bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐C‐224A‐08: A Scientific Comparison of Inverse Treatment Plan Quality Using a Convex Non‐Linear Programming Model as a Function of Beam Quality and Beam Number
Authors: Fox C , Lynch B , Aleman D , Li H , Romeijn H , Dempsey J 
Published: July 2006

Purpose: Recent advances in large scale fluence map optimizations for IMRT allow the use of large beam numbers that conform to the target to generate the desired target coverage while at the same time maintaining dose to critical organs below tolerance limits. Additionally, IMRT has effectively removed the need for high energy accelerator beams due to the excellent plan quality achievable with low beam quality. We investigate the diminishing returns in plan quality with increasing beam numbers and compare IMRT treatment planning of 6MV and 60Co therapy dose models. Method and Materials: A convex non‐linear model was used to compare the plan quality, from dose volume histograms and fluence maps, for three treatment sites (H & N, CNS and prostate) for a 6MV and 60Co dose model. Plans were calculated for 5, 7, 9, 11, 17, 35 and 71 equidistant beam angles and quality assessed on target coverage (R95% > RRx) and organ sparing for each case. Results: Similar target coverage was achieved for 60Co as with 6MV and equivalent organ sparing was also observed for all three sites. Increasing the number of beams provided some improvement in organ sparing while maintaining target coverage conditions. Dose calculation times increased linearly with beam number and FMO calculations increased by up to 900% between 5 and 71 beams. Conclusion: We have demonstrated that IMRT plan quality using a 60Co dose model produces similar dose distributions to 6MV. We also show that plan quality does not show considerable improvement above 11 beams for IMRT and significant increases in the treatment planning times are observed extending the number of treatment beams to 71 beams.This work supported in part by NSF grant DMI‐0457394 and the State of Florida DOH Grant 04‐NIR03.
TU‐C‐224A‐09: Implementation and Comparison of Several Proton IMRT Algorithms
Authors: Li H , Fox C , Romeijn H , Dempsey J 
Published: July 2006

Purpose: To computationally compare the plan quality provided by 3 different intensity modulation proton therapy (IMPT) techniques: 3D modulation; 2.5D modulation; and distal edge tracking (DET) with optimization. Plan quality, problem size, and efficiency were assessed. Method and Materials: The dose calculation was based a finite sized beamlet model, which was 1×1 cm2 at isocenter. The dose from each beamlet was the superposition/convolution of infinitesimal pencil beams falling within the beamlet. Ray tracing to each voxel was performed for each beamlet to find out the radiological depth to each voxel. In the 3D modulation algorithm, a stack of Bragg peaks were placed between the maximal and minimal radiological depths of targets passed by a beamlet with 2.5 mm spacing. The fluence of each Bragg peak was modulated independently by the optimizer. The placement of the Bragg peaks in the 2.5D algorithm was similar to the 3D algorithm, but the Bragg peaks belong to a beamlet were pre‐optimized to make a spread out Bragg (SOBP) whose dose level was equal to the prescription dose of the target it passed. The weights of SOBPs were optimization variables. In the DET algorithm, the Bragg peaks were set at the distal edge of the targets. Results: The 3D algorithm could produce the best plan with least beams, but the data size was large. The DET was most efficient in dose calculation and fluence map optimization, its plan quality was fair. The advantage of the 2.5D algorithm was in its small data size and efficiency in fluency map optimization. Conclusion: An appropriate algorithm should be selected to meet the trade‐off of plan quality versus computational and delivery efficiency.This work was supported in part by Florida DOH Grant 04‐NIR03.
TU‐C‐224A‐10: A Novel Neighborhood for Local Search and Simulated Annealing Methods in Beam Orientation Optimization in IMRT
Authors: Aleman D , Romeijn H , Dempsey J 
Published: July 2006

Purpose: To select quality coplanar solutions to the beam orientation optimization (BOO) problem in intensity‐modulated radiation therapy (IMRT) treatment planning, and to demonstrate that high‐quality treatment plans can be obtained using fewer beams than typically used in equi‐spaced plans. Method and Materials: We consider the problem of obtaining quality 3‐ and 4‐beam coplanar radiation treatment plans. Two methods to obtaining these solutions are tested: the simulated annealing (SA) algorithm, which provides a global approach to the problem, and the Add/Drop heuristic, which provides a locally optimal solution. In the algorithms, a novel neighborhood is considered wherein a beam's neighborhood consists of a number of beams adjacent to the current beam plus a number of beams adjacent to the parallel‐opposed beam, which we call the “flip neighborhood”. For the SA algorithm, several methods of obtaining neighboring solutions and different cooling schedules are considered. The algorithms were tested on six head‐and‐neck cases using coplanar beams on a 5° grid. The resulting treatment plans were compared to the 5‐ and 7‐beam equi‐spaced plans typically used in practice. Results: While the 3‐beam treatment plans were poor in quality, the 4‐beam treatment plans obtained using both the SA method and the Add/Drop heuristic had comparable or improved quality to the 5‐ and 7‐beam equi‐spaced plans typically used in head‐and‐neck treatment. Conclusion: For head‐and‐neck cases, quality plans with fewer beams than standard 5–7 beam treatment plans can be obtained if BOO is applied. We also show that although the flip neighborhood increases run time for the Add/Drop heuristic (the run‐time of the simulated annealing algorithm is unchanged), it improves the FMO value for both the simulated annealing algorithm and the Add/Drop heuristic.This work supported in part by NSF DMI‐0457394 and the NSF Alliances for Graduation Education and the Professoriate and Graduate Research Fellowship programs.
TU‐E‐330D‐02: Monte Carlo Simulation to Assess Fetal Dose From MDCT Imaging Using Patient Based Voxelized Models
Authors: Angel E , Wellnitz C , Goodsitt M , DeMarco J , Cagnon C , Cody D , Stevens D , McCollough C , Primak A , McNitt‐Gray M 
Published: July 2006

Purpose: To use detailed Monte Carlo simulations to investigate fetal dose from a multidetector CT (MDCT) using voxelized models created from actual patient images including early and late term pregnancies. Method and Materials: Detailed voxelized models of anatomy were created based on image data from a cohort of pregnant patients who had previously undergone abdomen/pelvis CT scans. The gestational ages ranged from less than 5 weeks to 33.7 weeks. Three regions, corresponding to fetus, gestational sac, and uterus, were contoured on each image series by a radiologist.A MDCT model was created using details about the source spectra, filtration, collimation, and geometry. To simulate an actual scan, a helical source path was defined and particles were transported through the anatomy of the voxelized patient models; radiation dose was tallied in voxels belonging to the three regions of interest. The simulated abdomen/pelvis scan used a helical scan of 120kVp, pitch 1, and 4 × 5 mm total nominal beam collimation.Dose on a per mAs basis was separately calculated for the fetus when the fetus was distinguishable from the gestational sac and uterus in the original image. These doses were then compared to two generally accepted fetus dose estimations: the Felmlee et al method and the ImPact estimation of dose to a uterus (for fetuses < 8 weeks). Results: The radiation dose to the fetus in the models with gestational ages of <5 weeks, 6.6 weeks, 7.1 weeks, and 28.3 weeks, were 8.31 mGy/100mAs, 9.67 mGy/100mAs, 14.22 mGy/100mAs, and 11.70 mGy/100mAs, respectively. The fetus dose estimate using the Felmlee technique was 11.30 mGy/100mAs. The ImPact dose estimate to a fetus was 13.0mGy/100mAs. Conclusion: Radiation dose to the fetus was successfully estimated at different gestational ages using detailed models of actual patient and fetus morphology, scanner geometry, and acquisition protocols.
TU‐E‐330D‐05: Potential Radiation Guidance Levels for Invasive Cardiology
Authors: Balter S , Bernardi G , Cotelo E , Faulkner K , Miller DL , Nowotny R , Ortiz Lopez P , Padovani R , Ramirez A , Vano E 
Published: July 2006

Purpose: An International Atomic Energy Coordinated Research Program investigated the feasibility of providing guidance levels for fluoroscopically guided invasive cardiology procedures. Method and Materials: A sample of 6,000 cases of coronary angiography (CA), coronary angioplasty (PTCA) or combined CA and PTCA from ten laboratories in four different countries were used for the analysis. Dosimetric and patient demographic data were collected. Intercalibration of kerma area product (KAP) meters and quality control tests were periodically performed. Image quality and skin dose distributions were evaluated in a small sample of procedures. Procedure complexity was evaluated in a subset of 1,000 PTCA cases. Results: Classification into three clean categories proved difficult due to the rapid evolution of interventional cardiology and considerable variability in routine clinical practice among the centers. It may be better to categorize cases as either coronary angiography only (DX) or interventional, with a variable CA component (RX).Median values of KAP (for similar procedures) varied by a factor of three between centers. Complexity has a factor of two influence on KAP. The data suggest that a laboratory can normalize its data by complexity scaling.Dose inefficient laboratories were identified by noting that the median value of procedures exceeded the third‐quartile value for the entire pool. One laboratory exceeded the guidance level because of the use of 25 fps imaging in place of the more common 12.5 fps. Another laboratory, not under routine QA testing, had high fluoroscopic and cinefluorographic dose rates. Conclusion: Guidance levels for invasive cardiology appear to be feasible. Suggested KAP guidance levels for a facility performing procedures of moderate complexity are 50 Gycm2 for DX and 120 Gycm2 for RX. These values should identify dose inefficient laboratories. Guidance for fluoro time and cine frame count is being developed. Further research is needed as clinical procedures and technologies evolve.
TU‐E‐ValA‐01: IMRT of the Central Nervous System
Authors: Munley M , Stieber V 
Published: July 2006

Intensity modulated radiation therapy (IMRT) for the central nervous system (CNS) is being used more frequently in radiation oncology clinics. There are two general situations that the treatment of CNS disease may benefit from the use of IMRT compared to conventional, three‐dimensional conformal radiation therapy: 1) when multiple critical structures confined within the intracranial vault are to be avoided, one may desire an optimal dose distribution that allows for the dose to these structures to be minimized, and 2) since high‐grade gliomas tend to recur locally, IMRT should allow for dose escalation proportional to the corresponding heterogeneous cell populations. Based on the anatomic location of the treatment volumes, one can visualize examples where IMRT could be of benefit. Patients with a concave or irregularly‐shaped target in a frontal lobe may require IMRT in order to spare the adjacent globe and any uninvolved optic apparatus. In patients with well‐lateralized tumors involving the brain parenchyma, complete sparing of the contralateral hemisphere is desirable. Patients with infiltrative gliomas traditionally have large margins placed around the treatment volumes, and these may often encompass uninvolved critical normal structures. For such cases, IMRT may allow for non‐uniform reduction of the treatment volume around these normal structures. The primary goal of this presentation is to provide a practical overview of IMRT for the CNS.Though much attention has been given to the inverse planning and quality assurance aspects of IMRT, one should have an adequate understanding of the entire process; from proper patient selection to positioning/immobilization and continuing through treatment. A discussion of the steps of the CNS IMRT process will include: patient selection, immobilization, recommended imaging acquisitions, structure delineation, planning strategies/parameters, dose objectives, plan evaluation, QA, and potential delivery issues. Guidelines and practical examples for each component of this process will be presented.To gain further familiarization of CNS IMRT, one should review the corresponding technological and clinical outcome literature. Comparisons to conventional radiotherapy methods will be examined in terms of technique, dosimetry and clinical outcome. Finally, current research and future directions of CNS IMRT will be introduced such as the novel use of sophisticated imaging techniques for improved structure definition, patient positioning and dose modulation.Educational Objectives:1. To understand the general practice of CNS IMRT from patient selection through actual treatment.2. To become familiar with specific details pertaining to the CNS IMRT process through several illustrative examples.3. To be introduced to some of the research and future directions of CNS IMRT.Research supported, in part, by Varian Medical Systems.
TU‐E‐224A‐01: Evaluation of Heterogeneity Corrections Algorithms Through the Irradiation of a Lung Phantom
Authors: Alvarez P , Molineu A , Hernandez N , Followill D , Ibbott G 
Published: July 2006

Purpose: To evaluate the impact of applying heterogeneity corrections to the calculation of prescribed doses to a target located within the lung. Method and Materials: The Radiological Physics Center's (RPC) anthropomorphic lung phantom was sent to institutions nationwide. This phantom simulates a patient not only in dimensions but also in densities for imaging and treatment purposes. This design includes two lungs with density of 0.33 g/cm3 and a target centrally located in the left lung with density near 1 g/cm3. TLD and radiochromic films were used as dosimeters within and near the target region. Institutions that received the phantom were requested to image, plan and treat the phantom as if a patient. The prescription dose, based on a stereotactic plan, was 20 Gy to the target, calculated without applying heterogeneity corrections. The institutions were asked to submit both the homogeneous and heterogeneity corrected treatment plans using the same number of monitor units. Results: Twenty‐one irradiations, mostly with 6 MV x‐rays, were analyzed from 7 different Treatment Planning Systems (TPS). The ratio of dose to the target from the plan with to the plan without heterogeneity corrections was calculated and analyzed based on the algorithms used for the heterogeneity correction. A comparison of corrected dose given by the TPS and dose given by TLD was performed. The average ratio between dose with to dose without the heterogeneity correction was 1.18 with values ranging from 1.12 to 1.21. The superposition convolution algorithms agreed better with measurements than the other algorithms studied. The average TLD/Inst dose ratio in the target was 0.97 ranging from 0.92 to 0.99. Conclusions: There continues to be a differences in the heterogeneity corrected tumor doses within the lung from different planning systems.Work supported by PHS grant CA10953 and CA081647 from the NCI, DHHS.
TU‐E‐ValB‐03: Simultaneous Integrated Boost Utilizing IMRT for the Treatment of Breast Cancer
Authors: Kirk M , Dickler A , Chu J , Chen S , Seif N , Mehta P , Griem K 
Published: July 2006

Introduction: We compare the dosimetric characteristics of simultaneous integrated boost (SIB) technique utilizing IMRT vs. conventional treatment consisting of medial and lateral tangents followed by an electron boost. Materials and Methods: To date, 5 women at our institution have been enrolled and treated using IMRT with SIB. Patients were treated using 25 fractions of 1.8 Gy to the whole breast (45Gy) while concurrently receiving 25 fractions of 2.4 Gy to tumor bed (60Gy). Conventional treatments were planned using the standard fractionation of 1.8 Gy × 25 fractions to the whole breast followed by 2 Gy × 8 fractions to the tumor bed.The patient data was used to compile population dose volume histograms (pDVH), based on the mean values and include error bars which represent the 1σ uncertainty of the mean. Results: The mean percent of the BoostPTV volume receiving 60Gy, was slightly higher for the conventional technique compared to SIB (Conventional = 98±1.4%, SIB=95.0±1.0%). The mean volume of the treated breast outside the BoostPTV, PTV45‐Boost, that received greater than 120% of the prescribed dose was more in the Conventional technique then SIB (Conventional=15.9±3.4%, SIB=6.1±1.6%). The mean volume of lung receiving 20Gy was equivalent in both techniques (Conventional=19.8±5.8%, SIB=17.1±5.2%). The mean ipsilateral lung dose was equivalent between techniques (Conventional=10.7±2.2 Gy, SIB=11.9±4.2 Gy). The mean dose to contralateral breast was systematically higher in SIB technique compared to the conventional technique (Conventional=69±39 Gy, SIB=191±126 Gy). The mean volume of the heart that received greater then 30Gy was small for both plans (Conventional=2.8% and SIB=0.4%). Conclusion: IMRT with SIB is feasible and allows patients to complete EBRT in about 20% less time than the standard treatment course. It offers improved dose homogeneity to treated breast, comparable normal tissue sparing, and excellent short term cosmesis.
TU‐E‐230C‐01: Digital Radiography QC Workshop I and II
Authors: Goldman L 
Published: July 2006

Computed radiography and digital radiography systems now comprise a large segment of radiography work. It is important that appropriate performance testing and quality control (QC) tools and procedures be made available for these systems. The vendors and/or manufacturers of digital imaging systems may provide‐or make available‐test tools, software and procedures for performance evaluation and routine quality control testing of their digital systems. Currently, such tools and programs vary significantly from manufacturer to manufacturer.This two‐part workshop will include both formal presentations and hands‐on demonstrations. During the first half of the workshop, each participating vendor or manufacturer will present a brief (12–15 minute) overview of tools and procedures for performance testing and QC of their systems. The second half of the workshop is dedicated to hands‐on demonstrations at table‐top exhibits hosted by each participating vendor. Exhibits will include test tools, workstations and samples of performance testing and QC test procedures.Companies participating in this workshop will include Agfa, Fuji, General Electric, Kodak, Konica, IDC, LoDox, Philips and potentially others.Educational Objectives:1. To understand performance test procedures used by various DR/CR systems.2. To see types QC test tools and procedures made available with DR/CR systems.3. To obtain hands‐on demonstration of DR/CR ttesting and QC procedures.
TU‐FF‐A3‐06: Dose Calculation in Presence of a Metallic Object Using Megavoltage Cone‐Beam CT
Authors: Aubin M , Morin O , Aubry J , Chen J , Descovich M , Pouliot J 
Published: July 2006

Purpose: CT image artefacts caused by the presence of metallic objects hinder organ delineation and preclude precise dose calculation. In contrast, the presence of high atomic number material has relatively little impact on the image quality of Megavoltage Cone‐beam CT (MVCBCT). The objective of this work was to determine if MVCBCT could be used for accurate dose calculation in the presence of metallic objects.Material: Experiments were performed with a 16cm diameter cylindrical water‐equivalent phantom. MVCBCT and kVCT images of the phantom were acquired with and without a 1.5 cm diameter steel rod (3 mm wall thickness) sitting on the phantom. Using a treatment planning system, dose distributions were calculated for a 6 MV 10 cm square field AP beam for these configurations. Dose measurements were performed using an ion chamber placed at isocenter and mosfet detectors placed at 35 locations in the phantom. Measured and calculated dose values were compared. Results: Without metal, dose calculated in the phantom using either the kVCT or the MVCBCT image corrected for cupping artefact were all within 2% of each other and of the measured values, showing the ability to use the MVCBCT for dose calculation. In the presence of the metallic object, erroneous density values, around the rod, made dose calculation on the kVCT unreliable. MVCBCT provided correct density values (within 5%) and differences between measured and calculated dose values were on average 3.2% (SD 3.4%). The two largest differences (10.6% and 8.9%) were found in a high dose gradient region below the rod. Conclusion: MVCBCT can be used in a treatment planning system for dose calculation in the presence of metallic objects. Results for non‐cylindrical geometries will also be presented.This research is supported by Siemens.
TU‐FF‐A4‐04: Intensity Modulation Patterns for Regional Exposure Control with Multiple Angle Slot Scan Imaging: Simulated Annealing Optimization Technique Approach
Authors: Tu S , Shaw C , Liu X , Altunbas M , Lai C , Wang T 
Published: July 2006

Purpose: To study the feasibility of using simulated annealing algorithm to determine the intensity modulation patterns for regional exposure control with multiple angle slot scan imaging. Method and Materials: We acquired a digital image from the chest radiography and then processed with a 2‐D Gaussian filter as an exposure equalization mask. Slot scanning exposures at evenly spaced angle between 0 and 180 degrees were used to achieve the ideal exposure distribution. An optimization technique, simulated annealing, was used to search the best intensity modulation patterns. This method is based on the theory of statistical physics and uses Boltzmann probability distribution to locate the minimum energy state. An objective function was mathematically constructed and Metropolis scheme was incorporated into the numerical computation. Various tuning parameters such as the control temperature setting for the annealing schedule were explored and the best combination was empirically chosen. We also calculated the percent root mean square error to quantify the results. Results: A wide range of scanning angles was tested in the study. For 8 projection angles, it took 10 minutes to complete the intensity modulation patterns search in a single processor computer and the percent root mean square error was 12.0%. The percent root mean square error can be further reduced by adding the number of scanning angles. Conclusion: Our study indicated that simulated annealing technique has the potential to determine the optimized intensity modulation patterns. Current work is focused on the reduction of both the computing time and percent root mean square error. Other optimization techniques such as the conjugate gradient method and the applications of parallel computing methods to accelerate the search algorithms are to be investigated.Supported in part by a research grant EB00117 by the National Institute of Biomedical Imaging and Bioengineering.