bluuebunny/crossref_metadata_2025 huggingface dataset:
SU‐E‐T‐684: A Comprehensive Dosimetric Study of Pancreatic Cancer Treatment Using Three Dimensional (3D) Conformal Radiation Therapy, Intensity‐Modulated Radiation Therapy (IMRT), Volumetric Modulated Radiation Therapy (VMAT), Passive Scattering and Modulated Scanning Proton Therapy (PT)
Authors: Ding X , Avery S , Kassaee A , Metz J , Prionas V , Huang L , McQuiggan S , Butterwick I , Martinsen A
Published: July 2013

Purpose: This study is to evaluate different radiation therapy modalities in pancreas cancer treatment and to explore the potential role of organs‐at‐risk (OARs) sparing using proton therapy (PT). Methods: Seven consecutive pancreatic cancer patients who had been previously treated with passive‐scattering PT were identified. The clinical target volume (CTV) include the pancreatic tumor bed as well as the adjacent high risk nodal areas. Treatment plans were generated using three‐field and four‐field 3DCRT, five‐field IMRT, two‐arc VMAT, two‐field passive‐scattering and modulated‐scanning PT. All plans delivered 50.4Gy to the initial planning target volume (PTV). 98% of PTV is covered by 95% of the prescription dose and 98% of CTV received 98% prescription dose. Posterior and right posterior oblique proton beams were used to minimize the range uncertainty and improve PT robustness. Pencil beam scanning (PBS) fields with single field uniform dose technique was used for modulated‐scanning PT. Results: All proton plans significantly reduced patient's body integrated dose. Both modulated‐scanning and passive‐scattering PT offer lower doses to the left kidney (mean and V18Gy) and bowel (mean and V20Gy). Modulated‐scanning PT reduced average stomach's mean dose to 168.2 cGy compare to 3‐field 3DCRT (1618.9 cGy P=0.0059), 4‐field 3DCRT (1565.3 cGy P=0.0062) IMRT (1003.47 cGy P=0.0162) and VMAT (1213.4 cGy P=0.0163), and average right kidney's mean dose to 765.7 cGy compared to 3‐field 3DCRT (2205.6 cGy P=0.0013), 4‐field 3DCRT(1825.9 cGy P=0.0009), IMRT(1515.5 cGy P=0.0028) and VMAT (1470.6 cGy P=0.0013). Moreover, modulated‐scanning PT offer lower bowel V20Gy(15.07%) compared to the passive‐scattering PT(28.18% P=0.006). However, IMRT and VMAT offer better target conformity compared to passive‐scattering PT (Passive‐scattering Conformity Index 80% =2.10±0.4, vs IMRT CI80=1.59 ±0.10 P=0.007, vs VMAT CI80=1.44 ±0.15 P=0.0015)Conclusion: The dosimetric advantage of modulated‐scanning PT points to the possibility of treating tumor bed and comprehensive nodal areas while providing a more tolerable treatment course.
SU‐E‐T‐685: Impact of Lesion Morphology and Separation On One‐Versus Two‐Isocenter Frameless Radiosurgery
Authors: Roper J , Chanyavanich V , Betzel G , Dhabaan A
Published: July 2013

Purpose: To investigate the dosimetric and localization effects of one‐versus two‐isocenter SRS. Methods: A library of 50 retrospective patient plans was compiled for cases of two brain lesions. One‐and two‐isocenter plans were generated. One‐isocenter plans consisted of four non‐coplanar‐VMAT arcs; isocenter was positioned midway between two lesions. In the two‐isocenter approach, each lesion was planned separately using four non‐coplanar DCA. DCA plans were summed. All plans were normalized so that 21 Gy covers 100% of the PTVs. Dosimetry and localization errors were studied for one‐and two‐isocenter plans. Normal tissue dose, V12, was evaluated as a function of lesion morphology and separation distance. Plans were exported to Velocity, where localization errors were simulated using rotations of 0°, 0.5°, 1°, and 2° about each isocenter. The effect of rotational misalignments on PTV coverage was compared for D95 and minimum dose. Results: Findings from 10 cases are reported. Analysis of one‐versus two‐isocenter plans shows that the V12 is comparable at lesion separations of 8 cm or less, while V12 is higher for one‐isocenter plans at greater separations. As lesion volume increases, V12 increases more for one‐isocenter plans. The effects of localization errors on target coverage were investigated. For 2° rotational errors on one‐isocenter plans, D95 decreases on average by 7%, whereas the decrease for two‐isocenter plans is 0.5%. Minimum PTV dose decreases more substantially: 12% versus 1% respectively for the one‐and two‐isocenter plans. The above values are averaged over all lesion separations. For the largest separation of 15 cm, minimum PTV dose decreases by 37% for the one‐isocenter plan. Conclusions: Localization becomes more important as separation increases for one‐isocenter SRS. Findings suggest that lesion morphology and separation should be considered when deciding between one‐and two‐isocenter SRS because of the effects on normal tissue dose and target coverage.
SU‐E‐T‐687: Reverse Auto‐Planning: Assessing Dose Escalation in Pancreatic Stereotactic Radiotherapy From a Shape Database of Prior Patients
Authors: Moore J , Yang W , Evans K , Herman J , McNutt T
Published: July 2013

Purpose: Automatic treatment planning can be used to determine achievable dose values before optimization. Reverse auto planning instead looks to find the highest target dose while still meeting critical structure objectives. A tool incorporating reverse auto planning is proposed for prediction of planning difficulty. Methods: A SQL database of 53 pancreas stereotactic body radiotherapy patients is populated with dose and structure information. Overlap volume histograms (OVH) are generated for each organ at risk (OAR) and target pair. For each structure, the lowest achievable target dose, which was calculated by selecting the lowest dose from all patients with a smaller distance to overlap, was queried together with maximum target dose. The lowest target dose from the list of maximum target dose per structure represents the highest achieved dose from the database population. Additional scaling can be used which scales the maximum achievable target dose per structure to the limiting dose of the OAR. Results: For patients analyzed using this tool, the predicted maximum target dose serves as a predictor of planning difficulty. If the predicted maximum target dose is high, plans which meet OAR objectives are easier to generate. If the predicted maximum target dose is low, plans are more difficult and planning objectives may not be achievable. Conclusion: A tool for predicting the maximum achievable target dose is developed. This tool estimates plan difficulty and achievability prior to planning and can be used to determine if dose escalation may be appropriate or if alternate treatment strategies should be used due to difficulty in achieving desired goals. Support by Philips Healthcare: Philips Radiation Oncology Services
SU‐E‐T‐689: Effects of Coordinate System Orientation On ICRU Bladder Point Dose
Authors: Parker B , Cox J
Published: July 2013

Purpose: To quantify the displacement and dosimetric errors on position of the ICRU bladder point due to coordinate system orientation in gynecological HDR procedures. Methods: Eight patients (23 treatment fractions) receiving HDR brachytherapy for gynecological malignancies were evaluated. Bladder points were placed for each of two coordinate systems (ICRU and applicator) for each patient fraction. The ICRU coordinate system refers to true anatomical orientations (e.g., ant/post) while the applicator coordinate system is transformed (translated and rotated) based on the location and orientation treatment applicator and is used to define prescription points and optimize planned dose distributions. In both cases, the ICRU bladder point definition was used to place the point (most posterior point of foley balloon on lateral image and center of foley balloon on AP image) with differences resulting from definition of coordinate system orientation. The displacement in three dimensions and point dose differences were calculated for each patient fraction. Results: Point displacement of the applicator coordinate system point (Bappl) relative to the ICRU point (BICRU) was 6.3 ± 0.7 mm (mean ± std err) with a range of 1.5 to 12.6 mm, a statistically significant Result. Dosimetrically, dose to Bappl was 7.3 ± 1.6% (mean ± std err) of the prescribed dose higher than BICRU with a range of −7.9 to 24.7%, a statistically and clinically significant Result. This results in an overestimation of bladder dose when using the applicator coordinate system and using ICRU point dose criteria for plan evaluation. Conclusion: Failure to use a true anatomical coordinate system can lead to statistically and clinically significant dosimetric errors in dose to the defined bladder point. Use of the applicator coordinate system to define the bladder point can potentially cause compromises in plan quality in attempting to meet normal tissue dose tolerances evaluated with incorrectly reported doses.
SU‐E‐T‐691: Comparison of 5‐Channel Versus Single and 9‐Channel Vaginal Cylinder Treatment Plans
Authors: White M , Syh J , Rosen L , Patel B , Syh J , Wu H
Published: July 2013

Purpose: To compare the quality of 5‐channel vaginal cylinder treatment plans for endometrial cancer to single channel and 9‐channel plans. Using more channels tends to spare the rectum and bladder, while creating hot spots and longer planning and treatment times. The objective is to determine if the 5‐channel plans offer a beneficial compromise to the single and 9‐channel plans. Methods: Fifteen treatment plans from 3 patients were evaluated using the Oncentra MasterPlan (Nucletron inc.) treatment planning system. Each of the 15 plans was previously treated with 9 channels from a 35mm diameter multi‐channel cylinder, using Oncentra's IPSA inverse planning tool. The prescribed dose was 500cGy × 5 fractions to the 5mm vaginal cuff rind. A 5‐channel plan was created by removing the 2 channels closest to the bladder and the 2 closest to the rectum from the 9‐channel plan, then proportionately adjusting the weights in inverse planning for the bladder, rectum, and D150, while keeping D95 within 0.1% (D95 is typically around 95%). The single channel plan was normalized to a 5mm distance from the cylinder wall. Results: When compared to single channel, the 5‐channel plans had an average of 3.5% and 6.7% lower doses to the bladder and rectum, respectively. The V200 was lower in 7/15 plans (−0.2% average), and V150 was higher than single channel on 13/15 plans (+5.7% average). When compared to 9‐channel, the 5‐channel plans had lower dose to the bladder on 9/15 plans (−0.3% average), and a lower V150 on 9/15 plans (−0.6% average). The 5‐channel rectum dose was higher on all plans (+4.4% average), and the V200 was higher on 8/15 plans (0.3% average). Conclusion: The 5‐channel vaginal cylinder plans offer a reasonable compromise between single channel and 9‐channel plans.
SU‐E‐T‐692: Validation of Permanent Interstitial I‐125 Implant Pre‐Plans Against An Experimentally Derived Nomogram Can Potentially Reduce Variability of Day 0 Post‐Implant Dosimetry
Authors: Wolthuis B , Dolan J , Shasha D , Santoro J , Ambrose R , Furhang E
Published: July 2013

Purpose: To evaluate whether standardization of total pre‐plan activity against a nomogram reduces variability of post‐implant dosimetry for I‐125 permanent interstitial prostate implants (PIPI). Methods: Between January 2007 and December 2011, 843 patients underwent TRUS guided PIPI (MPD 108Gy) in combination with external irradiation. The implants and all contouring for pre‐and post‐plans were performed by a single physician. Post‐implant dosimetry was determined based on CTs taken on the day of implant. Implants were grouped into the following categories based on their post‐implant dosimetry: 1.Excellent (90%< D90 <120% and V150>70%); 2.Hot (D90>120% and V150>70%); 3. Cold (D90<80%); and 4.Other. A known‐effective activity versus volume nomogram was derived from a fit of the data from the excellent implants. The actual activities used in the hot and cold implant groups were evaluated for deviations from the predictions of the known‐effective nomogram. The potential impact of imposing a tolerance window was investigated. Results: Of all implants, 347, 81, 37 and 378 were excellent, hot, cold and other, respectively. The activity versus volume data of the excellent implants were well fit with a power law (R^2=0.972). The average and standard deviation of the differences between actual implanted activity and the prediction of the known‐effective nomogram was 3.8% +/− 4.0 and −0.6% +/− 5.0 for the hot and cold groups, respectively. The implanted activity agreed with the known‐effective nomogram prediction within +/−4% for 514 plans. For these plans, 44%, 7.0% and 3.9% were excellent, hot and cold, respectively. Outside this tolerance window, the corresponding values were 36%, 14% and 5.2%. Conclusion: Imposing a quality assurance requirement that total pre‐plan activity agree with the prediction of a known‐effective nomogram should improve homogeneity of post‐implant dosimetric parameters by increasing the frequency of excellent implants and reducing the frequency of hot implants.
SU‐E‐T‐693: Comparison of Discrete Spot Scanning and Passive Scattering Craniospinal Proton Irradiation
Authors: Stoker J , Amos R , Li Y , Liu W , Park P , Sahoo N , Zhang X , Zhu X , Gillin M
Published: July 2013

Purpose: To compare plan robustness, dose variations at field junctions, and overall dose conformity to target between passive scattering and discrete spot scanning (DSS) proton craniospinal irradiation. Methods: A DSS treatment plan was generated for three craniospinal CT image sets. A forward planning approach was used to generate treatment plans for the cranium and lower spine, which exhibited dose tapering of about 10 Gy/cm towards the thoracic spine to facilitate the low‐gradient field junctions. In‐house software accomplished optimization of discrete spot weights for the thoracic‐level field, which was then imported into the Varian Eclipse clinical treatment planning system for dose calculation. Planning was guided using clinical targets defined for craniospinal irradiation with passively scattered proton beams. Robustness analysis was performed by varying the position of each beam isocenter +/−3 mm along each cardinal axis, simulating setup errors, as well as adjusting the CT number to relative stopping power curve to mimic +/−3.5% range variation, and then analyzing the resulting dose distribution. Dose profiles along the craniospinal axis were used to evaluate intrafraction dose variation at field junctions. Dose volume histograms (DVH) were generated for each robustness element, and then combined to create composite DVH illustrating a range of possible delivered dose. Results: Results of robustness analysis indicate that field isocenter shifts along the craniospinal axis can Result in dose intrafraction variations at the junction in excess of 25% for passive scattering proton plans. This value is markedly reduced for the same shifts applied to DSS plans using a tapered‐dose field matching technique. Conclusion: This work demonstrates the potential for improved robustness of proton craniospinal irradiations using a DSS delivery method, as well as significant decreases in clinic expenses. The use of apertures to define the sagittal plane field edge for DSS delivery improves the dose to target.
SU‐E‐T‐694: Correlation Between Geometric Information and Dose Fractionation in Lung SBRT Treatment Plans
Authors: Coroller T , Lewis J , Mak R , Chen A , Hacker F , Kozono D , Mannarino E , Molodowitch C , Killoran J
Published: July 2013

Purpose: Previously, a database‐driven decision support tool to assist clinical staff in assessing and improving lung SBRT treatment plans was developed. Using planning data collected by this software, we determined a simple metric that can be used for early identification of cases for which it will be particularly difficult to achieve desired dosimetric goals. Early detection of these cases will be of clinical value. Methods: This retrospective IRB‐approved study utilizes an existing database of treatment planning data for 121 lung SBRT patients. Patients who had multiple SBRT treatments or more than one lung tumor were excluded. In our department, SBRT patients receive treatment in either 3 fractions of 18Gy or 5 fractions of 10‐12Gy. Five fractions are generally used for cases in which planning goals are difficult to achieve in terms of target coverage vs. dose to OAR. Using the specific fractionation as a surrogate for plan difficulty, we examined possible correlations between fractionation and parameters including target size, total prescribed dose, number of fields and distance to OAR. Results: 84 patients received 3 fractions of treatment and 37 received 5 fractions. Patients with PTVs greater than 70 cm3 in size and ITVs greater than 40 cm3 were always treated with 5 fractions. These patients constituted approximately 20% of the 5 fraction patients. Tumors smaller than this size were sometimes (e.g. when situated close to an OAR) treated with 5 fractions. No correlation was observed between the fractionation and the number of fields. Conclusion: With large volume targets we can predict a treatment of 5 fractions. However, this represents a minority of patients. More powerful predictions could be possible by combining target size information with other metrics such as distance to nearby OARs. The ability to predict fractionation early in planning would allow for more efficient scheduling of LINAC time. Kaye Scholar Grant
SU‐E‐T‐695: Treatment Planning Optimization for Pulsed Low‐Dose‐Rate IMRT of Lung and Head and Neck Cancer
Authors: Kang S , Lang J , Wang P , Li J , Lin M , Chen X , Guo M , Chen F , Ma C
Published: July 2013

Purpose: Pulsed low dose rate radiotherapy has been used for treatment of recurrent cancer in some institutions. In this work, we use a commercial treatment planning system to generate a 10‐beam IMRT plan for PLDR treatment of lung and head and neck recurrent cancers. Methods: Ten head & neck cases and ten lung cases were investigated. The total dose per fraction was 200cGy, the individual gantry angles were delivered in 3min time intervals, which resulted in an effective dose rate of 6.67cGy/min. The maximum target dose from any particular gantry angle/port must be kept under 40cGy. The Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA) was used to generate all the IMRT and 3D conformal plans for PLDR treatments. Results: The maximum PTV dose per gantry angle/port for the 10 lung cases ranged from 21.7cGy to 38.7cGy, all of which met the PLDR criterion of Dmax < 40cGy. The maximum PTV dose per gantry angle ranged from 21.3 to 38.5cGy for the 10 head and neck cases, all of which met the requirement of the maximum dose limit of less than 40cGy. For all cases investigated, the IMRT plans were much better than 3D conformal plans in terms of target dose conformity and normal tissue sparing especially for cases with complex relationships between the target and critical structures for PLDR treatment. Conclusion: Manually optimized 10 gantry‐angle IMRT plans generated using existing commercially available treatment planning systems can be applied to PLDR treatments of lung and head and neck cancer. Besides dual‐arc intensity modulated radiotherapy, IMRT can be a viable option for PLDR treatment of complex lung and head and neck recurrent cancers.
SU‐F‐500‐09: Molecular Breast Imaging Using Emission Tomosynthesis
Authors: Gopan O , Gilland D , Weisenberger A , Kross B , Welch B
Published: July 2013

Purpose: Tour objective is to design a novel SPECT system for molecular breast imaging (MBI) and evaluate its performance. The limited angle SPECT system, or emission tomosynthesis, is designed to achieve 3D images of the breast with high spatial resolution/sensitivity. The system uses a simplified detector motion and is conducive to on‐board biopsy and multi‐modal imaging with mammography. Methods: The novel feature of the proposed gamma camera is a variable‐angle, slant‐hole (VASH) collimator, which is well suited for limited angle SPECT of a mildly compressed breast. The collimator holes change slant angle while the camera surface remains flush against the compression paddle. This allows the camera to vary the angular view (±30°, ±45°) for tomographic imaging while keeping the camera close to the object for high spatial resolution and/or sensitivity. Theoretical analysis and Monte Carlo simulations were performed assuming a point source and isolated breast phantom. Spatial resolution, sensitivity, contrast and SNR were measured. Results were compared to single‐view, planar images and conventional SPECT. For both conventional SPECT and VASH, data were reconstructed using iterative algorithms. Finally, a proof‐of‐concept VASH collimator was constructed for experimental evaluation. Results: Measured spatial resolution/sensitivity with VASH showed good agreement with theory including depth‐of‐interaction (DOI) effects. The DOI effect diminished the depth resolution by approximately 2 mm. Increasing the slant angle range from ±30° to ±45° resulted in an approximately 1 mm improvement in the depth resolution. In the breast phantom images, VASH showed improved contrast and SNR over conventional SPECT and improved contrast over planar scintimmammography. Reconstructed images from the proof‐of‐concept VASH collimator demonstrated reasonable depth resolution capabilities using limited angle projection data. Conclusion: We conclude that this limited angle SPECT approach using a VASH collimator can achieve superior 3D image quality for MBI in a design that has attractive characteristics for clinical imaging.
MO‐A‐137‐01: BEST IN PHYSICS (THERAPY) ‐ Predictive DVH Models Developed at a Large Institution Impact Clinically Relevant DVH Parameters in IMRT Plans at An Unrelated Radiotherapy Facility
Authors: Appenzoller L , Klaers J , Tan J , Yang D , Mutic S , Moore K
Published: July 2013

Purpose: The purpose of this work was to investigate the impact of a predictive DVH (pDVH) model developed at one institution on IMRT plan quality control (QC) at an unrelated radiotherapy facility. Methods: DICOM‐RT datasets for twenty randomly selected intact prostate cancer patients treated at a small clinic were analyzed with knowledge based pDVH models developed at a larger institution. Previously validated rectum and bladder pDVH models used in this study were derived based on the correlation of expected dose to the distance from a voxel to the PTV surface. A sum of residuals (SR) metric quantifying the integrated difference between clinical DVHs and the pDVHs was used to rank the 20 evaluated plans. The 5 plans with greatest deviation from the prediction were replanned by the small clinic to evaluate the ability to achieve rectum and bladder DVH predictions while maintaining PTV quality metrics per institutional standard. Metrics used to evaluate plan quality (V65 and V40) quantified the clinical gains in the rectum and bladder DVHs. The pDVHs were compared to the replan DVHs using dV65=V65(replan)‐V65(pred), dV40=V40(replan) ‐ V40(pred), and mean SR to measure DVH prediction accuracy. Results: The significance of IMRT QC using pDVHs was demonstrated by an average reduction in V65 and V40 in the 5 replanned patients of 4.8% ± 2.3% and 17.9% ± 10.3% for the rectum and 3.4% ± 2.1% and 6.0% ± 2.8% for the bladder, respectively. The pDVH models demonstrated excellent prediction accuracy with an average dV65 and dV40 of 0.9% ± 1.1% and 0.7% ± 1.4% for the rectum and 0.4% ± 0.5% and 0.6% ± 0.9% for the bladder, respectively. Conclusion: DICOM‐based pDVH modeling methods based on patient geometry accurately predict achievable rectum and bladder DVH parameters that are clinically relevant and may facilitate improved IMRT plan quality across multiple institutions. L.Appenzoller, S. Mutic, K. Moore: Patent Application # 13, 486,809 : Developing Predictive Dose‐Volume Relationships for a Radiotherapy Treatment.
MO‐A‐137‐10: Evaluation of A GPU‐Based In‐House Automatic Re‐Planning System for Adaptive Radiotherapy Re‐Planning for Head and Neck Cancer
Authors: Sutterley C , Gautier Q , Graves Y , Zarepisheh M , Li N , Tian Z , Jia X , Moore K , Rahn D , Murphy J , Mell L , Jiang S
Published: July 2013

Purpose: To evaluate the feasibility and quality of adaptive radiation therapy (ART) re‐planning for head‐and‐neck (H/N) cancer using SCORE, an in‐house graphics processing unit (GPU)‐based automatic re‐planning system. Methods: Our in‐house automatic re‐planning system SCORE utilizes GPU computational efficiency to register CT images, deform contours, and re‐optimize treatment plans. We used SCORE to generate two re‐plans for ten previously‐treated bilateral H/N patients who were re‐planned during the course of their IMRT treatment. The first plan (AUTOCONTOUR&AUTOPLAN) employed the full automatic replanning procedure while the second plan (AUTOPLAN) used the approved manually re‐contoured structures from the clinically treated re‐plan for SCORE optimization. To evaluate SCORE performance in terms of plan quality, both with and without human intervention in the contouring process, we compared the two SCORE plans to the clinically‐delivered plan. Results: We compared dose volume histograms along with max/mean organ dose for each plan to the clinically treated re‐plan. For AUTOCONTOUR&AUTOPLAN, we cast the manually re‐contoured structures over the dose distribution to be able to compare dose on the same contours. Averaging over 10 patients, AUTOPLAN&AUTOCONTOUR reduced max brainstem, max cord, mean left parotid, and mean right parotid relative dose by 17.2(SD:12.4)%, 3.5(SD:6.3)%, 9.1(SD:6.5)%, and 9.6(SD:6.4)%, respectively, but also decreased high dose PTV coverage with a relative dose difference of ‐ 10.3(SD:3.83)% at 99% of the volume. AUTOPLAN reduced max brainstem, max cord, mean left parotid, and mean right parotid relative dose by 22.7(SD:9.2)%, 10.8(SD:7.8)%, 9.1(SD:8.0)%, and 5.5(SD:5.8)%, respectively, while the high‐dose PTV at 99% of volume increased by 0.1(SD:1.6)% and volume greater than 110% of the dose increased by 5.7(SD:6.5)%. Conclusion: We found the automated AUTOCONTOUR&AUTOPLAN demonstrated organ sparing improvements, but decreased PTV coverage. The partially automated AUTOPLAN showed significant dosimetric improvements in terms of both organ sparing and PTV coverage but yielded plans that may be considered clinically hot.
MO‐A‐144‐01: High‐Intensity Focused Ultrasound Therapy Hands‐on Workshop
Authors: Sammet S
Published: July 2013

High‐intensity focused ultrasound (HIFU) therapy is a therapeutic modality that uses ultrasound waves as carriers of energy. HIFU is used to focus a beam of ultrasound energy into a small volume at specific target locations within the body. The focused beam causes localized high temperatures and produces a well‐defined regions of necrosis. This completely non‐invasive technology has great potential for tumor ablation and targeted drug delivery. The goal of this ultrasound therapy workshop is to demonstrate advancements in high intensity focused ultrasound. The workshop will offer lectures reviewing ultrasound physics and safety, current ultrasound technology, and an overview of the state‐of‐the art in ultrasound treatment. Furthermore, we will allow the attendees to see configurations, applications, and hands‐on demonstrations with on‐site instructors at separate stations. Target audience: Medical physicists and other medical professionals in diagnostic imaging or radiation oncology with interest in high‐intensity focused ultrasound.

Learning Objectives:

1. High‐intensity focused ultrasound as a therapeutic modality

2. Review of ultrasound physics and safety for HIFU applications

3. Introduction to current ultrasound technology and equipment

4. Overview of the state‐of‐the art in ultrasound treatment

• NCI funded Cancer Education and Career Development program (R25), Nanotechnology in Imaging and Radiotherapy

• Cancer Research Foundation Young Investigator Award

• Philips Healthcare Research Grant
MO‐D‐108‐10: 3D Reconstruction of Scintillation Light Emission From Mono‐Energetic Proton Beams Using a Limited Projection Approach: A Simulation Study
Authors: Hui C , Robertson D , Beddar S
Published: July 2013

Purpose: Large‐volume scintillator detectors show promise for fast, highresolution measurements of proton treatment fields, but previous work has been limited to observing 2D projections of the 3D scintillation light distribution. The purpose of this work is to develop a 3D reconstruction method for a scintillation dosimetry system consisting of a tank of liquid scintillator imaged by CCD cameras. Methods: To reconstruct the scintillation light produced by proton beams in 3D, we applied the maximum‐a‐posteriori (MAP) algorithm using projections from three views (2 orthogonal side projections and 1 forward projection). However, the small number of viewing angles in our system limits the efficiency of this approach. In this study, we exploited the axial symmetry of proton beams to create an improved initial estimation of the light distribution. Monte Carlo calculations were performed to simulate the light emission from a volume of liquid scintillator irradiated with proton pencil beams. Projection images of the light emission were calculated from the simulated data with known camera and scintillator artifacts. We compared the MAP reconstructed emissions obtained using a standard backprojection initial estimate with those using our proposed profile‐based initial estimation. Results: From our simulations, the root mean square (RMS) error of the MAP reconstruction was 5.6% using the backprojection estimate. It was reduced to 4.9% using the profile‐based estimate. In addition, our new approach also reduced visual artifacts in the low dose region. Using the profile‐based estimate, reconstruction converged at about 6 iterations. Using the backprojection estimate, 14 iterations were required for convergence. Conclusion: The proposed method allows more accurate 3D reconstruction with fewer artifacts and requiring fewer iterations. The application is useful in proton beam calibration and has the potential to make 3D quality assurance possible for intensity modulated proton therapy.
MO‐D‐141‐04: Brown Adipose Tissue Uptake Comparison Between Pharmacological and Environmental Control in a Pediatric PET Facility
Authors: Brady S , Davis W , Holman T , Minderman S , Davis L , Shulkin B
Published: July 2013

Purpose: Compare analgesic pharmacology vs. environmental means for controlling FDG uptake in brown adipose tissue (BAT) in a pediatric population with neoplasms. Methods: For two years (2009–2011) patients were sorted into two groups. (1) patients that required relaxation (Versed) or general anesthesia (Propofol); group one received ∼1 hour for uptake in a temperature controlled room before drug administration/scanning. (2) patients were warmed in a temperature controlled room for ∼1 hour prior to FDG injection and for ∼1 hour after injection. Patient images were evaluated for the presence of BAT: (0) no BAT uptake, (1) Less than uptake in the liver, (2) equal to uptake in the liver, and (3) greater than uptake in the liver. BAT uptake was investigated in the: neck (left and right), axilla (left and right), diaphragm, mediastinum, posterior thorax, and abdomen/pelvis. BAT uptake was considered in a patient with at least one anatomical region with a score > 0. Point biserial correlation, assuming dichotomous data, was calculated to determine statistical significance using a one‐sided t‐test. Results: Room temperatures for 623 patients were collected. Mean room temperature over the two years was 74.5° ± 1.3°. A total of 361 patients received sedation/anesthesia drugs. 129 patients were randomly selected; 114 patients (88%) had no BAT uptake and 15 (12%) demonstrated uptake. For group two, 143 patients were randomly selected from the 623. Room temperature for patients with BAT uptake (41%) was 74.4° ± 1.4°, and without BAT uptake (59%) was 75.0° ± 1.1°; a statistically significant difference (t‐value was 1.9, critical number was 1.7). Conclusion: A statistically significant improvement in BAT uptake was found for patients held for one hour in rooms with mean temperatures of 75° prior to FDG injection. BAT was not fully controlled using environmental controls as compared to patients that received analgesic pharmacology.
MO‐D‐141‐06: Multiscale PET/Cerenkov Image‐Guided Surgery: Demonstration in An Invasive Mouse Tumor Model
Authors: Carpenter CM , Sun C , Pratx G , Xing L
Published: July 2013

Purpose: Real‐time biological imaging is being investigated to delineate positive tumor margins which during oncological surgery. We investigated the ability of Cerenkov optical emission from Fluorodeoxyglucose (FDG) to resect neoplastic tissue, as guided by Positron Emission Tomography (PET). This technique was demonstrated in a TRAMP mouse model, where prostate cancer that had invaded beyond the capsule of the prostate was identified intra‐operatively. Methods: Studies were performed in vivo in a tumor mouse model. PET imaging was performed with a Siemens Inveon scanner; Cerenkov images were collected with a commercial optical imaging system (Perkin‐Elmer). A transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model was used to investigate the feasibility of imaging local invasion of the cancer beyond the prostate capsule. Four mice with ∼1cm prostate tumors with questionable invasion as determined by T2‐W MRI were injected with ∼1 mCi of FDG. The injection was followed by PET/CT after 75 minutes, and subsequent sacrifice; surgery commenced immediately after. PET/CT was used to identify tissues pre‐operatively. Resected tissues were analyzed with histology to identify tissues that contained tumor cells for correlation to Cerenkov imaging. Results: All four TRAMP mice exhibited extensive tumor invasion in the prostate with subsequent invasion into the seminal vesicles. No tumor tissue was identified in the other tissues, as confirmed by pathology. Cerenkov imaging was able to significantly differentiate between tissues involved with tumor and those with no tumor (P<0.01). Conclusion: The multiscale strategy, where PET helped to guide surgical resection of Cerenkov‐enhancing tissues, proved to significantly delineate tumor from non‐tumor tissue. This study demonstrates a potentially powerful technique to surgical resection of tumors. We acknowledge the NCI R01 CA128908, NIH ICMIC P50CA114747, DOD Breast Cancer Fellowship W81XWH‐10‐1‐0506, and the Center for Biomedical Imaging at Stanford (CBIS).
MO‐D‐141‐08: Multi‐Scale Analysis of Collagen Architecture for Classifying Tumor and Healthy Breast Tissue Images
Authors: Bredfeldt J , Liu Y , Wilke L , Keely P , Mackie T , Eliceiri K
Published: July 2013

Purpose: To quantify differences in collagen microarchitecture between healthy human breast tissue and breast cancer images using extended field of view second harmonic generation (EFOV SHG) microscopy coupled with analysis by the curvelet transform. Methods: Two frozen samples of normal associated human breast tissue (NAT) and invasive ductal carcinoma (IDC) were obtained through the University of Wisconsin BioBank. Samples were thawed, fixed, embedded in agar, cut into 300 micron thick sections using a vibratome and imaged using a custom inverted SHG microscope designed to allow for EFOV imaging. Individual SHG Images were captured at 0.79 micron resolution and a FOV of approximately 200 microns. The FOV was extended by stage scanning and image stitching to produce submicron resolution fields of view up to 2 cm2. NAT and IDC tissues were imaged, stitched using the Grid/Collection Stitching ImageJ plugin, and analyzed using features derived from the curvelet transform including variance in orientation and prevalence at various scales. These novel features were tested using support vector machine (SVM) cross validation. Results: IDC tissue contained linearly aligned, crisscrossing collagen while NAT tissue contained wavy, dense collagen. The mean curvelet alignment value for the normal images was approximately 2X higher than that for IDC. In addition, normal images had approximately 20% fewer closely correlated curvelets compared to IDC. Three‐fold cross validation of a linear SVM classifier revealed average sensitivity and specificity of 0.994 and 0.969 respectively. Conclusion: These results demonstrate the excellent potential for collagen architecture quantification based on features derived from the curvelet transform. We have also shown the value of EFOV SHG imaging to capture both large and small scale features necessary for quantifying collagen morphology. Future work will improve EFOV SHG imaging throughput and test classification capabilities of the curvelet based feature set on a large sample population. NIH R01 grants CA114462 and CA136590 to P.J.K. and K.W.E., T32 CA009206 to J.S.B and the Morgridge Institute for Research
MO‐D‐141‐09: An Investigation of the Feasibility of Volumetric Imaging of Fluorescent Bio‐Markers Using Optical‐ECT
Authors: Oldham M , Thomas A , Dewhirst M
Published: July 2013

Purpose: Toptical‐ECT is a technique with potential for high resolution 3D imaging of the distribution of fluoresent biomarkers (including reporter proteins like GFP) in un‐sectioned tissue samples. Accurate optical‐ECT data is only feasible if the biomarkers survive an optical clearing procedure. This work presents investigates this question, and the feasibility of extracting volume metrics from optical‐ECT data. Methods: 4T1 tumors were grown in window chambers on nude mice, following an approved protocol. Tumor cells constitutively expressed RFP, and endogenously expressed GFP labeling HIF‐1 transcription. Microvasculature was labeled by colloidal carbon. When the tumors were ∼5–7mm, they were imaged in‐vivo (in the chamber) using conventional epi‐fluorescent microspcopy. Tumors were then immediately removed, optically‐cleared, and imaged ex‐vivo by optical‐CT/ECT. Comparison of the in‐vivo and ex‐vivo images enabled investigation of the stability of the biomarkers through optical clearing. Volume measurements of regions expressing different markers (GFP and RFP) were generated though automatic thresholding. Results: Biomarker expressing regions (GFP and RFP) were generally consistent between comparable optical‐ECT projections and in‐vivo microscopy. In some tumors, GFP and RFP expression was observed to be partially obscured in in‐vivo images, due to absorption in overlying tissue. In optical‐ECT views, these regions became visible, due to optical clearing. In one tumor, 31% of the gross tumor was deemed viable, as determined from RFP expression. 13% of the tumor was hypoxic as inferred from HIF‐1 expression. Almost all the GFP hypoxic volume was within the viable RFP tumor volume. Conclusion: Our preliminary data supports several key concepts: fluorescent biomarkers can survive the optical clearing process representative of in‐vivo condition; the cleared tumor revealed new regions of signal that were partially obscured in in‐vivo images; and 3D quantitative metrics can be determined from optical‐CT/ECT that correspond to their 2D counterparts in standard microscopy (e.g. sub‐volume of HIF‐1 expression).
MO‐D‐141‐10: Development of 4D XCAT Pediatric Reference Phantoms for Multi‐Modality Imaging Research and Optimization
Authors: Norris H , Bond J , Zhang Y , Sturgeon G , Tward D , Ratnanather T , Miller M , Samei E , Segars P
Published: July 2013

Purpose: A set of 4D Extended Cardiac‐Torso (XCAT) pediatric reference phantoms were created for multimodality imaging research, which have highly detailed whole‐body anatomies, including cardiac and respiratory functions. Models were created for newborn, 1‐year, 5‐year, 10‐year, and 15‐year old males and females capturing the anatomical variations of childhood development. Methods: The initial anatomy of each phantom was obtained from the Duke University PET‐CT database. The major organs and structures for each phantom were segmented from the corresponding data using semiautomatic and manual segmentation. 3D Non‐Uniform Rational B‐Spline (NURBS) surfaces were fitted to the segmented data. Arms and legs were manually attached using scaled versions of the original XCAT adult male and female phantoms. Some patient datasets had incomplete skulls; skullcaps were manually matched to complete the skulls of these datasets. A multichannel large deformation diffeomorphic metric mapping (MC‐LDDMM) algorithm was used to calculate the transform from a template XCAT phantom to the target patient model, which filled in unsegmented structures within the target phantom and implemented the 4D cardiac and respiratory models in the new anatomy. Organ weights were matched to the 50th percentile ICRP publication 89 values within 5%. Results: A reference set of 10 pediatric phantoms were created with thousands of anatomical structures and cardiac and respiratory motions. These phantoms can be combined with existing simulation packages to simulate realistic imaging data. The phantoms provide a valuable tool to investigate radiation dose and image quality optimization. Conclusion: The development of patient‐derived pediatric computational phantoms is useful in providing variable anatomies for simulation. Future work will expand this 10‐phantom base to a host of pediatric phantoms representative of the public at large. This can provide a means to evaluate and improve pediatric imaging devices and to optimize CT protocols in terms of image quality and radiation dose.
MO‐D‐141‐11: Registration of Breast Magnetic Resonance Imaging and X‐Ray Mammography Through a Biomechanical Model Based On Clinical Data and a Finite Element Method
Authors: Ribes S , Gonneau E , Didierlaurent D , Decoster N , Feillel V , Courbon F , Caselles O
Published: July 2013

Purpose: Overcoming the drawbacks of x‐ray mammography and magnetic resonance imaging (MRI) by fusing the information in order to assist clinicians in the task of early detection of breast cancer. Methods: A detailed 3D computer‐generated breast phantom based on empirical data extracted from breast MRI was constructed for each patient. To achieve this goal, MRI data were classified into the different components of breast tissues (glandular, adipose, skin and eventually tumor) using a semi‐automated segmentation algorithm based on voxel intensity. Then, a geometrical model of the breast was constructed through the isosurfaces of this segmented volume. In order to perform a study on breast deformation using the finite element method, the geometrical model was automatically meshed into tetrahedral elements and material properties were assigned to the different kinds of breast tissues. To represent the large deformation of breast during a mammography exam, a neo‐Hookean hyperelastic model was chosen to describe the constitutive relations of breast tissues, and the compression was simulated using a stiff plate model. After compressing the phantom, mammograms were simulated based on the deformed configuration. During this step, a parametric optimization of the model was conducted (mesh refinement, mechanical properties and friction coefficient). Results: Small variations of the model parameters strongly influence the deformation and modify significantly the resultant simulated images. During the optimization process, both a better conservation of details and a convergence toward a distribution of components were observed for finer meshes, whereas the friction coefficient affects mostly the skin deformation. Conclusion: The phantom developed in this study allows the modeling of large deformations through the use of the finite element method, and also allows the simulation of mammographic images containing high‐resolution details. Moreover, this phantom combines flexibility and realism, and can be used for multimodality imaging research but also for clinical performance optimization.
MO‐D‐134‐02: Estimating Organ Dose From CT Scans Performed with Tube Current Modulated Scans
Authors: Khatonabadi M , Chu G , Oria D , Cagnon C , DeMarco J , McNitt‐Gray M
Published: July 2013

Purpose: To develop and evaluate a method for estimating organ dose from CT scans performed with tube current modulation (TCM) using a size metric that accounts for patient attenuation as well as a regional descriptor of scanner output. Methods: 100 chest and 81 abdomen/pelvis patient scans acquired using TCM on a Multidetector row CT scanner (CareDose 4D, Sensation 64, Siemens Healthcare) were collected under IRB approval to generate voxelized patient models. The TCM information was extracted from the raw projection data for use in Monte Carlo (MC) simulations which accounted for both scanner and patient details. For each patient, water equivalent diameter (WED) was used as the size metric to account for patient attenuation. WED was calculated on each image based on semiautomatic segmentation. A regional CTDIvol value was used as a normalization quantity to account for local variations in scanner output. MC simulations were used to estimate dose to lungs and glandular breast tissue in the chest models, and liver, spleen, and kidneys in the abdomen/pelvis models. Half of the models in each exam category were used as a training set to develop the organ dose estimation model based on WED and CTDIvol,regional; the remaining cases were used as a test set. Organ doses were estimated using each model and were compared to the detailed MC simulation results and an RMSE across cases was calculated. Results: For chest exams, the RMSE between the model and detailed MC simulations was 14.9% for lung and 13.6% for breast. For abdomen/pelvis exams, the RMSE was 15.0% for kidney, 9.2% for liver and 12.2% for spleen. Conclusion: This method to estimate organ dose from CT scans using TCM demonstrated agreement of within 33% between the model and detailed MC simulations and shows promise for estimating organ doses when TCM is used. Dr. Michael McNitt‐Gray: Institutional research agreement, Siemens AG Recipient research support Siemens AG Consultant, Flaherty Sensabaugh Bonasso PLLC Consultant, Fulbright and Jaworski, LLC Maryam Khatonabadi: Recipient research support Siemens AG
MO‐D‐134‐03: Quantification of Breast Dose From Thoracic Computed Tomography Examinations with Dose Reduction Methods
Authors: Mench A , Sinclair L , Griglock T , Cormack B , Bidari S , Arreola M
Published: July 2013

Purpose: To quantify the breast dose delivered to female patients undergoing routine thoracic Computed Tomography (CT) exams and assess the dose savings provided by the use of bismuth shielding as well as iterative image reconstruction algorithms. Methods: Breast shields have been used at the University of Florida for three years with unanimous agreement by radiologists in terms of acceptable image quality and nonexistent artifacts. To assess the dose savings provided by both bismuth shields and adaptive iterative reconstruction algorithms (AIDR 3D), breast doses were directly measured on cadaveric subjects using optically‐stimulated luminescent dosimeters (OSLDs) implanted via tubes into the subjects. The cadavers were scanned with the clinically standardized Chest protocol on a Toshiba Aquilion One 320‐slice CT scanner. Next, they were scanned again, with all other parameters unchanged, using the bismuth shield and finally using the AIDR 3D algorithm. Average breast doses were measured for four female cadaveric subjects of various Body Mass Indices (BMIs). Breast doses were measured with the bismuth shield in place for two cadavers, while the AIDR 3D algorithm was investigated using the second pair of subjects. Tube current modulation was activated for all scans. Results: Average breast doses for all four cadaver subjects ranged from 7 to 24 mGy. Dose savings offered by the bismuth breast shield were 27% for the smaller cadaver and 18% for the larger cadaver. The set of subjects scanned with AIDR 3D turned on received an average breast dose savings of 26% and 21%, for the lower and higher BMI subjects, respectively. Conclusion: This research reveals that both bismuth shielding and iterative reconstruction algorithms are effective methods of reducing radiation dose to highly radiosensitive breast tissue. Neither of these methods has impacted clinical image quality negatively. Employing dose savings methods, however trivial or complex, benefits patients tremendously.