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Hong, L

Publications and source records attributed to Hong, L.

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

SU-F-T-85: Energy Modulated Electron Postmastectomy Unreconstructed (PU) Chest Wall (CW) Irradiation Technique to Achieve Heart Sparing

Purpose: For left-sided PU patients requiring CW and nodal irradiation, sometimes partial wide tangents (PWT) are not feasible due to abnormal chest wall contour or heart position close to the anterior chest wall or unusual wide excision scar. We developed an energy modulated electron chest wall irradiation technique that will achieve heart sparing. Methods: Ten left-sided PU patients were selected for this dosimetry study. If PWT were used, the amount of the ipsilateral lung would be ranged 3.4 to 4.4 cm, and the amount of heart would be ranged 1.3 to 3.8 cm. We used electron paired fields that matched on the skin to achieve dose conformity to the chest wall. The enface electron fields were designed at extended SSD from a single isocenter and gantry angle with different energy beams using different cutout. Lower energy was used in the central chest wall part and higher energy was used in the periphery of the chest wall. Bolus was used for the electron fields to ensure adequate skin dose coverage. The electron fields were matched to the photon supra-clavicle field in the superior region. Daily field junctions were used to feather the match lines between all the fields. Target volumes and normal tissues were drawn according to institutional protocols. Prescription dose was 2Gy per fraction for a total 50Gy. Dose calculations were done with Eclipse EMC-11031 for Electron and AAA-11031 for photons. Results: Six patients were planned using 6/9MeV, three using 9/12MeV and one 6/12MeV. Target volumes achieved adequate coverage. For heart, V30Gy, V20Gy and Mean Dose were 0.6%±0.6%, 2.7%±1.7%, and 3.0Gy±0.8Gy respectively. For ipsilateral lung, V50Gy, V20Gy, V10Gy and V5Gy were 0.9%±1.1%, 34.3%±5.1%, 51.6%±6.3% and 64.1%±7.5% respectively. Conclusion: For left-sided PU patients with unusual anatomy, energy modulated electron CW irradiation technique can achieve heart sparing with acceptable lung dose.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-18: A Comparison of Planning Techniques for Bilateral Reconstructed Chest Wall Patients Undergoing Whole Breast Irradiation

Purpose: As we continuously see more bilateral reconstructed chest wall cases, new challenges are being presented to deliver left-sided breast irradiation. We herein compare three Deep Inspiration Breath Hold (DIBH) planning techniques (tangents, VMAT, and IMRT) and two free breathing techniques (VMAT and IMRT). Methods: Three left-sided chest wall patients with bilateral implants were studied. Tangents, VMAT, and IMRT plans were created for DIBH scans. VMAT and IMRT plans were created for free breathing scans. All plans were normalized so that 95% of the prescription dose was delivered to 95% of the planning target volume (PTV). The maximum point dose was constrained to less than 120% of the prescription dose. Since the success of DIBH delivery largely depends on patient’s ability to perform consistent breath hold during beam on time, smaller number of Monitor Units (MU) is in general desired. For each patient, the following information was collected to compare the planning techniques: heart mean dose, left and right lung V20 Gy, contra-lateral (right) breast mean dose, cord max dose, and MU. Results: The average heart mean dose over all patients are 1561, 692, 985, 1245, and 1121 cGy, for DIBH tangents, VMAT, IMRT, free breathing VMAT and IMRT, respectively. For left lung V20 are 60%, 28%, 26%, 30%, and 29%. For contra-lateral breast mean dose are 244, 687, 616, 783, 438 cGy. MU are 253, 853, 2048, 1035, and 1874 MUs. Conclusion: In the setting of bilateral chest wall reconstruction, opposed tangent beams cannot consistently achieve desired heart and left lung sparing. DIBH consistently achieves better healthy tissue sparing. VMAT appears to be preferential to IMRT for planning and delivering radiation to patients with bilaterally reconstructed chest walls being treated with DIBH.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-209: Comparison of Plan Quality Between Arm Avoidance (AA) Vs. Non Arm Avoidance VMAT Planning Techniques for Breast Cancer Patients with Bilateral Implant Reconstructions Receiving Postmastectomy Radiation

Purpose: Breast cancer patients with bilateral implant reconstructions who require postmastectomy radiotherapy can pose unique treatment planning challenges. The use of VMAT may provide advantages over conventional tangent or multi-beam IMRT techniques. Moreover, daily setup uncertainly of the arm position, however, could have significant impact on accurate dose delivery. This study compares the plan qualities between non-AA and AA VMAT techniques. Methods: Three breast cancer patients receiving left chest wall and regional nodal irradiation with bilateral implant reconstructions were studied. PTV included chest wall and IMNs (PTV-CW), and supraclavicular and axillary lymph nodes (PTV-SCV). For each patient, one non-AA VMAT plan (VMAT-S) with 4 partial arcs encompassing the ipsilateral arm and three AA VMAT plans where no arcs were entering or existing through the ipsilateral arm were generated. VMAT-AA1 uses 2 arcs for PTV-CW and 2 arcs for PTV-SCV. VMAT-AA2 used two static fields for PTV-SCV with 2 arcs for PTV-CW. VMAT-AA3 used 2 narrow arcs for PTV-CW and 2 long arcs for all PTVs. Prescription dose (PD) was 50 Gy (25 fractions). All plans were normalized to have 95% of PD to 95 % of PTV. PTV dose inhomogeneity and dose to the heart, left lung, right thyroid dose and left humerus were evaluated. Results: For VMAT-S, VMAT-AA1, VMAT-AA2 and VMAT-AA3, respectively, the average and standard deviation (in Gy unless specified otherwise) of PTV D05 are 54.7±0.9, 55.9±0.4, 56.7±0.7 and 55.7±0.4; mean Heart dose: 7.1±0.7, 7.2±0.8, 7.3±0.9 and 6.9±1.0; left lung V20Gy (in %): 28.1±1.0, 28.8+2.2, 32.2±4.1 and 27.8±2.0; mean right thyroid dose: 8.1±0.6, 5.1±2.1, 2.1±0.4 and 5.0±2.0; mean left humerus dose: 20.0±4.4,15.6±4.4, 15.2±8.2 and 15.3±4.6. Conclusion: AA VMAT can produce acceptable clinical plans while eliminating dosimetric impact related to arm setup uncertainty. These data require validation in larger planning studies prior to routine clinical implantation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-502: Initial Results of a Comparison of Treatment Plans Produced From Automated Prioritized Planning Method and a Commercial Treatment Planning System

Purpose We developed an automated treatment planning system based on a hierarchical goal programming approach. To demonstrate the feasibility of our method, we report the comparison of prostate treatment plans produced from the automated treatment planning system with those produced by a commercial treatment planning system. Methods In our approach, we prioritized the goals of the optimization, and solved one goal at a time. The purpose of prioritization is to ensure that higher priority dose-volume planning goals are not sacrificed to improve lower priority goals. The algorithm has four steps. The first step optimizes dose to the target structures, while sparing key sensitive organs from radiation. In the second step, the algorithm finds the best beamlet weight to reduce toxicity risks to normal tissue while holding the objective function achieved in the first step as a constraint, with a small amount of allowed slip. Likewise, the third and fourth steps introduce lower priority normal tissue goals and beam smoothing. We compared with prostate treatment plans from Memorial Sloan Kettering Cancer Center developed using Eclipse, with a prescription dose of 72 Gy. A combination of liear, quadratic, and gEUD objective functions were used with a modified open source solver code (IPOPT). Results Initial plan results on 3 different cases show that the automated planning system is capable of competing or improving on expert-driven eclipse plans. Compared to the Eclipse planning system, the automated system produced up to 26% less mean dose to rectum and 24% less mean dose to bladder while having the same D95 (after matching) to the target. Conclusion We have demonstrated that Pareto optimal treatment plans can be generated automatically without a trial-and-error process. The solver finds an optimal plan for the given patient, as opposed to database-driven approaches that set parameters based on geometry and population modeling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

TU-F-18C-09: Mammogram Surveillance Using Texture Analysis for Breast Cancer Patients After Radiation Therapy

Purpose: To study the feasibility of applying cancer risk model established from treated patients to predict the risk of recurrence on follow-up mammography after radiation therapy for both ipsilateral and contralateral breast. Methods: An extensive set of textural feature functions was applied to a set of 196 Mammograms from 50 patients. 56 Mammograms from 28 patients were used as training set, 44 mammograms from 22 patients were used as test set and the rest were used for prediction. Feature functions include Histogram, Gradient, Co-Occurrence Matrix, Run-Length Matrix and Wavelet Energy. An optimum subset of the feature functions was selected by Fisher Coefficient (FO) or Mutual Information (MI) (up to top 10 features) or a method combined FO, MI and Principal Component (FMP) (up to top 30 features). One-Nearest Neighbor (1-NN), Linear Discriminant Analysis (LDA) and Nonlinear Discriminant Analysis (NDA) were utilized to build a risk model of breast cancer from the training set of mammograms at the time of diagnosis. The risk model was then used to predict the risk of recurrence from mammogram taken one year and three years after RT. Results: FPM with NDA has the best classification power in classifying the training set of the mammogram with lesions versus those without lesions. The model of FPM with NDA achieved a true positive (TP) rate of 82% compared to 45.5% of using FO with 1-NN. The best false positive (FP) rates were 0% and 3.6% in contra-lateral breast of 1-year and 3-years after RT, and 10.9% in ipsi-lateral breast of 3-years after RT. Conclusion: Texture analysis offers high dimension to differentiate breast tissue in mammogram. Using NDA to classify mammogram with lesion from mammogram without lesion, it can achieve rather high TP and low FP in the surveillance of mammogram for patient with conservative surgery combined RT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-J-99: Reconstruction of Cone Beam CT Image Using Volumetric Modulated Arc Therapy Exit Beams

Purpose: To test the possibility of obtaining an image of the treated volume during volumetric modulated arc therapy (VMAT) with exit beams. Method: Using a Varian Clinac 21EX and MVCT detector the following three sets of detector projection data were obtained for cone beam CT reconstruction with and without a Catphan 504 phantom. 1) 72 projection images from 20 × 16 cm{sup 2} open beam with 3 MUs, 2) 72 projection images from 20 × 16 cm{sup 2} MLC closed beam with 14 MUs. 3) 137 projection images from a test RapicArc QA plan. All projection images were obtained in ‘integrated image’ mode. We used OSCaR code to reconstruct the cone beam CT images. No attempts were made to reduce scatter or artifacts. Results: With projection set 1) we obtained a good quality MV CBCT image by optimizing the reconstruction parameters. Using projection set 2) we were not able to obtain a CBCT image of the phantom, which was determined to be due to the variation of interleaf leakage with gantry angle. From projection set 3), we were able to obtain a weak but meaningful signal in the image, especially in the target area where open beam signals were dominant. This finding suggests that one might be able to acquire CBCT images with rough body shape and some details inside the irradiated target area. Conclusion: Obtaining patient images using the VMAT exit beam is challenging but possible. We were able to determine sources of image degradation such as gantry angle dependent interleaf leakage and beams with a large scatter component. We are actively working on improving image quality.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-502: Biometrically Accepted Patient Records

Purpose: To implement a clinically useful palm vein pattern recognition biometric system to treat the correct treatment plan to the correct patient each and every time and to check-in the patient into the department to access the correct medical record. Methods: A commercially available hand vein scanning system was paired to Aria and utilized an ADT interface from the hospital electronic health system. Integration at two points in Aria, version 11 MR2, first at the appointment tracker screen for the front desk medical record access and second at the queue screen on the 4D treatment console took place for patient daily time-out. A test patient was utilized to check accuracy of identification as well as to check that no unintended interactions take place between the 4D treatment console and the hand vein scanning system. This system has been in clinical use since December 2013. Results: Since implementation, 445 patients have been enrolled into our biometric system. 95% of patients learn the correct methodology of hand placement on the scanner in the first try. We have had two instances of patient not found because of a bad initial scan. We simply erased the scanned metric and the patient enrolled again in those cases. The accuracy of the match is 100% for each patient, we have not had one patient misidentified. We can state this because we still use patient photo and date of birth as identifiers. A QA test patient is run monthly to check the integrity of the system. Conclusion: By utilizing palm vein scans along with the date of birth and patient photo, another means of patient identification now exits. This work indicates the successful implementation of technology in the area of patient safety by closing the gap of treating the wrong plan to a patient in radiation oncology. FOJP Service Corporation covered some of the costs of the hardware and software of the palm vein pattern recognition biometric system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

CO2 Capture Using Phase-Changing Sorbents

A novel method for the postcombustion capture of CO2 from coal-fired power plants has been described utilizing an aminosilicone absorbent. 1,3-Bis(3-aminopropy1)-1,1,3,3-tetramethyldsiloxane (GAP-0) rapidly transforms from a low viscosity liquid to a friable solid upon exposure to CO2 in simulated flue gas. This material has excellent thermal stability, low vapor pressure, high CO2 loading capability, and a large dynamic CO2 capacity between rich and lean solvent loadings. Preliminary plant and process models assembled from experimental data show a decrease in parasitic energy loss from 30% to 18% when compared to the benchmark monoethanolamine (MEA) process and a concomitant lowering of the cost of electricity (COE) from 74% to 44% increase versus a plant without carbon capture.

Perry, RJ↗