Treatment planning of volumetric modulated arc therapy and positioning optimization for hippocampal‐avoidance prophylactic cranial irradiation

Fu, Qi; Chen, Deqi; Yan, Hui; Chen, Jiayun; Zhu, Ji; Yan, Lingling; Xu, Yi; Deng, Lei; Men, Kuo; Dai, Jianrong

doi:10.1002/acm2.13217

Cited by 6 publications

(5 citation statements)

References 21 publications

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“…Yuen 30 and Sood et al 31 proved that VMAT could decrease the dose of HP. Fu et al 32 designed a inclined head four full-arc VMAT plan for 16 patients who had whole-brain hippocampal avoidance, and the plan could decrease the Dmax of HP. Sun et al 33 studied the whole-brain prophylactic irradiation of 15 cases of NSCLC and found that VMAT could improve HP protection.…”

Section: Discussionmentioning

confidence: 99%

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Dosimetric comparison of helical tomotherapy and volumetric modulated arc therapy in hippocampal avoidance whole‐brain radiotherapy

Zhang,

Hu,

Pang

2023

J Applied Clin Med Phys

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ObjectiveThis study aimed to discuss the dosimetric advantages of helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) technology in hippocampal avoidance whole‐brain radiotherapy and provide references for clinical selection of ideal radiotherapy technology.MethodsA total of 20 patients with hippocampal avoidance whole‐brain radiotherapy were chosen randomly. Computed tomography (CT) and MRI scanning images were input into the treatment planning system (TPS). After the CT and enhanced magnetic resonance T1 weighted images were fused and registered, the same radiation therapy physician was invited to outline the tumor target volume. PTV‐HS refers to the whole brain subtracted by 5 mm outward expansion of the hippocampus (HP). The prescribed dose was 30 Gy/10 fractions. HT and VMAT plans were designed for each patient in accordance with PTV. Under the premise that the 95% isodose curve covers the PTV, dose–volume histogram was applied to evaluate the PTV, conformal index (CI), heterogeneity index (HI), maximum dose (Dmax), mean dose (Dmean), minimum dose (Dmin) and absorbed doses of organs at risk (OARs) in HT and VMAT plans. Paired t‐test was performed to compare the differences between two radiation therapy plans, and p < 0.05 was considered statistically significant.ResultsThese two plans had no significant difference in PTV‐HS (max, min, and mean). However, the HI and CI of the HT plan were significantly better than those of the VMAT plan, showing statistically significant difference (p < 0.05). The HT plan was significantly superior to the VMAT plan in terms of the Dmax, Dmin, and Dmean of HP, left and right eye lens, left and right eye, and spinal cord, showing statistically significant difference (p < 0.05). The HT plan was also better than the VMAT plan in terms of the Dmax of the left optic nerve. However, the two plans showed no obvious differences in terms of the absorbed doses of the right optic nerve and brainstem, without statistical significance.ConclusionsCompared with the VMAT plan of hippocampal avoidance, HT technology has significant dosimetric advantages. HT plans significantly decreased the radiation dose and radiation volume of OARs surrounding the target area (e.g., surrounding eye lens and eye, especially hippocampal avoidance area) while increasing the CI and HI of PTV dose in whole brain radiotherapy (WBRT) greatly, thus enabling the decrease in the incidence rate of radioactive nerve function impairment.

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Section: Discussionmentioning

confidence: 99%

“… 31 proved that VMAT could decrease the dose of HP. Fu et al 32 . designed a inclined head four full‐arc VMAT plan for 16 patients who had whole‐brain hippocampal avoidance, and the plan could decrease the Dmax of HP.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric comparison of helical tomotherapy and volumetric modulated arc therapy in hippocampal avoidance whole‐brain radiotherapy

Zhang,

Hu,

Pang

2023

J Applied Clin Med Phys

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“…Kim et al (47) demonstrated that tilting the head at an angle of approximately 11°improved the dose distribution and reduced the irradiated dose in the hippocampus during HA-WBRT using the VMAT technique. Fu et al (48) showed that the maximum and mean doses to the hippocampus from the modified VMAT regimen were 7.88 Gy and 6.32 Gy, respectively, which were significantly lower than those from the conventional VMAT regimen, and the maximum dose was lower than that from Tomo, with a significant dose advantage for tilted head positioning (Figure 3).…”

Section: Photon Rt Techniques Volumetric Arc Intensity-modulated Rtmentioning

confidence: 98%

“…Fu et al. ( 48 ) showed that the maximum and mean doses to the hippocampus from the modified VMAT regimen were 7.88 Gy and 6.32 Gy, respectively, which were significantly lower than those from the conventional VMAT regimen, and the maximum dose was lower than that from Tomo, with a significant dose advantage for tilted head positioning ( Figure 3 ).…”

Section: Photon Rt Techniquesmentioning

confidence: 99%

Hippocampal sparing in whole-brain radiotherapy for brain metastases: controversy, technology and the future

Liu,

Gong,

Meng

et al. 2024

Front. Oncol.

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Whole-brain radiotherapy (WBRT) plays an irreplaceable role in the treatment of brain metastases (BMs), but cognitive decline after WBRT seriously affects patients’ quality of life. The development of cognitive dysfunction is closely related to hippocampal injury, but standardized criteria for predicting hippocampal injury and dose limits for hippocampal protection have not yet been developed. This review systematically reviews the clinical efficacy of hippocampal avoidance - WBRT (HA-WBRT), the controversy over dose limits, common methods and characteristics of hippocampal imaging and segmentation, differences in hippocampal protection by common radiotherapy (RT) techniques, and the application of artificial intelligence (AI) and radiomic techniques for hippocampal protection. In the future, the application of new techniques and methods can improve the consistency of hippocampal dose limit determination and the prediction of the occurrence of cognitive dysfunction in WBRT patients, avoiding the occurrence of cognitive dysfunction in patients and thus benefiting more patients with BMs.

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“…Exploring the feasibility of treating a large number of brain metastases with conventional C-arm linac, a new technique called piecewise volumetric modulated arc therapy (P-VMAT) was applied in this study. Recently, the technique was proposed by our group for WBRT with hippocampal sparing to improve plan quality and better spare hippocampus [ 19 , 20 ]. This study designed P-VMAT plans for WBRT + SIB with a large number of brain metastases and compared it with HT.…”

Section: Introductionmentioning

confidence: 99%

Application of piecewise VMAT technique to whole-brain radiotherapy with simultaneous integrated boost for multiple metastases

Men

et al. 2022

Radiat Oncol

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Purpose This study implemented a piecewise volumetric modulated arc therapy (P-VMAT) for realizing whole-brain radiation therapy (WBRT) with simultaneous integrated boost (SIB) for multiple brain metastases (> 40 metastases) with a conventional C-arm linear accelerator. Materials and methods This study retrospectively analyzed 10 patients with multiple brain metastases (40–120 metastases, median 76), who underwent WBRT and SIB using helical tomotherapy (HT). The prescribed doses were 40 Gy/20 f and 60 Gy/20 f for WBRT and SIB, respectively. Corresponding new HT plans were designed with P-VMAT using 7 arcs. For each arc, the collimator was rotated to 45°, and the field width was limited to 2.5 cm with 0.5 cm overlap with adjacent arcs. Thus, each arc covered only one section of the brain target volume. A conventional dual arc VMAT (DA-VMAT) plan was also designed. HT, P-VMAT, and DA-VMAT plans were compared using dose distribution reviews and dosimetric parameters. ArcCHECK phantom measurements were performed for verification of P-VMAT plans. Results No significant differences in the mean coverage of the whole-brain target and metastases were observed between HT and P-VMAT (p > 0.05). The conformity index for the whole-brain target improved with P-VMAT compared with HT (p < 0.05). Furthermore, the volume of 44 Gy V44 (110% of prescribed dose for WBRT) received for whole-brain significantly reduced with P-VMAT from 38.2 ± 12.9% to 23.3 ± 9.4% (p < 0.05), and the maximum dose for organs at risks such as the hippocampus, optical nerve, optical chiasm, and spinal cord declined with P-VMAT (p < 0.05). Unlike HT and P-VMAT, DA-VMAT was clinically unacceptable because V44 in the whole-brain was too high (54.7 ± 8.2%). The mean absolute dose gamma passing rate for P-VMAT plans was 97.6 ± 1.1% (3%/3 mm criterion, 10%). Conclusions P-VMAT is favorable for WBRT and SIB for multiple brain metastases. It provides comparable coverage of whole-brain target and SIB, with better conformity, lower V44, and better dose sparing of organs at risk compared with HT. Furthermore, results show that DA-VMAT fails clinical practice even for a relatively large number of brain metastases with a high degree of plan complexity. The patient specific verification demonstrates the feasibility of P-VMAT for clinical application.

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Treatment planning of volumetric modulated arc therapy and positioning optimization for hippocampal‐avoidance prophylactic cranial irradiation

Cited by 6 publications

References 21 publications

Dosimetric comparison of helical tomotherapy and volumetric modulated arc therapy in hippocampal avoidance whole‐brain radiotherapy

Dosimetric comparison of helical tomotherapy and volumetric modulated arc therapy in hippocampal avoidance whole‐brain radiotherapy

Hippocampal sparing in whole-brain radiotherapy for brain metastases: controversy, technology and the future

Application of piecewise VMAT technique to whole-brain radiotherapy with simultaneous integrated boost for multiple metastases

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