scholarly journals Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy

2021 ◽  
Vol 20 ◽  
pp. 153303382110454
Author(s):  
Akihiko Ishibashi ◽  
Hiromasa Kurosaki ◽  
Kosei Miura ◽  
Nobuko Utsumi ◽  
Hideyuki Sakurai
Keyword(s):  
Dose Distribution ◽  
Irradiation Time ◽  
Body Position ◽  
Treatment Plan ◽  
Volumetric Modulated Arc Therapy ◽  
Whole Brain Radiotherapy ◽  
Whole Brain ◽  
Modulation Factor ◽  
Brain Radiotherapy ◽  
Computed Tomography Images

Objectives: Hippocampus-sparing whole-brain radiotherapy (HS-WBRT) using tomotherapy is known to provide a better dose distribution than volumetric-modulated arc therapy but requires an extended irradiation time. The present study aimed to investigate whether irradiation time can be shortened by reducing the modulation factor (MF) without losing the target dose distribution. Methods: Using six tilted computed tomography images in the head area, the planning target volume (PTV) and hippocampal doses, and the irradiation time was investigated with a jaw width of 1 cm, a pitch of 0.200, and the MF changed from 3.0 to 2.6, 2.2, 1.8, and 1.4. Results: No significant changes in the PTV or hippocampus were found with MF in the range from 3.0 to 1.8, but marked deterioration was found with that of 1.4. The irradiation time showed a linear relationship with the MF within the range from 3.0 to 1.8, with 1334, 1158, 986, and 817 s at modulation factors of 3.0, 2.6, 2.2, and 1.8, respectively. However, when the MF was 1.4, the irradiation time was 808 s. Conclusions: When HS-WBRT is performed with a tilted body position and a jaw width of 1 cm, with a MF of 1.8, a favorable balance between dose parameters and irradiation time is achieved, whereas with a MF of 1.4, the quality of the radiotherapy plan deteriorates, and the irradiation time is approximately the same as that with a MF of 1.8.

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.

Improvement of dose distribution with irregular surface compensator in whole brain radiotherapy

2014 ◽  
Vol 30 ◽  
pp. e79-e80
Author(s):  
Hideki Fujita ◽  
Nao Kuwahata ◽  
Hiroyuki Hattori ◽  
Hiroshi Kinoshita ◽  
Haruyuki Fukuda
Keyword(s):  
Dose Distribution ◽  
Whole Brain Radiotherapy ◽  
Irregular Surface ◽  
Whole Brain ◽  
Brain Radiotherapy

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.

Whole brain radiotherapy with volumetric-modulated arc therapy for pediatric intracranial embryonic carcinoma prevents permanent alopecia

2017 ◽  
Vol 64 (8) ◽  
pp. e26434 ◽  
Author(s):  
Atsushi Iwai ◽  
Katsutsugu Umeda ◽  
Megumi Uto ◽  
Hiroshi Nihira ◽  
Koji Kawaguchi ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Whole Brain Radiotherapy ◽  
Whole Brain ◽  
Embryonic Carcinoma ◽  
Brain Radiotherapy ◽  
Arc Therapy

Improvement of dose homogeneity with irregular surface compensator in whole brain radiotherapy

2016 ◽  
Vol 15 (3) ◽  
pp. 269-275
Author(s):  
H. Fujita ◽  
N. Kuwahata ◽  
H. Hattori ◽  
H. Kinoshita ◽  
H. Fukuda
Keyword(s):  
Maximum Dose ◽  
Treatment Plan ◽  
Whole Brain Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Irregular Surface ◽  
Medical Systems ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Dose Homogeneity

AbstractPurposeThe aim of this study was to evaluate the dosimetric aspects of whole brain radiotherapy (WBRT) using an irregular surface compensator (ISC) in contrast to conventional radiotherapy techniques.MethodsTreatment plans were devised for 20 patients. The Eclipse treatment planning system (Varian Medical Systems) was used for dose calculation. For the ISC, a fluence editor application was used to extend the range of optimal fluence. The treatment plan with the ISC was compared with the conventional technique in terms of doses in the planning target volume (PTV), dose homogeneity index (DHI), three-dimensional (3D) maximum dose, eye and lens doses and monitor unit (MU) counts required for treatment.ResultsCompared with conventional WBRT, the ISC significantly reduced the DHI, 3D maximum dose and volumes receiving 105% of the prescription dose, in addition to reducing both eye and lens doses (p<0·05 for all comparisons). In contrast, MU counts were higher for the ISC technique than for conventional WBRT (828 versus 328, p<0·01).ConclusionThe ISC technique for WBRT considerably improved the dose homogeneity in the PTV. As patients who receive WBRT have improved survival, the long-term side effects of radiotherapy are highly important.

EP-1264 SIMULTANEOUS BOOST AND WHOLE-BRAIN RADIOTHERAPY WITH VOLUMETRIC MODULATED ARC THERAPY FOR BRAIN METASTASES

2012 ◽  
Vol 103 ◽  
pp. S482-S483
Author(s):  
D. Russo ◽  
A. Paladini ◽  
C.D. Gianfreda ◽  
C. Accettura ◽  
C. Capomolla ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Volumetric Modulated Arc Therapy ◽  
Whole Brain Radiotherapy ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Arc Therapy
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