bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐G‐201‐01: What Therapy Physicists Need to Know About CT and PET/CT: Terminology and Latest Developments
Authors: Hua C. 
Published: June 2015

This session will update therapeutic physicists on technological advancements and radiation oncology features of commercial CT, MRI, and PET/CT imaging systems. Also described are physicists’ roles in every stage of equipment selection, purchasing, and operation, including defining specifications, evaluating vendors, making recommendations, and optimal and safe use of imaging equipment in radiation oncology environment.The first presentation defines important terminology of CT and PET/CT followed by a review of latest innovations, such as metal artifact reduction, statistical iterative reconstruction, radiation dose management, tissue classification by dual energy CT and spectral CT, improvement in spatial resolution and sensitivity in PET, and potentials of PET/MR. We will also discuss important technical specifications and items in CT and PET/CT purchasing quotes and their impacts.The second presentation will focus on key components in the request for proposal for a MRI simulator and how to evaluate vendor proposals. MRI safety issues in radiation Oncology, including MRI scanner Zones (4‐zone design), will be discussed. Basic MR terminologies, important functionalities, and advanced features, which are relevant to radiation therapy, will be discussed.In the third presentation, justification of imaging systems for radiation oncology, considerations in room design and construction in a RO department, shared use with diagnostic radiology, staffing needs and training, clinical/research use cases and implementation, will be discussed. The emphasis will be on understanding and bridging the differences between diagnostic and radiation oncology installations, building consensus amongst stakeholders for purchase and use, and integrating imaging technologies into the radiation oncology environment.Learning Objectives:

Learn the latest innovations of major imaging systems relevant to radiation therapy
Be able to describe important technical specifications of CT, MRI, and PET/CT
Understand the process of budget request, equipment justification, comparisons of technical specifications, site visits, vendor selection, and contract development
TU‐G‐210‐00: Treatment Planning Strategies, Modeling, Control
Authors: Christensen Douglas 
Published: June 2015

Modeling can play a vital role in predicting, optimizing and analyzing the results of therapeutic ultrasound treatments. Simulating the propagating acoustic beam in various targeted regions of the body allows for the prediction of the resulting power deposition and temperature profiles. In this session we will apply various modeling approaches to breast, abdominal organ and brain treatments. Of particular interest is the effectiveness of procedures for correcting for phase aberrations caused by intervening irregular tissues, such as the skull in transcranial applications or inhomogeneous breast tissues. Also described are methods to compensate for motion in targeted abdominal organs such as the liver or kidney.Douglas Christensen – Modeling for Breast and Brain HIFU Treatment PlanningTobias Preusser – TRANS‐FUSIMO – An Integrative Approach to Model‐Based Treatment Planning of Liver FUSTobias Preusser – TRANS‐FUSIMO – An Integrative Approach to Model‐Based Treatment Planning of Liver FUSLearning Objectives:

Understand the role of acoustic beam modeling for predicting the effectiveness of therapeutic ultrasound treatments.
Apply acoustic modeling to specific breast, liver, kidney and transcranial anatomies.
Determine how to obtain appropriate acoustic modeling parameters from clinical images.
Understand the separate role of absorption and scattering in energy delivery to tissues.
See how organ motion can be compensated for in ultrasound therapies.
Compare simulated data with clinical temperature measurements in transcranial applications.
Supported by NIH R01 HL172787 and R01 EB013433 (DC); EU Seventh Framework Programme (FP7/2007‐2013) under 270186 (FUSIMO) and 611889 (TRANS‐FUSIMO)(TP); and P01 CA159992, GE, FUSF and InSightec (UV).
TU‐G‐210‐01: Modeling for Breast and Brain HIFU Treatment Planning
Authors: Christensen D. 
Published: June 2015

Modeling can play a vital role in predicting, optimizing and analyzing the results of therapeutic ultrasound treatments. Simulating the propagating acoustic beam in various targeted regions of the body allows for the prediction of the resulting power deposition and temperature profiles. In this session we will apply various modeling approaches to breast, abdominal organ and brain treatments. Of particular interest is the effectiveness of procedures for correcting for phase aberrations caused by intervening irregular tissues, such as the skull in transcranial applications or inhomogeneous breast tissues. Also described are methods to compensate for motion in targeted abdominal organs such as the liver or kidney.Douglas Christensen – Modeling for Breast and Brain HIFU Treatment PlanningTobias Preusser – TRANS‐FUSIMO – An Integrative Approach to Model‐Based Treatment Planning of Liver FUSTobias Preusser – TRANS‐FUSIMO – An Integrative Approach to Model‐Based Treatment Planning of Liver FUSLearning Objectives:

Understand the role of acoustic beam modeling for predicting the effectiveness of therapeutic ultrasound treatments.
Apply acoustic modeling to specific breast, liver, kidney and transcranial anatomies.
Determine how to obtain appropriate acoustic modeling parameters from clinical images.
Understand the separate role of absorption and scattering in energy delivery to tissues.
See how organ motion can be compensated for in ultrasound therapies.
Compare simulated data with clinical temperature measurements in transcranial applications.
Supported by NIH R01 HL172787 and R01 EB013433 (DC); EU Seventh Framework Programme (FP7/2007‐2013) under 270186 (FUSIMO) and 611889 (TRANS‐FUSIMO)(TP); and P01 CA159992, GE, FUSF and InSightec (UV).
TU‐F‐CAMPUS‐T‐02: Risk Assessment of Scattered Neutrons for a Fetus From Proton Therapy of a Brain Tumor During Pregnancy
Authors: Geng C , Moteabbed M , Xu X , Paganetti H 
Published: June 2015

Purpose:To determine the scattered neutron dose and the resulting risk for a fetus from proton therapy for brain tumors during pregnancy.Methods:Using the Monte Carlo platform TOPAS, the ICRP reference parameters based anthropomorphic pregnancy phantoms for three stages (3‐, 6‐, 9‐month) were applied to evaluate the scattered neutron dose and dose equivalent. To calculate the dose equivalent, organ specific linear energy transfer (LET) based quality factor was used. Treatment plans from both passive scattering (PS) and pencil beam scanning (PBS) methods were considered in this study.Results:For pencil beam scanning, the neutron dose equivalent in the soft tissue of the fetus increases from 1.53x10−3 to 2.84x10−3 mSv per treatment Gy with increasing stage of gestation. This is due to scattered neutrons from the patient as the main contaminant source in PBS and a decrease in distance between the soft tissue of the fetus and GTV with increasing stage of gestation. For passive scattering, neutron dose equivalent to the soft tissue of the fetus shows a decrease from 0.17 to 0.13 mSv per treatment Gy in different stages, while the dose to the brain shows little difference around 0.18 mSv per treatment Gy because scattered neutrons from the treatment head contribute predominantly in passive scattering.Conclusion:The results show that the neutron dose to the fetus assuming a prescribed dose of 52.2 Gy is negligible for PBS, and is comparable to the scattered dose (0–10 mSv) from a head and neck CT scan for PS. It can be concluded that the dose to fetus is far lower than the thresholds of malformation, SMR and lethal death. The excess relative risk of childhood cancer induction would be increased by 0.48 and 0.103 using the Oxford Survey of Childhood Cancers and Japanese atomic model, respectively.Changran Geng is supported by the Chinese Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant No. 11475087).
TU‐F‐CAMPUS‐T‐03: Commissioning of a Custom Fetal Lead Shield for Radiotherapy
Authors: Owrangi A , Roberts D , Covington E , Hayman J , Masi K , Lee C , Moran J , Prisciandaro J 
Published: June 2015

Purpose:To evaluate the peripheral dose (PD) to a fetus during radiation therapy of pregnant patients when using a newly designed fetal lead shield (FLS).Methods:A custom FLS has been designed and fabricated for our department. The FLS (1.1 TVLs for 6 MV) is mounted on a mobile frame and can be adjusted vertically with a motor actuator. PD measurements were acquired for multiple simple square fields and for a variety of potential treatment sites a pregnant patient may be treated for including brain, head and neck (H&N) and thorax. For measurements of the brain, H&N, and thorax, an ionization chamber and OSLDs were positioned on average at a distance of 48, 29 and 26 cm, respectively, from the edge of treatment fields to mimic the approximate position of the fundus.Results:Based on our measurements, applying a 90° collimator rotation and using tertiary MLCs to define the field aperture in combination with jaws resulted in an average dose reduction of 60%. When using these planning strategies in combination with the FLS, on average, the PD was reduced by additional 25% for simple square fields and 20% for clinical plans.Conclusion:The custom FLS is a safe, effective, and relatively easy system to position. Commissioning measurements have demonstrated that the PD to the fetus can be significantly reduced when using the FLS. The comprehensive dataset obviates the need for individual patient pre‐treatment dose measurements as long as the geometry falls within the commissioning limits.
TU‐F‐CAMPUS‐I‐02: Contrast Enhanced Cone Beam CT Imaging with Dual‐ Gantry Image Acquisition and Constrained Iterative Reconstruction‐a Simulation Study for Liver Imaging Application
Authors: Zhong Y , Gupta S , Lai C , Wang T , Shaw C 
Published: June 2015

Purpose:Contrast time‐density curves may help differentiate malignant tumors from normal tissues or benign tumors. Repetitive scans using conventional CT or cone beam CT techniques, which Result in unacceptably high dose, may not achieve the desired temporal resolution. In this study we describe and demonstrate a 4D imaging technique for imaging and quantifying contrast flows requiring only one or two 360° scans.Methods:A dual‐gantry system is used to simultaneously acquire two projection images at orthogonal orientations. Following the scan, each or both of the two 360° projection sets are used to reconstruct an average contrast enhanced image set which is then segmented to form a 3D contrast map. Alternatively, a pre‐injection scan may be made and used to reconstruct a pre‐injection image set which is subtracted from the post‐injection image set to form the 3D contrast map. Each of the two 360° projection sets is divided into 12 subsets, thus creating 12 pairs of 30° limited angle projection sets, each corresponding to a time spanning over 1/12 of the scanning time. Each pair of the projection sets are reconstructed as a time specific 3D image set with the maximum likelihood estimation iterative algorithm using the contrast map as the constraint. As a demonstration, a 4D abdominal phantom was constructed from clinical CT images with blood flow through the normal tissue and a tumor modeled and imaging process simulated.Results:We have successfully generated a 4D image phantom, and calculated the projection images. The time density curves derived from the reconstructed image set matched well with the flow model used to generate the phantom.Conclusion:Dual‐gantry image acquisition and constrained iterative reconstruction algorithm may help to obtain time‐density curves of contrast agents in blood flows, which may help differentiate malignant tumors from normal tissues or benign tumors.
WE‐EF‐BRA‐04: Evaluation of Dosimetric Uncertainties in Individualized Targeted Radionuclide Therapy (TRT) Treatment Planning Using Pre‐Clinical Data
Authors: Besemer A , Grudzinski J , Titz B , Bednarz J B 
Published: June 2015

Purpose:Dosimetry for targeted radionuclide therapy (TRT) is moving away from conventional model‐based methods towards patient‐specific approaches. To address this need, a Monte Carlo (MC) dosimetry platform was developed to estimate patient‐specific therapeutic 3D dose distributions based on pre‐treatment imaging. However, because a standard practice for patient‐specific internal dosimetry has not yet been established, there are many sources of dosimetric uncertainties. The goal of this work was to quantify the sensitivity of various parameters on MC dose estimations.Methods:The ‘diapeutic’ agent, CLR1404, was used as a proof‐of‐principle compound in this work. CLR1404 can be radiolabeled with either 12⁴I for PET imaging or 131I for radiotherapy or SPECT imaging. PET/CT images of 5 mice were acquired out to 240 hrs post‐injection of 12⁴I‐CLR1404. The therapeutic 131I‐CLR1404 absorbed dose (AD) distribution was calculated using a Geant4‐based MC dosimetry platform. A series of sensitivity studies were performed. The variables that were investigated included the PET/CT voxel resolution, partial volume corrections (PVC), material segmentation, inter‐observer contouring variability, and the pre‐treatment image acquisition frequency.Results:Resampling the PET/CT voxel size between 0.2–0.8 mm resulted in up to a 13% variation in the mean AD. Application of the PVC increased the mean AD by 0.5–11.2%. Less than 1% differences in ROI mean AD were observed between the tissue segmentation schemes using 4 and 27 different material compositions. Inter‐observer contouring variability led to up to a 20% CoV (stdev/mean) in the mean AD between the users. Varying the number and frequency of pre‐treatment images used resulted in changes in mean AD up to 176% compared to the case using all 12 images.Conclusion:Voxel resolution, contour segmentation, the image acquisition protocol most significantly impacted patient‐specific TRT dosimetry. Further work is needed to develop a standard protocol that optimizes accuracy and efficiency for patient‐specific internal dosimetry.BT and JG are affiliated with Cellectar Biosciences which owns the licensing rights to CLR1404 and related compounds.
WE‐EF‐BRA‐05: Experimental Design for High‐Throughput In‐Vitro RBE Measurements Using Protons, Helium and Carbon Ions
Authors: Guan F , Titt U , Patel D , Bronk L , Taleei R , Peeler C , Mirkovic D , Grosshans D , Jakel O , Mohan R 
Published: June 2015

Purpose:To design and validate experimental setups for investigation of dose and LET effects in cell kill for protons, helium and carbon ions, in high throughput and high accuracy cell experiments.Methods:Using the Geant4 Monte Carlo toolkit, we designed 3 custom range compensators to simultaneously expose cancer cells to different doses and LETs from selected portions of pristine ion beams from the entrance to points just beyond the Bragg peak. To minimize the spread of LET, we utilized mono‐energetic uniformly scanned beams at the HIT facility with support from the DKFZ. Using different entrance doses and LETs, a matrix of cell survival data was acquired leading to a specific RBE matrix. We utilized the standard clonogenic assay for H460 and H1437 lung‐cancer cell lines grown in 96‐well plates. Using these plates, the data could be acquired in a small number of exposures. The ion specific compensators were located in a horizontal beam, designed to hold two 96‐wells plates (12 columns by 8 rows) at an angle of 30o with respect to the beam direction.Results:Using about 20 hours of beam time, a total of about 11,000 wells containing cancer cells could be irradiated. The H460 and H1437 cell lines exhibited a significant dependence on LET when they were exposed to comparable doses. The results were similar for each of the investigated ion species, and indicate the need to incorporate RBE into the ion therapy planning process.Conclusion:The experimental design developed is a viable approach to rapidly acquire large amounts of accurate in‐vitro RBE data. We plan to further improve the design to achieve higher accuracy and throughput, thereby facilitating the irradiation of multiple cell types. The results are indicative of the possibility to develop a new degree of freedom (variable RBE) for future clinical ion therapy optimization.Work supported by the Sister Institute Network Fund (SINF), University of Texas MD Anderson Cancer Center.
WE‐EF‐BRA‐06: Feasibility of Spatially Modulated Proton Beams for Small Animal Research
Authors: Lee E , Meyer J 
Published: June 2015

Purpose:To investigate the feasibility of proton minibeam radiotherapy (pMBRT) for small animal research. The motivation is to explore with protons the extraordinary normal tissue sparing effects to spatially modulated beams as observed on high flux synchrotron beam lines. We hypothesized that we can design a multi‐slit collimator for our proton beam line to produce planar‐parallel dose profiles with high modulation in the entrance region and homogenous dose coverage in the overlap of the Bragg peaks.Methods:The high dose rate 50 MeV research proton beamline at the University of Washington was modeled using the TOol for PArticle Simulation (TOPAS) Monte Carlo package. A brass collimator was implemented to generate proton minibeams. The collimator consists of an array of 2 cm long slits to cover an area of 2×2 cm2. The slit widths (0.1–1 mm), center‐to‐center (ctc) distances (1–3 mm) and collimator thickness (1–7 cm) were varied to evaluate the effect on dose rate, the peak‐to‐valley dose ratios (PVDR) and the change of penumbra and peak width (FWHM) with depth.Results:The Bragg peak was at a depth of ∼21 mm. The penumbra and FWHM remained relatively constant to a depth of about 10–15 mm. The PVDR ranged from 1.6 to 26 and the dose rate dropped exponentially with collimator thickness. A uniform dose can be achieved at depth with slightly compromised PVDRs and dose rate.Conclusion:The technical realization of pMBRT is feasible. The simulations have shown that it is possible to obtain uniform dose at depth while modulation is maintained on the entrance side. While the simulated beam widths are larger than on synchrotron generated microbeams the dosimetric advantage could avoid having to interlace two microbeams to achieve uniform dose in the target. The next steps are to build a collimator and verify the simulations experimentally.
WE‐EF‐BRA‐07: High Performance Preclinical Irradiation Through Optimized Dual Focal Spot Dose Painting and Online Virtual Isocenter Radiation Field Targeting
Authors: Stewart J , Lindsay P , Jaffray D 
Published: June 2015

Purpose:Advances in radiotherapy practice facilitated by collimation systems to shape radiation fields and image guidance to target these conformal beams have motivated proposals for more complex dose patterns to improve the therapeutic ratio. Recent progress in small animal radiotherapy platforms has provided the foundation to validate the efficacy of such interventions, but robustly delivering heterogeneous dose distributions at the scale and accuracy demanded by preclinical studies remains challenging. This work proposes a dual focal spot optimization method to paint spatially heterogeneous dose regions and an online virtual isocenter targeting method to accurately target the dose distributions.Methods:Two‐dimensional dose kernels were empirically measured for the 1 mm diameter circular collimator with radiochromic film in a solid water phantom for the small and large x‐ray focal spots on the X‐RAD 225Cx microirradiator. These kernels were used in an optimization framework which determined a set of animal stage positions, beam‐on times, and focal spot settings to optimally deliver a given desired dose distribution. An online method was developed which defined a virtual treatment isocenter based on a single image projection of the collimated radiation field. The method was demonstrated by optimization of a 6 mm circular 2 Gy target adjoining a 4 mm semicircular avoidance region.Results:The dual focal spot technique improved the optimized dose distribution with the proportion of avoidance region receiving more than 0.5 Gy reduced by 40% compared to the large focal spot technique. Targeting tests performed by irradiating ball bearing targets on radiochromic film pieced revealed the online targeting method improved the three‐dimensional accuracy from 0.48 mm to 0.15 mm.Conclusion:The dual focal spot optimization and online virtual isocenter targeting framework is a robust option for delivering dose at the preclinical level and provides a new experimental option for unique radiobiological investigationsThis work is supported, in part, by the Natural Sciences and Engineering Research Council of Canada and a Mitacs‐Accelerate fellowship. P.E. Lindsay, and D.A. Jaffray are listed as inventors of the system described herein. This system has been licensed to Precision X‐Ray Inc. for commercial development.
WE‐EF‐303‐11: Activity Distributions of Positron‐Emitting‐Isotopes Activated by Modulated Spot‐Scanning Particle Beams
Authors: Hsi W , Deng Y , Sun L , Li Y , Huang Z , Sheng Y , Zhao J , Zhao F 
Published: June 2015

Purpose:To present the characteristics of positron‐emitting‐isotope (PEI) activity distributions on homogeneous and CIRS thorax phantoms irradiated by modulated spot‐scanning carbon‐ions and protons in Siemens IONTRIS system.Methods and Materials:Cylindrical homogeneous wax was irradiated by carbon‐ions and protons of 10cm uniform square field with single‐energy‐layer ranges of 7cm, 16cm and 29cm. Images of PEI distributions were acquired over a period of 30 minutes at 10 minutes after each irradiation. Optimized uniform biological‐equivalent doses of carbon‐ions over a 5.0cm spherical target was delivered to CIRS phantom. Doses with range shifts in depths from 1mm to 6mm were also calculated and delivered to evaluate the accuracy of measuring activated PEI distributions.Results:Activated PEI distribution on homogeneous phantoms showed sharper peak near distal edge with flatter distribution toward proximal depth by carbon‐ions than by protons. For depths near at Bragg‐peak, penetration‐depth spreading for energies from 10MeV/u to 60 MeV/u are from 0.4mm to 10.3mm, and 1.2mm to 30.4mm for projectile‐fragments by carbon‐ions and target‐fragments by protons, respectively. For depths proximal to Bragg‐peak, target‐fragments for both carbon‐ions and protons had minimal energy dependence in depth. For complex dose distributions delivered to CIRS thorax phantom, similar PEI peak‐like distributions were still observed for carbon‐ions. And, the changes at locations and edges of measured PEI peak were correlated within 0.5mm of shifted ranges. Mean activities over 5.0cm spherical target were similar for CISR phantom irradiated by doses with various range shifts.Conclusions:Peak‐like PEI distributions by carbon‐ions with good correlation to distal edges in both homogeneous and CIRS thorax phantoms present the potential for the in‐vivo range verification while additional efforts is needed for protons. Due to flat distributions for depths at 6mm proximal to distal edges, mean activity at target might be used for in‐vivo dose verification of target.