotactic radiosurgery: The Importance of the six degree couch

Dosimetric comparison of multiple vs single isocenter technique for linear accelerator‐based stereotactic radiosurgery: The Importance of the six degree couch

Hippocampal Dosimetry and the Necessity of Hippocampal-Sparing in Gamma Knife Stereotactic Radiosurgery for Extensive Brain Metastases

Tumor-dose-rate variations during robotic radiosurgery of oligo and multiple brain metastases

Contact Info

Product

Resources

About