SU-E-T-407: Freedom from Conventional: Application of RapidArc for SBRT Lung Treatments

PURPOSE

Stereotactic body radiotherapy (SBRT) has been applied in treating early stage small lung lesions, delivering hypofractionated doses in a conformai manner. Studies have shown that SBRT has similar outcomes compared with surgery. Conventionally, SBRT lung treatments rely on utilization of multiple small, conformai, static fields in coplanar and non- coplanar arrangements. With the advent of RapidArc, it is important to evaluate the differences in dosimetry and delivery of conformai SBRT lung treatments for both conventional static field and VMAT techniques.

METHODS

A retrospective study of 12 patients at our institution who have received SBRT for primary lung lesions was used to evaluate the application of RapidArc for such cases. Originally treated plans utilized eight to ten conformai static coplanar and non-coplanar fields. RapidArc plans were generated in Eclipse using single and multiple arc setups.

RESULTS

As an ntensity-modulated modality, RapidArc provides greater freedom as compared to conventional static field delivery, as one can achieve dose uniformity throughout the PTV or replicate the dosimetry synonymous with conventional SBRT. RapidArc is capable of reproducing the high conformality achieved by conventional SBRT; dual arc plans, delivering uniform dose distributions, yielded an average CI100% of 1.11 and D2cm maximum of 63% of the prescribed dose, compared to 1.33 and 77% (p- values of .002 and .005, respectively) for conventional SBRT. Application of a short, non-coplanar arc, in conjunction with dual coplanar arcs, improved sparing of OARs in direct proximity of the PTV at the expense of treatment time. RapidArc allows for faster treatment delivery; conventional SBRT delivery averages 13.7 minutes at our institution, whereas coplanar dual arcs are estimated to average treatment durations of 4.2 minutes.

CONCLUSIONS

RapidArc is capable of generating conformai dose distributions and sparing of OARs, allows greater freedom in plan optimization, and reduces treatment time significantly.

SU-E-T-195: Experience in Implementing Intraoperative Radiation Therapy for Accelerated Partial Breast Irradiation Using Low-Energy X-Ray Source

PURPOSE

To present our preliminary experience and quality-assurance (QA) procedures in implementing intraoperative-radiation therapy (IORT) for accelerated-partial-breast irradiation (APBI) using the Axxent-system controller (Xoft Inc.) Methods: IORT was implemented in our institution utilizing a 50-keV x-ray source. APBI allows breast conserving in patients with early-stage-breast cancer by delivering radiation to the lumpectomy bed via an applicator balloon filled with water, to which a prescribed dose of 20 Gy was applied to its surface. In-situ anesthesiology, breast-surgery and radiation-oncology teams were required to achieve this procedure. Calibration of the source, including temperature and pressure corrections, was performed by the controller resulting in a calibration factor, which was manually introduced by a physicist into an in-house program providing the corrected dwell times. Evaluation of exposure measurements determined that personnel standing behind glass-rolling shields during irradiation were sufficient protection.

RESULTS

We have successfully treated four patients to date. Surgical times averaged about two hours, QA and setup of controller took about 30 minutes, while radiation-treatment times ranged 7.8-10.4 minutes. Exposure to personnel showed a negligible dose compared to background based on the in-vivo measurements. Our measurements have shown that placement of a shielding layer (FlexiShield) on top of the drape-protected breast reduced radiation exposure to in-room personnel. In one case, treatment was automatically stopped by the controller due to a sudden undetected cooling water flow; due to the pre-treatment training, treatment was successfully resumed within a minute after manual adjustment of the flow sensor.

CONCLUSIONS

Implementation of IORT to treat patients with APBI using low-energy x-ray source should follow the manufacturer's recommendations regarding to the acceptance and personnel training. Our experience indicates that two physicists are necessary at least at the implementation stage. Appropriate training to deal with potential problems is crucial before clinical treatment can be ready.

Microbial response to limited nutrients in shallow water immediately after the end-Permian mass extinction

Previous work indicates that a variety of microbes bloomed in the oceans after the end-Permian faunal mass extinction, but evidence is sporadically documented. Thus, the nature and geographic distribution of such microbes and their associations are unclear, addressed in this study using a series of biomarker groups. On the basis of microbial biomarker records of the 2-methylhopane index, evidence is presented for cyanobacterial blooms in both the western and eastern Tethys Sea and in both shallow and deep waters, after the mass extinction. The enhanced relative abundance of C(28) (expressed by the C(28) /C(29) ratio of) regular steranes suggests a bloom of prasinophyte algae occurred immediately after the end-Permian faunal extinction, comparable with those observed in some other mass extinctions in Phanerozoic. Significantly, cyanobacteria and prasinophyte algae show a synchronized onset of bloom in the shallow water Bulla section, north Italy, inferring for the first time their coupled response to the biotic crisis and the associated environmental conditions. However, in Meishan of Zhejiang Province in south China, the bloom declined earlier than in Bulla. The association of increased 2-methylhopane index with a negative shift in the nitrogen isotope composition infers a scenario of enhanced nitrogen fixation by cyanobacteria immediately after the faunal mass extinction. N(2) fixation by cyanobacteria is here interpreted to have provided prasinophyte algae with ammonium in nutrient-limited shallow waters, and thus caused their associated blooms.

Construction of tissue-engineered composite intervertebral disc and preliminary morphological and biochemical evaluation

The aim of this study was to construct tissue-engineered composite intervertebral disc (IVD) consisting of demineralized bone matrix gelatin (DBMG) and collagen II/hyaluronate/chondroitin-6-sulfate (CII/HyA-CS) scaffolds seeded with anulus fibrosus (AF) and nucleus pulposus (NP) cells, respectively. The cell-scaffold hybrids were implanted in the subcutaneous space of the dorsum of athymic mice and harvested at 4, 8, and 12 weeks. At each time point, the gross and histological morphology and biochemical properties were evaluated. Our results are as following: the gross morphology and histology of the composite resembled those of native IVD. Morphological studies revealed progressive tissue formation and junction integration between AF and NP regions. Biochemical composition detection indicated that the content of DNA, proteoglycan and hydroxyproline increased with time, and were similar to native tissue at 12 weeks. All these results demonstrated the feasibility of creating a tissue-engineered composite IVD with similar morphological and biochemical properties to the native tissue.

Photoemission electron microscopy using extreme ultraviolet attosecond pulse trains

We report the first experiments carried out on a new imaging setup, which combines the high spatial resolution of a photoemission electron microscope (PEEM) with the temporal resolution of extreme ultraviolet (XUV) attosecond pulse trains. The very short pulses were provided by high-harmonic generation and used to illuminate lithographic structures and Au nanoparticles, which, in turn, were imaged with a PEEM resolving features below 300 nm. We argue that the spatial resolution is limited by the lack of electron energy filtering in this particular demonstration experiment. Problems with extensive space charge effects, which can occur due to the low probe pulse repetition rate and extremely short duration, are solved by reducing peak intensity while maintaining a sufficient average intensity to allow imaging. Finally, a powerful femtosecond infrared (IR) beam was combined with the XUV beam in a pump-probe setup where delays could be varied from subfemtoseconds to picoseconds. The IR pump beam could induce multiphoton electron emission in resonant features on the surface. The interaction between the electrons emitted by the pump and probe pulses could be observed.

Tolerant T cells inhibit natural killer cells function in antigen-presenting cells in an independent fashion

Understanding the relationships among immune cells in the setting of immunologic tolerance is imperative to maintain organ and tissue transplants. T cells and natural killer (NK) cells are responsible for both immune tolerance and immune rejection; however, there is only limited knowledge about the relevance of T and NK cells in tolerance. To address this issue, we explored the possible actions of tolerant T cells on NK cells by the means of mixed lymphocyte co-cultures and NK cytotoxicity assays. We showed that tolerant T cell-induced blockade of the co-stimulatory pathway significantly inhibited NK cell function in vitro regarding antigen-presenting cells. This action was cell-cell-contact dependent. We argue that tolerant T cells and NK cells impart synergistic cooperation to maintain transplant tolerance.

A closer look at the number of lymph nodes examined in colorectal cancer: A VAMC experience

e15117

Background: Retrieval of 12 lymph nodes (LN) is a current benchmark in colorectal cancer (CRC) resections according to the National Quality Forum (NQF). Series of multiple institutions contain variability in surgical and pathologic techniques for lymph node retrieval. To ensure consistency in retrieving lymph nodes for satisfactory staging, we present a 12 year experience by a single surgeon and single pathology lab at one VAMC on 157 patients (mean age 67) undergoing CRC resection. Furthermore, the use of chemotherapy for Stage II patients <12 LN retrieved is controversial and yields only a small survival benefit. Methods: The records of 157 patients from one surgeon's case log from 1994–2007 were reviewed. Strict guidelines were applied to remove the same distribution of pericolonic fat. The lab followed a two step approach to LN dissection: Step 1 search for grossly identifiable LN; Step 2 overnight Carnoy's immersion to find smaller LN. Statview and SAS software analyzed 1)Overall survival (OS) and association with finding >12LN; 2)Number of LN identified and impact on AJCC tumor stage (TS) and overall survival; 3)Number of LN and WHO tumor grade (TG) with OS; 4)The impact of number of positive LN on OS. Results: Our mean LN found (14.75) is higher than the 12 recommended by the NQF and is not significantly associated with OS regardless of AJCC TS(p=0.06). The mean LN per TS was I=13.4(N=41)/II=16.3(N=56)/ III=14.3(N=38)/IV 14.2(N=22). Number of LN identified was not statistically significant in predicting TS(p=0.42) or OS(p=0.24). WHO TG is significantly associated to decreased OS, but only in AJCC TS II/III/IV and not stage I (Ip>0.05/IIp=0.008/ IIIp=0.01/IVp=0.025). Higher number of positive LN was associated with lower OS (per each +LN, survival decreases by 0.15 months p=0.001) Conclusions: Contrary to multicenter studies, total number of LN identified does not impact AJCC TS or OS. Higher WHO TG and higher number of positive LN is associated with worse OS. This suggests that the tumor biology is more indicative of OS rather than host response (reactive lymphoid tissue) to the tumor. Stage II patients <12 LN may not be ‘high risk’ and adjuvant chemotherapy based on this factor alone should be reconsidered. Further studies would be warranted.

No significant financial relationships to disclose.

A new multifunctional platform based on high aspect ratio interdigitated NEMS structures

A multifunctional NEMS platform based on a mass-producible, surface relief grating has been developed and fabricated directly in polymer materials. The pattern consists of high aspect ratio interdigitated nanometer-sized pairs of walls and can be produced in a low-complexity one-step patterning process with nanoimprint lithography. In this paper, we demonstrate the usefulness of the platform primarily by showing an application as a high-sensitivity mass sensor in air. The sensors, which are based on the high frequency resonant response of around 200 MHz, show a mass responsivity of the order of 0.1 Hz/zg per wall at room temperature and in ambient air. Their ability to selectively adsorb airborne target molecules, such as thiols, is also demonstrated. We also show that the same device can function as a varactor for electronic circuits based on its large tunable capacitive range.

Modulation of LPS-induced pulmonary neutrophil infiltration and cytokine production by the selective PPARbeta/delta ligand GW0742

OBJECTIVE

To define the anti-inflammatory effects of PPARbeta/delta activation by use of the selective PPARbeta/delta ligand (GW0742) in a model of lipopolysaccharide (LPS)-induced pulmonary inflammation.

METHODS

Male BALB/c mice were pretreated for three days with the PPARbeta/delta agonist, GW0742, prior to induction of LPS-mediated pulmonary inflammation. Bronchial alveolar lavage fluid (BALF) was analyzed for inflammatory cell influx and for levels of pro-inflammatory mediators. BALF-derived inflammatory cells were also collected for mRNA analysis.

RESULTS

Pretreatment with GW0742 resulted in a significant decrease in leukocyte recruitment into the pulmonary space. Protein and mRNA levels of the pro-inflammatory cytokines IL-6, IL-1beta and TNFalpha in BALF were found to be significantly decreased in GW0742-treated animals (30 mg/kg). A significant decrease in granulocyte macrophage-colony stimulating factor (GM-CSF), a major regulator of neutrophil chemotaxis (via its downstream actions on TNFalpha and other cytokines/chemokines), activation and survival, was also noted in the BALF levels of GW0742-treated animals.

CONCLUSIONS

The present study demonstrates that activation of PPARbeta/delta attenuates the degree of inflammation in a model of LPS-induced pulmonary inflammation and may therefore represent a novel therapeutic approach for the treatment of inflammation-mediated pathologies.

An efficient solvent-free synthesis of benzoxanthenes catalyzed by BSA or O-TSA

A series of 14-alkyl and aryl-14H-dibenzo[a.j]xanthenes have been synthesized with high yields through a one-pot condensation of beta-naphthol with alkyl or aryl aldehydes in the presence of BSA or o-TSA in a solvent-free medium.

ESDN is a marker of vascular remodeling and regulator of cell proliferation in graft arteriosclerosis

Vascular remodeling is a common feature of many vasculopathies, including graft arteriosclerosis (GA). We investigated whether endothelial and smooth muscle cell-derived neuropilin-like protein (ESDN) is a marker of vascular remodeling in GA. Immunostaining of human coronary arteries demonstrated high levels of ESDN in GA, but not in normal arteries. In a model of GA, where a segment of human coronary is transplanted into a severe combined immunodeficient mouse, followed by allogeneic human peripheral blood mononuclear cell (PBMC) reconstitution, ESDN was minimally expressed in transplanted human arteries in the absence of reconstitution. By 2 weeks following PBMC reconstitution, at a time corresponding to maximal vascular cell proliferation, high levels of ESDN were detected in the transplanted arteries. Similarly, injury-induced vascular remodeling in apoE(-/-) mice was associated with early and transient ESDN upregulation, in parallel with cell proliferation. In vascular smooth muscle cell (VSMC) cultures, ESDN expression was significantly higher in proliferating, as compared to growth-arrested cells. ESDN overexpression in VSMC led to a decline in growth curves, while ESDN knock down had the opposite effect. We conclude that ESDN is a marker of vascular remodeling and regulator of VSMC proliferation. ESDN may serve as a therapeutic or diagnostic target for GA.

Effects of Ischemia-Reperfusion Injury on Apolipoprotein M Expression in the Liver

The present study investigated the expression pattern of apolipoprotein M (apoM) mRNA in a rat model of hepatic ischemia-reperfusion injury (IRI). Animals were ischemic for 1 hour followed by various reperfusion times. As expected, serum alanine aminotransferase levels were significantly increased under IRI, which indicated the severity of liver injury. Hepatic mRNA levels of HSP70, which is the most common characterized protein within the family of heat-shock proteins (HSP), were significantly increased after 0.5 to 3 hours of IRI. Plasma C-reactive protein, high-density lipoprotein-cholesterol, and lipoprotein (a) levels were significantly increased after 1-hour ischemia followed by 0.5 to 3 hours of reperfusion. Interestingly, similar to HSP70, apoM mRNA levels in the liver were gradually increased after 0.5 to 3 hours of IRI, whereas it returned to a lower level after 6 or 24 hours of IRI, which indicated that hepatic apoM expression was significantly influenced by the acute phase of IRI. However, plasma apoM levels were not increased in parallel, even slightly decreasing after 0.5 or 1 hour of IRI. We concluded that apoM mRNA expression pattern, like HSP70, in the liver showed rapid, significant changes during hepatic local IRI.