This study reports the single-institution clinical experience of multifield pencil beam scanning (PBS) intensity-modulated proton therapy (IMPT) and dosimetric comparison to proton arc for uveal melanoma (UM) in a regular PBS gantry room. Eleven consecutive UM patients were treated with IMPT to 50 Gy in 5 fractions. A customized gaze-fixation device attached to the thermoplastic mask was used to reproduce the globe position for each patient. IMPT plans were robustly optimized with perturbations of 3 mm setup and 3.5 ± 1.0 ± 0.4 ± 0.23 vs. 0.88 ± 0.18, p = 0.11). Both modalities met all the clinical goals for organs-at-risk (OARs), while proton arc significantly reduced the maximum dose for the retina from, on average, 54.5 ± 0.7 to 53.2 ± 0.3 Gy (p < 0.01). Treatment evaluation on synthetic CT showed that the doses received by patients were highly consistent with the planned doses, with a relative target coverage (D95

Porous structures have attracted considerable interest for their impact on the transport and mechanical characteristics of materials. The fabrication of porous materials, however, often involves intricate preprocessing steps and typically lacks the ability to tailor porosity with ease. In the present study, we present a straightforward method to prepare porous Bi2Te2.5Se0.5 samples by employing low-pressure spark plasma sintering, with the porosity regulated by preset mass density using a modified graphite mold. This approach resulted in a substantial decrease in thermal conductivity, attributed to the introduction of pores that reduce mass density and disrupt phonon transmission. An accompanying decrease in electrical conductivity was also noted, arising from reduced carrier concentration and mobility. Despite these variations, all porous samples maintained similar levels of thermoelectric performance, with a peak zT of ca. 0.9 at 373 K. The average zT within the temperature range of 298–500 K remained slightly above 0.8 for all samples. Furthermore, the porous samples exhibited greatly enhanced mechanical properties. This work demonstrates a versatile and adaptable method to produce porous materials with controllable porosity, potentially applicable to other porous thermoelectric systems.

Purpose/Objective(s) A spirometer-based respiratory management system has demonstrated high reproducibility for internal organs in proton therapy. This study explores free-breathing respiratory-gated delivery (FBRGT) experimentally. The effect of gating-window widths (GW) and breathing speed on dose distribution are assessed for single spot and IMPT delivery. Materials/Methods The cranial-caudal movement of a dynamic lung phantom (3-cm diameter target) was synchronized with a QA syringe to generate the airflow. 4DCT images were acquired with 5 or 2 cm peak-to-peak amplitudes for single-spot or IMPT deliveries. Beam directions were perpendicular to the motion, and the gating window was selected towards the end of the exhalation phase. To study the interplay effect of different GW, a single spot (8 Gy center dose) was repeatedly delivered on seven GW: from 0% (static) to 50% (gated with 10% step), and 100% (non-gated). For IMPT delivery, motion analysis was applied to determine the optimal gating window of 50% (< 1cm motion) for respiratory periods of 3 and 5 seconds and irregular breathing (over-exhale) scenarios. An averaged CT was reconstructed within the optimal GW. ITV was generated and overridden with an averaged HU of the target. The four-field IMPT plan (30 Gy in 5 fractions) was robustly optimized (SFO) on the phase-averaged CT with perturbations of 3 mm setup and 3.5% range uncertainties. Films were sandwiched inside the target and moved with the phantom during delivery under different scenarios. Results Profiles for the single-spot film measurements showed that with an increase in GW width (e.g., 40% GW), the center of the dose shifted more towards inhalation (1 cm), the dose spread-out increased (55%), and the peak dose dropped (10%). The dose profiles for IMPT deliveries showed that the target was well covered for the static and 12 breaths/min scenarios but not for faster and irregular breathing conditions. The profile widths at 90%/50% of prescription dose level were 39.7/53.8, 38.9/54.5, 36.6/55.2, 36.2/54.9 and 30.5/57.9 mm for static, 12 breaths/min, 20 breaths/min, irregular breathing and non-gated scenarios, respectively. Due to the communication delay between the gating and delivery system, the dose shifted towards inhalation for faster breathing and irregular breathing scenarios, resulting in dose variation around ± 10% at the plateau. The total beam-on times for four-field IMPT deliveries were 79 seconds for static delivery and 129/119 seconds for gated delivery of 20/12 breaths per minute. Conclusion FBRGT is successfully demonstrated experimentally. Gated delivery achieves target coverage for free breathing treatment with the cost of a longer delivery time. A series of clinical validations are warranted in the future.

Purpose/Objective(s) The treatment of ocular cancers presents a significant challenge: delivering sufficient doses to tumors while preserving the functions of the nearby critical organs-at-risk (OARs). This study investigates the efficacy of proton pencil beam scanning (PBS) combined with Bragg-peak FLASH (BP-FLASH) biological optimization (FBO) in ocular treatment. We hypothesize that BP-FLASH FBO can increase treatment dose while enhancing OAR protection. Materials/Methods The BP-FLASH technique can provide similar tumor control as conventional PBS(CONV) treatment with additional normal-tissue sparing due to FLASH effect. However, the FLASH sparing effect has not been incorporated into the treatment planning system for plan optimization. In this study, FLASH-sparing factors for various normal tissues around the eyes were derived from literature to model the FLASH-sparing effect and incorporated into the FBO module of an in-house treatment planning system (TPS). Ten consecutive ocular patients previously treated with CONV-SBRT to 50Gy in 5 fractions were included in this study. Each case was replanned using the single-energy BP-FLASH technique with non-aperture PBS. Dose metrics of the CONV-SBRT and BP-FLASH plans were compared, including the CTV coverage, and the mean and maximal dose to surrounding OARs: cornea, eye, optic nerves, retina, lacrimal gland, and conjunctiva. Dose escalation was also performed by increasing the prescription dose to 60Gy in 5 fractions for the BP-FLASH plans, and the plan quality was then evaluated to assess if all clinical constraints were met. Results All plans for both techniques met the clinical objectives for all OARs, although the clinical CONV-SBRT plans slightly outperformed the BP-FLASH plan for the regimen of 50Gy in 5 fractions. When planning using the FBO method, the maximum doses to the cornea, eye, optic nerves, retina, lacrimal gland, and conjunctiva of BP-FLASH plans were, on average 11.2%, 15.8%, 30.1%, 20.1%, 14.4% and 17.6% lower, respectively, than those of CONV-SBRT plans. In comparison to the CONV-SBRT 50Gy plans, the BP-FLASH 60Gy plan using FBO had achieved reduced maximum doses to the eye, optic nerves, retina, lacrimal gland, and conjunctiva by a mean of 16.1%, 28.9%, 22.3%, 15.0%, and 18.7%, respectively. Conclusion BP-FLASH is capable of producing treatment plans comparable in quality to those of CONV-PBS for the existing 10 Gy x 5 SBRT protocol. Through FBO, BP-FLASH can increase the dose to 60 Gy in 5 fractions, without an expected increase in toxicity relative to CONV-SBRT treatments using 50Gy, demonstrating BP-FLASH’s potential to reduce ORA doses for ocular treatment significantly.

Porous structures have attracted considerable interest for their impact on the transport and mechanical characteristics of materials. The fabrication of porous materials, however, often involves intricate preprocessing steps and typically lacks the ability to tailor porosity with ease. In the present study, we present a straightforward method to prepare porous Bi2Te2·5Se0.5 samples by employing low-pressure spark plasma sintering, with the porosity regulated by preset mass density using a modified graphite mold. This approach resulted in a substantial decrease in thermal conductivity, attributed to the introduction of pores that reduce mass density and disrupt phonon transmission. An accompanying decrease in electrical conductivity was also noted, arising from reduced carrier concentration and mobility. Despite these variations, all porous samples maintained similar levels of thermoelectric performance, with a peak zT of ca. 0.9 at 373 K. The average zT within the temperature range of 298–500 K remained slightly above 0.8 for all samples. Furthermore, the porous samples exhibited greatly enhanced mechanical properties. This work demonstrates a versatile and adaptable method to produce porous materials with controllable porosity, potentially applicable to other porous thermoelectric systems.

Purpose/Objective(s) The reirradiation of recurrent lung cancers following definitive radiotherapy (RT) doses presents significant challenges due to the heightened risk of toxicities of the surrounding organs-at-risk (OARs) heart, lungs, spinal cord, and esophagus. We hypothesized that the novel Bragg peak FLASH technique (BP-FLASH) may provide enhanced protection for these OARs, thus allowing for higher treatment doses aimed at curative outcomes. Materials/Methods A model quantifying FLASH effectiveness was created based on existing biological evidence. In the design of FLASH plans for recurrent lung patients, a FLASH-sparing biological optimization (FBO) approach was integrated into the inverse treatment planning optimization. This process took into account the doses from prior RT during the optimization of FLASH planning, focusing on optimizing the FLASH ratio (V40Gy/s) to OARs that had received significant RT doses in the initial treatment. Ten consecutive lung cancer patients, previously treated with conventional proton pencil beam scanning (PBS)(CONV-PBS) reirradiation were selected for FBO. Three distinct reirradiation regimens were employed, consisting of doses of 40Gy, 50Gy, and 60Gy delivered in 5 fractions, which equate to EQD2 (equivalent doses in 2 Gy per fraction) of 60, 83.3, and 110 Gy, respectively. The EQD2 values for both CONV-PBS and BP-FLASH plans were determined, combined with the doses from previous radiotherapy, and a comprehensive analysis of all dose metrics was conducted. Results For the combined dose (prior-RT plus reirradiation), all BP-FLASH FBO plans targeting up to 60Gy (equivalent to 110Gy in EQD2) adhered to clinical guidelines and showed comparatively lower total dose metrics than the CONV-PBS 50Gy plan (equivalent to 83.3Gy EQD2). This decrease was noted in key OARs, with comparisons of BP-FLASH-EQD2-110Gy with CONV-PBS-83.3 Gy showing: for the esophagus-V60, 6.8 ± 7.1% versus 11.4 ± 9.0% (P = 0.07); for lung-V20, 17.0 ± 11.9% versus 16.9 ± 11.8% (P = 0.38); for heart-V40, 6.0 ± 5.8% versus 6.4 ± 5.8% (P = 0.07); and for spinal cord maximum dose, 30.8 ± 15.7 Gy versus 34.0 ± 17.3Gy (P = 0.24). Conclusion The FBO approaches utilizing BP-FLASH enable an escalation of the target dose to 60Gy while adhering to acceptable dose constraints. Integrating BP-FLASH with FBO presents a viable option for effective curative treatments in lung reirradiation.

Porous structures have attracted considerable interest for their impact on the transport and mechanical characteristics of materials. The fabrication of porous materials, however, often involves intricate preprocessing steps and typically lacks the ability to tailor porosity with ease. In the present study, we present a straightforward method to prepare porous Bi 2 Te 2.5 Se 0.5 samples by employing low-pressure spark plasma sintering, with the porosity regulated by preset mass density using a modified graphite mold. This approach resulted in a substantial decrease in thermal conductivity, attributed to the introduction of pores that reduce mass density and disrupt phonon transmission. An accompanying decrease in electrical conductivity was also noted, arising from reduced carrier concentration and mobility. Despite these variations, all porous samples maintained similar levels of thermoelectric performance, with a peak zT of ca . 0.9 at 373 K. The average zT within the temperature range of 298-500 K remained slightly above 0.8 for all samples. Furthermore, the porous samples exhibited greatly enhanced mechanical properties. This work demonstrates a versatile and adaptable method to produce porous materials with controllable porosity, potentially applicable to other porous thermoelectric systems.

Magnetic resonance imaging at simulation combined with proton radiotherapy for female sexual organ sparing may provide a technically feasible route to more equitable sexual outcomes for female patients. These results will guide future studies to optimize proton treatment techniques for female sexual organ sparing for future trials.

The optimal carrier concentration of thermoelectric materials increases with increasing temperature. However, conventional aliovalent doping usually provides an approximately constant carrier concentration over the whole temperature range, which can only match the optimal carrier concentration in a narrow temperature range. In this work, n-type indium and aluminum codoped PbTe were prepared with high-pressure synthesis, followed by spark plasma sintering. While Al doping can provide a roughly constant carrier concentration with varying temperatures, In doping can trap electrons at low temperatures and release them at high temperatures, thus optimizing the carrier concentration over a broad temperature range. As a result, both electrical transport properties and thermal conductivity are optimized, and a significantly enhanced thermoelectric performance is achieved in InxAl0.02Pb0.98Te. The optimal In0.008Al0.02Pb0.98Te shows a peak ZT of 1.3 and an average ZT of 1, with a decent conversion efficiency of 14%. Current work demonstrates that optimizing carrier concentration with varying temperatures is effective to enhance the thermoelectric performance of n-type PbTe.

In the most diverse and largest proton SBRT experience delivered in the world over the past 3 years, over 300 patients were treated, demonstrating the feasibility and efficiency of delivering proton SBRT in a very busy center. The planning and treatment parameter statistics reported serve as a helpful reference for the proton community.

The study provided the first independent quantitative experimental modeling of the beam delivery time parameters without any information from vendors. Such machine-specific delivery sequence models could pave the foundation of precise interplay effect evaluation for clinical decision-making.

Porous BiSbTe bulks with a unique microstructure featuring closely bonded quasi-equiaxed grains show excellent thermoelectric and mechanical properties.

Both systems can automatically generate synthetic CTs from CBCTs. The dosimetric similarities of synCT plans compared with verCT plans were higher for treatment sites with less heterogeneities such as breast patients when compared with head and neck patients. Outliers can happen when there are significant anatomy changes which result in inaccurate synthetic CTs due to inadequate image deformation or HU corrections. Users should pay extra attention to tissue discrepancies while evaluating the images. The Dmax for critical structures can vary greatly between synCT and verCT, so a small volumetric analysis is recommended. Both systems can be used to reduce verification CT scans while a patient is on treatment and can improve the adaptive plan workflow. Synthetic CT generation can be a more effective way to discover significant dosimetric differences caused by changes in patient anatomy, and therefore a more efficient path to adaptive treatment.

P-type CaxFe1.3CO2.7Sb12 skutterudites were successfully synthesized with a high pressure synthesis method followed by spark plasma sintering. The structure, composition and thermoelectric properties were investigated. With fixed Fe substitution level, the hole concentration was tuned with Ca filling. Compared with the unfilled Co(3.2)5Fe(0.73)Sb(12), Ca-filled samples possessed a relatively large effective mass, which is beneficial for enhancements in Seebeck coefficient and power factor. Moreover, the joint impurity and rattling mode scattering further suppressed the lattice thermal conductivity. Consequently, the Ca0.6Fe1.3CO2.7Sb12 sample showed the optimal ZT of 0.70 at 820 K. Composition analysis and simple electron counting suggested 0.77 hole per molecular formula for this sample, close to the value (about 0.7) we proposed for optimal filling and substitution contents in Co-rich p-type skutterudites. (C) 2020 Elsevier B.V. All rights reserved.

A facile and efficient way in optimizing thermoelectric performance of Bi2Te3 alloy was reported through synergy of Pb acceptor doping and superstructure modulation. By varying the amount of Pb doping, the substitutional defect \({\text{Pb}}^{\prime}_{\text{Bi}}\), arranging along the c-axis of PbBi2Te4 and PbBi4Te7 and acting as electron acceptor and superstructure, was formed successively in the Bi2Te3 matrix. This significantly reduced the lattice thermal conductivity and suppressed the bipolar effect. The figure of merit was enhanced and modulated, exhibiting a peak ZT of 1.06 and a broadened and optimized average ZT of 0.9 in a wide temperature range of 323–503 K.

Al doped PbTe-PbSe alloys were successfully prepared with high pressure synthesis followed by spark plasma sintering. The incorporation of Se shows a dual effect on the system. Firstly, the carrier concentration can be further modified with varying Se content, on the basis of Al doping. Secondly, the lattice thermal conductivity can be greatly suppressed due to the alloying effect. Beneficial from this, the average ZT of AlxPbTe1-ySey samples are remarkably enhanced compared with the unalloyed ones. The highest average ZT of 0.82 is achieved in Al0.02PbTe0.75Se0.25, which is 60% higher than that of Al0.02PbTe. Combining strategies of dynamic doping and/or hierarchical phonon scattering, the thermal performance of n-type PbTe-based materials may be further enhanced.

To compare imaging of multi-modality for evaluating children patients with rhabdomyosacroma. To analyze the spatial relationship of tumor volumes between different imaging techniques. To identify the high risk sub-regions in tumor volumes. 16 pediatric patients with rhabdomyosarcoma underwent imaging with PET/CT, T2-MRI, ADC and spectral CT with iodine contrast. From the spectral CT, the volumetric iodine density and effective Z of patients' images were extracted. Tumor/GTV contours were generated by clinical physicians on simulation CT. The images of different modalities were rigidly registered on the simulation CTs and the tumor contours were populated to other images in the same coordinate of simulation CTs. The tumor subvolumes of modalities were defined by isothreshold and fuzzy mean clustering. The spatial relations of these sub regions including similarity and incongruity were then evaluated with Dice's coefficient and ANOVA. The modalities can be categorized with two groups. Group 1: ADC and T2-MRI; Group 2: iodine density, effective Z from spectral CT and PET. In the same patient of most cases, the sub-regions of ADC and T2 had high similarity. The sub-regions of iodine, effective Z and PET had high similarity. The sub-region of ADC showed a disjoint spatial relation with the sub-region of iodine density, e.g. the high iodine density signal of the sub region expressed a low ADC signal in the same region. The fuzzy mean clustering showed the better performance of sub volume determination. The average similarity of between and T2 images has Dice coefficient of 0.88±0.082. The average similarity of between iodine density, effective Z from spectral CT and PET images has Dice coefficient of 0.78±0.042. The average similarity of between ADC and iodine density images has Dice coefficient of 0.14±0.12. The sub-regions of tumor volumes were investigated between images of five modalities. Each modality provides different type of functional imaging based on physical properties of tumor tissues. The spatial correlation of sub-volumes in different modalities can help physicians identify the high risk sub-region of GTV for treatment planning.

Most of Proton Range Telescopes (PRT) consist of tracking detectors and a stack of scintillators for the residual range determination for exiting protons. In this type of PRT, all exiting protons deposit their energy into the stacked scintillators and created one curve and hence the energy for all exit protons can be derived. This kind of PRT has many limitations for non-uniform medium. In this study, a more precise in-house PRT has been designed to record positions and momentums of exiting protons which can be used in non-uniform medium like human body. The PRT has a box of magnetic field sandwiched with two layers (entry/exit) of tracking detectors. These two layers detectors are made of silicon strips and used to record proton's entry and exiting positions through the magnetic field. Multiple layers tracking wires will record proton bending tracks in the magnetic field. A software is developed to reconstruct the track for each proton. Each proton's momentum can be obtained using the track's curvature in the magnetic field. A precise proton radiograph will be reconstructed with each proton's positions and momentum. The entry and exit tracking device position resolution is depending on the space resolution of the silicon strip. The typical resolution is 20-30 micron meter (μm) which is sufficient for our PRT. The detector energy resolution depends not only on the space resolution but also on magnetic field strength. If we have B=1T, we will have ΔP/P<1% for each exiting proton which is much better than the resolution from the scintillator detector. For current proton treatment, CT image is used to derive Relative Stopping Power (RSP) for treatment planning. This method causes proton range calculation uncertainties. The protons with energy 250MeV can penetrate 36 cm depth of water which can used for image children and head neck cases, while much higher energy about 350 MeV will be needed for the adult whole body proton radiography. When the mono-energy protons go throughs a non-uniform medium, 1. all protons will experience energy loss, 2. some protons will have deflected angles, 3. a small fraction of protons will stop in the medium, 4.exiting protons will have energy spread. Current scintillator based PRT cane be used to reduce the range uncertainty but it can't detect the situation 2,3 and 4. The new PRT has been proposed for precise measurement momentum and position for each proton. The energy spread and proton divergence for exiting protons also can be measured which can reduce the imaging noise significantly. It could be applied on reducing range uncertainty of patient CT and validating target volume before each treatment.

Single elemental doped n-type PbTe compounds were successfully prepared with high pressure synthesis followed by spark plasma sintering. Thermoelectric properties investigation indicates the performance of these samples is regulated by the carrier concentration. For each doping element, the maximal ZT increases and occurs at higher temperature with increasing carrier concentration. However, the average ZT over the measurement temperature range is getting smaller due to substantially smaller ZT at low temperature. For the optimal carrier concentration near 1 x 10(19) cm(-3), a relatively high average ZT of ca. 0.7 is achieved for most of the doping elements. Since the average ZT determines the device performance of thermoelectric materials, our study can serve as a basis for further performance enhancement of n-type PbTe through combining strategies of dynamic doping and/or hierarchical phonon scattering. (C) 2019 Elsevier B.V. All rights reserved.