Integration method of 3D MR spectroscopy into treatment planning system for glioblastoma IMRT dose painting with integrated simultaneous boost

Abstract

BackgroundTo integrate 3D MR spectroscopy imaging (MRSI) in the treatment planning system (TPS) for glioblastoma dose painting to guide simultaneous integrated boost (SIB) in intensity-modulated radiation therapy (IMRT).MethodsFor sixteen glioblastoma patients, we have simulated three types of dosimetry plans, one conventional plan of 60-Gy in 3D conformational radiotherapy (3D-CRT), one 60-Gy plan in IMRT and one 72-Gy plan in SIB-IMRT. All sixteen MRSI metabolic maps were integrated into TPS, using normalization with color-space conversion and threshold-based segmentation. The fusion between the metabolic maps and the planning CT scans were assessed. Dosimetry comparisons were performed between the different plans of 60-Gy 3D-CRT, 60-Gy IMRT and 72-Gy SIB-IMRT, the last plan was targeted on MRSI abnormalities and contrast enhancement (CE).ResultsFusion assessment was performed for 160 transformations. It resulted in maximum differences <1.00 mm for translation parameters and ≤1.15° for rotation. Dosimetry plans of 72-Gy SIB-IMRT and 60-Gy IMRT showed a significantly decreased maximum dose to the brainstem (44.00 and 44.30 vs. 57.01 Gy) and decreased high dose-volumes to normal brain (19 and 20 vs. 23% and 7 and 7 vs. 12%) compared to 60-Gy 3D-CRT (p < 0.05).ConclusionsDelivering standard doses to conventional target and higher doses to new target volumes characterized by MRSI and CE is now possible and does not increase dose to organs at risk. MRSI and CE abnormalities are now integrated for glioblastoma SIB-IMRT, concomitant with temozolomide, in an ongoing multi-institutional phase-III clinical trial. Our method of MR spectroscopy maps integration to TPS is robust and reliable; integration to neuronavigation systems with this method could also improve glioblastoma resection or guide biopsies.

EANO guideline for the diagnosis and treatment of anaplastic gliomas and glioblastoma

“…29 Patients with adverse prognostic factors defined by age or performance status or both are now commonly treated with hypofractionated RT, e.g., 40 Gy in 15 fractions. 30 In the elderly, this is now the preferred regimen for patients with tumors lacking MGMT promoter methylation. 23,31 Neither accelerated hyper-nor hypofractionated regimens nor brachytherapy nor radiosurgery or a stereotactic RT boost have been shown to be superior to standard fractionation in terms of survival.…”

Commissioning an in‐room mobile CT for adaptive proton therapy with a compact proton system

“…However, larger criterion of 3%, 3 mm was assessed because clinically we utilize a 3% + 3 mm as our range uncertainty for proton plans. Also, this criterion for gamma analysis is utilized for IMRT QA and gives some clinical reference regarding the acceptability of comparing two different dose planes 13, 14, 15, 16. Plans were evaluated at treatment isocenter in the coronal, sagittal, and transverse planes.…”

“…Those that do are either limited to one room only with specific adaptations for a CT such as a “track” solution or cone‐beam CT (CBCT). An alternative to mobile helical CT scanners for image‐guided proton therapy is the gantry‐mounted cone‐beam CT (CBCT) 5, 6, 7, 8, 9. Gantry‐mounted CT systems may provide more convenience than mobile scanners.…”

Volumetric‐based image guidance is superior to marker‐based alignments for stereotactic body radiotherapy of prostate cancer

“…Several recent SBRT studies showed local control rates and toxicity profiles were comparable to the conventional dose regimen of 2 Gy per fraction (2 Gy/Fx) 2, 3. It has been reported that with a prescription dose of 7.25 Gy/Fx or higher in SBRT treatment planning, margins are usually 5 mm or smaller to spare the surrounding organs at risk such as rectum, urethra, and bladder 1.…”