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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Clinical Outcomes of Intensity-Modulated Pelvic Radiation Therapy for Carcinoma of the Cervix

Purpose: To evaluate disease outcomes and toxicity in cervical cancer patients treated with pelvic intensity-modulated radiation therapy (IMRT). Methods and Materials: We included all patients with Stage I-IVA cervical carcinoma treated with IMRT at three different institutions from 2000-2007. Patients treated with extended field or conventional techniques were excluded. Intensity-modulated radiation therapy plans were designed to deliver 45 Gy in 1.8-Gy daily fractions to the planning target volume while minimizing dose to the bowel, bladder, and rectum. Toxicity was graded according to the Radiation Therapy Oncology Group system. Overall survival and disease-free survival were estimated by use of the Kaplan-Meier method. Pelvic failure, distant failure, and late toxicity were estimated by use of cumulative incidence functions. Results: The study included 111 patients. Of these, 22 were treated with postoperative IMRT, 8 with IMRT followed by intracavitary brachytherapy and adjuvant hysterectomy, and 81 with IMRT followed by planned intracavitary brachytherapy. Of the patients, 63 had Stage I-IIA disease and 48 had Stage IIB-IVA disease. The median follow-up time was 27 months. The 3-year overall survival rate and the disease-free survival rate were 78% (95% confidence interval [CI], 68-88%) and 69% (95% CI, 59-81%), respectively. The 3-year pelvic failure rate and the distant failure rate were 14% (95% CI, 6-22%) and 17% (95% CI, 8-25%), respectively. Estimates of acute and late Grade 3 toxicity or higher were 2% (95% CI, 0-7%) and 7% (95% CI, 2-13%), respectively. Conclusions: Intensity-modulated radiation therapy is associated with low toxicity and favorable outcomes, supporting its safety and efficacy for cervical cancer. Prospective clinical trials are needed to evaluate the comparative efficacy of IMRT vs. conventional techniques.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Optimal Normal Tissue Sparing in Craniospinal Axis Irradiation Using IMRT With Daily Intrafractionally Modulated Junction(s)

Purpose: To develop a treatment technique for craniospinal irradiation using intensity-modulated radiotherapy (IMRT) with improved dose homogeneity at the field junction(s), increased target volume conformity, and minimized dose to the organs at risk (OARs). Methods and Materials: Five patients with high-risk medulloblastoma underwent CT simulation in supine position. For each patient, an IMRT plan with daily intrafractionally modulated junction(s) was generated, as well as a treatment plan based on conventional three-dimensional planning (3DCRT). A dose of 39.6 Gy in 22 daily fractions of 1.8 Gy was prescribed. Dose-volume parameters for target volumes and OARs were compared for the two techniques. Results: The maximum dose with IMRT was <107% in all patients. V{sub <95} and V{sub >107} were <1 cm{sup 3} for IMRT compared with 3-9 cm{sup 3} for the craniospinal and 26-43 cm{sup 3} for the spinal-spinal junction with 3DCRT. These observations corresponded with a lower homogeneity index and a higher conformity index for the spinal planning target volume with IMRT. IMRT provided considerable sparing of acute and late reacting tissues. V{sub 75} for the esophagus, gastroesophageal junction, and intestine was 81%, 81%, and 22% with 3DCRT versus 5%, 0%, and 1% with IMRT, respectively. V{sub 75} for the heart and thyroid was 42% and 32% vs. 0% with IMRT. Conclusion: IMRT with daily intrafractionally modulated junction results in a superior target coverage and junction homogeneity compared with 3DCRT. A significant dose reduction can be obtained for acute as well as late-reacting tissues.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Hypofractionated Concomitant Intensity-Modulated Radiotherapy Boost for High-Risk Prostate Cancer: Late Toxicity

Purpose: To report the acute and late toxicities of patients with high-risk localized prostate cancer treated using a concomitant hypofractionated, intensity-modulated radiotherapy boost combined with long-term androgen deprivation therapy. Methods and Materials: A prospective Phase I-II study of patients with any of the following: clinical Stage T3 disease, prostate-specific antigen level {>=}20 ng/mL, or Gleason score 8-10. A dose of 45 Gy (1.8 Gy/fraction) was delivered to the pelvic lymph nodes with a concomitant 22.5 Gy prostate intensity-modulated radiotherapy boost, to a total of 67.5 Gy (2.7 Gy/fraction) in 25 fractions within 5 weeks. Image guidance was performed using three gold seed fiducials. The National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0, and Radiation Therapy Oncology Group late morbidity scores were used to assess the acute and late toxicities, respectively. Biochemical failure was determined using the Phoenix definition. Results: A total of 97 patients were treated and followed up for a median of 39 months, with 88% having a minimum of 24 months of follow-up. The maximal toxicity scores were recorded. The grade of acute gastrointestinal toxicity was Grade 0 in 4%, 1 in 59%, and 2 in 37%. The grade of acute urinary toxicity was Grade 0 in 8%, 1 in 50%, 2 in 39%, and 3 in 4%. The grade of late gastrointestinal toxicity was Grade 0 in 54%, 1 in 40%, and 2 in 7%. No Grade 3 or greater late gastrointestinal toxicities developed. The grade of late urinary toxicity was Grade 0 in 82%, 1 in 9%, 2 in 5%, 3 in 3%, and 4 in 1% (1 patient). All severe toxicities (Grade 3 or greater) had resolved at the last follow-up visit. The 4-year biochemical disease-free survival rate was 90.5%. Conclusions: A hypofractionated intensity-modulated radiotherapy boost delivering 67.5 Gy in 25 fractions within 5 weeks combined with pelvic nodal radiotherapy and long-term androgen deprivation therapy was well tolerated, with low rates of severe toxicity. The biochemical control rate at early follow-up has been promising. Additional follow-up is needed to determine the long-term biochemical control and prostate biopsy results.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Positron Emission Tomography/Computed Tomography-Guided Intensity-Modulated Radiotherapy for Limited-Stage Small-Cell Lung Cancer

Purpose: Omitting elective nodal irradiation from planning target volumes does not compromise outcomes in patients with non-small-cell lung cancer, but whether the same is true for those with limited-stage small-cell lung cancer (LS-SCLC) is unknown. Therefore, in the present study, we sought to determine the clinical outcomes and the frequency of elective nodal failure in patients with LS-SCLC staged using positron emission tomography/computed tomography and treated with involved-field intensity-modulated radiotherapy. Methods and Materials: Between 2005 and 2008, 60 patients with LS-SCLC at our institution underwent disease staging using positron emission tomography/computed tomography before treatment using an intensity-modulated radiotherapy plan in which elective nodal irradiation was intentionally omitted from the planning target volume (mode and median dose, 45 Gy in 30 fractions; range, 40.5 Gy in 27 fractions to 63.8 Gy in 35 fractions). In most cases, concurrent platinum-based chemotherapy was administered. We retrospectively reviewed the clinical outcomes to determine the overall survival, relapse-free survival, and failure patterns. Elective nodal failure was defined as recurrence in initially uninvolved hilar, mediastinal, or supraclavicular nodes. Survival was assessed using the Kaplan-Meier method. Results: The median age of the study patients at diagnosis was 63 years (range, 39-86). The median follow-up duration was 21 months (range, 4-58) in all patients and 26 months (range, 4-58) in the survivors. The 2-year actuarial overall survival and relapse-free survival rate were 58% and 43%, respectively. Of the 30 patients with recurrence, 23 had metastatic disease and 7 had locoregional failure. We observed only one isolated elective nodal failure. Conclusions: To our knowledge, this is the first study to examine the outcomes in patients with LS-SCLC staged with positron emission tomography/computed tomography and treated with definitive intensity-modulated radiotherapy. In these patients, elective nodal irradiation can be safely omitted from the planning target volume for the purposes of dose escalation and toxicity reduction.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Interfractional Dose Variations in Intensity-Modulated Radiotherapy With Breath-Hold for Pancreatic Cancer

Purpose: To investigate the interfractional dose variations for intensity-modulated radiotherapy (RT) combined with breath-hold (BH) at end-exhalation (EE) for pancreatic cancer. Methods and Materials: A total of 10 consecutive patients with pancreatic cancer were enrolled. Each patient was fixed in the supine position on an individualized vacuum pillow with both arms raised. Computed tomography (CT) scans were performed before RT, and three additional scans were performed during the course of chemoradiotherapy using a conventional RT technique. The CT data were acquired under EE-BH conditions (BH-CT) using a visual feedback technique. The intensity-modulated RT plan, which used five 15-MV coplanar ports, was designed on the initial BH-CT set with a prescription dose of 39 Gy at 2.6 Gy/fraction. After rigid image registration between the initial and subsequent BH-CT scans, the dose distributions were recalculated on the subsequent BH-CT images under the same conditions as in planning. Changes in the dose-volume metrics of the gross tumor volume (GTV), clinical target volume (CTV = GTV + 5 mm), stomach, and duodenum were evaluated. Results: For the GTV and clinical target volume (CTV), the 95th percentile of the interfractional variations in the maximal dose, mean dose, dose covering 95% volume of the region of structure, and percentage of the volume covered by the 90% isodose line were within {+-}3%. Although the volume covered by the 39 Gy isodose line for the stomach and duodenum did not exceed 0.1 mL at planning, the volume covered by the 39 Gy isodose line for these structures was up to 11.4 cm{sup 3} and 1.8 cm{sup 3}, respectively. Conclusions: Despite variations in the gastrointestinal state and abdominal wall position at EE, the GTV and CTV were mostly ensured at the planned dose, with the exception of 1 patient. Compared with the duodenum, large variations in the stomach volume receiving high-dose radiation were observed, which might be beyond the negligible range in achieving dose escalation with intensity-modulated RT combined with BH at EE.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Tumor Control Outcomes After Hypofractionated and Single-Dose Stereotactic Image-Guided Intensity-Modulated Radiotherapy for Extracranial Metastases From Renal Cell Carcinoma

Purpose: To report tumor local progression-free outcomes after treatment with single-dose, image-guided, intensity-modulated radiotherapy and hypofractionated regimens for extracranial metastases from renal cell primary tumors. Patients and Methods: Between 2004 and 2010, 105 lesions from renal cell carcinoma were treated with either single-dose, image-guided, intensity-modulated radiotherapy to a prescription dose of 18-24 Gy (median, 24) or hypofractionation (three or five fractions) with a prescription dose of 20-30 Gy. The median follow-up was 12 months (range, 1-48). Results: The overall 3-year actuarial local progression-free survival for all lesions was 44%. The 3-year local progression-free survival for those who received a high single-dose (24 Gy; n = 45), a low single-dose (<24 Gy; n = 14), or hypofractionation regimens (n = 46) was 88%, 21%, and 17%, respectively (high single dose vs. low single dose, p = .001; high single dose vs. hypofractionation, p < .001). Multivariate analysis revealed the following variables were significant predictors of improved local progression-free survival: 24 Gy dose compared with a lower dose (p = .009) and a single dose vs. hypofractionation (p = .008). Conclusion: High single-dose, image-guided, intensity-modulated radiotherapy is a noninvasive procedure resulting in high probability of local tumor control for metastatic renal cell cancer generally considered radioresistant according to the classic radiobiologic ranking.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Comparison of Heart and Coronary Artery Doses Associated With Intensity-Modulated Radiotherapy Versus Three-Dimensional Conformal Radiotherapy for Distal Esophageal Cancer

Purpose: To compare heart and coronary artery radiation exposure using intensity-modulated radiotherapy (IMRT) vs. four-field three-dimensional conformal radiotherapy (3D-CRT) treatment plans for patients with distal esophageal cancer undergoing chemoradiation. Methods and Materials: Nineteen patients with distal esophageal cancers treated with IMRT from March 2007 to May 2008 were identified. All patients were treated to 50.4 Gy with five-field IMRT plans. Theoretical 3D-CRT plans with four-field beam arrangements were generated. Dose-volume histograms of the planning target volume, heart, right coronary artery, left coronary artery, and other critical normal tissues were compared between the IMRT and 3D-CRT plans, and selected parameters were statistically evaluated using the Wilcoxon rank-sum test. Results: Intensity-modulated radiotherapy treatment planning showed significant reduction (p < 0.05) in heart dose over 3D-CRT as assessed by average mean dose (22.9 vs. 28.2 Gy) and V30 (24.8% vs. 61.0%). There was also significant sparing of the right coronary artery (average mean dose, 23.8 Gy vs. 35.5 Gy), whereas the left coronary artery showed no significant improvement (mean dose, 11.2 Gy vs. 9.2 Gy), p = 0.11. There was no significant difference in percentage of total lung volume receiving at least 10, 15, or 20 Gy or in the mean lung dose between the planning methods. There were also no significant differences observed for the kidneys, liver, stomach, or spinal cord. Intensity-modulated radiotherapy achieved a significant improvement in target conformity as measured by the conformality index (ratio of total volume receiving 95% of prescription dose to planning target volume receiving 95% of prescription dose), with the mean conformality index reduced from 1.56 to 1.30 using IMRT. Conclusions: Treatment of patients with distal esophageal cancer using IMRT significantly decreases the exposure of the heart and right coronary artery when compared with 3D-CRT. Long-term studies are necessary to determine how this will impact on development of coronary artery disease and other cardiac complications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

A Computational Model of Cellular Response to Modulated Radiation Fields

Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Intensity Modulated Proton and Photon Therapy for Early Prostate Cancer With or Without Transperineal Injection of a Polyethylen Glycol Spacer: A Treatment Planning Comparison Study

Purpose: Rectal toxicity is a serious adverse effect in early-stage prostate cancer patients treated with curative radiation therapy (RT). Injecting a spacer between Denonvilliers' fascia increases the distance between the prostate and the anterior rectal wall and may thus decrease the rectal radiation-induced toxicity. We assessed the dosimetric impact of this spacer with advanced delivery RT techniques, including intensity modulated RT (IMRT), volumetric modulated arc therapy (VMAT), and intensity modulated proton beam RT (IMPT). Methods and Materials: Eight prostate cancer patients were simulated for RT with or without spacer. Plans were computed for IMRT, VMAT, and IMPT using the Eclipse treatment planning system using both computed tomography spacer+ and spacer- data sets. Prostate {+-} seminal vesicle planning target volume [PTV] and organs at risk (OARs) dose-volume histograms were calculated. The results were analyzed using dose and volume metrics for comparative planning. Results: Regardless of the radiation technique, spacer injection decreased significantly the rectal dose in the 60- to 70-Gy range. Mean V{sub 70Gy} and V{sub 60Gy} with IMRT, VMAT, and IMPT planning were 5.3 {+-} 3.3%/13.9 {+-} 10.0%, 3.9 {+-} 3.2%/9.7 {+-} 5.7%, and 5.0 {+-} 3.5%/9.5 {+-} 4.7% after spacer injection. Before spacer administration, the corresponding values were 9.8 {+-} 5.4% (P=.012)/24.8 {+-} 7.8% (P=.012), 10.1 {+-} 3.0% (P=.002)/17.9 {+-} 3.9% (P=.003), and 9.7 {+-} 2.6% (P=.003)/14.7% {+-} 2.7% (P=.003). Importantly, spacer injection usually improved the PTV coverage for IMRT. With this technique, mean V{sub 70.2Gy} (P=.07) and V{sub 74.1Gy} (P=0.03) were 100 {+-} 0% to 99.8 {+-} 0.2% and 99.1 {+-} 1.2% to 95.8 {+-} 4.6% with and without Spacer, respectively. As a result of spacer injection, bladder doses were usually higher but not significantly so. Only IMPT managed to decrease the rectal dose after spacer injection for all dose levels, generally with no observed increase to the bladder dose. Conclusions: Regardless of the radiation technique, a substantial decrease of rectal dose was observed after spacer injection for curative RT to the prostate.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Linear Energy Transfer-Guided Optimization in Intensity Modulated Proton Therapy: Feasibility Study and Clinical Potential

Purpose: To investigate the feasibility and potential clinical benefit of linear energy transfer (LET) guided plan optimization in intensity modulated proton therapy (IMPT). Methods and Materials: A multicriteria optimization (MCO) module was used to generate a series of Pareto-optimal IMPT base plans (BPs), corresponding to defined objectives, for 5 patients with head-and-neck cancer and 2 with pancreatic cancer. A Monte Carlo platform was used to calculate dose and LET distributions for each BP. A custom-designed MCO navigation module allowed the user to interpolate between BPs to produce deliverable Pareto-optimal solutions. Differences among the BPs were evaluated for each patient, based on dose–volume and LET–volume histograms and 3-dimensional distributions. An LET-based relative biological effectiveness (RBE) model was used to evaluate the potential clinical benefit when navigating the space of Pareto-optimal BPs. Results: The mean LET values for the target varied up to 30% among the BPs for the head-and-neck patients and up to 14% for the pancreatic cancer patients. Variations were more prominent in organs at risk (OARs), where mean LET values differed by a factor of up to 2 among the BPs for the same patient. An inverse relation between dose and LET distributions for the OARs was typically observed. Accounting for LET-dependent variable RBE values, a potential improvement on RBE-weighted dose of up to 40%, averaged over several structures under study, was noticed during MCO navigation. Conclusions: We present a novel strategy for optimizing proton therapy to maximize dose-averaged LET in tumor targets while simultaneously minimizing dose-averaged LET in normal tissue structures. MCO BPs show substantial LET variations, leading to potentially significant differences in RBE-weighted doses. Pareto-surface navigation, using both dose and LET distributions for guidance, provides the means for evaluating a large variety of deliverable plans and aids in identifying the clinically optimal solution.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Dynamic Collimator Angle Adjustments During Volumetric Modulated Arc Therapy to Account for Prostate Rotations

Purpose: Rotations of the prostate gland induce considerable geometric uncertainties in prostate cancer radiation therapy. Collimator and gantry angle adjustments can correct these rotations in intensity modulated radiation therapy. Modern volumetric modulated arc therapy (VMAT) treatments, however, include a wide range of beam orientations that differ in modulation, and corrections require dynamic collimator rotations. The aim of this study was to implement a rotation correction strategy for VMAT dose delivery and validate it for left-right prostate rotations. Methods and Materials: Clinical VMAT treatment plans of 5 prostate cancer patients were used. Simulated left-right prostate rotations between +15° and −15° were corrected by collimator rotations. We compared corrected and uncorrected plans by dose volume histograms, minimum dose (D{sub min}) to the prostate, bladder surface receiving ≥78 Gy (S78) and rectum equivalent uniform dose (EUD; n=0.13). Each corrected plan was delivered to a phantom, and its deliverability was evaluated by γ-evaluation between planned and delivered dose, which was reconstructed from portal images acquired during delivery. Results: On average, clinical target volume minimum dose (D{sub min}) decreased up to 10% without corrections. Negative left-right rotations were corrected almost perfectly, whereas D{sub min} remained within 4% for positive rotations. Bladder S78 and rectum EUD of the corrected plans matched those of the original plans. The average pass rate for the corrected plans delivered to the phantom was 98.9% at 3% per 3 mm gamma criteria. The measured dose in the planning target volume approximated the original dose, rotated around the simulated left-right angle, well. Conclusions: It is feasible to dynamically adjust the collimator angle during VMAT treatment delivery to correct for prostate rotations. This technique can safely correct for left-right prostate rotations up to 15°.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Trajectory Modulated Arc Therapy: A Fully Dynamic Delivery With Synchronized Couch and Gantry Motion Significantly Improves Dosimetric Indices Correlated With Poor Cosmesis in Accelerated Partial Breast Irradiation

Purpose: To develop planning and delivery capabilities for linear accelerator–based nonisocentric trajectory modulated arc therapy (TMAT) and to evaluate the benefit of TMAT for accelerated partial breast irradiation (APBI) with the patient in prone position. Methods and Materials: An optimization algorithm for volumetrically modulated arc therapy (VMAT) was generalized to allow for user-defined nonisocentric TMAT trajectories combining couch rotations and translations. After optimization, XML scripts were automatically generated to program and subsequently deliver the TMAT plans. For 10 breast patients in the prone position, TMAT and 6-field noncoplanar intensity modulated radiation therapy (IMRT) plans were generated under equivalent objectives and constraints. These plans were compared with regard to whole breast tissue volume receiving more than 100%, 80%, 50%, and 20% of the prescription dose. Results: For TMAT APBI, nonisocentric collision-free horizontal arcs with large angular span (251.5 ± 7.9°) were optimized and delivered with delivery time of ∼4.5 minutes. Percentage changes of whole breast tissue volume receiving more than 100%, 80%, 50%, and 20% of the prescription dose for TMAT relative to IMRT were −10.81% ± 6.91%, −27.81% ± 7.39%, −14.82% ± 9.67%, and 39.40% ± 10.53% (P≤.01). Conclusions: This is a first demonstration of end-to-end planning and delivery implementation of a fully dynamic APBI TMAT. Compared with IMRT, TMAT resulted in marked reduction of the breast tissue volume irradiated at high doses.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Limited Impact of Setup and Range Uncertainties, Breathing Motion, and Interplay Effects in Robustly Optimized Intensity Modulated Proton Therapy for Stage III Non-small Cell Lung Cancer

Purpose: To investigate the impact of setup and range uncertainties, breathing motion, and interplay effects using scanning pencil beams in robustly optimized intensity modulated proton therapy (IMPT) for stage III non-small cell lung cancer (NSCLC). Methods and Materials: Three-field IMPT plans were created using a minimax robust optimization technique for 10 NSCLC patients. The plans accounted for 5- or 7-mm setup errors with ±3% range uncertainties. The robustness of the IMPT nominal plans was evaluated considering (1) isotropic 5-mm setup errors with ±3% range uncertainties; (2) breathing motion; (3) interplay effects; and (4) a combination of items 1 and 2. The plans were calculated using 4-dimensional and average intensity projection computed tomography images. The target coverage (TC, volume receiving 95% of prescribed dose) and homogeneity index (D{sub 2} − D{sub 98}, where D{sub 2} and D{sub 98} are the least doses received by 2% and 98% of the volume) for the internal clinical target volume, and dose indexes for lung, esophagus, heart and spinal cord were compared with that of clinical volumetric modulated arc therapy plans. Results: The TC and homogeneity index for all plans were within clinical limits when considering the breathing motion and interplay effects independently. The setup and range uncertainties had a larger effect when considering their combined effect. The TC decreased to <98% (clinical threshold) in 3 of 10 patients for robust 5-mm evaluations. However, the TC remained >98% for robust 7-mm evaluations for all patients. The organ at risk dose parameters did not significantly vary between the respective robust 5-mm and robust 7-mm evaluations for the 4 error types. Compared with the volumetric modulated arc therapy plans, the IMPT plans showed better target homogeneity and mean lung and heart dose parameters reduced by about 40% and 60%, respectively. Conclusions: In robustly optimized IMPT for stage III NSCLC, the setup and range uncertainties, breathing motion, and interplay effects have limited impact on target coverage, dose homogeneity, and organ-at-risk dose parameters.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Numerical and experimental analysis of mechanically induced failure in electric vehicle battery modules

Mitigating thermal runaway and cell-to-cell propagation is essential for improving the safety of electric and hybrid vehicles. Enhancing digital twin capabilities to predict battery mechanical abuse is particularly critical for automotive and aerospace applications, where crashworthiness is a key concern. Understanding failure conditions and propagation in battery modules during mechanical abuse is complex due to interactions between structural deformation, heat transfer, electrochemical processes, exothermic reactions and mechanical fracture. While prior studies have focused on modeling cell-level behavior, extending these models to module or pack level is necessary for a system level understating of electric vehicle safety. This study develops coupled large deformation finite element models that simultaneously solve for electrochemistry, material failure, internal short circuit and thermal runaway propagation. The models account for mechanical and thermal interactions between lithium-ion cells and other battery components while the contact interfaces are evolving with time. Model-predicted voltage, temperature and force responses are compared with experimental data for validation. The results demonstrate that the approach captures key failure mechanisms, including thermal propagation through heat transfer, electrical propagation from short circuits in parallel-connected cells, and mechanical propagation via penetration and crack formation. These findings show that computational models are valuable tools for understanding battery module failure and providing insight that can reduce the need for extensive experimental testing.

25 ENERGY STORAGE↗
DOE OSTI2017

Phosphate modulated luminescence in lanthanum vanadate nanorods- Catechin, polyphenolic ligand

Rare earth orthovanadates and phosphates offer a very high opportunity for fabrication of nanoscale devices that exploit their luminescence properties. Optimization of luminescence by way of modulation of size, shape, structure, and morphology has been an area of study for several researchers. There has been a debate as to whether doped orthophosphate or orthovanadate is better luminescent material as both are chemically similar. It has been reported earlier that catechin hydrate can play the role of a structure director and thus influence the luminescence properties of orthovanadates. In this work, a catechin modulated the synthesis of Eu-doped lanthanum orthophosphate by phosphate substitution into vanadate host lattice is reported. A mechanistic understanding of the luminescence changes in LaMO{sub 4} has been proposed. During the substitution of V with P, catechin modulates the structure between 1D nanorods and nanowires. The host crystal structure, shape, and size influence the luminescence properties in doped LaMO{sub 4}. - Graphical abstract: Schematic illustration for the formation process of LAP nanowires using catechin. Display Omitted - Highlights: • Lanthanum phosphate nanowires are prepared by catechin -natural product. • Morphology tuned from nanorods to nanowires with tune in host lattice. • Quenching of luminescence – Zeolite water and Eu{sup 3+} to Eu{sup 2+} reduction. • The crystal structures was investigated by XRD, NMR, XPS and EPR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

A novel research approach on the dynamic properties of photogenerated charge carriers at Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films by a frequency-modulated surface photovoltage technology

Graphical abstract: The changed SPV with chopping frequencies indicate the separation speeds of photogenerated charge carriers in different films. - Highlights: • Ag{sub 2}S-sensitized TiO{sub 2} films show good photoelectric responses in visible-light region. • Frequency-modulated SPV give dynamic information and evidence of Ag{sub 2}S QDSSCs’ performance. • Frequency-modulated SPV can supply complementary information in the study of Ag{sub 2}S ODSSCs. - Abstract: Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films with different amount of Ag{sub 2}S were fabricated by a successive ionic layer adsorption and reaction (SILAR) method. The separation and transport of photogenerated charge carriers at different spectral regions were studied by the frequency-modulated surface photovoltage technology. Some novel dynamic information of photogenerated charge carriers in a wide spectral range is found. The results indicate that the rate and direction of separation (diffusion) for photogenerated charge carriers are closely related to the performance of quantum-dots-sensitized solar cells (QDSSCs) based on the Ag{sub 2}S/TiO{sub 2} nano-structure.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Modulating domain structures in Al2O3-based oxide heterostructures

Highlights: • The trigonal-structure Al{sub 2}O{sub 3} nanotubes and orthorhombic-structure Al{sub 2}O{sub 3} nanosheets are successfully synthesized under high temperature and analyzed based on the electron microscopy. • More importantly, the unexpected Mg-Al-O/Al{sub 2}O{sub 3} heterostructures nucleate, whereas the orthorhombic-structure Al{sub 2}O{sub 3} can effectively modulate the occurrence of monoclinic domains in Mg-Al-O. • This work may provide a meaningful insight for growing specific epitaxial films with suitable alumina substrate. - Abstract: Metal oxide has been the focus of research for decades. In this work, besides the trigonal-structure Al{sub 2}O{sub 3} nanotubes and orthorhombic-structure Al{sub 2}O{sub 3} nanosheets, novel Mg-Al-O/Al{sub 2}O{sub 3} heterostructure nanowires were successfully synthesized at high temperature. The structural characteristics of these oxides were investigated based on electron microscopy and group theory analysis. More importantly, it was found that incorporating the orthorhombic-structure Al{sub 2}O{sub 3} could effectively modulate the occurrence of monoclinic domains and thus the related properties of Mg-Al-O/Al{sub 2}O{sub 3} heterostructures. This work provides a reference for understanding and modulating the complex structures with multiple domain variants in Mg-Al-O oxides.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Assessing the feasibility of volumetric-modulated arc therapy using simultaneous integrated boost (SIB-VMAT): An analysis for complex head-neck, high-risk prostate and rectal cancer cases

Intensity-modulated radiotherapy (IMRT) allowed the simultaneous delivery of different doses to different target volumes within a single fraction, an approach called simultaneous integrated boost (SIB). As consequence, the fraction dose to the boost volume can be increased while keeping low doses to the elective volumes, and the number of fractions and overall treatment time will be reduced, translating into better radiobiological effectiveness. In recent years, volumetric-modulated arc therapy (VMAT) has been shown to provide similar plan quality with respect to fixed-field IMRT but with large reduction in treatment time and monitor units (MUs) number. However, the feasibility of VMAT when used with SIB strategy has few investigations to date. We explored the potential of VMAT in a SIB strategy for complex cancer sites. A total of 15 patients were selected, including 5 head-and-neck, 5 high-risk prostate, and 5 rectal cancer cases. Both a double-arc VMAT and a 7-field IMRT plan were generated for each case using Oncentra MasterPlan treatment planning system for an Elekta Precise linac. Dosimetric indexes for targets and organs at risk (OARs) were compared based on dose-volume histograms. Conformity index, homogeneity index, and dose-contrast index were used for target analyses. The equivalent uniform doses and the normal tissue complication probabilities were calculated for main OARs. MUs number and treatment time were analyzed to score treatment efficiency. Pretreatment dosimetry was performed using 2-dimensional (2D)-array dosimeter. SIB-VMAT plans showed a high level of fluence modulation needed for SIB treatments, high conformal dose distribution, similar target coverage, and a tendency to improve OARs sparing compared with the benchmark SIB-IMRT plans. The median treatment times reduced from 13 to 20 minutes to approximately 5 minutes for all cases with SIB-VMAT, with a MUs reduction up to 22.5%. The 2D-array ion-chambers' measurements reported an agreement of more than 95% for a criterion of 3% to 3 mm. SIB-VMAT was able to combine the advantages of conventional SIB-IMRT with its highly conformal dose distribution and OARs sparing and the advantages of 3D-conformal radiotherapy with its fast delivery.

61 RADIATION PROTECTION AND DOSIMETRY↗