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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Forward Intensity-Modulated Radiotherapy Planning in Breast Cancer to Improve Dose Homogeneity: Feasibility of Class Solutions

Purpose: To explore forward planning methods for breast cancer treatment to obtain homogeneous dose distributions (using International Commission on Radiation Units and Measurements criteria) within normal tissue constraints and to determine the feasibility of class solutions. Methods and Materials: Treatment plans were optimized in a stepwise procedure for 60 patients referred for postlumpectomy irradiation using strict dose constraints: planning target volume (PTV){sub 95%} of >99%; V{sub 107%} of <1.8 cc; heart V{sub 5Gy} of <10% and V{sub 10Gy} of <5%; and mean lung dose of <7 Gy. Treatment planning started with classic tangential beams. Optimization was done by adding a maximum of four segments before adding beams, in a second step. A breath-hold technique was used for heart sparing if necessary. Results: Dose constraints were met for all 60 patients. The classic tangential beam setup was not sufficient for any of the patients; in one-third of patients, additional segments were required (<3), and in two-thirds of patients, additional beams (<2) were required. Logistic regression analyses revealed central breast diameter (CD) and central lung distance as independent predictors for transition from additional segments to additional beams, with a CD cut-off point at 23.6 cm. Conclusions: Treatment plans fulfilling strict dose homogeneity criteria and normal tissue constraints could be obtained for all patients by stepwise dose intensity modification using limited numbers of segments and additional beams. In patients with a CD of >23.6 cm, additional beams were always required.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Planning Hybrid Intensity Modulated Radiation Therapy for Whole-breast Irradiation

Purpose: To test tangential and not-tangential hybrid intensity modulated radiation therapy (IMRT) for whole-breast irradiation. Methods and Materials: Seventy-eight (36 right-, 42 left-) breast patients were randomly selected. Hybrid IMRT was performed by direct aperture optimization. A semiautomated method for planning hybrid IMRT was implemented using Pinnacle scripts. A plan optimization volume (POV), defined as the portion of the planning target volume covered by the open beams, was used as the target objective during inverse planning. Treatment goals were to prescribe a minimum dose of 47.5 Gy to greater than 90% of the POV and to minimize the POV and/or normal tissue receiving a dose greater than 107%. When treatment goals were not achieved by using a 4-field technique (2 conventional open plus 2 IMRT tangents), a 6-field technique was applied, adding 2 non tangential (anterior-oblique) IMRT beams. Results: Using scripts, manual procedures were minimized (choice of optimal beam angle, setting monitor units for open tangentials, and POV definition). Treatment goals were achieved by using the 4-field technique in 61 of 78 (78%) patients. The 6-field technique was applied in the remaining 17 of 78 (22%) patients, allowing for significantly better achievement of goals, at the expense of an increase of low-dose ({approx}5 Gy) distribution in the contralateral tissue, heart, and lungs but with no significant increase of higher doses ({approx}20 Gy) in heart and lungs. The mean monitor unit contribution to IMRT beams was significantly greater (18.7% vs 9.9%) in the group of patients who required 6-field procedure. Conclusions: Because hybrid IMRT can be performed semiautomatically, it can be planned for a large number of patients with little impact on human or departmental resources, promoting it as the standard practice for whole-breast irradiation.

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

Scrotal Irradiation in Primary Testicular Lymphoma: Review of the Literature and In Silico Planning Comparative Study

We examined adjuvant irradiation of the scrotum in primary testicular lymphoma (PTL) by means of a literature review in MEDLINE, a telephone survey among Dutch institutes, and an in silico planning comparative study on scrotal irradiation in PTL. We did not find any uniform adjuvant irradiation technique assuring a safe planning target volume (PTV) coverage in published reports, and the definition of the clinical target volume is unclear. Histopathologic studies of PTL show a high invasion rate of the tunica albuginea, the epididymis, and the spermatic cord. In retrospective studies, a prescribed dose of at least 30 Gy involving the scrotum is associated with best survival. The majority of Dutch institutes irradiate the whole scrotum without using a planning computed tomography scan, with a single electron beam and a total dose of 30 Gy. The in silico planning comparative study showed that all evaluated approaches met a D{sub 95%} scrotal dose of at least 85% of the prescription dose, without exceeding the dose limits of critical organs. Photon irradiation with 2 oblique beams using wedges resulted in the best PTV coverage, with a mean value of 95% of the prescribed dose, with lowest maximum dose. Adjuvant photon or electron irradiation of the whole scrotum including the contralateral testicle with a minimum dose of 30 Gy is recommended in PTL. Computed tomography-based radiation therapy treatment planning with proper patient positioning and position verification guarantees optimal dose coverage.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Implications of Intercellular Signaling for Radiation Therapy: A Theoretical Dose-Planning Study

Purpose: Recent in vitro results have shown significant contributions to cell killing from signaling effects at doses that are typically used in radiation therapy. This study investigates whether these in vitro observations can be reconciled with in vivo knowledge and how signaling may have an impact on future developments in radiation therapy. Methods and Materials: Prostate cancer treatment plans were generated for a series of 10 patients using 3-dimensional conformal therapy, intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy techniques. These plans were evaluated using mathematical models of survival following modulated radiation exposures that were developed from in vitro observations and incorporate the effects of intercellular signaling. The impact on dose–volume histograms and mean doses were evaluated by converting these survival levels into “signaling-adjusted doses” for comparison. Results: Inclusion of intercellular communication leads to significant differences between the signalling-adjusted and physical doses across a large volume. Organs in low-dose regions near target volumes see the largest increases, with mean signaling-adjusted bladder doses increasing from 23 to 33 Gy in IMRT plans. By contrast, in high-dose regions, there is a small decrease in signaling-adjusted dose due to reduced contributions from neighboring cells, with planning target volume mean doses falling from 74 to 71 Gy in IMRT. Overall, however, the dose distributions remain broadly similar, and comparisons between the treatment modalities are largely unchanged whether physical or signaling-adjusted dose is compared. Conclusions: Although incorporating cellular signaling significantly affects cell killing in low-dose regions and suggests a different interpretation for many phenomena, their effect in high-dose regions for typical planning techniques is comparatively small. This indicates that the significant signaling effects observed in vitro are not contradicted by comparison with clinical observations. Future investigations are needed to validate these effects in vivo and to quantify their ranges and potential impact on more advanced radiation therapy techniques.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Predictive Treatment Management: Incorporating a Predictive Tumor Response Model Into Robust Prospective Treatment Planning for Non-Small Cell Lung Cancer

Purpose: We hypothesized that a treatment planning technique that incorporates predicted lung tumor regression into optimization, predictive treatment planning (PTP), could allow dose escalation to the residual tumor while maintaining coverage of the initial target without increasing dose to surrounding organs at risk (OARs). Methods and Materials: We created a model to estimate the geometric presence of residual tumors after radiation therapy using planning computed tomography (CT) and weekly cone beam CT scans of 5 lung cancer patients. For planning purposes, we modeled the dynamic process of tumor shrinkage by morphing the original planning target volume (PTV{sub orig}) in 3 equispaced steps to the predicted residue (PTV{sub pred}). Patients were treated with a uniform prescription dose to PTV{sub orig}. By contrast, PTP optimization started with the same prescription dose to PTV{sub orig} but linearly increased the dose at each step, until reaching the highest dose achievable to PTV{sub pred} consistent with OAR limits. This method is compared with midcourse adaptive replanning. Results: Initial parenchymal gross tumor volume (GTV) ranged from 3.6 to 186.5 cm{sup 3}. On average, the primary GTV and PTV decreased by 39% and 27%, respectively, at the end of treatment. The PTP approach gave PTV{sub orig} at least the prescription dose, and it increased the mean dose of the true residual tumor by an average of 6.0 Gy above the adaptive approach. Conclusions: PTP, incorporating a tumor regression model from the start, represents a new approach to increase tumor dose without increasing toxicities, and reduce clinical workload compared with the adaptive approach, although model verification using per-patient midcourse imaging would be prudent.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Quality Assurance With Plan Veto: Reincarnation of a Record and Verify System and Its Potential Value

Purpose: To quantify the potential impact of the Integrating the Healthcare Enterprise–Radiation Oncology Quality Assurance with Plan Veto (QAPV) on patient safety of external beam radiation therapy (RT) operations. Methods and Materials: An institutional database of events (errors and near-misses) was used to evaluate the ability of QAPV to prevent clinically observed events. We analyzed reported events that were related to Digital Imaging and Communications in Medicine RT plan parameter inconsistencies between the intended treatment (on the treatment planning system) and the delivered treatment (on the treatment machine). Critical Digital Imaging and Communications in Medicine RT plan parameters were identified. Each event was scored for importance using the Failure Mode and Effects Analysis methodology. Potential error occurrence (frequency) was derived according to the collected event data, along with the potential event severity, and the probability of detection with and without the theoretical implementation of the QAPV plan comparison check. Failure Mode and Effects Analysis Risk Priority Numbers (RPNs) with and without QAPV were compared to quantify the potential benefit of clinical implementation of QAPV. Results: The implementation of QAPV could reduce the RPN values for 15 of 22 (71%) of evaluated parameters, with an overall average reduction in RPN of 68 (range, 0-216). For the 6 high-risk parameters (>200), the average reduction in RPN value was 163 (range, 108-216). The RPN value reduction for the intermediate-risk (200 > RPN > 100) parameters was (0-140). With QAPV, the largest RPN value for “Beam Meterset” was reduced from 324 to 108. The maximum reduction in RPN value was for Beam Meterset (216, 66.7%), whereas the maximum percentage reduction was for Cumulative Meterset Weight (80, 88.9%). Conclusion: This analysis quantifies the value of the Integrating the Healthcare Enterprise–Radiation Oncology QAPV implementation in clinical workflow. We demonstrate that although QAPV does not provide a comprehensive solution for error prevention in RT, it can have a significant impact on a subset of the most severe clinically observed events.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Treating benign optic nerve tumors with a 3-D conformal plan

A 68 year old male patient presented for radiation therapy for treatment of a benign tumor, a glioma of his left optic nerve. The radiation oncologist intended to prescribe 52.2 Gy to the planning target volume, while maintaining a maximum of 54 Gy to the optic nerves and the optic chiasm and a maximum of 40–45 Gy to the globes in order to minimize the possibility of damaging the optic system, which is especially important as this is a benign tumor. The dosimetrist devised a conformal non-coplanar three-dimensional plan with a slightly weighted forward planning component. This plan was created in approximately 15 minutes after the critical organs and the targets were delineated and resulted in an extremely conformal and homogenous plan, treating the target while sparing the nearby critical structures. This approach can also be extended to other tumors in the brain - benign or malignant.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Pencil beam scanning proton therapy vs rotational arc radiation therapy: A treatment planning comparison for postoperative oropharyngeal cancer

Patients diagnosed with head and neck cancer are traditionally treated with photon radiotherapy. Proton therapy is currently being used clinically and may potentially reduce treatment-related toxicities by minimizing the dose to normal organs in the treatment of postoperative oropharyngeal cancer. The finite range of protons has the potential to significantly reduce normal tissue toxicity compared to photon radiotherapy. Seven patients were planned with both proton and photon modalities. The planning goal for both modalities was achieving the prescribed dose to 95% of the planning target volume (PTV). Dose-volume histograms were compared in which all cases met the target coverage goals. Mean doses were significantly lower in the proton plans for the oral cavity (1771 cGy photon vs 293 cGy proton, p < 0.001), contralateral parotid (1796 cGy photon vs 1358 proton, p < 0.001), and the contralateral submandibular gland (3608 cGy photon vs 3251 cGy proton, p = 0.03). Average total integral dose was 9.1% lower in proton plans. The significant dosimetric sparing seen with proton therapy may lead to reduced side effects such as pain, weight loss, taste changes, and dry mouth. Prospective comparisons of protons vs photons for disease control, toxicity, and patient-reported outcomes are therefore warranted and currently being pursued.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2017

A comparative study of standard intensity-modulated radiotherapy and RapidArc planning techniques for ipsilateral and bilateral head and neck irradiation

The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8 Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is recommended. For bilateral neck irradiation, 2- or 3-arc techniques are dosimetrically comparable to intensity-modulated radiotherapy, but more work is needed to determine the optimal approaches by disease site.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2018

Monaco treatment planning system tools and optimization processes

The Monaco treatment planning system combines Monte Carlo dose calculation accuracy with robust optimization tools to provide high-quality radiotherapy treatment plans for three-dimensional conformal radiotherapy (3D CRT), intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Recent technology advances have allowed for fast calculation speeds, which allow clinicians and patients to benefit from the accuracy of the Monte Carlo algorithm while reducing overall planning time. A collection of biological and physical dose-based planning tools and templates simplify the planning process and allow for consistent results across organizations. At the same time, multicriteria optimization (MCO) ensures critical organs are spared to the greatest possible degree while maintaining target coverage. Monaco encompasses a full suite of treatment modalities, including conventional radiotherapy and particle therapy, and is paving the way for real-time adaptive treatments with developments in magnetic resonance (MR)-guided radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Cyberknife stereotactic radiosurgery and radiation therapy treatment planning system

CyberKnife is an image-guided stereotactical dose delivery system designed for both focal irradiation and radiation therapy (SRT). Focal irradiation refers the use of many small beams to deliver highly focus dose to a small target region in a few fractions. The system consists of a 6-MV linac mounted to a robotic arm, coupled with a digital x-ray imaging system. The radiation dose is delivered using many beams oriented at a number of defined or nodal positions around the patients. The CyberKnife can be used for both intracranial and extracranial treaments unlike the Gamma Knife which is limited to intracranial cases. Multiplan (Accuray Inc., Sunnyvale, CA) is the treatment planning system developed to cooperate with this accurate and versatile SRS and SRT system, and exploit the full function of Cyberknife in high-precision radiosurgery and therapy. Optimized inverse treatment plan can be achieved by fine-tuning contours and planning parameters. Precision is the newest version of Cyberknife treatment planning system (TPS) and an upgrade to Multiplan. It offers several new features such as Monte Carlo for multileaf collimator (MLC) and retreatment for other modalities that added more support for the Cyberknife system. The Cybeknife TPS is an easy-to-use and versatile inverse planning platform, suitable for stereotactic radiosurgery and radiation therapy. The knowledge and experience of the planner in this TPS is essential to improve the quality of patient care.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Dosimetric evaluation of PLATO and Oncentra treatment planning systems for High Dose Rate (HDR) brachytherapy gynecological treatments

This study compares the dosimetric differences in HDR brachytherapy treatment plans calculated with Nucletron's PLATO and Oncentra MasterPlan treatment planning systems (TPS). Ten patients (1 T1b, 1 T2a, 6 T2b, 2 T4) having cervical carcinoma, median age of 43.5 years (range, 34-79 years) treated with tandem and ring applicator in our institution were selected retrospectively for this study. For both Plato and Oncentra TPS, the same orthogonal films anterior-posterior (AP) and lateral were used to manually draw the prescription and anatomical points using definitions from the Manchester system and recommendations from the ICRU report 38. Data input for PLATO was done using a digitizer and Epson Expression 10000XL scanner was used for Oncentra where the points were selected on the images in the screen. The prescription doses for these patients were 30 Gy to points right A (RA) and left A (LA) delivered in 5 fractions with Ir-192 HDR source. Two arrangements: one dwell position and two dwell positions on the tandem were used for dose calculation. The doses to the patient points right B (RB) and left B (LB), and to the organs at risk (OAR), bladder and rectum for each patient were calculated. The mean dose and the mean percentage difference in dose calculated by the two treatment planning systems were compared. Paired t-tests were used for statistical analysis. No significant differences in mean RB, LB, bladder and rectum doses were found with p-values > 0.14. The mean percent difference of doses in RB, LB, bladder and rectum are found to be less than 2.2%, 1.8%, 1.3% and 2.2%, respectively. Dose calculations based on the two different treatment planning systems were found to be consistent and the treatment plans can be made with either system in our department without any concern.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2020

Development and Clustering of Rate-Oriented Load Metrics for Customer Price-Plan Analysis

One of the few methods electric utilities can use to motivate and change customer energy consumption is through retail rate structures. Utilities are increasingly moving toward more dynamic rate plans to encourage energy conservation, utilization of onsite renewable generation, peak demand reduction and flattening of demand profiles. This paper creates a set of rate-oriented load metrics that are the determinants of customers' bills under four unique rate plans. These metrics are not only indicative of which rate structure can provide customer bill reductions based on their load profile characteristics, but also convey useful information about load consumption behavior. With these metrics, utilities can analyze their customers and identify classes that are rewarded under each rate plan. This can help inform utilities whether the customers rewarded under each rate plans are meeting their original objectives. To develop these customer classes, we calculate these rate-oriented load metrics for each customer and perform k-means clustering. The analysis is conducted on a set of 300 customer profiles, examining four different rate plans, different numbers of clusters, customer bills and cluster load profile characteristics.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Stochastic Generation Capacity Expansion Planning with Approximate Dynamic Programming

Failing to consider the many long-term uncertainties that affect the performance of a power generation portfolio can result in suboptimal generation expansion plans. Further, traditional deterministic approaches can omit flexible plans that are able to adapt to future events. In this paper, we explore the use of approximate dynamic programming (ADP) to create forward-looking generation expansion plans. A case study is included with three sequential decision periods; three generation technologies; and four uncertainties: demand growth, natural gas prices, renewable portfolio standards, and the adoption of customer-driven solar generation. The flexible plans found through ADP show a 3 % reduction in total expected cost when compared to myopic planning heuristics while circumventing the computational burdens that accompany high-dimensional dynamic programs.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Performance Evaluation of District Energy Microgrids Planning Tool for Non-Technical Users

Community Microgrids are increasingly gaining popularity worldwide for their efficiency, cost-effectiveness, and local resilience improvement. Microgrid planning tools play a crucial role in their deployment. In the process, tentative designs of the microgrid are simulated, analyzed, and optimized. Due to the complexity of the problem, planning tools must carefully balance computational efficiency while seeking the most optimal solutions. This paper investigates the impact of algorithm selection on CPU and memory utilization of a Community Microgrid planning tool that is specifically designed for non-technical users. We compare two version of the code with two alternatives for Community Microgrid planning tools: a Greedy Algorithm, and a Linear Programming Approach. This comparison examines scenarios spanning from 2 to 50 buildings. Our findings revealed a significant difference in performance between the two algorithms, underscoring the critical role of algorithm selection in optimizing the efficiency of Community Microgrid Planning Tools.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Optimal Nested Test Plan for Combinatorial Quantitative Group Testing

We consider the quantitative group testing problem where the objective is to identify defective items in a given population based on results of tests performed on subsets of the population. Under the quantitative group testing model, the result of each test reveals the number of defective items in the tested group. The minimum number of tests achievable by nested test plans was established by Aigner and Schughart in 1985 within a minimax framework. Furthermore, the optimal nested test plan offering this performance, however, was not obtained. In this paper, we establish the optimal nested test plan in a closed form. This optimal nested test plan is also order optimal among all test plans as the population size approaches infinity. Using heavy-hitter detection as a case study, we show via simulation examples orders of magnitude improvement of the group testing approach over two prevailing sampling-based approaches in detection accuracy and counter consumption. Other applications include anomaly detection and wideband spectrum sensing in cognitive radio systems.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2010

Fundus image fusion in EYEPLAN software: An evaluation of a novel technique for ocular melanoma radiation treatment planning

Purpose: The purpose of this study is to evaluate a novel approach for treatment planning using digital fundus image fusion in EYEPLAN for proton beam radiation therapy (PBRT) planning for ocular melanoma. The authors used a prototype version of EYEPLAN software, which allows for digital registration of high-resolution fundus photographs. The authors examined the improvement in tumor localization by replanning with the addition of fundus photo superimposition in patients with macular area tumors. Methods: The new version of EYEPLAN (v3.05) software allows for the registration of fundus photographs as a background image. This is then used in conjunction with clinical examination, tantalum marker clips, surgeon's mapping, and ultrasound to draw the tumor contour accurately. In order to determine if the fundus image superimposition helps in tumor delineation and treatment planning, the authors identified 79 patients with choroidal melanoma in the macular location that were treated with PBRT. All patients were treated to a dose of 56 GyE in four fractions. The authors reviewed and replanned all 79 macular melanoma cases with superimposition of pretreatment and post-treatment fundus imaging in the new EYEPLAN software. For patients with no local failure, the authors analyzed whether fundus photograph fusion accurately depicted and confirmed tumor volumes as outlined in the original treatment plan. For patients with local failure, the authors determined whether the addition of the fundus photograph might have benefited in terms of more accurate tumor volume delineation. Results: The mean follow-up of patients was 33.6{+-}23 months. Tumor growth was seen in six eyes of the 79 macular lesions. All six patients were marginal failures or tumor miss in the region of dose fall-off, including one patient with both in-field recurrence as well as marginal. Among the six recurrences, three were managed by enucleation and one underwent retreatment with proton therapy. Three patients developed distant metastasis and all three patients have since died. The replanning of six patients with their original fundus photograph superimposed showed that in four cases, the treatment field adequately covered the tumor volume. In the other two patients, the overlaid fundus photographs indicated the area of marginal miss. The replanning with the fundus photograph showed improved tumor coverage in these two macular lesions. For the remaining patients without local failure, replanning with fundus photograph superimposition confirmed the tumor volume as drawn in the original treatment plan. Conclusions: Local control was excellent in patients receiving 56 GyE of PBRT for uveal melanomas in the macular region, which traditionally can be more difficult to control. Posterior lesions are better defined with the additional use of fundus image since they can be difficult to mark surgically. In one-third of treatment failing patients, the superposition of the fundus photograph would have clearly allowed improved localization of tumor. The current practice standard is to use the superimposition of the fundus photograph in addition to the surgeon's clinical and clip mapping of the tumor and ultrasound measurement to draw the tumor volume.

60 APPLIED LIFE SCIENCES↗