Draft mitogenomes of the invasive ant Lepisiota frauenfeldi (Mayr 1855) (Hymenoptera: Formicidae).

We present the draft mitochondrial genomes (mitogenomes) of two Lepisiota frauenfeldi (Mayr 1855) workers from two separate invasive populations detected in Western Australia (Perth OK569858) and Queensland (Brisbane OK5569859), Australia. The draft mitogenomes ranged between 16,657 and 17,090 bp and contained 37 genes (13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and two ribosomal RNA (rRNA) genes). As with other arthropod mitogenomes, we observed high A + T content (A: 39.4-39.8%, T: 40.55-41.5%). We confirmed the species identity by molecular diagnostics based on the partial mtCOI gene that showed >99% similarity between the Australian populations and other L. frauenfeldi sequences reported to date, and in the process identified putative origins of the invasive populations as Pakistan and India for the WA and Qld incursions respectively that suggested separate introductions.

Structure and Processes of Existing Practice in Radiotherapy Peer Review: A Systematic Review of the Literature.

Peer review in radiotherapy is an essential step in clinical quality assurance to avoid planning-related errors that can impact on patient safety and treatment outcomes. Despite recommendations that radiotherapy centres should include peer review in their regular quality assurance pathway, adoption of the practice has not been universal, and to date there have been no formal guidelines set out to standardise the process. We undertook a systematic review of the literature to determine existing practice in radiotherapy peer review internationally, with respect to meeting structure and processes, in order to define a standardised framework. A PubMed and Web of Science search identified 17 articles detailing peer review practice. The results revealed significant variation in peer review processes between institutions, and a lack of consensus on documentation and reporting. Variations in the grading of outcomes of peer review were also noted. Taking into account the results of this review, a framework for standardising the process and outcome documentation for peer review has been developed. This can be utilised by radiotherapy centres introducing or updating peer review practice, and can facilitate meaningful evaluation of the clinical impact of peer review in the future.

MRIgRT head and neck anthropomorphic QA phantom: Design, development, reproducibility, and feasibility study.

PURPOSE: The purpose of this paper was to design, manufacture, and evaluate a tissue equivalent, dual magnetic resonance/computed tomography (MR/CT) visible anthropomorphic head and neck (H&N) phantom. This phantom was specially designed as an end-to-end quality assurance (QA) tool for MR imaging guided radiotherapy (MRIgRT) systems participating in NCI-sponsored clinical trials. METHOD: The MRIgRT H&N phantom was constructed using a water-fillable acrylic shell and a custom insert that mimics an organ at risk (OAR) and target structures. The insert consists of a primary and secondary planning target volume (PTV) manufactured of a synthetic Clear Ballistic gel, an acrylic OAR and surrounding tissue fabricated using melted Superflab. Radiochromic EBT3 film and thermoluminescent detectors (TLDs) were used to measure the dose distribution and absolute dose, respectively. The phantom was evaluated by conducting an end-to-end test that included: imaging on a GE Lightspeed CT simulator, planning on Monaco treatment planning software (TPS), verifying treatment setup with MR, and irradiating on Elekta's 1.5 T Unity MR linac system. The phantom was irradiated three times using the same plan to determine reproducibility. Three institutions, equipped with either ViewRay MRIdian 60 Co or ViewRay MRIdian Linac, were used to conduct a feasibility study by performing independent end-to-end studies. Thermoluminescent detectors were evaluated in both reproducibility and feasibility studies by comparing ratios of measured TLD to reported TPS calculated values. Radiochromic film was used to compare measured planar dose distributions to expected TPS distributions. Film was evaluated by using an in-house gamma analysis software to measure the discrepancies between film and TPS. RESULTS: The MRIgRT H&N phantom on the Unity system resulted in reproducible TLD doses (SD < 1.5%). The measured TLD to calculated dose ratios for the Unity system ranged from 0.94 to 0.98. The Viewray dose result comparisons had a larger range (0.95-1.03) but these depended on the TPS dose calculations from each site. Using a 7%/4 mm gamma analysis, Viewray institutions had average axial and sagittal passing rates of 97.3% and 96.2% and the Unity system had average passing rates of 97.8% and 89.7%, respectively. All of the results were within the Imaging and Radiation Oncology Core in Houston (IROC-Houston) standard credentialing criteria of 7% on TLDs, and >85% of pixels passing gamma analysis using 7%/4 mm on films. CONCLUSIONS: An MRIgRT H&N phantom that is tissue equivalent and visible on both CT and MR was developed. The results from initial reproducibility and feasibility testing of the MRIgRT H&N phantom using the tested MGIgRT systems suggests the phantom's potential utility as a credentialing tool for NCI-clinical trials.

MRIgRT dynamic lung motion thorax anthropomorphic QA phantom: Design, development, reproducibility, and feasibility study.

PURPOSE: To design, manufacture, and evaluate a dynamic magnetic resonance imaging/computed tomography (MRI/CT)-compatible anthropomorphic thorax phantom used to credential MR image-guided radiotherapy (MRIgRT) systems participating in NCI-sponsored clinical trials. METHOD: The dynamic anthropomorphic thorax phantom was constructed from a water-fillable acrylic shell that contained several internal structures representing radiation-sensitive organs within the thoracic region. A custom MR/CT visible cylindrical insert was designed to simulate the left lung with a centrally located tumor target. The surrounding lung tissue was constructed from a heterogeneous in-house mixture using petroleum jelly and miniature (2-4 mm diameter) styrofoam balls and the tumor structure was manufactured from liquid PVC plastic. An MR conditional pneumatic system was developed to allow the MRIgRT insert to move in similar inhale/exhale motions. TLDs and radiochromic EBT3 film were inserted into the phantom to measure absolute point doses and dose distributions, respectively. The dynamic MRIgRT thorax phantom was evaluated through a reproducibility study and a feasibility study. Comprehensive end-to-end examinations were done where the phantom was imaged on a CT, an IMRT treatment plan was created and an MR image was captured to verify treatment setup. Then, the phantom was treated on an MRIgRT system. The reproducibility study evaluated how well the phantom could be reproduced in an MRIgRT system by irradiating three times on an Elekta's 1.5 T Unity system. The phantom was shipped to three independent institutions and was irradiated on either an MRIdian cobalt-60 (60 Co) or an MRIdian linear accelerator system. Treatment evaluations used TLDs and radiochromic film to compare the planned treatment reported on the treatment planning software against the measured dose on the dosimeters. RESULTS: The phantom on the Unity system had reproducible TLD doses measurements (SD < 1.5%). The measured TLD to calculated dose ratios from the reproducibility and feasibility studies ranged from 0.93 to 1.01 and 0.96 to 1.03, respectively. Using a 7%/5 mm gamma analysis criteria, the reproducibility and feasibility studies resulted in an average passing rate of 93.3% and 96.8%, respectively. No difference was noted in the results between the MRIdian 60 Co and MRIdian 6 MV linac delivery to the phantom and all treatment evaluations were within IROC-Houston's acceptable criterion. CONCLUSIONS: A dosimetrically tissue equivalent, CT/MR visible, motion-enabled anthropomorphic MRIgRT thorax phantom was constructed to simulate a lung cancer patient and was evaluated as an appropriate NIH credentialing tool used for MRIgRT systems.

Investigation of TLD and EBT3 performance under the presence of 1.5T, 0.35T, and 0T magnetic field strengths in MR/CT visible materials.

PURPOSE: The aim of this study was to investigate thermoluminescent dosimeters (TLD) and radiochromic EBT3 film inside MR/CT visible geometric head and thorax phantoms in the presence of: 0, 0.35, and 1.5 T magnetic fields. METHODS: Thermoluminescent Dosimeters reproducibility studies were examined by irradiating IROC-Houston's TLD acrylic block five times under 0 and 1.5 T configurations of Elekta's Unity system and three times under 0 and 0.35 T configurations of ViewRay's MRIdian Cobalt-60 (60 Co) system. Both systems were irradiated with an equivalent 10 × 10 cm2 field size, and a prescribed dose of 3 Gy to the maximum depth deposition (dmax). EBT3 film and TLDs were investigated using two geometrical Magnetic Resonance (MR)-guided Radiation Therapy (MRgRT) head and thorax phantoms. Each geometrical phantom had eight quadrants that combined to create a centrally located rectangular tumor (3 × 3 × 5 cm3 ) surrounded by tissue to form a 15 × 15 × 15 cm3 cubic phantom. Liquid polyvinyl chloride plastic and Superflab were used to simulate the tumor and surrounding tissue in the head phantom, respectively. Synthetic ballistic gel and a heterogeneous in-house mixture were used to construct the tumor and surrounding tissue in the thorax phantom, respectively. EBT3 and double-loaded TLDs were used in the phantoms to compare beam profiles and point dose measurements with and without magnetic fields. GEANT4 Monte Carlo simulations were performed to validate the detectors for both Unity 0 T/1.5 T and MRIdian 0 T/0.35 T configurations. RESULTS: Average TLD block measurements which, compared the magnetic field effects (magnetic field vs 0 T) on the Unity and MRIdian systems, were 0.5% and 0.6%, respectively. The average ratios between magnetic field effects for the geometric thorax and head phantoms under the Unity system were -0.2% and 1.6% and for the MRIdian system were 0.2% and -0.3%, respectively. Beam profiles generated with both systems agreed with Monte Carlo measurements and previous literature findings. CONCLUSIONS: TLDs and EBT3 film dosimeters could potentially be used in MR/CT visible tissue equivalent phantoms that will experience a magnetic field environment.

Novel molecular approach to define pest species status and tritrophic interactions from historical Bemisia specimens.

Museum specimens represent valuable genomic resources for understanding host-endosymbiont/parasitoid evolutionary relationships, resolving species complexes and nomenclatural problems. However, museum collections suffer DNA degradation, making them challenging for molecular-based studies. Here, the mitogenomes of a single 1912 Sri Lankan Bemisia emiliae cotype puparium, and of a 1942 Japanese Bemisia puparium are characterised using a Next-Generation Sequencing approach. Whiteflies are small sap-sucking insects including B. tabaci pest species complex. Bemisia emiliae's draft mitogenome showed a high degree of homology with published B. tabaci mitogenomes, and exhibited 98-100% partial mitochondrial DNA Cytochrome Oxidase I (mtCOI) gene identity with the B. tabaci species known as Asia II-7. The partial mtCOI gene of the Japanese specimen shared 99% sequence identity with the Bemisia 'JpL' genetic group. Metagenomic analysis identified bacterial sequences in both Bemisia specimens, while hymenopteran sequences were also identified in the Japanese Bemisia puparium, including complete mtCOI and rRNA genes, and various partial mtDNA genes. At 88-90% mtCOI sequence identity to Aphelinidae wasps, we concluded that the 1942 Bemisia nymph was parasitized by an Eretmocerus parasitoid wasp. Our approach enables the characterisation of genomes and associated metagenomic communities of museum specimens using 1.5 ng gDNA, and to infer historical tritrophic relationships in Bemisia whiteflies.

Innovations in Radiotherapy Technology.

Many low- and middle-income countries, together with remote and low socioeconomic populations within high-income countries, lack the resources and services to deal with cancer. The challenges in upgrading or introducing the necessary services are enormous, from screening and diagnosis to radiotherapy planning/treatment and quality assurance. There are severe shortages not only in equipment, but also in the capacity to train, recruit and retain staff as well as in their ongoing professional development via effective international peer-review and collaboration. Here we describe some examples of emerging technology innovations based on real-time software and cloud-based capabilities that have the potential to redress some of these areas. These include: (i) automatic treatment planning to reduce physics staffing shortages, (ii) real-time image-guided adaptive radiotherapy technologies, (iii) fixed-beam radiotherapy treatment units that use patient (rather than gantry) rotation to reduce infrastructure costs and staff-to-patient ratios, (iv) cloud-based infrastructure programmes to facilitate international collaboration and quality assurance and (v) high dose rate mobile cobalt brachytherapy techniques for intraoperative radiotherapy.

The complete mitochondrial DNA genome of Aedes vigilax (Diptera: Culicidae).

The complete mitochondrial genomes of two main clades of the medically significant saltmarsh mosquito Aedes vigilax Skuse (Diptera: Culicidae) were obtained using combined Illumina and Sanger sequencing. The two 15,877 bp circular genomes share 99.0% nucleotide identity and encode 37 genes with identical gene arrangement similar to previously published Culicidae species with a non-coding A + T rich region between rns and tRNA-Ile. Protein initiation codon is ATN apart from ND5 (GTG) and COX1 (TCG). Eight protein-coding genes encode full TAA stop codon, while five are completed by mRNA polyadenylation. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

The complete mitochondrial DNA genomes for two lineages of Aedes notoscriptus (Diptera: Culicidae).

The complete mitochondrial genomes for two deeply divergent lineages of the urban adapted mosquito Aedes notoscriptus Skuse (Diptera: Culicidae) in Australia were sequenced using a combination of next generation Illumina and traditional Sanger sequencing. The 15,846 and 15,851 bp circular genomes share 95.0% nucleotide identity. They both have the full complement of 37 metazoan genes and identical gene arrangements to previously published Culicidae species with the one non-coding A + T rich control region present between rns and tRNA-Ile. All protein initiation codons are ATN apart from COX1 (TCG). Eight protein coding genes encode full TAA stop codons, one uses an incomplete TA and four use T. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

Complete mitochondrial DNA genome of Bemisia tabaci cryptic pest species complex Asia I (Hemiptera: Aleyrodidae).

The complete length of the Asia I member of the Bemisia tabaci species complex mitochondrial DNA genome (mitogenome) is 15,210 bp (GenBank accession no. KJ778614) with an A-T biased nucleotide composition (A: 32.7%; T: 42.4%; G: 14.0%; C: 10.8%). The mitogenome consists of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNA (rRNAs) and a 467 bp putative control region which also includes the A+T rich repeat region. All PCGs have an ATA (n = 8) or ATG (n = 5) start codon. Gene synteny of Asia I is overall similar to B. afer and two other members of the B. tabaci species complex Mediterranean and New World 1, and contains the tRNA-Ser2 located between the Cytb and ND1 genes found in Mediterranean and New World 1, but which is absent in B. afer. The orientation of the tRNA-Arg in Asia I is on the "plus" strand and differed from Mediterranean which is found on the "minus" strand. The Asia I mitogenome size is currently ranked the second smallest after B. afer (14,968 bp) followed by New World 1 (15,322 bp) and Mediterranean (15,632 bp).

[Doctor Francoise Cathala and history of prions diseases]. / Le docteur Francoise Cathala Pagesy et l'histoire des maladies à prions.

Doctor Françoise Cathala Pagesy, MD, MS, born on July 7, 1921 in Paris, passed away peacefully at home on November 5, 2012. Unconventional, passionate and enthusiastic neurologist and virologist, she devoted her life to research on latent and slow viral infections, specializing mainly on unconventional transmissible agents or prions. As a research member of Inserm (French Institute for Medical Research), she soon joined the team of Carlton Gajdusek (the NINCDS - National Institute of Nervous Central System and Stroke - of NIH), who first demonstrated the transmissibility of kuru and Creutzfeldt-Jakob disease to monkeys. When she came back to Paris, where she was followed by one of NIH members, Paul Brown, she joined the Centre de Recherches du Service de Santé des Armées (Army Health Research Center), in Percy-Clamart, where she found the experimental design and the attentive help needed for her research, which appeared heretical to many French virologists, including some authorities. A large number of research programs were set up with numerous collaborations involving CEA (Center for Atomic Energy) and other institutions in Paris and Marseilles on epidemiology, results of tissue inoculation, electrophysiology and neuropathology of human and animal prions diseases, and resistance of the infectious agent. International symposia were set up, where met, in the Val-de-Grâce hospital in Paris, the research community on "slow viral diseases". Stanley Prusiner introduced the concept - then badly accepted and still in evolution - of prion, a protein only infectious agent. Before retiring from Inserm, Françoise Cathala predicted and was involved in some of the huge sanitary crises in France. These were, first, Creutzfeldt-Jakob disease from contaminated growth hormone extracted from cadavers, which led parents to instigate legal procedure - a quite unusual practice in France. The second was Mad cow disease in the United Kingdom then in France, followed by new variant of Creutzfeldt-Jakob human epidemics, paradigmatic food safety crisis bringing together the poles of production (beef and meat-and-bone meal) and consumption, and leading to an unexpected social bang. Through Françoise Cathala exemplary life, the history of French, and more generally of worldwide prions diseases is dealt with.

SU-E-T-575: To Analyze the Clinical Impact of Esophageal Sparing on Treatment Plans for Patients with Grade 3 Esophagitis.

PURPOSE: To analyze the clinical impact of esophageal sparing on treatment plans for patients with grade 3 esophagitis. METHODS: The treatment plans of 8 patients (project total: 20 patients) who were treated with IMRT and exhibited stage 3 esophagitis were re-planned to give a simulated clinical plan with dose distribution that mirrored our current clinical practice (74Gy to the target, and 5mm margins), and a plan that emphasized esophageal sparing. Doses to the esophagus, heart, cord, lung and PTV were compared. RESULTS: Comparing the esophageal sparing plan to the simulated clinical plan, the mean reduction in esophageal volume receiving 50, 55, 60, 65, and 70Gy were 2.0, 3.2, 5.0, 7.2, and 10.9 cm3 , respectively. The mean reduction in the continuous length of esophagus receiving 50, 55, 60, 65, and 70Gy were 12, 24, 38, 40, and 47mm, respectively. The associated reduction in dose to 90% and 95% of the PTV was 2.2 and 3.8Gy, respectively. Of the 8 patients examined, 2 showed a significant decrease in PTV coverage (4.6Gy, 12.3Gy for 90% of PTV), 4 showed decreases under 1.1Gy, but 2 showed an increase of 1.4Gy and 0.5Gy for 90% PTV. Cord dose was maintained below 50Gy, and there was a slight increase in mean heart dose and mean lung dose of 2.4Gy, and 2.7Gy, respectively. Data will also be presented comparing these plans with the actual treated plans (for which the patients had grade 3 esophagitis) and plans that emphasize PTV coverage. CONCLUSIONS: Treatment planning to emphasize esophageal sparing can reduce the volume and continuous length of the esophagus which receives high doses. There is some associated modest reduction in PTV coverage. In summary, in many cases esophageal sparing can be accomplished for lung cancer cases while maintaining adequate PTV coverage, although there is variability between patients.

SU-E-T-560: Inter- and Intra-Fraction Variations in Esophageal Dose for Lung Cancer Patients, and the Impact of Setup Technique and Treatment Modality.

PURPOSE: To understand the dose-response of the esophagus in photon and proton therapy, it is important to appreciate the variations in delivered dose caused by inter- and intra-fraction motion. METHODS: Four lung cancer patients were identified who had experienced grade 3 esophagitis during their treatment, and for whom their esophagus was close, but not encompassed by, the treatment volume. Each patient had been treated with proton therapy using 35-37 2Gy fractions, and had received weekly 4DCT imaging. IMRT plans were also created using the same treatment planning constraints. In-house image registration software was used to deform the esophagus contour from the treatment plan to each phase of the 4DCT for each weekly image set. Daily setup using both bony and soft tissue (GTV) registration was simulated, and the treatment dose calculated for each CT image. Changes to the esophagus DVH relative to the treatment plan were quantified in terms of the relative volume of the esophagus receiving 45, 55, and 65Gy (V45, V55 and V65). RESULTS: For all combinations of treatment modality (photon, proton) and setup method (bony, GTV), intra-fraction motion resulted in a range of V45, V55 and V65 from 3.6 to 5.5%. Inter-fraction motion comparing daily exhale or inhale phases showed the range of V45, V55 and V65 from 8.5 to 18.6% (exhale) and 9.8 to 16.3% (inhale). CONCLUSIONS: Inter-fractional motion resulted in larger variations in dose delivered to the esophagus than intra-fractional motion. The inter-fraction range for V45, V55 and V65 varied by around 10% between patients. The treatment modality (photon, proton) and setup technique (bony, GTV) had minimal impact on the results.

SU-E-T-86: Development and Implementation of the Use of Optically Stimulated Luminescent Detectors in the Radiological Physics Center Anthropomorphic Quality Assurance Phantoms.

PURPOSE: To study the angular dependence of optically stimulated luminescence dosimeters (OSLD) in the Radiological Physics Center anthropomorphic quality assurance pelvic phantom to provide accurate dosimetric measurements as a replacement for TLD. METHODS: A spherical phantom was constructed to investigate the angular response of the OSLD as oriented in the RPC pelvic phantom. Three OSLD per irradiation angle, placed at the center of the spherical phantom, were irradiated with 100 cGy from six different angles. The angular response at each angle was determined relative to the OSLD response when the beam was incident normally on the OSLD surface. A pelvic phantom dosimetry insert was modified to include both TLD and OSLD. Three treatment plans were developed in Pinnacle v9.0 and one in Accuray's Multiplan, each with increasing angular beam delivery (4 field, IMRT, SmartArc, CyberKnife) for the pelvic phantom using a common dose prescription and constraints. Each plan was delivered to the phantom three times, containing two TLD and two OSLD, oriented in the transverse plane, at the center of the PTV. The dose delivered to the TLD and OSLD was calculated for each treatment and then compared. RESULTS: The angular dependence correction factor for the spherical phantom was found to be uniformly 1.041 ± 0.003 from single beam edge-on irradiations. The angular dependence correction in the pelvic phantom from multiple beam orientation irradiations was 1.024 ± 0.002, such that the OSLD dose agreed with the TLD dose. Applying the OSLD pelvic phantom correction factor, the RPC measured dose to planning system calculated dose ratio was 0.995 ± 0.009. The established RPC phantom TLD dose to calculated dose ratio was 0.995 ± 0.010. CONCLUSIONS: An anthropomorphic phantom OSLD angular dependence correction factor was established such that the final OSLD dose measurements agreed with RPC's TLD dose measurements to within 1%. Work supported by grant CA 10953, awarded by NCI, DHHS.

SU-E-T-394: Comparison of Planned Dose Distribution Vs. Delivered Dose Distribution for Both IMRT and Proton Therapy Using Weekly Repeat 4DCT Data Sets.

PURPOSE: To evaluate treatment deviations and the impact of treatment modality in the presence of breathing motion and anatomical changes during the course of lung cancer radiotherapy. METHODS: Two non-small cell lung cancer patients were enrolled in a randomized clinical trial to compare IMRT and proton therapy. To rigorously evaluate the impact of motion and anatomical changes, we used a '5D' dose accumulation approach to sum dose distributions from phase-to-phase and week-to-week to the reference (end-expiration) phase of the original planning 4DCT data set. Six to eight weekly 4DCT data sets that consisted of 10 breathing phases were acquired during the treatment course. The original plan was re-calculated for each phase and deformably mapped to the reference phase to compare the 'delivered' dose distribution with the planned dose distribution of both the IMRT plan and the proton plan for each patient. DVHs derived from delivered dose distribution were compared to that from the planned dose distribution. RESULTS: The delivered dose showed 3% and 2% increase in the dose to the CTV for IMRT and proton plan respectively. Target coverage remained acceptable despite tumor shrinkage from 29% to 49%. The doses to normal structures, such as lung and heart, increased more in the proton plan than in the IMRT plan. The V20 of the total lung volume increased by 4% and 6% from the delivered dose compared to the planned dose for IMRT and proton plan, respectively. CONCLUSIONS: The results showed sufficient target coverage was maintained for both modalities. Increases in lung dose were observed in both modalities, but more in the proton arm, perhaps due to weight loss and tumor shrinkage. Adaptive proton therapy strategy is recommended to minimize normal tissue doses. Supported in part by NCI P01 CA021239-29A1.

SU-E-T-250: Dose-Response Curves for the Esophagus.

PURPOSE: To determine the dose-response curve for the esophagus, using esophageal thickening as a surrogate for radiation injury. METHODS: 15 esophageal cancer patients were selected who had received weekly 4DCT images throughout their course of concurrent chemo-radiotherapy (IMRT) to a total of 50.4Gy. Each patient had a length of at least 4cm of esophagus that was outside the GTV but received the full prescription dose. The weekly CT images were registered with the original treatment planning CT images using deformable registration techniques, and the esophagus contours mapped to the weekly images. The relative change in esophagus size was calculated as the average ratio of the cross-sectional area of the esophagus (minus air) in the weekly images to the area in the planning images for a 1cm long region of the esophagus in the center of the CTV (i.e. away from the GTV and field edge). We are considering this region to be 'normal esophagus.' RESULTS: Thirteen of the 15 patients experienced mild esophagitis. The average relative expansion increased as the treatment progressed. For all patients the esophagus was thicker at the final week of treatment than its pre-treatment size. For 7/15 patients the esophageal expansion was larger than 1.3. The average relative expansion of the esophagus was 1.30±0.19 (range: 1.04 - 1.67). We will present dose-response curves calculated from the weekly 4DCTs. CONCLUSIONS: The esophagus expands in response to radiation, reaching approximately a 30% increase in cross-sectional area during the final week of a 50.4Gy treatment, although there is much variability between patients.

SU-F-BRCD-05: Mean Regional Dose to the Esophagus Predicts Acute Toxicity Rate for Lung Cancer Patients.

PURPOSE: The relationship between spatial aspects of the dose distribution and incidence of acute radiation esophagitis for non-small-cell lung cancer (NSCLC) patients is not well understood. Specifically, the location of dose along the superior-inferior (SI) axis of the esophagus has not been previously considered. We introduce the concept of mean regional dose (MRD) calculated for esophageal subvolumes, and test for significance for prediction of acute esophagitis (AE). METHODS: The 3D dose distribution within the esophagus was extracted for 541 NSCLC patients treated with definitive photon therapy. The esophagus contour was divided into equal geometric halves, thirds, and fourths along the SI direction of the structure. MRD in each subvolume was calculated. Univariate logistic regression was performed to determine the correlation between MRD and CTCAE3.0 AE grade = 2 (medical intervention). The MRD was incorporated into an existing NTCP model (based on mean dose for the total esophageal volume) as a separate additive factor. RESULTS: Univariate analysis indicated a significant correlation between AE grade = 2 and MRD in each of the esophageal subvolumes except for the inferior third and inferior-most quarter. There was a statistically significant improvement when including the additive MRD factor for the superior/inferior halves, superior/inferior thirds, and superior-most/inferior-most quarters into the NTCP model. CONCLUSIONS: This study investigates previously unexplored regional differences in delivered dose to the esophagus of patients treated for NSCLC. There is evidence to suggest that dose to the superior portions of the esophagus is more important as it relates to the potential for acute toxicity. The 541 patient cohort is the largest database used to investigate AE in patients treated for NSCLC, strengthening the power of the statistical results. Additional methods to incorporate dose in individual esophagus voxels (along the SI axis) into the NTCP model are also being explored.

SU-E-J-52: Validation of 3D Structure Projection Onto 2D DRR in Commercial Treatment Planning Systems.

PURPOSE: The use of structure overlay on setup DRRs can aid the image alignment procedure for daily image-guided setup procedures. However, the accuracy of a 3D region-of-interest (ROI) projected on a 2D digitally reconstructed radiograph (DRR) has rarely been evaluated quantitatively. The goal of this study is to test the accuracy of two commercial treatment planning systems (TPS) in producing overlay structures on setup DRRs. METHOD AND MATERIALS: We designed a novel method to identify landmarks which were on the boundary of the projected ROI on a DRR. The 3D ROIvolume is composed of a stack of 2D curves. We first mathematically project each 2D curve onto a beams-eye-view (BEV) plane. Next, we detectthe boundary points of the projected curves. Those boundary points serve aslandmarks. Finally, we project the binary mask of the 3D ROI volume using ray tracing method onto the BEV plane. This projected binary mask is used to exclude the false landmarks. Once those landmarks are detected, wecompute the distance between the landmarks and ROI outlines from the TPS. RESULTS: We applied our validation method to 13 ROIs from a lung patient and 4 simulated ROIs on 2 BEV DRRs for two different TPS (Eclipse and Pinnacle). Average distance between the landmarks and ROIoutlines was 0.5mm for both Eclipse and Pinnacle approaches, which is close to the pixel resolution of the DRR. The maximum distance andaverage maximum distance was 2mm and 1 mm, respectively, for both TPS.The maximum distance occurred at points where the ROI curve has a sharpchange between slices. CONCLUSION: The accuracy of Eclipse and Pinnacle ROI projection method seems to be acceptable to within 1mm althoughprojection error can be as large as 2mm when structure shape has a sharp variation from one slice to the next.

SU-E-T-184: LINAC Commissioning Measurements Utilizing the Cylindrical Arc Check Phantom.

PURPOSE: New devices for IMRT and VMAT QA are continually becoming available. Despite the availability of these devices they are underutilized for routine mechanical QA. In this work we take advantage of the cylindrical geometry of the Arc Check phantom to perform tests that are an integral part of commissioning and routine QA. METHODS: The Arc Check is a cylindrical phantom with a diameter of 26.59cm and a 1386 diode array arranged on a cylindrical plane. Owing to its cylindrical design it is capable of measuring entry and exit radiation. For this experiment the Arc Check was set up using the mechanical pointer at 86.7cm SSD. The device was leveled using its inclinometer and was properly rotated to align with the lasers and cross-hair. With the phantom set up at the expected isocenter of the LINAC, 100MUs with a 10×10 field were delivered at different gantry angles, couch and collimator rotations. Each delivery was recorded individually and for each one the radiation center at the entry and exit levels of the detector were estimated. That provided the path of the radiation center through the device. The radiation path was reconstructed for each rotation individually and the coincidence of the mechanical and radiation isocenter was evaluated. RESULTS: A procedure and MATLAB routine were developed that accepted as input the text files that are the output of the Arc Check measurement and geometrically reconstructed in 3-dimensions the isocenter and radiation central axis for each rotation. The coincidence of the radiation and mechanical isocenter was verified. CONCLUSIONS: This work demonstrates that by utilizing the geometry of a commercially available device multiple mechanical LINAC tests that are part of routine QA can be evaluated in one single setup.