Dataset Information

Interinstitutional Plan Quality Assessment of 2 Linac-Based, Single-Isocenter, Multiple Metastasis Radiosurgery Techniques.

ABSTRACT: Purpose:Interest and application of stereotactic radiosurgery for multiple brain metastases continue to increase. Various planning systems are available for linear accelerator (linac)-based single-isocenter multiple metastasis radiosurgery. Two of the most advanced systems are BrainLAB Multiple Metastases Elements (MME), a dynamic conformal arc (DCA) approach, and Varian RapidArc (RA), a volumetric modulated arc therapy (VMAT) approach. In this work, we systematically compared plan quality between the 2 techniques. Methods and Materials:Thirty patients with 4 to 10 metastases (217 total; median 7.5; Vmin = 0.014 cm3; Vmax = 17.73 cm3) were planned with both Varian RA and MME at 2 different institutions with extensive experience in each respective technique. All plans had a single isocenter and used Varian linac equipped with high-definition multileaf collimator. RA plans used 2 to 4 noncoplanar VMAT arcs with 10 MV flattening filter-free beam. MME plans used 4 to 9 noncoplanar DCAs and 6 MV flattening filter-free beam, (minimum planning target volume [PTVmin] = 0.49 cm3; PTVmax = 27.32 cm3; PTVmedian = 7.05 cm3). Prescriptions were 14 to 24 Gy in a single fraction. Target coverage goal was 99% of volume receiving prescription dose (D99% ? 100%). Plans were evaluated by Radiation Therapy Oncology Group/Paddick conformity index (CI) score, 12 Gy volume (V12Gy), V8Gy, V5Gy, mean brain dose (Dmean), and beam-on time. Results:Conformity was favorable among RA plans (median: MME CIRTOG = 1.38; RA CIRTOG = 1.21; P < .0001). V12Gy and V8Gy were lower for RA plans (median: MME V12 = 23.7 cm3; RA V12 = 19.2 cm3; P = .0001; median: MME V8Gy = 53.6 cm3; RA V8Gy = 44.1 cm3; P = .024). V5Gy was lower for MME plans (median: MME V5Gy = 141.4 cm3; RA V5Gy = 142.8 cm3; P = .009). Mean brain was lower for MME plans (median: MME Dmean = 2.57 Gy; RA Dmean = 2.76 Gy; P < .0001). Conclusions:For linac-based multiple metastasis stereotactic radiosurgery, RapidArc VMAT facilitates favorable conformity and V12Gy/V8Gy volume compared with the MME DCA plan. MME planning facilitates reduced dose spill at levels ?V5Gy.

SUBMITTER: Liu H

PROVIDER: S-EPMC7560574 | biostudies-literature | 2020 Sep-Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Interinstitutional Plan Quality Assessment of 2 Linac-Based, Single-Isocenter, Multiple Metastasis Radiosurgery Techniques.

Liu Haisong H Thomas Evan M EM Li Jun J Yu Yan Y Andrews David D Markert James M JM Fiveash John B JB Shi Wenyin W Popple Richard A RA

Advances in radiation oncology 20191202 5

<h4>Purpose</h4>Interest and application of stereotactic radiosurgery for multiple brain metastases continue to increase. Various planning systems are available for linear accelerator (linac)-based single-isocenter multiple metastasis radiosurgery. Two of the most advanced systems are BrainLAB Multiple Metastases Elements (MME), a dynamic conformal arc (DCA) approach, and Varian RapidArc (RA), a volumetric modulated arc therapy (VMAT) approach. In this work, we systematically compared plan quali ...[more]

PMID: 33089021

Similar Datasets

Project description:The aim of this study is to provide a practical approach to the planning technique and evaluation of plan quality for the multi-lesion, single-isocenter stereotactic ablative radiotherapy (SABR) of the lung. Eleven patients with two or more lung lesions underwent single-isocenter volumetric-modulated arc therapy (VMAT) radiosurgery or IMRS. All plans were normalized to the target maximum dose. For each plan, all targets were treated to the same dose. Plan conformity and dose gradient were maximized with dose-control tuning structures surrounding targets. For comparison, multi-isocenter plans were retrospectively created for four patients. Conformity index (CI), homogeneity index (HI), gradient index (GI), and gradient distance (GD) were calculated for each plan. V5, V10, and V20 of the lung and organs at risk (OARs) were collected. Treatment time and total monitor units (MUs) were also recorded. One patient had four lesions and the remainder had two lesions. Six patients received VMAT and five patients received intensity-modulated radiosurgery (IMRS). For those treated with VMAT, two patients received 3-arc VMAT and four received 2-arc VMAT. For those treated with IMRS, two patients were treated with 10 and 11 beams, respectively, and the rest received 12 beams. Prescription doses ranged from 30 to 54?Gy in three to five fractions. The median prescribed isodose line was 84% (range: 80-86%). The median maximum dose was 57.1?Gy (range: 35.7-65.1?Gy). The mean combined PTV was 49.57?cm(3) (range: 14.90-87.38?cm(3)). For single-isocenter plans, the median CI was 1.15 (range: 0.97-1.53). The median HI was 1.19 (range: 1.16-1.28). The median GI was 4.60 (range: 4.16-7.37). The median maximum radiation dose (Dmax) to total lung was 55.6?Gy (range: 35.7-62.0?Gy). The median mean radiation dose to the lung (Dmean) was 4.2?Gy (range: 1.1-9.3?Gy). The median lung V5 was 18.7% (range: 3.8-41.3%). There was no significant difference in CI, HI, GI, GD, V5, V10, and V20 (lung, heart, trachea, esophagus, and spinal cord) between single-isocenter and multi-isocenter plans. This multi-lesion, single-isocenter lung SABR planning technique demonstrated excellent plan quality and clinical efficiency and is recommended for radiosurgical treatment of two or more lung targets for well-suited patients.

Project description:PurposeAs radiation therapy treatment precision increases with advancements in imaging and radiation delivery, dose painting treatment becomes increasingly feasible, where targets receive a nonuniform radiation dose. The high precision of stereotactic radiosurgery (SRS) makes it a good candidate for dose painting treatments, but no suitable metrics to assess dose painting SRS plans exist. Existing dose painting assessment metrics weigh target overdose and underdose equally but are unsuited for SRS plans, which typically avoid target underdose more. Current SRS metrics also prioritize reducing healthy tissue dose through selectivity and dose fall-off, and these metrics assume single prescriptions. We propose a set of metrics for dose painting SRS that would meet clinical needs and are calculated with nonuniform dose painting prescriptions.Methods and materialsSample dose painting SRS prescriptions are first created from Gamma Knife SRS cases, apparent diffusion coefficient magnetic resonance images, and various image-to-prescription functions. Treatment plans are found through semi-infinite linear programming optimization and using clinically determined isocenters, then assessed with existing and proposed metrics. Modified versions of SRS metrics are proposed, including coverage, selectivity, conformity, efficiency, and gradient indices. Quality factor, a current dose painting metric, is applied both without changes and with modifications. A new metric, integral dose ratio, is proposed as a measure of target overdose.ResultsThe merits of existing and modified metrics are demonstrated and discussed. A modified conformity index using mean or minimum prescription dose would be suitable for dose painting SRS with integral or maximum boost methods, respectively. Either modified efficiency index is a suitable replacement for the existing gradient index.ConclusionsThe proposed modified SRS metrics are appropriate measures of plan quality for dose painting SRS plans and have the advantage of giving equal values as the original SRS metrics when applied to single-prescription plans.

Project description:This study was performed to examine the quality of planning and treatment modality using a CyberKnife (CK) robotic radiosurgery system with multileaf collimator (MLC)-based plans and IRIS (variable aperture collimator system)-based plans in relation to the dose-response of secondary cancer risk (SCR) in patients with benign intracranial tumors. The study population consisted of 15 patients with benign intracranial lesions after curative treatment using a CyberKnife M6 robotic radiosurgery system. Each patient had a single tumor with a median volume of 6.43 cm3 (range, 0.33-29.72 cm3). The IRIS-based plan quality and MLC-based plan quality were evaluated by comparing the dosimetric indices, taking into account the planning target volume (PTV) coverage, the conformity index (CI), and the dose gradient (R10% and R50%). The dose-response SCR with sarcoma/carcinoma induction was calculated using the concept of the organ equivalent dose (OED). Analyses of sarcoma/carcinoma induction were performed using excess absolute risk (EAR) and various OED models of dose-response type/lifetime attributable risk (LAR). Moreover, analyses were performed using the BEIR VII model. PTV coverage using both IRIS-based plans and MLC-based plans was identical, although the CI values obtained using the MLC-based plans showed greater statistical significance. In comparison with the IRIS-based plans, the MLC-based plans showed better dose falloff for R10% and R50% evaluation. The estimated difference between Schneider's model and BEIR VII in linear-no-threshold (Lnt) cumulative EAR was about twofold. The average values of LAR/EAR for carcinoma, for the IRIS-based plans, were 25% higher than those for the MLC-based plans using four SCR models; for sarcoma, they were 15% better in Schneider's SCR models. MLC-based plans showed slightly better conformity, dose gradients, and SCR reduction. There was a slight increase in SCR with IRIS-based plans in comparison with MLC-based plans. EAR analyses did not show any significant difference between PTV and brainstem analyses, regardless of the tumor volume. Nevertheless, an increase in target volume led to an increase in the probability of SCR. EAR showed statistically significant differences in the soft tissue according to tumor volume (1-10 cc and ≥10 cc).

Dataset Information

Interinstitutional Plan Quality Assessment of 2 Linac-Based, Single-Isocenter, Multiple Metastasis Radiosurgery Techniques.

Publications

Interinstitutional Plan Quality Assessment of 2 Linac-Based, Single-Isocenter, Multiple Metastasis Radiosurgery Techniques.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets