scholarly journals Longitudinal Grouping of Target Volumes for Volumetric-Modulated Arc Therapy of Multiple Brain Metastases

2021 ◽  
Vol 11 ◽  
Author(s):  
Yingjie Xu ◽  
Junjie Miao ◽  
Qingfeng Liu ◽  
Peng Huang ◽  
Pan Ma ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Brain Tissue ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Normal Brain ◽  
Normal Brain Tissue ◽  
Arc Therapy ◽  
Target Volumes ◽  
Prescription Dose ◽  
Single Isocenter

PurposeTreatment of multiple brain metastases with single-isocenter volumetric modulated arc therapy causes unnecessary exposure to normal brain tissue. In this study, a longitudinal grouping method was developed to reduce such unnecessary exposure.Materials and MethodsThis method has two main aspects: grouping brain lesions longitudinally according to their longitudinal projection positions in beam’s eye view, and rotating the collimator to 90° to make the multiple leaf collimator leaves conform to the targets longitudinally group by group. For 11 patients with multiple (5–30) brain metastases, two single-isocenter volumetric modulated arc therapy plans were generated using a longitudinal grouping strategy (LGS) and the conventional strategy (CVS). The prescription dose was 52 Gy for 13 fractions. Dose normalization to 100% of the prescription dose in 95% of the planning target volume was adopted. For plan quality comparison, Paddick conformity and the gradient index of the planning target volume, and the mean dose, the V100%, V50%, V25%, and V10% volumes of normal brain tissue were calculated.ResultsThere were no significant differences between the LGS and CVS plans in Paddick conformity (p = 0.374) and the gradient index (p = 0.182) of the combined planning target volumes or for V100% (p = 0.266) and V50% (p = 0.155) of the normal brain. However, the V25% and V10% of the normal brain which represented the low-dose region were significantly reduced in the LGS plans (p = 0.004 and p = 0.003, respectively). Consistently, the mean dose of the entire normal brain was 12.04 and 11.17 Gy in the CVS and LGS plans, respectively, a significant reduction in the LGS plans (p = 0.003).ConclusionsThe longitudinal grouping method can decrease unnecessary exposure and reduces the low-dose range in normal brain tissue.

scholarly journals Noncoplanar VMAT for Brain Metastases: A Plan Quality and Delivery Efficiency Comparison With Coplanar VMAT, IMRT, and CyberKnife

2019 ◽  
Vol 18 ◽  
pp. 153303381987162 ◽  
Author(s):  
Shuming Zhang ◽  
Ruijie Yang ◽  
Chengyu Shi ◽  
Jiaqi Li ◽  
Hongqing Zhuang ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Brain Metastases ◽  
Brain Tissue ◽  
Dose Level ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Normal Brain ◽  
Normal Brain Tissue ◽  
Intensity Modulated ◽  
Arc Therapy

Purpose: To compare plan quality and delivery efficiency of noncoplanar volumetric modulated arc therapy with coplanar volumetric modulated arc therapy, intensity-modulated radiation therapy, and CyberKnife for multiple brain metastases. Methods: For 15 patients with multiple brain metastases, noncoplanar volumetric modulated arc therapy, coplanar volumetric modulated arc therapy, intensity-modulated radiation therapy, and CyberKnife plans with a prescription dose of 30 Gy in 3 fractions were generated. Noncoplanar volumetric modulated arc therapy and coplanar volumetric modulated arc therapy plans consisted of 4 noncoplanar arcs and 2 full coplanar arcs, respectively. Intensity-modulated radiation therapy plans consisted of 7 coplanar fields. CyberKnife plans used skull tracking to ensure accurate position. All plans were generated to cover 95% target volume with prescription dose. Gradient index, conformity index, normal brain tissue volume ( V 3Gy − V 24Gy), monitor units, and beam on time were evaluated. Results: Gradient index was the lowest for CyberKnife (3.49 ± 0.65), followed by noncoplanar volumetric modulated arc therapy (4.21 ± 1.38), coplanar volumetric modulated arc therapy (4.87 ± 1.35), and intensity-modulated radiation therapy (5.36 ± 1.98). Conformity index was the largest for noncoplanar volumetric modulated arc therapy (0.87 ± 0.03), followed by coplanar volumetric modulated arc therapy (0.86 ± 0.04), CyberKnife (0.86 ± 0.07), and intensity-modulated radiation therapy (0.85 ± 0.05). Normal brain tissue volume at high-to-moderate dose spreads ( V 24Gy − V 9Gy) was significantly reduced in noncoplanar volumetric modulated arc therapy over that of intensity-modulated radiation therapy and coplanar volumetric modulated arc therapy. Normal brain tissue volume for noncoplanar volumetric modulated arc therapy was comparable with noncoplanar volumetric modulated arc therapy at high-dose level ( V 24Gy − V 15Gy) and larger than CyberKnife at moderate-to-low dose level ( V 12Gy − V 3Gy). Monitor units was highest for CyberKnife (28 733.59 ± 7197.85), followed by intensity-modulated radiation therapy (4128.40 ± 1185.38), noncoplanar volumetric modulated arc therapy (3105.20 ± 371.23), and coplanar volumetric modulated arc therapy (2997.27 ± 446.84). Beam on time was longest for CyberKnife (30.25 ± 7.32 minutes), followed by intensity-modulated radiation therapy (2.95 ± 0.85 minutes), noncoplanar volumetric modulated arc therapy (2.61 ± 0.07 minutes), and coplanar volumetric modulated arc therapy (2.30 ± 0.23 minutes). Conclusion: For brain metastases far away from organs-at-risk, noncoplanar volumetric modulated arc therapy generated more rapid dose falloff and higher conformity compared to intensity-modulated radiation therapy and coplanar volumetric modulated arc therapy. Noncoplanar volumetric modulated arc therapy provided a comparable dose falloff with CyberKnife at high-dose level and a slower dose falloff than CyberKnife at moderate-to-low dose level. Noncoplanar volumetric modulated arc therapy plans had less monitor units and shorter beam on time than CyberKnife plans.

The Study of Cerebral Blood Flow Variations Following Radiation Dose Gradients for Brain Metastasis Patients During Radiotherapy

2020 ◽  
Author(s):  
Chuanke Hou ◽  
Guanzhong Gong ◽  
Lizhen Wang ◽  
Ya Su ◽  
Jie Lu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Radiation Dose ◽  
Brain Metastases ◽  
Brain Tissue ◽  
Normal Brain ◽  
Peritumoral Edema ◽  
Sectional Area ◽  
Normal Brain Tissue ◽  
Cross Sectional

Abstract Brackground: Changes of cereberal blood flow in different brain regions of patients with brain metastases after radiotherapy are worth exploring. This study aims to investigate the radiation dose range of normal brain tissue and tumor target area by evaluating the cerebral blood flow(CBF) for brain metastases (BMs) patients applying with 3D arterial spin labeling (ASL).Methods: A total of 26 patients harboring 54 BMs treated with radiotherapy (RT) were imaged with magnetic resonance (MR) before and 30-40Gy post RT. The high signal area of BMs on enhanced T1-weighted images (T1WI), normal brain tissue, and peritumoral edema region were defined as regions of interest (ROIs). Changes and correlation of largest cross-sectional area and maximum CBF in BMs before and after RT were analyzed. Maximum CBF change in the three ROIs under different gradients created by thresholding the individual dose maps at 10 Gy steps were assessed.Results: In terms of 54 BMs, a significant decrease of CBF of 29.64% (P<0.05) compared to largest cross-sectional area of 26.46% (P<0.05). The decrease of CBF was more pronounced for 30-40 Gy (33.75%) than for 40-50Gy and >50Gy (24.61% and 27.55%). In normal brain tissue with dose gradients of 30-40Gy, CBF decreased to the maximum, 20.23% (P<0.05),which was similar to BMs. In contrast, the decrement rate of CBF in the peritumoral edema region increased as the dose gradients increased.Conclusions: CBF decreased significantly during the course of RT. According to CBF variations, the dose to the normal brain tissue should be controlled below 30 Gy as much as possible, whereas tumor with high perfusion and peritumoral edema region should be given a higher dose.

Left-sided breast radiotherapy after conservative surgery: comparison of techniques between volumetric modulated arc therapy, forward-planning intensity-modulated radiotherapy and conventional technique

2016 ◽  
Vol 16 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Upendra Kumar Giri ◽  
Biplab Sarkar ◽  
Kanan Jassal ◽  
Anusheel Munshi ◽  
Tharmar Ganesh ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiotherapy ◽  
Conservative Surgery ◽  
Target Volume ◽  
Conventional Technique ◽  
Breast Radiotherapy ◽  
Intensity Modulated ◽  
Arc Therapy ◽  
Prescription Dose ◽  
Comparison Of Techniques

AbstractObjectiveThis study was conducted for comparison of techniques between volumetric modulated arc therapy (VMAT), forward-planning intensity-modulated radiotherapy (FIMRT) and conventional technique for left-sided breast radiotherapy after conservative surgery.MethodsIn all, 20 postoperative left breast carcinoma patients were included in this study. In all plans the planning target volume (PTV) was the breast tissue with appropriate margin as per our institutional protocol. The contouring was done on a Monaco Sim (V5.00.02) contouring workstation. All patient were planned using partial arc VMAT in Monaco treatment planning system (TPS) (V5.00.02) and treated on Elekta Synergy linear accelerator. The 3D conformal radiotherapy (3DCRT) and FIMRT planning were done in CMS XIO (V5.00.01.1) TPS. The 3DCRT planning consisted of conventional medial and tangential wedge portals with multileaf collimator field shaping conforming to the target volume. For all the plans generated the following metrics were scored: V105%, V100%, V95%, mean dose (for PTV), V5%, V20%, D2cc and mean dose (for organs at risk).ResultsThe mean PTV volume for 20 patients was 1,074·6±405·1 cc. The highest PTV dose coverage was observed in the 3DCRT technique with 94·1±1·8% of the breast PTV receiving 95% of the prescription dose (V95%). However, it was also observed that this technique resulted in 21·3±10% of the PTV receiving more than 105% of the prescription dose (V105%), which was highest among the three techniques. In contrast, VMAT yielded lowest V95% of 93·0±1·8 and 3·3±5·5% of V105%.ConclusionThis study concluded equivalent result between FIMRT and VMAT. However, VMAT was found to be the choice of radiotherapy technique as it produces lesser dose distribution to heart compared with any other technique.

Sign in / Sign up

Export Citation Format

Share Document