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At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Hemobilia after CT-guided radiofrequency ablation of liver tumors: frequency, risk factors, and clinical significance

Purpose: The purpose of the study is to evaluate the frequency, risk factors, and clinical significance of hemobilia after percutaneous computed tomography (CT)-guided radiofrequency ablation (RFA) of liver tumors. Materials and methods: From January 2013 to September 2016, 195 patients received 267 sessions of CT-guided RFA for liver tumors at our institution. The CT images during and immediately after the RFA were retrospectively reviewed. The frequency of hemobilia development and clinical outcome of patients with hemobilia were studied. Risk factors were identified by comparison between the hemobilia and non-hemobilia groups using univariate and multivariate analysis. The clinical courses of patients with hemobilia were also reviewed. Results: The frequency of CT detected hemobilia after RFA was 8.2% (22/267). The majority of the clinical courses were self-limited. Univariate analysis showed that the tumor numbers (p = 0.015), the central type puncture track (p < 0.001), the length of the puncture track (p = 0.033), and the platelet count (p = 0.026) were significantly associated with the development of hemobilia. Multivariate analysis demonstrated that the central type puncture track (p < 0.024) and the platelet count (p = 0.023) were significant independent risk factors. Conclusion: Detection of hemobilia on CT images immediately after percutaneous RFA for liver tumors was not rare. Low platelet count and central type puncture track are independent risk factors. In most cases, hemobilia presented as a minor complication with favorable prognosis.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Combination therapy of transarterial chemoembolization (TACE) and radiofrequency ablation (RFA) for small hepatocellular carcinoma: comparison with TACE or RFA monotherapy

Purpose: To compare the safety and efficacy of combined transarterial chemoembolization (TACE) and radiofrequency ablation (RFA) for small hepatocellular carcinoma (HCC) with those of TACE or RFA monotherapy. Methods: This study included 34 combined TACE and RFA (TACE-RFA), 87 TACE, and 136 ultrasound-guided RFA, which were performed to treat HCC (≤ 3 cm, 3 or fewer) between March and August 2009. The safety (Child–Pugh score indicating hepatic functional reserve, patient discomfort requiring medication, duration of hospitalization, and complications) and efficacy (1-month, 6-month, and 1-year tumor responses) profiles of each treatment were evaluated and compared. Results: TACE-RFA group showed longer hospital stay and more frequent patient discomfort requiring medication than TACE or RFA group (P < 0.001). The frequency of overall complications after TACE-RFA was higher than TACE (P = 0.006) or RFA (P = 0.009). There were no statistical differences in major complication rates between the three groups (P = 0.094). Child–Pugh score at 1-month follow-up showed no significant difference between the three groups (P = 0.162). 1-month, 6-month, and 1-year tumor responses of TACE-RFA were similar to those of RFA and better than those of TACE. Conclusions: TACE-RFA appears to result in more frequent patient discomfort requiring medication, longer hospital stay, and more frequent complications than TACE or RFA monotherapy. Tumor response of TACE-RFA seems to be similar to that of RFA and better than TACE monotherapy. Thus, TACE-RFA for treating small HCC may be required for the selected patients, especially patients with small HCC ineligible for RFA monotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Acute Cor Pulmonale and Right Heat Failure Complicating Ethanol Ablative Therapy: Anesthetic and Radiologic Considerations and Management

Ethanol is an effective ablative agent used for the treatment of certain solid organ tumors and vascular malformations (VMs). The egress of ethanol beyond the target tissue can be associated with significant changes to the cardiopulmonary system that can lead to cardiac arrest. This article reviews the contemporary role of ethanol in tumor and VM treatment and discusses the physiological mechanisms of acute pulmonary hypertension and cardiovascular collapse. The importance of periprocedural recognition of the hemodynamic changes that can occur with the use of ethanol and the treatment of this condition are discussed.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Reiterative Radiofrequency Ablation in the Management of Pediatric Patients with Hepatoblastoma Metastases to the Lung, Liver, or Bone

Background and Purpose: Conventional treatments of systemic chemotherapy and surgical resection for recurrent or metastatic hepatoblastoma (HB) may be inhibitive for the pediatric patient and family who have already been through extensive therapies. This single-institution case series evaluates the safety and efficacy of percutaneous radiofrequency ablation (RFA) in the management of metastatic HB. Materials and Methods: Between March 2008 and February 2015, RFA was used as part of multidisciplinary management for HB recurrence or metastasis in 5 children (median 5.0 years old) in an attempt to provide locoregional control and preclude additional surgery. Combined local treatments of 38 metachronous metastases included surgical metastasectomy (14 lesions: 7 lung, 7 liver), percutaneous RFA (23 lesions: 21 lung, 1 liver, 1 bone), and stereotactic radiotherapy (1 liver lesion). Results: For lesions treated with RFA (median diameter 6 mm, range 3–15 mm), local control was achieved in 22/23 metastases (95.6%) with median follow-up of 30.1 months after RFA (range 18.9–65.7). Median hospitalization was 3 days (2–7), with major complications limited to 1 pneumothorax requiring temporary small-caliber chest tube. Four children remain in complete remission with median follow-up of 67 months (range 41.2–88.8) after primary tumor resection, with mean disease-free survival of 31.7 months after last local treatment. One child succumbed to rapidly progressive disease 12 months after RFA (23.9 months after primary tumor resection). Conclusion: RFA provides a safe and effective reiterative treatment option in the multidisciplinary management of children with metastatic HB.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2019

Radiofrequency Ablation of the Marginal Venous System in Patients with Venous Malformations

Purpose: To evaluate radiofrequency ablation (RFA) for closure of marginal veins in pediatric and adult patients with venous malformations. Materials and methods: Medical records, imaging and procedure details were retrospectively reviewed in patients who underwent RFA of the marginal vein in a 17-month period. Additional sclerotherapy (n = 19) and coil embolization of the marginal vein were performed (n = 2). Results: A total of 23 marginal veins were treated in 20 patients. Mean age at treatment was 16 years ± 9.4 (1–37 years). Pre-procedural magnetic resonance imaging revealed thoracoabdominal marginal veins in 3 patients. A type I marginal vein (draining in the great saphenous vein below the popliteal vein) was identified in 1 and type IIa/IIb (draining in a median/lateral accessory saphenous vein) in 2/8 cases. Type III (draining into the profunda femoral vein) was detected in 8, and type IV (draining into gluteal veins) in 1. Mean diameter of the marginal veins was 13.2 mm ± 4 (7–20 mm). Patency was found in 1 during follow-up (22 months ± 9.8). Complete or partial occlusion was achieved in 94.5% of the veins. One patient showed signs of thrombophlebitis after the procedure, and another incomplete paresis of the peroneal nerve. Conclusion: RFA is effective as minimally invasive treatment of the marginal venous system. These veins should be treated early in life. Marginal veins with large diameter, residual tributaries and the intrafascial courses usually require adjunct coil embolization and sclerotherapy. Level of Evidence: Case series, Level IV.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Isotopic Analysis of Uranium in NIST SRM Glass by Femtosecond Laser Ablation

We employed femtosecond Laser Ablation Multicollector Inductively Coupled Mass Spectrometry for the 11 determination of uranium isotope ratios in a series of standard reference material glasses (NIST 610, 612, 614, and 12 616). This uranium concentration in this series of SRM glasses is a combination of isotopically natural uranium in 13 the materials used to make the glass matrix and isotopically depleted uranium added to increase the uranium 14 elemental concentration across the series. Results for NIST 610 are in excellent agreement with literature values. 15 However, other than atom percent 235U, little information is available for the remaining glasses. We present atom 16 percent and isotope ratios for 234U, 235U, 236U, and 238U for all four glasses. Our results show deviations from the 17 certificate values for the atom percent 235U, indicating the need for further examination of the uranium isotopes in 18 NIST 610-616. Our results are fully consistent with a two isotopic component mixing between the depleted 19 uranium spike and natural uranium in the bulk glass.

Duffin, Andrew M.↗
DOE OSTI2019

Effects of laser fluence on the Cd(OH){sub 2}/CdO nanostructures produced by pulsed laser ablation method

In this experimental study, Cd (OH){sub 2}/CdO nanostructures were produced by pulsed laser ablation method. The beam of a Q-switched Nd:YAG laser with wavelength of 1064 nm at different fluences was employed to irradiate the cadmium target in distilled water. The obtained products at different fluences of laser pulse were characterized by UV–Vis-NIR spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results show that both morphology and chemical bonds of produced Cd nanostructures were changed by increasing the laser fluence. The absorption spectra shows that the Cd(OH){sub 2} nanostructures could be transformed into CdO nanostructures with increasing the laser fluence. XRD analysis showed the presence of crystalline γ-Cd(OH){sub 2}, Cd(OH){sub 2} and CdO phases, in the monoclinic, hexagonal and cubic structure, respectively. Results revealed that obtained nanostructures are particle in lowest fluence, while wire shaped nanostructures were formed with increasing the laser fluence. An increase of the laser fluence induced the synthesis of higher aspect ratio nanowires with a smaller tendency of adhesion.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Defect Characterization Using Positron Annihilation Spectroscopy on Laser-Ablated Surfaces

In recent years, short, pulsed laser ablation has been gaining popularity for machining small-scale test geometries from bulk samples and for efficient serial sectioning. These laser-based techniques are being added to the toolbox in material science, which makes it necessary to understand the changes in the material that occur from the laser–material interaction. Positron annihilation spectroscopy is a unique, nondestructive technique to investigate small defects in materials difficult to investigate by other tools. In this work, Doppler broadening and positron lifetime annihilation spectroscopy are utilized to help quantify the damage in materials treated with short, pulsed lasers. Using a femtosecond laser on single crystal silicon, this manuscript shows that clusters of vacancy-like defects and small voids increase systematically with laser power. Lastly, the damage induced by the laser can also reach to micrometer depths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Calcium fluoride as a dominating matrix for quantitative analysis by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS): A feasibility study

Here, calcium fluoride formed by the reaction between ammonium bifluoride and calcium chloride was investigated as a dominating matrix for quantitative analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Transformation from a solid sample to the calcium fluoride-based matrix permitted quantitative analysis based on calibration standards made from elemental standards. A low abundance stable calcium isotope, i.e. 44 Ca + , was monitored as the internal standard for quantitative analysis by LA-ICP-MS. Correlation coefficient factors for multiple elements were obtained with values over 0.999. The results for multiple elements in a certified reference material of soil (NIST SRM 2710a) agreed with the certified values in the range of expanded uncertainty, indicating the present method was valid for quantitation of elements in solid samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Effect of ghrelin on the motor deficit caused by the ablation of nigrostriatal dopaminergic cells or the inhibition of striatal dopamine receptors

Highlights: • A functional ghrelin receptor GHSR1a is dominantly found in DA neurons in the SNc. • GHSR1a is also located on GABAergic neurons in the SNr. • Activation of GHSRs on SNc-DA neurons improves motor deficits. • GHSRs located on non-DA cells are not associated with motor function. Ghrelin plays roles in a wide range of central functions by activating the growth hormone secretagogue receptor (GHSR). This receptor has recently been found in the substantia nigra (SN) to control dopamine (DA)-related physiological functions. The dysregulation of DA neurons in the SN pars compacta (SNc) and the consequent depletion of striatal DA are known to underlie the motor deficits observed in Parkinson's disease (PD). In the present study, we further investigated the role of the SN-ghrelin system in motor function under the stereotaxic injection of AAV-CMV-FLEX-diphtheria toxin A (DTA) into the SN of dopamine transporter (DAT)-Cre (DAT{sup SN}::DTA) mice to expunge DA neurons of the SNc. First, we confirmed the dominant expression of GHSR1a, which is a functional GHSR, in tyrosine hydroxylase (TH)-positive DA neurons in the SNc of control mice. In DAT{sup SN}::DTA mice, we clearly observed motor dysfunction using several behavioral tests. An immunohistochemical study revealed a dramatic loss of TH-positive DA neurons in the SNc and DAT-labeled axon terminals in the striatum, and an absence of mRNAs for TH and DAT in the SN of DAT{sup SN}::DTA mice. The mRNA level of GHSR1a was drastically decreased in the SN of these mice. In normal mice, we also found the mRNA expression of GHSR1a within GABAergic neurons in the SN pars reticulata (SNr). Under these conditions, a single injection of ghrelin into the SN failed to improve the motor deficits caused by ablation of the nigrostriatal DA network using DAT{sup SN}::DTA mice, whereas intra-SN injection of ghrelin suppressed the motor dysfunction caused by the administration of haloperidol, which is associated with the transient inhibition of DA transmission. These findings suggest that phasic activation of the SNc-ghrelin system could improve the dysregulation of nigrostriatal DA transmission related to the initial stage of PD, but not the motor deficits under the depletion of nigrostriatal DA. Although GHSRs are found in non-DA cells of the SNr, GHSRs on DA neurons in the SNc may play a crucial role in motor function.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Targeted cancer cell ablation in mice by an α-particle-emitting astatine-211-labeled antibody against major histocompatibility complex class I chain-related protein A and B

Highlights: • MICA/B is expressed in several human cancer cells. • We generated an α-particle-emitting {sup 211}At-labelled antibody targeting MICA/B. • {sup 211}At-labelled antibody specifically killed human cancer cells expressing MICA/B. • {sup 211}At-labelled antibody targeting MICA/B showed anti-tumor activity in vivo. Major histocompatibility complex class I chain-related protein A and B (MICA/B) are ligands of the immune receptor, natural-killer group 2 member D. MICA/B expression is often found in several types of cancer but is restricted in normal tissues. Here, we show that an α-particle emitting astatine-211 ({sup 211}At)-labeled antibody targeting MICA/B ({sup 211}At-anti MICA/B Ab) efficiently ablates cancer cells in vitro and in vivo. We generated {sup 211}At-anti MICA/B Ab, an anti-MICA/B antibody conjugated with a highly cytotoxic α-particle emitting radionuclide {sup 211}At. {sup 211}At-anti MICA/B Ab binds to human osteosarcoma SaOS2 and U2OS cells that exhibit high levels of MICA/B expression and efficiently kills those cells in vitro. Biodistribution analysis using xenograft mouse models of HCT116 p53{sup −/−} positive for MICA/B expression, showed increased {sup 211}At in the xenografts for up to 22 h after injection as time proceeded. A single dose of {sup 211}At-anti MICA/B Ab (1 MBq) showed significant reduction in the tumor growth rate of HCT116 p53{sup −/−} xenografts compared to {sup 211}At-labeled mouse IgG (1 MBq) at 21 days after injection. No body weight loss and erythrocytopenia was evident in mice that received {sup 211}At-anti MICA/B. Leukocytopenia and thrombocytopenia were observed within a week after {sup 211}At-anti MICA/B injection, but counts of red blood cells and platelets were recovered to control levels at about 3–4 weeks after injection. Taken together, these data strongly demonstrate that targeted α-particle therapy using {sup 211}At-anti-MICA/B Ab emitting highly cytotoxic α-particles is a potential new therapeutic option for several types of cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Inkless, dry printing nanographene via in-Situ Coordinated laser ablation and sintering processes

Printing carbon, such as graphene and other carbon structures, for flexible and printed electronics currently relies on either ink-based printing, laser-induced forward transfer (LIFT), or laser-induced graphitization (LIG) to convert carbon-rich precursor materials, such as polymers, to graphene-like carbon structures. Liquid inks contain toxic solvents, surfactants, and stabilizing additives that degrade electrical conductivity and require high-temperature post-processing. On the other hand, LIG is limited by the substrate. Here, this study introduces an additive manufacturing method for dry-printing carbon nanomaterials, ranging from amorphous carbon to crystalline graphene-like structures, on various substrates. The system utilizes laser ablation of a solid graphite target to create pure carbon nanoparticles in situ and on demand. An inert gas carries the nanoparticles onto the substrate, where they can be deposited either as amorphous structures or laser-sintered in real time to form various graphitic structures. The study of laser processing parameters, specifically fluence and pulse repetition frequency, revealed three unique regimes of nanostructure evolution that influence the morphological and electrical properties of these printed structures. Raman spectroscopy confirmed graphitization with a resistivity slightly higher than that of the bulk graphite target. The conductivity/resistivity could be tuned as a function of sintering laser power. Scanning transmission electron microscopy (STEM) revealed that turbostratic nanographene formed with an interlayer spacing of 0.40 nm. Despite ink-based printing methods, such as screen printing, inkjet printing (IJP), and aerosol jet printing (AJP), this eco-friendly and green manufacturing technique could eliminate toxic chemicals, reduce environmental impact, and enable single-step fabrication of carbon-based devices for applications in wearable sensors, energy storage, flexible electronics, and Internet of Things (IoT) devices.

Additive nanomanufacturing↗
DOE OSTI2019

Early time dynamics of laser-ablated silicon using ultrafast grazing incidence X-ray scattering

Controlling the morphology of laser-derived nanomaterials is dependent on developing a better understanding of the particle nucleation dynamics in the ablation plume. Here in this paper, we utilize the femtosecond-length pulses from an x-ray free electron laser to perform time-resolved grazing incidence x-ray scattering measurements on a laser-produced silicon plasma plume. At 20 ps we observe a dramatic increase in the scattering amplitude at small scattering vectors, which we attribute to incipient formation of liquid silicon droplets. These results demonstrate the utility of XFELs as a tool for characterizing the formation dynamics of nanomaterials in laser-produced plasma plumes on ultrafast timescales.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Impact of ablator thickness and laser drive duration on a platform for supersonic, shockwave-driven hydrodynamic instability experiments

Here, we discuss changes to a target design that improved the quality and consistency of data obtained through a novel experimental platform that enables the study of hydrodynamic instabilities in a compressible regime. The experiment uses a laser to drive steady, supersonic shockwave over well-characterized initial perturbations. Early experiments were adversely affected by inadequate experimental timescales and, potentially, an unintended secondary shockwave. These issues were addressed by extending the 4 x 10 13 W/cm 2 laser pulse from 19 ns to 28 ns, and increasing the ablator thickness from 185 µm to 500 µm. We present data demonstrating the performance of the platform.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Outcomes of Stereotactic Ablative Radiotherapy in Patients With Potentially Operable Stage I Non-Small Cell Lung Cancer

Background: Approximately two-thirds of patients with early-stage non-small-cell lung cancer (NSCLC) in The Netherlands currently undergo surgical resection. As an increasing number of fit patients have elected to undergo stereotactic ablative radiotherapy (SABR) in recent years, we studied outcomes after SABR in patients with potentially operable stage I NSCLC. Methods and Materials: In an institutional prospective database collected since 2003, 25% of lung SABR cases (n = 177 patients) were found to be potentially operable when the following patients were excluded: those with (1) synchronous lung tumors or other malignancy, (2) prior high-dose radiotherapy/pneumonectomy, (3) chronic obstructive pulmonary disease with a severity score of 3-4 according to the Global initiative for Obstructive Lung Disease classification. (4) a performance score of {>=}3, and (5) other comorbidity precluding surgery. Study patients included 101 males and 76 females, with a median age of 76 years old, 60% of whom were staged as T1 and 40% of whom were T2. Median Charlson comorbidity score was 2 (range, 0-5). A SABR dose of 60 Gy was delivered using a risk-adapted scheme in 3, 5, or 8 fractions, depending on tumor size and location. Follow-up chest computed tomography scans were obtained at 3, 6, and 12 months and yearly thereafter. Results: Median follow-up was 31.5 months; and median overall survival (OS) was 61.5 months, with 1- and 3-year survival rates of 94.7% and 84.7%, respectively. OS rates at 3 years in patients with (n = 59) and without (n = 118) histological diagnosis did not differ significantly (96% versus 81%, respectively, p = 0.39). Post-SABR 30-day mortality was 0%, while predicted 30-day mortality for a lobectomy, derived using the Thoracoscore predictive model (Falcoz PE et al. J Thorac Cardiovasc Surg 2007;133:325-332), would have been 2.6%. Local control rates at 1 and 3 years were 98% and 93%, respectively. Regional and distant failure rates at 3 years were each 9.7%. Toxicity was mild, with grade {>=}3 radiation pneumonitis and rib fractures in 2% and 3%, respectively. Conclusions: Patients with potentially operable disease who underwent primary SABR had a median OS that exceeded 5 years. This finding supports ongoing randomized clinical trials comparing surgery and SABR in cases of operable stage I NSCLC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Tumor Volume-Adapted Dosing in Stereotactic Ablative Radiotherapy of Lung Tumors

Purpose: Current stereotactic ablative radiotherapy (SABR) protocols for lung tumors prescribe a uniform dose regimen irrespective of tumor size. We report the outcomes of a lung tumor volume-adapted SABR dosing strategy. Methods and Materials: We retrospectively reviewed the outcomes in 111 patients with a total of 138 primary or metastatic lung tumors treated by SABR, including local control, regional control, distant metastasis, overall survival, and treatment toxicity. We also performed subset analysis on 83 patients with 97 tumors treated with a volume-adapted dosing strategy in which small tumors (gross tumor volume <12 mL) received single-fraction regimens with biologically effective doses (BED) <100 Gy (total dose, 18-25 Gy) (Group 1), and larger tumors (gross tumor volume {>=}12 mL) received multifraction regimens with BED {>=}100 Gy (total dose, 50-60 Gy in three to four fractions) (Group 2). Results: The median follow-up time was 13.5 months. Local control for Groups 1 and 2 was 91.4% and 92.5%, respectively (p = 0.24) at 12 months. For primary lung tumors only (excluding metastases), local control was 92.6% and 91.7%, respectively (p = 0.58). Regional control, freedom from distant metastasis, and overall survival did not differ significantly between Groups 1 and 2. Rates of radiation pneumonitis, chest wall toxicity, and esophagitis were low in both groups, but all Grade 3 toxicities developed in Group 2 (p = 0.02). Conclusion: A volume-adapted dosing approach for SABR of lung tumors seems to provide excellent local control for both small- and large-volume tumors and may reduce toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Residual {sup 18}F-FDG-PET Uptake 12 Weeks After Stereotactic Ablative Radiotherapy for Stage I Non-Small-Cell Lung Cancer Predicts Local Control

Purpose: To investigate the prognostic value of [{sup 18}F]fluorodeoxyglucose positron emission tomography (FDG-PET) uptake at 12 weeks after stereotactic ablative radiotherapy (SABR) for stage I non-small-cell lung cancer (NSCLC). Methods and Materials: From November 2006 to February 2010, 132 medically inoperable patients with proven Stage I NSCLC or FDG-PET-positive primary lung tumors were analyzed retrospectively. SABR consisted of 60 Gy delivered in 3 to 8 fractions. Maximum standardized uptake value (SUV{sub max}) of the treated lesion was assessed 12 weeks after SABR, using FDG-PET. Patients were subsequently followed at regular intervals using computed tomography (CT) scans. Association between post-SABR SUV{sub max} and local control (LC), mediastinal failure, distant failure, overall survival (OS), and disease-specific survival (DSS) was examined. Results: Median follow-up time was 17 months (range, 3-40 months). Median lesion size was 25 mm (range, 9-70 mm). There were 6 local failures: 15 mediastinal failures, 15 distant failures, 13 disease-related deaths, and 16 deaths from intercurrent diseases. Glucose corrected post-SABR median SUV{sub max} was 3.0 (range, 0.55-14.50). Using SUV{sub max} 5.0 as a cutoff, the 2-year LC was 80% versus 97.7% for high versus low SUV{sub max}, yielding an adjusted subhazard ratio (SHR) for high post-SABR SUV{sub max} of 7.3 (95% confidence interval [CI], 1.4-38.5; p = 0.019). Two-year DSS rates were 74% versus 91%, respectively, for high and low SUV{sub max} values (SHR, 2.2; 95% CI, 0.8-6.3; p = 0.113). Two-year OS was 62% versus 81% (hazard ratio [HR], 1.6; 95% CI, 0.7-3.7; p = 0.268). Conclusions: Residual FDG uptake (SUV{sub max} {>=}5.0) 12 weeks after SABR signifies increased risk of local failure. A single FDG-PET scan at 12 weeks could be used to tailor further follow-up according to the risk of failure, especially in patients potentially eligible for salvage surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Predicting Radiation Pneumonitis After Stereotactic Ablative Radiation Therapy in Patients Previously Treated With Conventional Thoracic Radiation Therapy

Purpose: To determine the incidence of and risk factors for radiation pneumonitis (RP) after stereotactic ablative radiation therapy (SABR) to the lung in patients who had previously undergone conventional thoracic radiation therapy. Methods and Materials: Seventy-two patients who had previously received conventionally fractionated radiation therapy to the thorax were treated with SABR (50 Gy in 4 fractions) for recurrent disease or secondary parenchymal lung cancer (T <4 cm, N0, M0, or Mx). Severe (grade {>=}3) RP and potential predictive factors were analyzed by univariate and multivariate logistic regression analyses. A scoring system was established to predict the risk of RP. Results: At a median follow-up time of 16 months after SABR (range, 4-56 months), 15 patients had severe RP (14 [18.9%] grade 3 and 1 [1.4%] grade 5) and 1 patient (1.4%) had a local recurrence. In univariate analyses, Eastern Cooperative Oncology Group performance status (ECOG PS) before SABR, forced expiratory volume in 1 second (FEV1), and previous planning target volume (PTV) location were associated with the incidence of severe RP. The V{sub 10} and mean lung dose (MLD) of the previous plan and the V{sub 10}-V{sub 40} and MLD of the composite plan were also related to RP. Multivariate analysis revealed that ECOG PS scores of 2-3 before SABR (P=.009), FEV1 {<=}65% before SABR (P=.012), V{sub 20} {>=}30% of the composite plan (P=.021), and an initial PTV in the bilateral mediastinum (P=.025) were all associated with RP. Conclusions: We found that severe RP was relatively common, occurring in 20.8% of patients, and could be predicted by an ECOG PS score of 2-3, an FEV1 {<=}65%, a previous PTV spanning the bilateral mediastinum, and V{sub 20} {>=}30% on composite (previous RT+SABR) plans. Prospective studies are needed to validate these predictors and the scoring system on which they are based.

62 RADIOLOGY AND NUCLEAR MEDICINE↗