Target Point, Target Volume, “Whole Brain” Stereotaxis: Remarks on Some Present Trends of Evolution in Stereotactic Neurosurgery

1980 ◽  
pp. 1-3 ◽  
Author(s):  
Gábor Szikla
Keyword(s):  
Target Volume ◽  
Target Point ◽  
Stereotactic Neurosurgery ◽  
Whole Brain ◽  
Point Target

scholarly journals Use of a Head-Tilting Baseplate During Tomotherapy to Shorten the Irradiation Time and Protect the Hippocampus and Lens in Hippocampal Sparing-Whole Brain Radiotherapy

2021 ◽  
Vol 20 ◽  
pp. 153303382098682
Author(s):  
Kosei Miura ◽  
Hiromasa Kurosaki ◽  
Nobuko Utsumi ◽  
Hideyuki Sakurai
Keyword(s):  
At Risk ◽  
Planning Target Volume ◽  
Irradiation Time ◽  
Organs At Risk ◽  
Absorbed Dose ◽  
Whole Brain Radiotherapy ◽  
Target Volume ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Hippocampal Sparing

Purpose: The aim of this study is to comparatively examine the possibility of reducing the exposure dose to organs at risk, such as the hippocampus and lens, and improving the dose distribution of the planned target volume with and without the use of a head-tilting base plate in hippocampal-sparing whole-brain radiotherapy using tomotherapy. Methods: Five paired images of planned head computed tomography without and with tilt were analyzed. The hippocampus and planning target volume were contoured according to the RTOG 0933 contouring atlas protocol. The hippocampal zone to be avoided was delineated using a 5-mm margin. The prescribed radiation dose was 30 Gy in 10 fractions. The absorbed dose to planning target volume dose, absorbed dose to the organ at risk, and irradiation time were evaluated. The paired t-test was used to analyze the differences between hippocampal-sparing whole-brain radiotherapy with head tilts and without head tilts. Results: Hippocampal-sparing whole-brain radiotherapy with tilt was not superior in planning target volume doses using the homogeneity index than that without tilt; however, it showed better values, and for Dmean and D2%, the values were closer to 30 Gy. Regarding the hippocampus, dose reduction with tilt was significantly greater at Dmax, Dmean, and Dmin, whereas regarding the lens, it was significantly greater at Dmax and Dmin. The irradiation time was also predominantly shorter. Conclusion: In our study, a tilted hippocampal-sparing whole-brain radiotherapy reduced the irradiation time by >10%. Therefore, our study indicated that hippocampal-sparing whole-brain radiotherapy with tomotherapy should be performed with a tilt. The head-tilting technique might be useful during hippocampal-sparing whole-brain radiotherapy. This method could decrease the radiation exposure time, while sparing healthy organs, including the hippocampus and lens.

scholarly journals RADI-26. DOSIMETRIC EVALUATION OF 6 MV VERSUS 10 MV PHOTONS FOR HIPPOCAMPAL AVOIDANCE WHOLE BRAIN RADIOTHERAPY

2019 ◽  
Vol 1 (Supplement_1) ◽  
pp. i26-i27
Author(s):  
Diana Julie ◽  
Sean Mahase ◽  
Diana No ◽  
Khaled Salah ◽  
Jonathan Knisely
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Whole Brain Radiotherapy ◽  
Target Volume ◽  
Brain Parenchyma ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Hippocampal Avoidance ◽  
Signed Rank ◽  
Dose Homogeneity ◽  
Dose Constraints

Abstract OBJECTIVE: Whole brain radiotherapy (WBRT) causes neurocognitive decline. Hippocampal avoidance WBRT (HA-WBRT) reduces hippocampal irradiation, potentially mitigating neurocognitive sequelae. We compared hippocampal and brain dosimetry with HA-WBRT with 6 megavoltage (MV) versus 10 MV photon energies. METHODS: Twenty consecutive patients treated with WBRT were retrospectively replanned with HA-WBRT techniques using 6 MV and 10 MV photons. Coplanar volumetric modulated arc therapy was employed, with a prescription dose of 3000 cGy in 10 fractions. Planning was done with Eclipse version 13.6 or 15.6. Nine patients were planned with 2.5 mm multileaf collimator leaves, with the remainder planned with 5 mm leaves. The hippocampi were contoured and a HA structure was generated using a uniform 5 mm expansion. A planning target volume (PTV) was defined as the brain parenchyma minus the HA structure. NRG-CC001 dose constraints were used. For each variable, descriptive statistics were calculated. Comparisons were made using two-tailed Wilcoxon signed rank tests or paired t-tests. RESULTS: The minimum hippocampal dose (D100%) was improved with 6 MV plans, 841 cGy compared to 914 cGy with 10 MV (p< 0.005). The maximum hippocampal dose (D0.03cc) was reduced with 6 MV planning, 1614 cGy versus 1676 cGy for 10 MV (p< 0.0001). With 6 MV photons, a greater number of plans met NRG-CC001 constraints without deviations. 6 MV photons improved PTV coverage by the 95% isodose line, 96.6% compared to 95.9% for 10 MV (p=0.021). 6 MV photon plans decreased the volume of PTV receiving ≥105% of the prescription, 84.2% versus 87.9% for 10 MV (p=0.006). The mean dose, hot spots, and cold spots did not differ by photon energy. PTV dose constraints were always met. CONCLUSION: 6 MV photon HA-WBRT plans are dosimetrically superior to 10 MV, reducing hippocampal radiation dose, without compromise in brain coverage and improved target dose homogeneity.

scholarly journals RONC-06. VOLUMETRIC-MODULATED ARC WHOLE-BRAIN RADIOTHERAPY FOR THE PREVENTION OF PERMANENT ALOPECIA IN PEDIATRIC PATIENTS

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii457-iii457
Author(s):  
Megumi Uto ◽  
Katsutsugu Umeda ◽  
Yoshiki Arakawa ◽  
Keiichi Takehana ◽  
Tatsuya Kamitori ◽  
...  
Keyword(s):  
Pediatric Patients ◽  
Late Complication ◽  
Whole Brain Radiotherapy ◽  
Target Volume ◽  
Cranial Irradiation ◽  
Hair Follicles ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Meningeal Dissemination ◽  
Spinal Mri

Abstract Permanent alopecia is a grave late complication of multi-drug chemotherapy (CTx) plus cranial irradiation, reducing both patient self-esteem and quality of life in pediatric patients. We started to use craniospinal irradiation (CSI) using the volumetric-modulated arc whole-brain radiotherapy (VMAT-WBRT) in order to prevent permanent alopecia. We treated 5 pediatric patients with CSI using VMAT-WBRT, and report the initial clinical outcome. Five consecutive patients (4–11 years old) who received CSI using VMAT-WBRT from June 2015 to November 2018 were included into this study. One patient with embryonic carcinoma received radiotherapy (RT) with concurrent CTx; four patients with medulloblastoma (two patients with standard risk, and two patients with high risk) received RT followed by CTx. The prescribed doses of CSI were 23.4–35.2 Gy in 13–22 fractions, respectively. Optimization for VMAT-WBRT was performed to reduce doses to the hair follicles with keeping the dose coverage to the planning target volume. Although all patients experienced temporary alopecia, their hair fully recovered over the whole scalp within 8 months after finishing RT. One patient had disease progression after 6 months after completing CTx; this patient who was diagnosed as Group 3 subtype had diffuse meningeal dissemination confirmed with contrast enhanced spinal MRI before RT. The other four patients had no evidence of recurrence. Although CSI with VMAT-WBRT might be one of considerable options, more cases are needed to verify the efficacy to prevent permanent alopecia for pediatric patients who receive multi-drug CTx and cranial irradiation.

scholarly journals Total target volume is a better predictor of whole brain dose from gamma stereotactic radiosurgery than the number, shape, or location of the lesions

2013 ◽  
Vol 40 (9) ◽  
pp. 091714 ◽  
Author(s):  
Ganesh Narayanasamy ◽  
Adam Smith ◽  
Emily Van Meter ◽  
Ronald McGarry ◽  
Janelle A. Molloy
Keyword(s):  
Stereotactic Radiosurgery ◽  
Target Volume ◽  
Whole Brain

Digital Radiography for Target Point Evaluation in Stereotactic Neurosurgery

1983 ◽  
Vol 46 (1-4) ◽  
pp. 206-210
Author(s):  
M. Fröder ◽  
D. Seitzer ◽  
G. Büren ◽  
G. Dieckmann
Keyword(s):  
Digital Radiography ◽  
Target Point ◽  
Stereotactic Neurosurgery ◽  
Point Evaluation

A novel miniature robotic guidance device for stereotactic neurosurgical interventions: preliminary experience with the iSYS1 robot

2017 ◽  
Vol 126 (3) ◽  
pp. 985-996 ◽  
Author(s):  
Georgi Minchev ◽  
Gernot Kronreif ◽  
Mauricio Martínez-Moreno ◽  
Christian Dorfer ◽  
Alexander Micko ◽  
...  
Keyword(s):  
Clinical Application ◽  
Setup Time ◽  
Target Point ◽  
Stereotactic Neurosurgery ◽  
Target Error ◽  
Data Application ◽  
Robotic Devices ◽  
Tumor Biopsies ◽  
Positioning Time ◽  
Guidance Device

OBJECTIVE Robotic devices have recently been introduced in stereotactic neurosurgery in order to overcome the limitations of frame-based and frameless techniques in terms of accuracy and safety. The aim of this study is to evaluate the feasibility and accuracy of the novel, miniature, iSYS1 robotic guidance device in stereotactic neurosurgery. METHODS A preclinical phantom trial was conducted to compare the accuracy and duration of needle positioning between the robotic and manual technique in 162 cadaver biopsies. Second, 25 consecutive cases of tumor biopsies and intracranial catheter placements were performed with robotic guidance to evaluate the feasibility, accuracy, and duration of system setup and application in a clinical setting. RESULTS The preclinical phantom trial revealed a mean target error of 0.6 mm (range 0.1–0.9 mm) for robotic guidance versus 1.2 mm (range 0.1–2.6 mm) for manual positioning of the biopsy needle (p < 0.001). The mean duration was 2.6 minutes (range 1.3–5.5 minutes) with robotic guidance versus 3.7 minutes (range 2.0–10.5 minutes) with manual positioning (p < 0.001). Clinical application of the iSYS1 robotic guidance device was feasible in all but 1 case. The median real target error was 1.3 mm (range 0.2–2.6 mm) at entry and 0.9 mm (range 0.0–3.1 mm) at the target point. The median setup and instrument positioning times were 11.8 minutes (range 4.2–26.7 minutes) and 4.9 minutes (range 3.1–14.0 minutes), respectively. CONCLUSIONS According to the preclinical data, application of the iSYS1 robot can significantly improve accuracy and reduce instrument positioning time. During clinical application, the robot proved its high accuracy, short setup time, and short instrument positioning time, as well as demonstrating a short learning curve.

Magnetic resonance image—directed stereotactic neurosurgery: use of image fusion with computerized tomography to enhance spatial accuracy

1995 ◽  
Vol 83 (2) ◽  
pp. 271-276 ◽  
Author(s):  
Eben Alexander ◽  
Hanne M. Kooy ◽  
Marcel van Herk ◽  
Marc Schwartz ◽  
Patrick D. Barnes ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Image Fusion ◽  
Computerized Tomography ◽  
Target Volume ◽  
Stereotactic Neurosurgery ◽  
Content Type ◽  
Geometric Precision ◽  
Fine Print

✓ Distortions of the magnetic field, such as those caused by susceptibility artifacts and peripheral magnetic field warping, can limit geometric precision in the use of magnetic resonance (MR) imaging in stereotactic procedures. The authors have routinely found systematic error in MR stereotactic coordinates with a median of 4 mm compared to computerized tomography (CT) coordinates. This error may place critical neural structures in jeopardy in some procedures. A description is given of an image fusion technique that uses a chamfer matching algorithm; the advantages of MR imaging in anatomical definition are combined with the geometric precision of CT, while eliminating most of the anatomical spatial distortion of stereotactic MR imaging. A stereotactic radiosurgical case is presented in which the use of MR localization alone would have led to both irradiation of vital neural structures outside the desired target volume and underdose of the intended target volume. The image fusion approach allows for the use of MR imaging, combined with stereotactic CT, as a reliable localizing technique for stereotactic neurosurgery and radiosurgery.

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