Shiang-Huei Jiang

BNCT for locally recurrent head and neck cancer: preliminary clinical experience from a phase I/II trial at Tsing Hua Open-Pool Reactor.

To introduce our preliminary experience of treating locally and regionally recurrent Head and Neck cancer patients at Tsing Hua Open-Pool Reactor in Taiwan, four patients (M/F=3/1, median age 68 Y/O) were enrolled. BNCT with BPA (400 mg/kg) injected in 2 phases and prescription dose of 12-35 Gy (Eq.)/fraction for 2 fractions at 30 day interval can be given with sustained blood boron concentration and tolerable early toxicities for recurrent H & N cancer.

A hybrid method for calculating absolute peak efficiency of germanium detectors

Abstract We propose a hybrid method using the Moens concept of effective solid angle for calculating absolute peak efficiency of germanium detectors for extended sources. The effective solid angle is evaluated according to Monte Carlo integration instead of conventional numerical integration. The proposed hybrid method was tested for point, disk, cylinder, and Marinelli-beaker sources with essentially identical results as compared with those calculated using conventional numerical integration. The off-axis effect of source positions and the absolute peak efficiency for cuboid sources were also analyzed to demonstrate the powerful capability of the proposed hybrid method.

In situ measurements of gamma-ray intensity from radon progeny in rainwater

The radon progeny concentration in raindrops as well as in cloud droplets has been determined based on a simplified rainout model from the in situ measurement of gamma-ray intensity using an HPGe detector. The radon concentration in cloud air was deduced from the radon progeny concentration in cloud droplets by applying the Junges equation. From the measured radon progeny concentration in raindrops the additional exposure rate due to rainfall has been evaluated and compared with the HPIC monitoring data.

Neutron spectra measurement and comparison of the HFR and THOR BNCT beams

This paper aims to measure the spectra of HB11 (high flux reactor, HFR) and the Tsing Hua open-pool reactor (THOR) boron neutron capture therapy (BNCT) beams by multiple activation foils. The self-shielding corrections were made with the aid of MCNP calculations. The initial spectra were adjusted by a sophisticated process named coarse-scaling adjustment using SAND-EX, which can adjust a given coarse-group spectrum into a fine-group structure, i.e. 640 groups, with excellent continuity. The epithermal neutron flux of the THOR beam is about three times of HB11. The thermal neutron flux, boron and gold reaction rates along the central axis of a PMMA phantom are calculated for both adjusted spectra for comparison.

Fractionated BNCT for locally recurrent head and neck cancer: experience from a phase I/II clinical trial at Tsing Hua Open-Pool Reactor.

To introduce our experience of treating locally and regionally recurrent head and neck cancer patients with BNCT at Tsing Hua Open-Pool Reactor in Taiwan, 12 patients (M/F=10/2, median age 55.5 Y/O) were enrolled and 11 received two fractions of treatment. Fractionated BNCT at 30-day interval with adaptive planning according to changed T/N ratios was feasible, effective and safe for selected recurrent head and neck cancer in this trial.

A theoretical investigation of calibration methods for radwaste radioactivity detection systems

Abstract The three-dimensional point-kernel computer code QAD-CGGP is used to calibrate the Q2 detection system proposed as the detection system for measuring uncollided photon fluence rate from low-level radwaste at the Kuosheng and Maanshan Nuclear Power Plants in Taiwan. The calibration drum in the Q2 detection system was originally divided into seven concentric regions of equal volume. This was replaced by seven thin source tubes to eliminate storage problems associated with the uniformly distributed sources for each concentric region, and was found that the position of the source tube in the outermost region of the drum can significantly affect calibration accuracy. This phenomenon becomes more serious for highly attenuated radwaste such as sand. Although proper adjustment of the source tube position in the outermost region improves calibration accuracy, especially for highly attenuated radwaste, the new source tube position is too close to the surface of the drum and can increase calibration inaccuracy when the materials in the source tube and in the rest of the drum are different. We propose an improved method that divides the calibration drum into three region sources. Appropriate arrangement of the source tube positions within these regions was found to improve calibration accuracy, simplify calibration procedures, and save calibration time.

Fractionated Boron Neutron Capture Therapy in Locally Recurrent Head and Neck Cancer: A Prospective Phase I/II Trial

PURPOSE To investigate the efficacy and safety of fractionated boron neutron capture therapy (BNCT) for recurrent head and neck (H&N) cancer after photon radiation therapy. METHODS AND MATERIALS In this prospective phase 1/2 trial, 2-fraction BNCT with intravenous L-boronophenylalanine (L-BPA, 400 mg/kg) was administered at a 28-day interval. Before each fraction, fluorine-18-labeled-BPA-positron emission tomography was conducted to determine the tumor/normal tissue ratio of an individual tumor. The prescription dose (D80) of 20 Gy-Eq per fraction was selected to cover 80% of the gross tumor volume by using a dose volume histogram, while minimizing the volume of oral mucosa receiving >10 Gy-Eq. Tumor responses and adverse effects were assessed using the Response Evaluation Criteria in Solid Tumors v1.1 and the Common Terminology Criteria for Adverse Events v3.0, respectively. RESULTS Seventeen patients with a previous cumulative radiation dose of 63-165 Gy were enrolled. All but 2 participants received 2 fractions of BNCT. The median tumor/normal tissue ratio was 3.4 for the first fraction and 2.5 for the second, whereas the median D80 for the first and second fraction was 19.8 and 14.6 Gy-Eq, respectively. After a median follow-up period of 19.7 months (range, 5.2-52 mo), 6 participants exhibited a complete response and 6 exhibited a partial response. Regarding acute toxicity, 5 participants showed grade 3 mucositis and 1 participant showed grade 4 laryngeal edema and carotid hemorrhage. Regarding late toxicity, 2 participants exhibited grade 3 cranial neuropathy. Four of six participants (67%) receiving total D80 > 40 Gy-Eq had a complete response. Two-year overall survival was 47%. Two-year locoregional control was 28%. CONCLUSIONS Our results suggested that 2-fraction BNCT with adaptive dose prescription was effective and safe in locally recurrent H&N cancer. Modifications to our protocol may yield more satisfactory results in the future.

A rainout model for the study of the additional exposure rate due to rainfall

A simplified rainout model is presented in this study. According to this model formulations have been derived to relate the exposure rate on the ground to the radon progeny concentration in raindrops as well as the radon concentration in cloud air. By normalizing the saturation exposure rate of the calculation to the HPIC measured value and by the use of reasonably assumed values for some other parameters, the radon progeny concentration in raindrops as well as the radon concentration in cloud air has been determined.

BNCT EPITHERMAL NEUTRON BEAM MAPPING BY USING INDIRECT NEUTRON RADIOGRAPHY

Abstract This paper aims to measure the neutron flux distribution over the cross section of the boron neutron capture therapy epithermal neutron beam at the Tsing Hua Open-pool Reactor (THOR) by using indirect neutron radiography. It is successfully performed using an aluminum plate coupled with an imaging plate (IP). The developed high-resolution image represents the relative distribution of the neutron flux across the aluminum plate. The horizontal profiles of 28Al activity, according to the measurement using IP and calculations using MCNP with different angular source distributions, were given. In addition, horizontal profiles of 56Mn and 198Au activities measured using AuAl and MnNi foils, respectively, were provided. From the comparison between the measurements and calculations, source angular characteristics of the beam were inferred.

Effective dose evaluation for BNCT brain tumor treatment based on voxel phantoms

For BNCT treatments, in addition to tumor target doses, non-negligible doses will result in all the remaining organs of the body. This work aims to evaluate the effective dose as well as the average absorbed doses of each of organs of patients with brain tumor treated in the BNCT epithermal neutron beam at THOR. The effective doses were evaluated according to the definitions of ICRP Publications 60 and 103 for the reference male and female computational phantoms developed in ICRP Publication 110 by using the MCNP5 Monte Carlo code with the THOR-Y09 beam source. The effective dose acquired in this work was compared with the results of our previous work calculated for an adult hermaphrodite mathematical phantom. It was found that the effective dose for the female voxel phantom is larger than that for the male voxel phantom by a factor of 1.2-1.5 and the effective dose for the voxel phantom is larger than that for the mathematical phantom by a factor of 1.3-1.6. For a typical brain tumor BNCT, the effective dose was calculated to be 1.51Sv and the average absorbed dose for eye lenses was 1.07Gy.