25 results on '"Gu, Xuejun"'
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2. Stereotactic Radiosurgery for Cranial and Spinal Hemangioblastomas: A Single-Institution Retrospective Series
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Yoo, Kelly H., Park, David J., Marianayagam, Neelan J., Gu, Xuejun, Pollom, Erqi L., Soltys, Scott G., Chang, Steven D., and Meola, Antonio
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- 2024
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3. Online quantification of nicotine in e-cigarette aerosols by vacuum ultraviolet photoionization mass spectrometryElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ay00279b
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Ye, Shaoxin, Wen, Zuoying, Xie, Kai, Gu, Xuejun, Wang, Jian, Tang, Xiaofeng, and Zhang, Weijun
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The growing popularity of e-cigarettes and the associated risks of nicotine addiction present a new challenge to global public health security. Measuring the nicotine levels in e-cigarette aerosols is essential to assess the safety of e-cigarettes. In this study, a rapid in situmethod was developed for online quantification of nicotine in e-cigarette aerosols by using a homemade vacuum ultraviolet photoionization aerosol mass spectrometer (VUV-AMS). E-cigarette liquids with different nicotine concentrations were prepared to generate aerosols containing different levels of nicotine, which were employed as the calibration sources for nicotine quantification by VUV-AMS. The results showed that the mass concentration of nicotine in e-cigarette aerosols has a good linear relationship with its signal intensity in the mass spectrum, and the limits of detection and quantitation of nicotine by VUV-AMS were found to be 2.0 and 6.2 μg per puff respectively. Then the online method was utilized to measure five commercial e-cigarettes, and their nicotine yields were determined to be between 31 and 188 μg per puff with the nicotine fluxes from 7.7 to 70 μg s−1, agreeing with the results of the gas chromatography with a flame ionization detector (GC-FID). This study demonstrated the feasibility and advantages of VUV-AMS for quick quantification of nicotine in e-cigarette aerosols within seconds.
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- 2024
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4. A How-To Compendium for GammaPod Treatments, Clinical Workflow, and Clinical Program at an Early Adopting Institution.
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Zhang-Velten, Elizabeth, Zhang, You, Radpour, Sepeadeh, Gu, Xuejun, Kim, D. Nathan, Alluri, Prasanna, Nwachukwu, Chika, Chiu, Tsuicheng, Lu, Weiguo, Parsons, David, Tan, Jun, Gillespie, Jennifer, Stevenson, Stella, Choy, Hak, Timmerman, Robert, and Rahimi, Asal
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In 2019, our institution became the second in the world to go live with GammaPod (Xcision Medical Systems, LLC, Columbia, MD), a device dedicated for stereotactic radiation therapy of breast cancer, with breast immobilization, real-time imaging, and highly-conformal dosimetry. At our institution, GammaPod is used for 5-fraction adjuvant partial breast irradiation, single-fraction tumor cavity boost before whole-breast irradiation, single-fraction preoperative radiation, and (in poor surgical candidates), single-fraction definitive radiation. Here, we describe our workflow, observed procedure step times, and homegrown techniques for improved efficiency in our institutional experience of 93 patients treated between 2019 and 2021. [ABSTRACT FROM AUTHOR]
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- 2022
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5. Radiation Therapy for Pediatric Brain Tumors using Robotic Radiation Delivery System and Intensity Modulated Proton Therapy.
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Lin, Mu-Han, Yang, Ming, Dougherty, Jingjing, Tasson, Alexandria, Zhang, Yan, Mohamad, Osama, Dan, Tu, Yan, Yulong, Gu, Xuejun, Timmerman, Robert, Laack, Nadia, and Beltran, Chris
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This study recruited 2 centers with expertise in treating pediatric brain tumors with robotic radiation delivery system photon therapy and proton therapy, respectively, to study the plan quality and dose deposition characteristics of robotic radiation delivery system photon therapy and intensity modulated proton therapy (IMPT) plans. A total of 18 patients clinically treated with the robotic radiation delivery system were planned with IMPT. Cases were planned per the standard of care of each institution but respected the same planning objectives. The comparison included 3 aspects: plan quality, dose fall-off characteristics around the target volume, and the volume of the high-, intermediate-, and low-dose baths. All robotic radiation delivery system and IMPT plans met the planning objectives. However, IMPT significantly reduced the maximum dose to organs at risk away from the planning target volume (PTV), such as the cochlea and eye (P <.05), and the mean dose to the normal brain (P <.05). No statistically significant difference was observed in the maximum dose to the optical pathway and brain stem. Robotic radiation delivery system plans demonstrated a sharper dose fall-off within 5 mm around the PTV (P <.05), whereas IMPT significantly lowered the dose to the normal tissue beyond 10 mm from the PTV (P <.05). The robotic radiation delivery system offers a smaller high-dose bath whereas IMPT offers a smaller low-dose bath (P <.05). However, the difference in intermediate dose is not statistically significant. In general, robotic radiation delivery system plans exhibit reduced high-dose exposure to normal tissue, and IMPT plans have considerably smaller volumes of low-dose exposure with differences in medium-range dose baths increasingly favoring protons as tumor size increases. [ABSTRACT FROM AUTHOR]
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- 2020
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6. Electron modulated arc therapy (EMAT) using photon MLC for postmastectomy chest wall treatment I: Monte Carlo-based dosimetric characterizations.
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Ma, Chaoqiong, Parsons, David, Chen, Mingli, Jiang, Steve, Hou, Qing, Gu, Xuejun, and Lu, Weiguo
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• Characteristics of pMLC-delivered electron arc beams are presented. • The radial dose rate is a major cause of difference between static and arc beam dose. • This study provides the basis of EMAT treatment planning for chest wall. To study the dosimetric properties of electron arc beams delivered by photon-beam multi-leaf collimators (pMLC) in electron modulated arc therapy (EMAT) for postmastectomy chest wall treatments. Using the Monte Carlo method, we simulated a 2100EX Varian linear accelerator and verified the beam models in a water tank. Dosimetric characterizations were performed on cylindrical water phantoms of elliptical bases with various field sizes, arc ranges and source-to-surface distances (SSDs) for 6, 9 and 12 MeV beam energy. The arc beam has a higher bremsstrahlung dose than the static beam at the isocenter due to crossfire, but choosing a field size greater than 5 cm effectively reduces the bremsstrahlung dose. The depths of the 90% maximum dose located at 1.7, 2.8 and 4.1 cm for 6, 9 and 12 MeV, respectively, are similar to those of the static beams and independent of the field size and arc range. Based on the study, we recommend using the 5 cm field width for electron arc beams considering both bremsstrahlung dose at the isocenter and the arc profile penumbra. To ensure sufficient PTV edge coverage, we recommend a field length extension of at least 4 cm from PTV's edge for all beam energies and an arc extension of around 7°, 5°, and 5° for beam energies 6, 9, and 12 MeV, respectively. These dosimetric characterizations are the basis of pMLC-delivered EMAT treatment planning for postmastectomy chest wall patients. [ABSTRACT FROM AUTHOR]
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- 2019
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7. Incorporating biomechanical modeling and deep learning into a deformation-driven liver CBCT reconstruction technique
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Gilat Schmidt, Taly, Chen, Guang-Hong, Bosmans, Hilde, Zhang, You, Chen, Liyuan, Li, Bin, Folkert, Michael, Jia, Xun, Gu, Xuejun, and Wang, Jing
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- 2019
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8. Theoretical study on atmospheric gaseous reactions of glyoxal with sulfuric acid and ammonia.
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Lin, Xin, Huang, Mingqiang, Zhu, Mincong, Zhao, Weixiong, Gu, Xuejun, and Zhang, Weijun
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GLYOXAL ,SULFURIC acid ,AMMONIA ,AMMONIUM sulfate ,WEATHER ,LOW temperatures - Abstract
[Display omitted] • Glyoxal reacts with H 2 SO 4 and NH 3 to generate organosulfates and carbinolamine. • NH 3 promotes the yield of organosulfates at high concentration and low temperature. • H 2 SO 4 has strong catalytic ability for glyoxal reacts with NH 3 to form carbinolamine. The reaction mechanisms and rate constants of the gaseous reactions of glyoxal with H 2 SO 4 , NH 3 -catalyzed glyoxal with H 2 SO 4 , glyoxal with NH 3 , and H 2 SO 4 -catalyzed glyoxal with NH 3 are studied detailedly using M06-2X followed by CCSD(T) calculations and conventional transition state theory in current study. The results show that NH 3 has a certain catalytic ability to reduce the barrier for reaction of glyoxal with H 2 SO 4 , and increases their rate constant by 10
3 times to 2.66 × 10-15 cm3 molecule-1 s−1 under atmospheric condition ·NH 3 can facilitate the formation of organosulfates at high concentration and low temperature. H 2 SO 4 has a strong catalytic ability, significantly reduces the barrier of glyoxal with NH 3 , and increases their rate constant to 4.52 × 10-12 cm3 molecule-1 s−1 , which is slightly less than the rate coefficient of OH radicals and glyoxal. These provide the basis for clarifying the characteristic mechanism of gaseous reaction of glyoxal to form organosulfates and carbinolamine. [ABSTRACT FROM AUTHOR]- Published
- 2023
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9. Real-time measurements of airborne biologic particles using fluorescent particle counter to evaluate microbial contamination: Results of a comparative study in an operating theater.
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Dai, Chunyang, Zhang, Yan, Ma, Xiaoling, Yin, Meiling, Zheng, Haiyang, Gu, Xuejun, Xie, Shaoqing, Jia, Hengmin, Zhang, Liang, and Zhang, Weijun
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Background Airborne bacterial contamination poses a risk for surgical site infection, and routine surveillance of airborne bacteria is important. Traditional methods for detecting airborne bacteria are time consuming and strenuous. Measurement of biologic particle concentrations using a fluorescent particle counter is a novel method for evaluating air quality. The current study was to determine whether the number of biologic particles detected by the fluorescent particle counter can be used to indicate airborne bacterial counts in operating rooms. Methods The study was performed in an operating theater at a university hospital in Hefei, China. The number of airborne biologic particles every minute was quantified using a fluorescent particle counter. Microbiologic air sampling was performed every 30 minutes using an Andersen air sampler (Pusong Electronic Instruments, Changzhou, China). Correlations between the 2 different methods were analyzed by Pearson correlation coefficients. Results A significant correlation was observed between biologic particle and bacterial counts (Pearson correlation coefficient = 0.76), and the counting results from 2 methods both increased substantially between operations, corresponding with human movements in the operating room. Conclusion Fluorescent particle counters show potential as important tools for monitoring bacterial contamination in operating theatres. [ABSTRACT FROM AUTHOR]
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- 2015
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10. Differentiation of cysts from solid tumors in the breast with diffuse optical tomography.
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Gu, Xuejun, Zhang, Qizhi, Bartlett, Matthew, Schutz, Leonard, Fajardo, Laurie L., and Jiang, Huabei
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TOMOGRAPHY ,IMAGING systems ,OPTICAL images ,CYSTS (Pathology) - Abstract
Rationale and Objectives. Near-infrared diffuse optical tomography (DOT) is an emerging imaging technology that has the potential to offer enhanced contrast resolution over the existing technologies for detection and diagnosis of breast cancer. Thus far, the clinical evaluation of DOT has been largely limited to solid tumors. A pilot clinical study focused on DOT imaging of breasts with cysts is presented.Materials and Methods. Six cases were studied using the recently developed compact, parallel-detection DOT system. Images characterizing the tissue absorption and scattering were obtained with a finite element-based reconstruction algorithm. The optical images were compared with the mammograms and sonograms. In one case, in vitro measurements of optical properties were conducted for the fluid obtained from needle aspiration.Results. Substantial contrast between cyst and adjacent parenchyma is observed. For the six cases evaluated, the locations and sizes of cysts imaged optically are accurate and consistent with the mammographic and sonographic findings. For the case that aspiration was performed, the absorption and scattering coefficients imaged in the cyst region are quantitatively accurate compared with that measured in vitro from the fluid aspirated.Conclusion. This pilot study shows that cysts ranging from 1–4 cm in diameter can be quantitatively imaged. They can be differentiated from solid breast tumors because cysts generally demonstrate lower absorption and scattering coefficients compared with the surrounding normal tissue, whereas solid tumors show concurrent higher absorption and scattering related to the normal tissue. [Copyright &y& Elsevier]
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- 2004
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11. Simultaneous motion estimation and image reconstruction (SMEIR) for 4D cone-beam CT
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Whiting, Bruce R., Hoeschen, Christoph, Wang, Jing, and Gu, Xuejun
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- 2014
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12. Frequency-domain sensitivity analysis for small imaging domains using the equation of radiative transfer
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Gu, Xuejun, Ren, Kui, and Hielscher, Andreas H.
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Optical tomography of small imaging domains holds great promise as the signal-to-noise ratio is usually high, and the achievable spatial resolution is much better than in large imaging domains. Emerging applications range from the imaging of joint diseases in human fingers to monitoring tumor growth or brain activity in small animals. In these cases, the diameter of the tissue under investigation is typically smaller than 3 cm, and the optical path length is only a few scattering mean-free paths. It is well known that under these conditions the widely applied diffusion approximation to the equation of radiative transfer (ERT) is of limited applicability. To accurately model light propagation in these small domains, the ERT has to be solved directly. We use the frequency-domain ERT to perform a sensitivity study for small imaging domains. We found optimal source-modulation frequencies for which variations in optical properties, size, and location of a tissue inhomogeneity lead to maximal changes in the amplitude and phase of the measured signal. These results will be useful in the design of experiments and optical tomographic imaging systems that probe small tissue volumes.
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- 2007
13. Spatially varying optical and acoustic property reconstruction using finite-element-based photoacoustic tomography
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Jiang, Huabei, Yuan, Zhen, and Gu, Xuejun
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A finite-element reconstruction algorithm for simultaneous reconstruction of both optical and acoustic properties of heterogeneous media is presented. The algorithm is based on the Helmholtz-like photoacoustic wave equation in the frequency domain. A dual meshing scheme is described and an adjoint sensitivity method is adopted for efficient inverse computation. The algorithm is implemented with the second-order absorbing boundary conditions and with a multireceiving and multifrequency strategy. The algorithm is evaluated using simulated data under various practical cases including different noise levels, varied range of receiving frequency, different contrast levels between the heterogeneity and background region, and multiple targets. The effect of acoustic heterogeneity on conventional pure optical absorption reconstruction is also studied.
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- 2006
14. In vivo breast imaging with diffuse optical tomography based on higher-order diffusion equations
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Xu, Yong, Gu, Xuejun, Fajardo, Laurie L., and Jiang, Huabei
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We report on in vivo absorption and scattering imaging of a human breast cyst and implant, using a reconstruction algorithm based on our third-order diffusion equations. To validate these in vivo images, a series of phantom experiments were conducted, in which we used low-absorbing and low-scattering heterogeneities to mimic a breast cyst or implant. These heterogeneities or targets were composed of pure water or a mixture of water and very dilute Intralipid (0.05% and 0.1%). The phantom experiments confirmed the quantitative imaging capability of our improved algorithm for reconstructing heterogeneities where the conventional diffusion approximation is inadequate. Pilot clinical results from female volunteers indicate that enhanced diffuse optical tomography can quantitatively image findings such as breast cysts or implants in which the absorption and scattering coefficients are usually low.
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- 2003
15. Strategies for Improved dCO2Removal in Large‐Scale Fed‐Batch Cultures
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Mostafa, Sigma S. and Gu, Xuejun (Sherry)
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Carbon dioxide buildup in large‐scale reactors can be detrimental to cell growth and productivity. In case of protein X, a therapeutic glycoprotein, when cultures were scaled up from bench scale to the pilot plant, there was a 40% loss of specific productivity. The dissolved CO2(dCO2) level was 179 ± 9 mmHg at the pilot plant scale and 68 ± 13 mmHg at bench scale. The authors proposed a comprehensive approach to maintain dCO2levels between 40 and 120 mmHg throughout the 14‐day fed‐batch process. A cell‐free experiment was used to investigate the impact of the following parameters on dCO2removal: (1) sparge rate, (2) agitator speed, (3) bubble size, (4) bicarbonate concentration, (5) impeller position, and (6) aeration rate at the headspace of bioreactor. dCO2was measured using a fiber optic based probe. dCO2removal rate was a strong function of sparge rate and a weak function of agitator speed. Bubble size was modulated by the presence or absence of a sparge stone (10 μm pore size, 1 cm pipe i.d.). Open pipe provided 3‐ to 4‐fold better dCO2removal for the same mass transfer coefficient ( kLa) value. A mathematical model and a bench‐scale experiment indicated that the benefit of a lower level of sodium bicarbonate in the culture medium was transient for batch and fed‐batch cultures. Thus, this strategy was not used at pilot scale. Decreasing top impeller position improved kLa of dCO2by 2‐fold. Changing headspace aeration rate from 0.02 to 0.04 vvm had no impact on dCO2removal. Two pilot runs were conducted using (A) open pipe and (B) antifoam in the presence of sparge stone, both in conjunction with lower impeller position. The presence of antifoam may interfere in product purification; however, demonstration of antifoam removal can be difficult. Open pipe allowed an alternative to using antifoam, as foam level with open pipe was significantly less. Both strategies successfully reduced dCO2level by 2.5‐fold (179 ± 9 vs 72 ± 9 mmHg). Titer at day 10 of culture improved by 1.5‐fold. Specific productivity improved by 41%. Historically, cultures were harvested around day 9–11 because of the high amount of foam; both strategies allowed the cultures to be extended up to day 14, resulting in 2‐fold higher titer compared to that of the historical control without compromising protein quality.
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- 2003
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16. Absorption and scattering images of heterogeneous scattering media can be simultaneously reconstructed by use of dc data
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Xu, Yong, Gu, Xuejun, Khan, Taufiquar, and Jiang, Huabei
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We present a carefully designed phantom experimental study aimed to provide solid evidence that both absorption and scattering images of heterogeneous scattering media can be reconstructed independently from dc data. We also study the important absorption–scattering cross-talk issue. In this regard, we develop a simple normalizing scheme that is incorporated into our nonlinear finite-element-based reconstruction algorithm. Our results from the controlled phantom experiments show that the cross talk of an absorption object appearing in scattering images can be eliminated and that the cross talk of a scattering object appearing in absorption images can be reduced considerably. In addition, these carefully designed phantom experiments clearly suggest that both absorption and scattering images can be simultaneously recovered and quantitatively separated in highly scattering media by use of dc measurements. Finally, we discuss our results in light of recent theoretical findings on nonuniqueness for dc image reconstruction.
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- 2002
17. Gamma-interferon production and quality in stoichiometric fed-batch cultures of Chinese hamster ovary (CHO) cells under serum-free conditions
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Xie, Liangzhi, Nyberg, Gregg, Gu, Xuejun, Li, Hanyuan, Möllborn, Fredrik, and Wang, Daniel I. C.
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The application of a stoichiometric medium design approach was studied in fed-batch cultivation of Chinese hamster ovary (CHO) cells. A serum-free medium containing a very low protein concentration (2 mg/L insulin) was developed. A supplemental medium was formulated according to the stoichiometric equation governing cell growth using cell composition obtained from hybridoma cells. Fed-batch culture was conducted in spinner flasks using the supplemental medium for feeding. Significant improvement in cell growth, by-product reduction, and Gamma-Interferon (IFN-γ) production was achieved as compared to a typical batch culture. Results indicate that the stoichiometric approach, originally developed for hybridoma cultures, is a fast and effective method for cell culture process design and improvement. The glycosylation of IFN-γ was monitored off-line during the culture process. The accumulative IFN-γ glycosylation efficiency was slightly improved as compared to that of the batch culture, due to the nutritional control through the stoichiometric feeding. Periodic glucose starvation was observed during the fed-batch culture as a result of the manual feeding. Pulse-chase radiolabeling assay shows that glucose starvation leads to a deteriorated IFN-γ glycosylation efficiency. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 577582, 1997.
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- 1997
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18. Influence of Primatone RL supplementation on sialylation of recombinant human interferon-γ produced by Chinese hamster ovary cell culture using serum-free media
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Gu, Xuejun, Xie, Liangzhi, Harmon, Bryan J., and Wang, Daniel I. C.
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Although serum-free media have been widely used in mammalian cell culture for therapeutic protein production, the effects of serum-substitutes on product quality have not been extensively examined. This study observed an adverse effect of Primatone RL, an animal tissue hydrolysate commonly used as a serum-substitute to promote cell growth, on sialylation of interferon-γ (IFN-γ) derived from Chinese hamster ovary (CHO) cell culture in both batch and fed-batch modes. In batch cultures, decreased sialylation was observed at each of the glycosylation sites (i.e., Asn25 and Asn97) of IFN-γ with the use of elevated concentrations of the peptone. Although poorest sialylation was obtained with the use of a growth-inhibiting concentration of Primatone RL, diminished sialylation was observed at the optimal peptone concentration for cell growth and product yield. Since incubation of the product in Primatone RL-supplemented acellular medium did not result in decreased sialylation, the negative effect of Primatone RL could not be attributed to extracellular desialylation of IFN-γ by components of the peptone. In the fed-batch mode, a culture utilizing a serum-free feeding medium supplemented with Primatone RL demonstrated poorer sialylation than a similar culture not fed the peptone. The results of both the batch and fed-batch experiments indicate that the adverse effect of the peptone was not due solely to ammonia accumulation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 353360, 1997.
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- 1997
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19. Site- and branch-specific sialylation of recombinant human interferon-γ in Chinese hamster ovary cell culture
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Gu, Xuejun, Harmon, Bryan J., and Wang, Daniel I.C.
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Since sialic acid content is known to be a critical determinant of the biological properties of glycoproteins, it is essential to characterize and monitor sialylation patterns of recombinant glycoproteins intended for therapeutic use. This study reports site- and branch-specific differences in sialylation of human interferon-γ (IFN-γ) derived from Chinese hamster ovary (CHO) cell culture. Sialylation profiles were quantitated by reversed-phase HPLC separations of the site-specific pools of tryptic glycopeptides representing IFN-γ's two potential N-linked glycosylation sites (i.e., Asn25 and Asn97). Although sialylation at each glycosylation site was found to be incomplete, glycans of Asn25 were more heavily sialylated than those of Asn97. Furthermore, Man(α13) arms of the predominant complex biantennary structures were more favorably sialylated than Man(α16) branches at each glycosylation site. When the sialylation profile was analyzed throughout a suspension batch culture, sialic acid content at each site and branch was found to be relatively constant until a steady decrease in sialylation was observed coincident with loss of cell viability. The introduction of a competitive inhibitor of sialidase into the culture supernatant prevented the loss of sialic acid after the onset of cell death but did not affect sialylation prior to cell death. This finding indicated that incomplete sialylation prior to loss of cell viability could be attributed to incomplete intracellular sialylation while the reduction in sialylation following loss of cell viability was due to extracellular sialidase activity resulting from cell lysis. Thus, both intracellular and extracellular processes defined the sialic acid content of the final product. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 390398, 1977.
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- 1997
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20. Improvement of interferon-γ sialylation in Chinese hamster ovary cell culture by feeding of <TOGGLE>N</TOGGLE>-acetylmannosamine
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Gu, Xuejun and Wang, Daniel I. C.
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Because the presence of sialic acid can extend circulatory lifetime, a high degree of sialylation is often a desirable feature of therapeutic glycoproteins. In this study, the incomplete intracellular sialylation of interferon-γ (IFN-γ), produced by Chinese hamster ovary cell culture, was minimized by supplementing the culture medium with N-acetylmannosamine (ManNAc), a direct intracellular precursor for sialic acid synthesis. By introducing 20 mM ManNAc into the culture medium, incompletely sialylated biantennary glycan structures were reduced from 35% to 20% at the Asn97 glycosylation site. This effect was achieved without affecting cell growth or product yield. The intracellular pool of CMP-sialic acid, the nucleotide sugar substrate for sialyltransferase, was also extracted and quantified by HPLC. Feeding of 20 mM ManNAc increased this intracellular pool of CMP-sialic acid by nearly thirtyfold compared with unsupplemented medium. When radiolabeled ManNAc was used to trace the incorporation of the precursor, it was found that supplemental ManNAc was exclusively incorporated into IFN-γ as sialic acid and that, at 20 mM ManNAc feeding, nearly 100% of product sialylation originated from the supplemental precursor. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58: 642648, 1998.
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- 1998
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21. Volumetric Modulated Arc Therapy Enabled Total Body Irradiation (VMAT-TBI): Six-year Clinical Experience and Treatment Outcomes
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Zhang-Velten, Elizabeth Ren, Parsons, David, Lee, Pam, Chambers, Eric, Abdulrahman, Ramzi, Desai, Neil B., Dan, Tu, Wardak, Zabi, Timmerman, Robert, Vusirikala, Madhuri, Patel, Prapti, Simms-Waldrip, Tiffany, Aquino, Victor, Koh, Andrew, Tan, Jun, Iqbal, Zohaib, Zhang, You, Reynolds, Robert, Chiu, Tsuicheng, Joo, Mindy, Hrycushko, Brian, Ouyang, Luo, Lamphier, Richard, Yan, Yulong, Jiang, Steve B., Kumar, Kiran A., and Gu, Xuejun
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Total body irradiation is an important part of the conditioning regimens frequently used to prepare patients for allogeneic hematopoietic stem cell transplantation (SCT). Volumetric-modulated arc therapy enabled total body irradiation (VMAT-TBI), an alternative to conventional TBI (cTBI), is a novel radiotherapy treatment technique that has been implemented and investigated in our institution. The purpose of this study is to (1) report our six-year clinical experience in terms of treatment planning strategy and delivery time and (2) evaluate the clinical outcomes and toxicities in our cohort of patients treated with VMAT-TBI. This is a retrospective single center study. Forty-four patients at our institution received VMAT-TBI and chemotherapy conditioning followed by allogeneic SCT between 2014 and 2020. Thirty-two patients (73%) received standard-dose TBI (12-13.2 Gy in 6-8 fractions twice daily), whereas 12 (27%) received low-dose TBI (2-4 Gy in one fraction). Treatment planning, delivery, and treatment outcome data including overall survival (OS), relapse-free survival (RFS), and toxicities were analyzed. The developed VMAT-TBI planning strategy consistently generated plans satisfying our dose constraints, with planning target volume coverage >90%, mean lung dose ∼50% to 75% of prescription dose, and minimal hotspots in critical organs. Most of the treatment deliveries were <100 minutes (range 33-147, mean 72). The median follow-up was 26 months. At the last follow-up, 34 of 44 (77%) of patients were alive, with 1- and 2-year OS of 90% and 79% and RFS of 88% and 71%, respectively. The most common grade 3+ toxicities observed were mucositis (31 patients [71%]) and nephrotoxicity (6 patients [13%]), both of which were deemed multifactorial in cause. Four patients (9%) in standard-dose cohort developed grade 3+ pneumonitis, with 3 cases in the setting of documented respiratory infection and only 1 (2%) deemed likely related to radiation alone. VMAT-TBI provides a safe alternative to cTBI. The dose modulation capability of VMAT-TBI may lead to new treatment strategies, such as simultaneous boost and further critical organ sparing, for better malignant cell eradication, immune suppression, and lower toxicities.
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- 2021
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22. Three-dimensional printer-aided casting of soft, custom silicone boluses (SCSBs) for head and neck radiation therapy.
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Chiu, Tsuicheng, Tan, Jun, Brenner, Mathew, Gu, Xuejun, Yang, Ming, Westover, Kenneth, Strom, Tobin, Sher, David, Jiang, Steve, and Zhao, Bo
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Purpose Custom tissue compensators provide dosimetric advantages for treating superficial or complex anatomy, but currently available fabrication technology is expensive or impractical for most clinical operations and yields compensators that are difficult for patients to tolerate. We aimed to develop an inexpensive, clinically feasible workflow for generating patient-specific, soft, custom silicone boluses (SCSBs) for head-and-neck (HN) radiation therapy. Methods and materials We developed a method using 3-dimensional printed parts for generating SCSBs for the treatment of HN cancers. The clinical workflow for generation of SCSBs was characterized inclusive of patient simulation to treatment in terms of resource time and cost. Dosimetric properties such as percentage depth dose and dose profiles were measured for SCSBs using GaF films. Comprehensive measurements were also conducted on an HN phantom. SCSBs were generated and used for electron or photon based radiation treatments of 7 HN patients with lesions at nose, cheek, eye, or ears. In vivo dose measurements with optically simulated luminescence dosimeters were performed. Results Total design and fabrication time from patient simulation to radiation treatment start required approximately 1 week, with fabrication constituting 1 to 2 working days depending on bolus surface area, volume, and complexity. Computed tomography and dosimetric properties of the soft bolus were similar to water. In vivo dose measurements on 7 treated patients confirmed that the dose deposition conformed to planned doses. Material costs were lower than currently available hard plastic boluses generated with 3-dimensional printing technology. All treated patients tolerated SCSBs for the duration of therapy. Conclusions Generation and use of SCSBs for clinical use is feasible and effective for the treatment of HN cancers. [ABSTRACT FROM AUTHOR]
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- 2018
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23. Deep inspiration breathhold for left-sided breast cancer patients with unfavorable cardiac anatomy requiring internal mammary nodal irradiation.
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Mohamad, Osama, Shiao, Jean, Zhao, Bo, Roach, Karen, Ramirez, Ezequiel, Vo, Dat T., Thomas, Kimberly, Gu, Xuejun, Spangler, Ann, Albuquerque, Kevin, and Rahimi, Asal
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Purpose The purpose of this study was to evaluate the utility of moderate deep inspiration breathhold (mDIBH) in reducing heart exposure in left breast cancer patients who have unfavorable cardiac anatomy and need internal mammary lymph node (IMLN) radiation therapy (RT). Methods and materials We used maximum heart distance (MHD), defined as the maximum distance of the heart within the treatment field, >1 cm as a surrogate for unfavorable cardiac anatomy. Twenty-two left breast cancer patients with unfavorable cardiac anatomy requiring IMLN-RT underwent free-breathing (FB) and mDIBH computed tomography simulation and planning. Three-dimensional partially wide tangents (3D-PWTs) and intensity modulated RT plans were generated. Dose-volume histograms were used to compare heart and lung dosimetric parameters. Duration of treatment delivery was recorded for all fractions. Results MHD decreased significantly in mDIBH scans. mDIBH significantly reduced mean heart dose (222.7 vs 578.4 cGy; P < .0001) and percentage of left lung receiving doses ≥20 Gy (V20; 31.93 vs 38.41%; P = .0006) in both 3D-PWT and intensity modulated RT plans. The change in MHD after breathhold reliably predicted mean heart dose reduction after mDIBH. Radiation was effectively delivered in 11.31 ± 3.40 minutes with an average of 10.06 ± 2.74 breathholds per fraction. Conclusions mDIBH is efficient and can effectively decrease mean heart dose in patients with unfavorable cardiac anatomy who need IMLN-RT, thus simplifying planning and delivery for them. The reduction in mean heart dose is proportional to the reduction in maximum heart distance. [ABSTRACT FROM AUTHOR]
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- 2017
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24. Retrieval of Atmospheric Fine Particulate Density Based on Merging Particle Size Distribution Measurements: Multi‐instrument Observation and Quality Control at Shouxian
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Li, Zhengqiang, Wei, Yuanyuan, Zhang, Ying, Xie, Yisong, Li, Lei, Li, Kaitao, Ma, Yan, Sun, Xiaobing, Zhao, Weixiong, and Gu, Xuejun
- Abstract
Density of fine mode particles is an important physical parameter. However, its measurement and validation in the actual atmosphere are still difficult. In this study, the measurements at Shouxian, Anhui province, China (32.56°N, 116.78°E, elevation 22.7 m) in winter, are used for density retrieval and quality control. The effective density and number size distribution of fine mode aerosol can be obtained in real time, by using the scanning mobility particle sizer and aerodynamic particle sizer. During the experiment, the average density is about 1.66 ± 0.15 g/cm3with the uncertainty of 0.19 g/cm3calculated from the residuals in the overlap region of scanning mobility and aerodynamic particle sizers. A multi‐instrument measurement and quality control scheme is proposed to identify large measurement uncertainties. The extinction and scattering coefficients calculated from the merged fine particle number size distributions by Mie theory are comparable with the measurements from cavity‐enhanced albedometer. The differences between the calculated and observed scattering and extinction coefficients are less than 2%. Meanwhile, the deduced aerosol complex refractive index nand kare obtained by minimizing the sum of squared residuals of extinction and scattering coefficients and comparable with the values retrieved from the Sun‐sky radiometer CE318 measurements. The correlation coefficient on nis 0.72. However, the correlation on kis not optimized, explained by the influence of anthropogenic aerosol particles with strong absorption near ground and the poor accuracy of k. Compared with independent observations, a good agreement between the optical parameters is also obtained. The merging algorithm to achieve the real‐time retrieval of fine mode aerosol density and number size distribution is improvedA method for estimating the uncertainties of retrieved densities and merged number size distributions from the fit residuals is proposedA scheme of multi‐instrument observation and quality control is proposed
- Published
- 2018
- Full Text
- View/download PDF
25. Design and development of soft robot for head and neck cancer radiotherapy
- Author
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Bar-Cohen, Yoseph, Almubarak, Yara, Joshi, Aniket, Ogunmolu, Olalekan, Gu, Xuejun, Jiang, Steve, Gans, Nicholas, and Tadesse, Yonas
- Published
- 2018
- Full Text
- View/download PDF
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