Assessment of dose rate scaling factors used in NCTPlan treatment planning code for the BNCT beam of THOR

Hsu, F.Y.; Liu, M.T.; Tung, C. J.; Liu, Y.W. Hsueh; Chang, Chih‐Chieh; Liu, H.M.; Chou, Fong‐In

doi:10.1016/j.apradiso.2009.03.033

Cited by 2 publications

(4 citation statements)

References 6 publications

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“…The DRSF values derived from measured and computed depth-dose-rate distributions by least-squares criteria were 0.64, 1.39, 0.96, and 0.65, for thermal neutron, fast neutron, photon, and 10 B, respectively [17]. The T/N ratio for boron concentration in the brain tumor was assumed to be 3.5 according to a previous glioblastoma study [18].…”

Section: Methodsmentioning

confidence: 99%

“…Previously, an RBE factor of 3.2 was used for THOR epithermal neutron beam high-LET components, such as the products of thermal neutron capture in nitrogen and fast neutrons, while a RBE factor of 0.5 was used for photons [17]. The default neutron power and flux values were 1.2 MW and 1.28 × 10 9 n·cm −2 ·s −1 , respectively, for THOR conditions [20].…”

Section: Methodsmentioning

confidence: 99%

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The Dosimetric Impact of Shifts in Patient Positioning during Boron Neutron Capture Therapy for Brain Tumors

Lee

Chen

Chuang

et al. 2018

BioMed Research International

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Unlike conventional photon radiotherapy, sophisticated patient positioning tools are not available for boron neutron capture therapy (BNCT). Thus, BNCT remains vulnerable to setup errors and intra-fractional patient motion. The aim of this study was to estimate the impact of deviations in positioning on the dose administered by BNCT for brain tumors at the Tsing Hua open-pool reactor (THOR). For these studies, a simulated head model was generated based on computed tomography (CT) images of a patient with a brain tumor. A cylindrical brain tumor 3 cm in diameter and 5 cm in length was modeled at distances of 6.5 cm and 2.5 cm from the posterior scalp of this head model (T6.5 cm and T2.5 cm, respectively). Radiation doses associated with positioning errors were evaluated for each distance, including left and right shifts, superior and inferior shifts, shifts from the central axis of the beam aperture, and outward shifts from the surface of the beam aperture. Rotational and tilting effects were also evaluated. The dose prescription was 20 Gray-equivalent (Gy-Eq) to 80 % of the tumor. The treatment planning system, NCTPlan, was used to perform dose calculations. The average decreases in mean tumor dose for T6.5 cm for the 1 cm, 2 cm, and 3 cm lateral shifts composed by left, right, superior, and inferior sides, were approximately 1 %, 6 %, and 11 %, respectively, compared to the dose administered to the initial tumor position. The decreases in mean tumor dose for T6.5 cm were approximately 5 %, 11 %, and 15 % for the 1 cm, 2 cm, and 3 cm outward shifts, respectively. For a superficial tumor at T2.5cm, no significant decrease in average mean tumor dose was observed following lateral shifts of 1 cm. Rotational and tilting up to 15° did not result in significant difference to the tumor dose. Dose differences to the normal tissues as a result of the shifts in positioning were also minimal. Taken together, these data demonstrate that the mean dose administered to tumors at greater depths is potentially more vulnerable to deviations in positioning, and greater shift distances resulted in reduced mean tumor doses at the THOR. Moreover, these data provide an estimation of dose differences that are caused by setup error or intra-fractional motion during BNCT, and these may facilitate more accurate predictions of actual patient dose in future treatments.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Dosimetric Impact of Shifts in Patient Positioning during Boron Neutron Capture Therapy for Brain Tumors

Lee

Chen

Chuang

et al. 2018

BioMed Research International

View full text Add to dashboard Cite

show abstract

“…The dose-rate scaling factor values derived from the measured and computed depth-dose-rate distributions by least-squares criteria were 0.64, 1.39, 0.96, and 0.65, for thermal neutron, fast neutron, photon, and B-10, respectively [13]. Although the T/N ratio between boron concentrations in DIPG remains unknown, because most DIPGs are composed of glioblastoma, we assumed a T/N ratio of 3.5 according to a previous glioblastoma study [14].…”

Section: Methodsmentioning

confidence: 99%

“…A RBE of 3.2 for THOR epithermal neutron beam high-LET components, such as the products of thermal neutron capture in nitrogen and fast neutrons, and a RBE of 0.5 for photon [13]. The default neutron power and flux were 1.2 MW and 1.28 × 10 9 (n·cm -2 ·s -1 ), respectively, for the conditions of THOR [15].…”

Section: Methodsmentioning

confidence: 99%

Preliminary dosimetric study on feasibility of multi-beam boron neutron capture therapy in patients with diffuse intrinsic pontine glioma without craniotomy

et al. 2017

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Diffuse intrinsic pontine glioma is a very frustrating disease. Since the tumor infiltrates the brain stem, surgical removal is often impossible. For conventional radiotherapy, the dose constraint of the brain stem impedes attempts at further dose escalation. Boron neutron capture therapy (BNCT), a targeted radiotherapy, carries the potential to selectively irradiate tumors with an adequate dose while sparing adjacent normal tissue. In this study, 12 consecutive patients treated with conventional radiotherapy in our institute were reviewed to evaluate the feasibility of BNCT. NCTPlan Ver. 1.1.44 was used for dose calculations. Compared with two and three fields, the average maximal dose to the normal brain may be lowered to 7.35 ± 0.72 Gy-Eq by four-field irradiation. The mean ratio of minimal dose to clinical target volume and maximal dose to normal tissue was 2.41 ± 0.26 by four-field irradiation. A therapeutic benefit may be expected with multi-field boron neutron capture therapy to treat diffuse intrinsic pontine glioma without craniotomy, while the maximal dose to the normal brain would be minimized by using the four-field setting.

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Assessment of dose rate scaling factors used in NCTPlan treatment planning code for the BNCT beam of THOR

Cited by 2 publications

References 6 publications

The Dosimetric Impact of Shifts in Patient Positioning during Boron Neutron Capture Therapy for Brain Tumors

The Dosimetric Impact of Shifts in Patient Positioning during Boron Neutron Capture Therapy for Brain Tumors

Preliminary dosimetric study on feasibility of multi-beam boron neutron capture therapy in patients with diffuse intrinsic pontine glioma without craniotomy

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