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Title: Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy

Abstract

The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called {sup 11}B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 {mu}m, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 {mu}m, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 {mu}m and a nucleus radius of 5 {mu}m is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than themore » published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.« less

Authors:
; ; ;  [1];  [2];  [2]
  1. Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871 (China)
  2. (China)
Publication Date:
OSTI Identifier:
20853840
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 33; Journal Issue: 12; Other Information: DOI: 10.1118/1.2358849; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; APPROXIMATIONS; BIOPHYSICS; BORON 10; BORON 11; COMPUTERIZED SIMULATION; HELIUM 4; LITHIUM 7; MICRODOSIMETRY; MONTE CARLO METHOD; NEUTRON CAPTURE THERAPY; POINT KERNELS; RADIATION DOSES; RADIOBIOLOGY; THERMAL NEUTRONS

Citation Formats

Ma Yunzhi, Geng Jinpeng, Gao Song, Bao Shanglian, Department of Nuclear Physics, Chinese Institute of Atomic Energy, Beijing, 102413, and Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871. Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy. United States: N. p., 2006. Web. doi:10.1118/1.2358849.
Ma Yunzhi, Geng Jinpeng, Gao Song, Bao Shanglian, Department of Nuclear Physics, Chinese Institute of Atomic Energy, Beijing, 102413, & Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871. Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy. United States. doi:10.1118/1.2358849.
Ma Yunzhi, Geng Jinpeng, Gao Song, Bao Shanglian, Department of Nuclear Physics, Chinese Institute of Atomic Energy, Beijing, 102413, and Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871. Fri . "Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy". United States. doi:10.1118/1.2358849.
@article{osti_20853840,
title = {Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy},
author = {Ma Yunzhi and Geng Jinpeng and Gao Song and Bao Shanglian and Department of Nuclear Physics, Chinese Institute of Atomic Energy, Beijing, 102413 and Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871},
abstractNote = {The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called {sup 11}B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 {mu}m, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 {mu}m, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 {mu}m and a nucleus radius of 5 {mu}m is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.},
doi = {10.1118/1.2358849},
journal = {Medical Physics},
number = 12,
volume = 33,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
  • Purpose: To analyze the dose-volume histogram (DVH) of head-and-neck tumors treated with boron neutron capture therapy (BNCT) and to determine the advantage of the intra-arterial (IA) route over the intravenous (IV) route as a drug delivery system for BNCT. Methods and Materials: Fifteen BNCTs for 12 patients with recurrent head-and-neck tumors were included in the present study. Eight irradiations were done after IV administration of boronophenylalanine and seven after IA administration. The maximal, mean, and minimal doses given to the gross tumor volume were assessed using a BNCT planning system. Results: The results are reported as median values with themore » interquartile range. In the IA group, the maximal, mean, and minimal dose given to the gross tumor volume was 68.7 Gy-Eq (range, 38.8-79.9), 45.0 Gy-Eq (range, 25.1-51.0), and 13.8 Gy-Eq (range, 4.8-25.3), respectively. In the IV group, the maximal, mean, and minimal dose given to the gross tumor volume was 24.2 Gy-Eq (range, 21.5-29.9), 16.4 Gy-Eq (range, 14.5-20.2), and 7.8 Gy-Eq (range, 6.8-9.5), respectively. Within 1-3 months after BNCT, the responses were assessed. Of the 6 patients in the IV group, 2 had a partial response, 3 no change, and 1 had progressive disease. Of 4 patients in the IA group, 1 achieved a complete response and 3 a partial response. Conclusion: Intra-arterial administration of boronophenylalanine is a promising drug delivery system for head-and-neck BNCT.« less
  • Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. Employing an experimental model of liver metastases in rats, we recently demonstrated that BNCT mediated by boronophenylalanine (BPA-BNCT) at 13 Gy prescribed to tumor is therapeutically useful at 3-week follow-up. The aim of the present study was to evaluate dose–response at 5-week follow-up, based on retrospective dose assessment in individual rats. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA-BNCT (n = 19), Beam only (n = 8) and Sham (n = 7) (matched manipulation, no treatment). For eachmore » rat, neutron flux was measured in situ and boron content was measured in a pre-irradiation blood sample for retrospective individual dose assessment. For statistical analysis (ANOVA), individual data for the BPA-BNCT group were pooled according to absorbed tumor dose, BPA-BNCT I: 4.5–8.9 Gy and BPA-BNCT II: 9.2–16 Gy. At 5 weeks post-irradiation, the tumor surface area post-treatment/pre-treatment ratio was 12.2 +/- 6.6 for Sham, 7.8 +/- 4.1 for Beam only, 4.4 +/- 5.6 for BPA-BNCT I and 0.45 +/- 0.20 for BPA-BNCT II; tumor nodule weight was 750 +/- 480 mg for Sham, 960 +/- 620 mg for Beam only, 380 +/- 720 mg for BPA-BNCT I and 7.3 +/- 5.9 mg for BPA-BNCT II. The BPA-BNCT II group exhibited statistically significant tumor control with no contributory liver toxicity. Potential threshold doses for tumor response and significant tumor control were established at 6.1 and 9.2 Gy, respectively.« less
  • At least 8 classes of compounds are being evaluated in various laboratories around the world as possible vehicles for the transport of boron to tumors for neutron capture therapy (NCT). A parameter of major importance is the minimum concentration of boron needed in tumors in order to produce improved results in cancer therapy. Calculations are made here of the minimum boron content in tumors necessary for NCT. These estimations are obtained for various neutron beams, on the basis of therapeutic gain produced by the effective dose (absorbed dose X relative biological effect). The effects of repair are considered, in anticipationmore » of having boronated bio-molecules with selective and long- term binding to tumor cells, thus allowing protracted irradiations. Pure epithermal neutron beams (free of significant fast neutron and gamma contamination) are found to offer major advantages, particularly when the effects of repair are included. The various boron compounds being investigated for NCT are evaluated on the basis of necessary minimum boron content in tumor.« less
  • The method of an evaluation for the dose characteristics of BNCT is presented, and an eccentric core design for the TRIGA-II reactor is proposed. The authors have defined the [open quotes]irradiation time[close quotes] as the time of irradiation in which the [open quotes]maximum 1 [mu]g/g dose[close quotes] becomes 3,000 RBE-cGy, because they assumed that the normal tissue contained 1 [mu]g/g [sup 10]B. They have also changed the RBE values and calculated the absorbed dose in the irradiation time by using an arrangement including both a facility structure and a body phantom. Moreover, they have modified the dose criteria for BNCTmore » as follows: The [open quotes]eye dose[close quotes], [open quotes]total body dose[close quotes], and [open quotes]except-head dose[close quotes] should be less than 200, 100, and 50 RBE-cGy, respectively. They have added one more criteria for BNCT-that the thermal neutron fluence at the tumor position (5 cm from the surface) should be over 2.5 [times] 10[sup 12] n/cm[sup 2] in the irradiation time. The distance from the core side to the irradiation port is a very important factor in designing a neutron irradiation field for BNCT. They can get the acceptable dose for BNCT with only 1-h irradiation by using a 100 kW reactor if they can get the irradiation port at the distance of 120 cm from the core side. 4 refs., 6 figs., 4 tabs.« less
  • Simulation models based on the neutron and photon Monte Carlo code MCNP were used to study the therapeutic possibilities of the HB11 epithermal neutron beam at the High Flux Reactor in Petten. Irradiations were simulated in two types of phantoms filled with water or tissue-equivalent material for benchmark treatment planning calculations. In a cuboid phantom the influence of different field sizes on the thermal-neutron-induced dose distribution was investigated. Various shapes of collimators were studied to test their efficacy in optimizing the thermal-neutron distribution over a planning target volume and healthy tissues. Using circular collimators of 8, 12 and 15 cmmore » diameter it was shown that with the 15-cm field a relatively larger volume within 85% of the maximum neutron-induced dose was obtained than with the 8- or 12-cm-diameter field. However, even for this large field the maximum diameter of this volume was 7.5 cm. In an ellipsoid head phantom the neutron-induced dose was calculated assuming the skull to contain 10 ppm {sup 10}B, the brain 5 ppm {sup 10}B and the tumor 30 ppm {sup 10}B. It was found that with a single 15-cm-diameter circular beam a very inhomogeneous dose distribution in a typical target volume was obtained. Applying two equally weighted opposing 15-cm-diameter fields, however, a dose homogeneity within {+-} 10% in this planning target volume was obtained. The dose in the surrounding healthy brain tissue is 30% at maximum of the dose in the center of the target volume. Contrary to the situation for the 8-cm field, combining four fields of 15 cm diameter gave no large improvement of the dose homogeneity over the target volume or a lower maximum dose in the healthy brain. Therapy with BNCT on brain tumors must be performed either with an 8-cm four-field irradiation or with two opposing 15- or 12-cm fields to obtain an optimal dose distribution. 27 refs., 10 figs., 3 tabs.« less