Optimizing Patient Positioning for Intensity Modulated Radiation Therapy in Hippocampal-Sparing Whole Brain Radiation Therapy

Siglin, Joshua; Chapman, Katherine L.; Vakhnenko, Yelena; Witek, Matthew E.; Harrison, A; Xiao, Yufen; Liu, H.; Dicker, Adam P.; Shi, William T.

doi:10.1016/j.ijrobp.2011.06.1378

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, if a patient’s head is tilted forward at a certain degree, the long axis of the hippocampus will be turned to be parallel to gantry rotation axis, which may help multi‐leaf collimator (MLC) leaves to spare the hippocampus. Two recent studies reported that when patients received HA‐PCI with 30° tilted head positioning, the dose to the hippocampus and other normal tissues could be further decreased 16,17 . In order to spare normal tissues, especially the hippocampus, to the maximum, we chose the tilt angle of patient’s head to be 45° for this study after analyzing hippocampal tilt angle and eyeballs position relative to brain for different patients.…”

Section: Methodsmentioning

confidence: 99%

“…Two recent studies reported that when patients received HA-PCI with 30°tilted head positioning, the dose to the hippocampus and other normal tissues could be further decreased. 16,17 In order to spare normal tissues, especially the hippocampus, to the maximum, we chose the tilt angle of patient's head to be 45°for this study after analyzing hippocampal tilt angle and eyeballs position relative to brain for different patients. For the sake of simplicity, we rotated CT images of 0°position to simulate the situation of a 45°tilted head position.…”

Section: D | Tilted Head Positioningmentioning

confidence: 99%

See 1 more Smart Citation

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

Chen

Yan

et al. 2021

J Applied Clin Med Phys

View full text Add to dashboard Cite

Background: Hippocampal-avoidance prophylactic cranial irradiation (HA-PCI) offers potential neurocognitive benefits but raises technical challenges to treatment planning. This study aims to improve the conventional planning method using volumetric modulated arc therapy (VMAT) technique and investigate a better patient's head positioning to achieve a high quality of HA-PCI treatment plans.Methods: The improved planning method set a wide expansion of hippocampus as a special region for dose decline. The whole brain target was divided into two parts according to whether the slice included hippocampus and their optimization objectives were set separately. Four coplanar full arcs with partial field sizes were employed to deliver radiation dose to different parts of the target. The collimator angle for all arcs was 90°. Tilting patient's head was achieved by rotating CT images.The improved planning method and tilted head positioning were verified using datasets from 16 patients previously treated with HA-PCI using helical tomotherapy (HT).Results: For the improved VMAT plans, the max and mean doses to hippocampus were 7.88 Gy and 6.32 Gy, respectively, significantly lower than those for the conventional VMAT plans (P < 0.001). Meanwhile, the improved planning method significantly improved the plan quality. Compared to the HT plans, the improved VMAT plans result in similar mean dose to hippocampus (P > 0.1) but lower max dose (P < 0.02). Besides, the target coverage was the highest for the improved VMAT plans. The tilted head positioning further reduced the max and mean doses to hippocampus (P < 0.05), significantly decreased the max dose to lens (P < 0.001) and resulted in higher plan quality as compared to nontilted head positioning. Conclusions:The improved planning method enables the VMAT plans to meet the clinical requirements of HA-PCI treatment with high plan quality and convenience.The tilted head positioning provides superior dosimetric advantages over the nontilted head positioning, which is recommended for clinical application.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: D | Tilted Head Positioningmentioning

confidence: 99%