Comparison of Multiple Treatment Planning Techniques for High-Grade Glioma Tumors Near to Critical Organs

Abstract

Aim: The purpose of this study was to compare 6 treatment planning methods (5-beam coplanar intensity-modulated radiotherapy (IMRT), 7-beam coplanar IMRT, 7-beam noncoplanar IMRT, 2 full arc coplanar volumetric modulated arc therapy (VMAT), 2 half partial arc coplanar VMAT, and 2 half partial arc noncoplanar VMAT) for high-grade gliomas with planning target volumes (PTVs) overlapping the optic pathway and/or brainstem. Patients and Methods: 27 previously-treated patients with high-grade gliomas were replanned for treatment with IMRT₅, IMRT₇, IMRT_7-non, VMAT_2f, VMAT_2h, and VMAT_2h-non. In order to perform a comparative study of the treatment outcomes, 3 tumor localizations (right-sided, left-sided, and central tumors) were selected. Patients were administered a PTV dose of 60 Gy in 30 fractions with a maximum permitted dose of 110%. Results: Comparison of the 3 IMRT plans and 3 VMAT plans was performed for all 27 patients. The median conformity index was significantly higher (p < 0.05) in all IMRT plans compared to all VMAT plans in the case of right sided tumors. Significant differences were also observed between coplanar and noncoplanar plans in IMRT and VMAT in right-sided tumors (p < 0.05). Differences in brainstem mean doses were only found to be significant between coplanar and noncoplanar plans in centrally-located tumors. In right- and left-sided tumors, the VMAT_2f plans demonstrated higher values than all IMRT plans in their mean values for radiation doses to the ipsilateral optic nerves, contralateral optic nerves, ipsilateral lens, ipsilateral eye, contralateral lens, contralateral eye, and contralateral optic nerves, as well in the maximums for the optic chiasm and contralateral optic nerves. Significantly faster treatment times were achieved with all VMAT plans compared to IMRT plans. Conclusion: IMRT techniques provided better target coverage than VMAT plans. However, VMAT techniques reduced treatment delivery time more than IMRT techniques. Technique selection for tumors located in 3 different localizations should be individualized in accordance with patients' specific parameters.

Identification of differentially expressed microRNAs and the potential of microRNA‑455‑3p as a novel prognostic biomarker in glioma

“…Glioma is an aggressive brain cancer with high morbidity and mortality rates (1) characterized by aggressive proliferation, invasion and dismal prognosis (2). Although great progress has been made in the therapeutic field, the prognosis of patients with glioma remains poor (3).…”

Dose distribution of the brain tissue associated with cognitive functions in high-grade glioma patients

“…No difference was observed in terms of normal brain exposure. The use of full or partial arcs, based namely on PTV location and extent, could also modify the OAR exposure [24].…”

“…24.3 dedicated platform. The PTV coverage was assessed using the following parameters: the homogeneity index (HI), the conformity index (CI) and the Paddick index (PI), defined by the respective formulas: Doses to the areas implied in cognition -Jacob HI = (D2%-D98%)/D50%[15];…”

Multi-Planar VMAT Plans for High-Grade Glioma and Glioblastoma Targeting the Hypothalamic-Pituitary Axis Sparing

“…It has been applied for treating prostate cancer [6,7] and liver cancer [8,9] in coplanar VMAT and lung cancer in non-coplanar VMAT [10]. In view of cranial regions, previous studies suggested that non-coplanar VMAT demonstrated a dose reduction to organs at risk (OARs) located in the peripheral regions, including the hippocampus [11][12][13], normal brain tissue, the temporal lobe and the cochlea [14,15]. A significant dose reduction to these organs helped to minimize the side effects, such as cognitive decline and auditory impairment.…”

“…Previous studies revealed that growth hormone (GH) deficiency may occur when the pituitary gland receives 30 Gy, and thyroid stimulating hormone deficiency may occur if it receives over 40 Gy [17,23,24]. The risk of hypopituitarism increases steadily from 15 Gy to 70 Gy without a particular threshold [23]. To minimize the dose to the hypothalamic-pituitary axis is crucial for patients' long-term benefit.…”