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At least 577 records · Page 32
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DOE OSTI2015

SU-E-T-262: Development of An In-House Forward Planning System for Conformal Arc Therapy

Purpose: Conformal radiotherapy with forward planning has many practical advantages (e.g., more uniform target dose) and has been used routinely for stereotactic body radiation therapy (SBRT) and other conventional treatment. This study investigates a forward-planning approach for conformal arc therapy and a dedicated treatment planning system (TPS) for a newly designed cobalt 60 machine with a ring type gantry and a multileaf collimator (MLC). Methods: Conformal arcs were modeled with continuous delivery of treatment fields conformal to the target cross-section. Treatment plans were further optimized by weighting or offsetting beams based on the target-critical structure relationship. CT and structure data of seven previous SBRT patients treated at our center were used for plan evaluation. An in-house forward planning tool was developed to aid the forward planning process. A graphical user interface (GUI) was designed with interactive and automatic adjustment between beam gantry angle and the beam weight. Dose distributions were calculated using our in-house Monte Carlo based TPS. Dose contributions from individual beam angles were summed together with different weight factors, which were continuously optimized until the pre-set dose conformity goal was met. Results: We were able to achieve target coverage and critical structure sparing to meet the required clinical criteria in all studied cases. It should be mentioned that those cases were selected having critical structures not proximal to the target. However, this was usually the case in the majority of SBRT cases especially those involving lung targets. The developed GUI tool was very useful in the forward treatment planning process. Conclusion: Conformal arcs can be used successfully on the new Cobalt 60 modality for the treatment of a sizeable fraction of cancer patients, which can be efficiently planned with our simple forward planning approach.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-F-BRA-13: Knowledge-Based Treatment Planning for Prostate LDR Brachytherapy Based On Principle Component Analysis

Purpose: To create a knowledge-based algorithm for prostate LDR brachytherapy treatment planning that standardizes plan quality using seed arrangements tailored to individual physician preferences while being fast enough for real-time planning. Methods: A dataset of 130 prior cases was compiled for a physician with an active prostate seed implant practice. Ten cases were randomly selected to test the algorithm. Contours from the 120 library cases were registered to a common reference frame. Contour variations were characterized on a point by point basis using principle component analysis (PCA). A test case was converted to PCA vectors using the same process and then compared with each library case using a Mahalanobis distance to evaluate similarity. Rank order PCA scores were used to select the best-matched library case. The seed arrangement was extracted from the best-matched case and used as a starting point for planning the test case. Computational time was recorded. Any subsequent modifications were recorded that required input from a treatment planner to achieve an acceptable plan. Results: The computational time required to register contours from a test case and evaluate PCA similarity across the library was approximately 10s. Five of the ten test cases did not require any seed additions, deletions, or moves to obtain an acceptable plan. The remaining five test cases required on average 4.2 seed modifications. The time to complete manual plan modifications was less than 30s in all cases. Conclusion: A knowledge-based treatment planning algorithm was developed for prostate LDR brachytherapy based on principle component analysis. Initial results suggest that this approach can be used to quickly create treatment plans that require few if any modifications by the treatment planner. In general, test case plans have seed arrangements which are very similar to prior cases, and thus are inherently tailored to physician preferences.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

MO-F-CAMPUS-T-02: An Electronic Whiteboard Platform to Manage Treatment Planning Process

Purpose: In an effort to improve patient safety and streamline the radiotherapy treatment planning (TP) process, a software based whiteboard had been developed and put in use in our facility Methods: The electronic whiteboard developed using SQL database (DB) and PHP/JavaScript based web interface, is published via department intranet and login credentials. The DB stores data for each TP process such as patient information, plan type, simulation/start dates, physician, dosimetrist, QA and the current status in planning process. Users interact with the DB per plan and perform status updates in real time as the planning process progresses. All user interactions with the DB are recorded with timestamps so as to calculate statistical information for TP process management such as contouring times, planning and review times, dosimetry, physics and therapist QA times. External beam and brachytherapy plans are categorized according to complexity (ex: IMRT, 3D, HDR, LDR etc) and treatment types and applicators. Each plan category is assigned specific timelines for each planning process. When a plan approaches or passes the predetermined timeline, users are alerted via color coded graphical cues. When certain process items are not completed in time, pre-determined actions are triggered such as a delay in treatment start date. Results: Our institution has been using the electronic whiteboard for two years. Implementation of pre-determined actions based on the statistical information collected by the whiteboard improved our TP process. For example, the average time for normal tissue contouring decreased from 0.73±1.37 to 0.24±0.33 days. The average time for target volume contouring decreased from 3.2±2.84 to 2.37±2.54 days. This increase in efficiency allows more time for quality assurance processes, improving patient safety. Conclusion: The electronic whiteboard has been an invaluable tool for streamlining our TP processes. It facilitates timely and accurate communication between all parties involved in the TP process increasing patient safety.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

MO-G-304-04: Generating Well-Dispersed Representations of the Pareto Front for Multi-Criteria Optimization in Radiation Treatment Planning

Purpose: To present a novel multi-criteria optimization (MCO) solution approach that generates well-dispersed representation of the Pareto front for radiation treatment planning. Methods: Different algorithms have been proposed and implemented in commercial planning software to generate MCO plans for external-beam radiation therapy. These algorithms consider convex optimization problems. We propose a grid-based algorithm to generate well-dispersed treatment plans over Pareto front. Our method is able to handle nonconvexity in the problem to deal with dose-volume objectives/constraints, biological objectives, such as equivalent uniform dose (EUD), tumor control probability (TCP), normal tissue complication probability (NTCP), etc. In addition, our algorithm is able to provide single MCO plan when clinicians are targeting narrow bounds of objectives for patients. In this situation, usually none of the generated plans were within the bounds and a solution is difficult to identify via manual navigation. We use the subproblem formulation utilized in the grid-based algorithm to obtain a plan within the specified bounds. The subproblem aims to generate a solution that maps into the rectangle defined by the bounds. If such a solution does not exist, it generates the solution closest to the rectangle. We tested our method with 10 locally advanced head and neck cancer cases. Results: 8 objectives were used including 3 different objectives for primary target volume, high-risk and low-risk target volumes, and 5 objectives for each of the organs-at-risk (OARs) (two parotids, spinal cord, brain stem and oral cavity). Given tight bounds, uniform dose was achieved for all targets while as much as 26% improvement was achieved in OAR sparing comparing to clinical plans without MCO and previously proposed MCO method. Conclusion: Our method is able to obtain well-dispersed treatment plans to attain better approximation for convex and nonconvex Pareto fronts. Single treatment plan can be achieved when given bounds on the objectives.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-AB-201-01: A Comprehensive Planning Comparison Study Between a Novel Direction Modulated Brachytherapy Tandem Applicator and Conventional T&R Applicator for Image Guided Cervical Cancer Brachytherapy

Purpose: To demonstrate that utilization of a novel, intensity modulation capable, direction modulated brachytherapy (DMBT) tandem applicator can improve plan quality compared with conventional T&R applicator during an image guided cervical cancer brachytherapy. Methods: 45 cervical cancer patients treated with PDR brachytherapy were reviewed. Of them, a) 27 were treated using T&R only, b) 9 were treated using T&R with needles attached to the ring, and c) the remaining 9 were treated using T&R with needles attached to the ring (AN) as well as additional free-hand-loaded needles (FN). The DMBT tandem design has 6 peripheral holes of 1.3-mm diameter, grooved along a nonmagnetic tungsten alloy rod, enclosed in a plastic sheath with total 6.0-mm diameter. An in-house-coded inverse planning system was used for planning DMBT and T&R cases. All typical clinical constraints including OAR dose limits, dwell times, and loading patterns were respected. For the DMBT and T&R applicators, the plans were optimized with the same conventional ring in place, but repeatedly planned with and without AN/FN needles. All generated plans were normalized to the same D90 of the clinically treated plans. Results: For the plans in category a), DMBT generally outperformed T&R with average reduction in D2cc of −2.39%, −5.21%, and −2.69% for bladder, rectum, and sigmoid, respectively. For the plans in category b) and c), DMBT generally outperformed T&R if the same needles in AN/FN were utilized in both cases with average reduction in D2cc of −1.82%, −3.40%, and −6.04%, respectively. For the cases where the needles were not utilized for both applicators, an average D2cc reduction of −7.45%, −7.61%, and 17.47% were observed, respectively. Conclusions: Under the same clinical conditions, with/without needles, the DMBT applicator tends to generate more favorable plans compared with the conventional T&R applicator, and hence, is a promising technology.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Technical Note: Improving the VMERGE treatment planning algorithm for rotational radiotherapy

Purpose: The authors revisit the VMERGE treatment planning algorithm by Craft et al. [“Multicriteria VMAT optimization,” Med. Phys. 39, 686–696 (2012)] for arc therapy planning and propose two changes to the method that are aimed at improving the achieved trade-off between treatment time and plan quality at little additional planning time cost, while retaining other desirable properties of the original algorithm. Methods: The original VMERGE algorithm first computes an “ideal,” high quality but also highly time consuming treatment plan that irradiates the patient from all possible angles in a fine angular grid with a highly modulated beam and then makes this plan deliverable within practical treatment time by an iterative fluence map merging and sequencing algorithm. We propose two changes to this method. First, we regularize the ideal plan obtained in the first step by adding an explicit constraint on treatment time. Second, we propose a different merging criterion that comprises of identifying and merging adjacent maps whose merging results in the least degradation of radiation dose. Results: The effect of both suggested modifications is evaluated individually and jointly on clinical prostate and paraspinal cases. Details of the two cases are reported. Conclusions: In the authors’ computational study they found that both proposed modifications, especially the regularization, yield noticeably improved treatment plans for the same treatment times than what can be obtained using the original VMERGE method. The resulting plans match the quality of 20-beam step-and-shoot IMRT plans with a delivery time of approximately 2 min.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-C-202-01: Incorporating Time-Dependent Hypoxia in IMRT Planning

Purpose: To incorporate uncertainties in oxygenation of tumor cells into radiation therapy planning via robust optimization. The model is demonstrated using a clinical prostate cancer case. Methods: The tumor oxygenation levels are determined based on pre- and mid-treatment PET scans. To account for oxygenation changes, we use a radio-sensitivity factor for the effective dose necessary to treat hypoxic cells. Due to the unpredictable nature of re-oxygenation of hypoxic cells, the radio-sensitivity factor and its change is modeled to reside in a time-dependent uncertainty set. This uncertainty can adapt to both pre- and mid-treatment scans, resulting in a two-stage robust treatment planning model. We develop a robust counterpart reformulation that transforms the original NP-hard problem into a linear program consisting of finitely many linear constraints, which can be solved efficiently. Results: The robust plan is compared to both the corresponding fractionated plan which ignores hypoxia, and to the commonly practiced dose-escalated plan that uniformly increases dose based on initial oxygen concentrations. For PTV, the robust plan improves D{sub 50}, D{sub 95}, and EUD by 4% on average compared to fractionated, and by 11% compared to the optimal escalated plan. Moreover, the robust plan spared organs at risk similar to the fractionated plan, while the escalated plan led to over 170% increase of Bladder D{sub 30}. Conclusion: The proposed robust adaptive model can improve tumor coverage by increasing dose to hypoxic tumor voxels that is overlooked by common fractionated treatments. In addition, the robust model anticipates the re-oxygenation process, thus reducing the excess dose at later fractions in comparison to uniform dose-escalation methods.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-P-37: Implementation of An End-To-End QA Test of the Radiation Therapy Imaging, Planning and Delivery Process to Identify and Correct Possible Sources of Deviation

Purpose: To implement an end-to-end QA test of the radiation therapy imaging, planning and delivery process, aimed to assess the dosimetric agreement accuracy between planned and delivered treatment, in order to identify and correct possible sources of deviation. To establish an internal standard for machine commissioning acceptance. Methods: A test involving all steps of the radiation therapy: imaging, planning and delivery process was designed. The test includes analysis of point dose and planar dose distributions agreement between TPS calculated and measured dose. An ad hoc 16 cm diameter PMMA phantom was constructed with one central and four peripheral bores that can accommodate calibrated electron density inserts. Using Varian Eclipse 10.0 and Elekta XiO 4.50 planning systems, IMRT, RapidArc and 3DCRT with hard and dynamic wedges plans were planned on the phantom and tested. An Exradin A1SL chamber is used with a Keithley 35617EBS electrometer for point dose measurements in the phantom. 2D dose distributions were acquired using MapCheck and Varian aS1000 EPID.Gamma analysis was performed for evaluation of 2D dose distribution agreement using MapCheck software and Varian Portal Dosimetry Application.Varian high energy Clinacs Trilogy, 2100C/CD, 2000CR and low energy 6X/EX where tested.TPS-CT# vs. electron density table were checked for CT-scanners used. Results: Calculated point doses were accurate to 0.127% SD: 0.93%, 0.507% SD: 0.82%, 0.246% SD: 1.39% and 0.012% SD: 0.01% for LoX-3DCRT, HiX-3DCRT, IMRT and RapidArc plans respectively. Planar doses pass gamma 3% 3mm in all cases and 2% 2mm for VMAT plans. Conclusion: Implementation of a simple and reliable quality assurance tool was accomplished. The end-to-end proved efficient, showing excellent agreement between planned and delivered dose evidencing strong consistency of the whole process from imaging through planning to delivery. This test can be used as a first step in beam model acceptance for clinical use.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-55: Reproducibility of Interstitial HDR Brachytherapy Plans

Purpose: Treating gynecological cancers with interstitial high-dose-rate (HDR) brachytherapy requires precise reconstruction of catheter positions to obtain accurate dosimetric plans. In this study, we investigated the degree of reproducibility of dosimetric plans for Syed HDR brachytherapy. Methods: We randomly selected five patients having cervix-vaginal cancer who were recently treated in our clinic with interstitial HDR brachytherapy with a prescription dose of 25–30 Gy in five fractions. Interstitial needles/catheters were placed under fluoroscopic guidance and intra-operative 3T MRI scan was performed to confirm the desired catheter placement for adequate target volume coverage. A CT scan was performed and fused with the MRI for delineating high-risk CTV (HR-CTV), intermediate-risk CTV (IR-CTV) and OARs. HDR treatment plans were generated using Oncentra planning software. A single plan was used for all five fractions of treatment for each patient. For this study, we took the original clinical plan and removed all the reconstructed catheters from the plan keeping the original contours unchanged. Then, we manually reconstructed all the catheters and entered the same dwell time from the first original clinical plan. The dosimetric parameters studied were: D90 for HR-CTV and IR-CV, and D2cc for bladder, rectum, sigmoid and bowel. Results: The mean of absolute differences in dosimetric coverage (D90) were (range): 1.3% (1.0–2.0%) and 2.0% (0.9–3.6%) for HR-CTV and IR-CTV, respectively. In case of OARs, the mean of absolute variations in D2cc were (range): 4.7% (0.7–8.9%) for bladder, 1.60% (0.3–3.2%) for rectum, 1.6% (0–3.9%) for sigmoid, and 1.8% (0–5.1%) for bowel. Conclusion: Overall, the reproducibility of interstitial HDR plans was within clinically acceptable limit. Observed maximum variation in D2cc for bladder. If number of catchers and dwell points were relatively low or any one catheter was heavily loaded, then reproducibility of the plan was more sensitive to the accuracy of catheter reconstruction.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-94: Plan2pdf - a Software Tool for Automatic Plan Report for Philips Pinnacle TPS

Purpose: To implement an automatic electronic PDF plan reporting tool for Philips Pinnacle treatment planning system (TPS) Methods: An electronic treatment plan reporting software is developed by us to enable fully automatic PDF report from Pinnacle TPS to external EMR programs such as MOSAIQ. The tool is named “plan2pdf”. plan2pdf is implemented using Pinnacle scripts, Java and UNIX shell scripts, without any external program needed. plan2pdf supports full auto-mode and manual mode reporting. In full auto-mode, with a single mouse click, plan2pdf will generate a detailed Pinnacle plan report in PDF format, which includes customizable cover page, Pinnacle plan summary, orthogonal views through each plan POI and maximum dose point, DRR for each beam, serial transverse views captured throughout the dose grid at a user specified interval, DVH and scorecard windows. The final PDF report is also automatically bookmarked for each section above for convenient plan review. The final PDF report can either be saved on a user specified folder on Pinnacle, or it can be automatically exported to an EMR import folder via a user configured FTP service. In manual capture mode, plan2pdf allows users to capture any Pinnacle plan by full screen, individual window or rectangular ROI drawn on screen. Furthermore, to avoid possible patients’ plan mix-up during auto-mode reporting, a user conflict check feature is included in plan2pdf: it prompts user to wait if another patient is being exported by plan2pdf by another user. Results: plan2pdf is tested extensively and successfully at our institution consists of 5 centers, 15 dosimetrists and 10 physicists, running Pinnacle version 9.10 on Enterprise servers. Conclusion: plan2pdf provides a highly efficient, user friendly and clinical proven platform for all Philips Pinnacle users, to generate a detailed plan report in PDF format for external EMR systems.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-99: Data Visualization From a Treatment Planning Tracking System for Radiation Oncology

Purpose: A treatment planning process tracker database with input forms and a TV-viewable display webpage was developed and implemented in our clinic to collect time data points throughout the process. Tracking plan times is important because it directly affects the patient quality of care. Simply, the longer a patient waits after their initial simulation CT for treatment to begin, the more time the cancer has to progress. The tracker helps to drive workflow through the clinic, while the data collected can be used to understand and manage the process to find and eliminate inefficiencies. Methods: The overall process steps tracked are CT-simulation, mark patient, draw normal contours, draw target volumes, create plan, and review/approve plan. Time stamps for task completion were extracted and used to generate a set of clinic metrics, among which include average time for each step in the process split apart by type of treatment, average time to completion for plans started in a given week, and individual overall completion time per plan. Results: Trends have been tracked for fourteen weeks of clinical data (196 plans). On average, drawing normal contours and target volumes is taking 2–5 times as long as creating the plan itself. This is potentially an issue because it could mean the process is taking too long initially, and it could be forcing the planning step to be done in a short amount of time. We also saw from our graphs that there appears to be no clear trend on the average amount of time per plan week-to-week. Conclusion: A tracker of this type has the potential to provide insight into how time is utilized in our clinic. By equipping our dosimetrists, radiation oncologists, and physicists with individualized metric sets, the tracker can help provide visibility and drive workflow. Funded in part by CPRIT (RP140105).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-269: Preliminary Experience of Kuwait Cancer Control Center (KCCC) On IMRT Treatment Planning and Pre-Treatment Verification

Purpose: The complexity of IMRT delivery requires pre-treatment quality assurance and plan verification. KCCC has implemented IMRT clinically in few sites and will extend to all sites. Recently, our Varian linear accelerator and Eclipse planning system were upgraded from Millennium 80 to 120 Multileaf Collimator (MLC) and from v8.6 to 11.0 respectively. Our preliminary experience on the pre-treatment quality assurance verification is discussed. Methods: Eight Breast, Three Prostate and One Hypopharynx cancer patients were planned with step and shoot IMRT. All breast cases were planned before the upgrade with 60% cases treated. The ICRU 83 recommendations were followed for the dose prescription and constraints to OAR for all cases. Point dose measurement was done with CIRS cylindrical phantom and PTW 0.125 cc ionization chamber. Measured dose was compared with calculated dose at the point of measurement. Map CHECK diode array phantom was used for the plan verification. Planned and measured doses were compared by applying gamma index of 3% (dose difference) / 3 mm DTA (average distance to agreement). For all cases, a plan is considered to be successful if more than 95% of the tested diodes pass the gamma test. A prostate case was chosen to compare the plan verification before and after the upgrade. Results: Point dose measurement results were in agreement with the calculated doses. The maximum deviation observed was 2.3%. The passing rate of average gamma index was measured higher than 97% for the plan verification of all cases. Similar result was observed for plan verification of the chosen prostate case before and after the upgrade. Conclusion: Our preliminary experience from the obtained results validates the accuracy of our QA process and provides confidence to extend IMRT to all sites in Kuwait.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

SU-F-T-344: Commissioning Constant Dose Rate VMAT in the Raystation Treatment Planning System for a Varian Clinac IX

Purpose: To demonstrate the commissioning of constant dose rate volumetric modulated arc therapy (VMAT) in the Raystation treatment planning system for a Varian Clinac iX with Exact couch. Methods: Constant dose rate (CDR) VMAT is an option in the Raystation treatment planning system, enabling VMAT delivery on Varian linacs without a RapidArc upgrade. Raystation 4.7 was used to commission CDR-VMAT for a Varian Clinac iX. Raystation arc model parameters were selected to match machine deliverability characteristics. A Varian Exact couch model was added to Raystation 4.7 and commissioned for use in VMAT optimization. CDR-VMAT commissioning checks were performed on the linac, including patient-specific QA measurements for 10 test patients using both the ArcCHECK from Sun Nuclear Corporation and COMPASS from IBA Dosimetry. Multi-criteria optimization (MCO) in Raystation was used for CDR-VMAT planning. Results: Raystation 4.7 generated clinically acceptable and deliverable CDR-VMAT plans for the Varian Clinac. VMAT plans were optimized including a model of the Exact couch with both rails in the out positions. CDR-VMAT plans generated with MCO in Raystation were dosimetrically comparable to Raystation MCO-generated IMRT plans. Patient-specific QA measurements with the ArcCHECK on the couch showed good agreement with the treatment planning system prediction. Patient-specific, structure-specific, multi-statistical parameter 3D QA measurements with gantry-mounted COMPASS also showed good agreement. Conclusion: Constant dose rate VMAT was successfully modeled in Raystation 4.7 for a Varian Clinac iX, and Raystation’s multicriteria optimization generated constant dose rate VMAT plans which were deliverable and dosimetrically comparable to IMRT plans.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-419: Evaluation of PlanIQ Feasibility DVH as Planning Objectives for Skull Base SBRT Patients

Purpose: PlanIQ(Sun Nuclear Corporation) can provide feasibility measures on organs-at-risk(OARs) around the target based on depth, local anatomy density and energy of radiation beam used. This study is to test and evaluate PlanIQ feasibility DVHs as optimization objectives in the treatment planning process, and to investigate the potential to use them in routine clinical cases to improve planning efficiency. Methods: Two to three arcs VMAT Treatment plans were generated in Pinnacle based on PlanIQ feasibility DVH for six skull base patients who previously treated with SBRT. The PlanIQ feasibility DVH for each OAR consists of four zones – impossible (at 100% target coverage), difficult, challenging and probable. Constrains to achieve DVH in difficult zone were used to start plan optimization. Further adjustment was made to improve coverage. The plan DVHs were compared to PlanIQ feasibility DVH to assess the dose received by 0%(D0), 5%(D5), 10%(D10) and 50%(D50) of the OAR volumes. Results: A total of 90 OARs were evaluated for 6 patients (mean 15 OARs, range 11–18 OARs). We used >98% PTV coverage as planning goal since it’s difficult to achieve 100% target coverage. For the generated plans, 96.7% of the OARs achieved D0 or D5 within difficult zone or impossible zone (ipsilateral OARs 93.5%, contralateral OARs 100%), while 90% and 65.6% of the OARs achieved D10 and D50 within difficult zone, respectively. Seventeen of the contralateral and out of field OARs achieved DVHs in impossible zone. For OARs adjacent or overlapped with target volume, the D0 and D5 are challenging to be optimized into difficult zone. All plans were completed within 2–4 adjustments to improve target coverage and uniformity. Conclusion: PlanIQ feasibility tool has the potential to provide difficult but achievable initial optimization objectives and therefore reduce the planning time to obtain a well optimized plan.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-427: Utilization and Evaluation of Diagnostic CT Imaging with MAR Technique for Radiation Therapy Treatment Planning

Purpose: The objective was to utilize and evaluate diagnostic CT-MAR technique for radiation therapy treatment planning. Methods: A Toshiba-diagnostic-CT acquisition with SEMAR(Single-energy-MAR)-algorism was performed to make the metal-artifact-reduction (MAR) for patient treatment planning. CT-imaging datasets with and without SEMAR were taken on a Catphan-phantom. Two sets of CT-numbers were calibrated with the relative electron densities (RED). A tissue characterization phantom with Gammex various simulating material rods was used to establish the relationship between known REDs and corresponding CT-numbers. A GE-CT-sim acquisition was taken on the Catphan for comparison. A patient with bilateral hip arthroplasty was scanned in the radiotherapy CT-sim and the diagnostic SEMAR-CT on a flat panel. The derived SEMAR images were used as a primary CT dataset to create contours for the target, critical-structures, and for planning. A deformable registration was performed with VelocityAI to track voxel changes between SEMAR and CT-sim images. The SEMAR-CT images with minimal artifacts and high quality of geometrical and spatial integrity were employed for a treatment plan. Treatment-plans were evaluated based on deformable registration of SEMAR-CT and CT-sim dataset with assigned CT-numbers in the metal artifact regions in Eclipse v11 TPS. Results: The RED and CT-number relationships were consistent for the datasets in CT-sim and CT’s with and without SEMAR. SEMAR datasets with high image quality were used for PTV and organ delineation in the treatment planning process. For dose distribution to the PTV through the DVH analysis, the plan using CT-sim with the assigned CT-number showed a good agreement to those on deformable CT-SEMAR. Conclusion: A diagnostic-CT with MAR-algorithm can be utilized for radiotherapy treatment planning with CT-number calibrated to the RED. Treatment planning comparison and DVH shows a good agreement in the PTV and critical organs between the plans on CT-sim with assigned CT-number and the deformable SEMAR CT datasets.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-440: The Feasibility Research of Checking Cervical Cancer IMRT Pre- Treatment Dose Verification by Automated Treatment Planning Verification System

Purpose: To assess the preliminary feasibility of automated treatment planning verification system in cervical cancer IMRT pre-treatment dose verification. Methods: The study selected randomly clinical IMRT treatment planning data for twenty patients with cervical cancer, all IMRT plans were divided into 7 fields to meet the dosimetric goals using a commercial treatment planning system(PianncleVersion 9.2and the EclipseVersion 13.5). The plans were exported to the Mobius 3D (M3D)server percentage differences of volume of a region of interest (ROI) and dose calculation of target region and organ at risk were evaluated, in order to validate the accuracy automated treatment planning verification system. Results: The difference of volume for Pinnacle to M3D was less than results for Eclipse to M3D in ROI, the biggest difference was 0.22± 0.69%, 3.5±1.89% for Pinnacle and Eclipse respectively. M3D showed slightly better agreement in dose of target and organ at risk compared with TPS. But after recalculating plans by M3D, dose difference for Pinnacle was less than Eclipse on average, results were within 3%. Conclusion: The method of utilizing the automated treatment planning system to validate the accuracy of plans is convenientbut the scope of differences still need more clinical patient cases to determine. At present, it should be used as a secondary check tool to improve safety in the clinical treatment planning.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-G-TeP4-06: An Integrated Application for Radiation Therapy Treatment Plan Directives, Management, and Reporting

Purpose: With electronic medical records, patient information for the treatment planning process has become disseminated across multiple applications with limited quality control and many associated failure modes. We present the development of a single application with a centralized database to manage the planning process. Methods: The system was designed to replace current functionalities of (i) static directives representing the physician intent for the prescription and planning goals, localization information for delivery, and other information, (ii) planning objective reports, (iii) localization and image guidance documents and (iv) the official radiation therapy prescription in the medical record. Using the Eclipse Scripting Application Programming Interface, a plug-in script with an associated domain-specific SQL Server database was created to manage the information in (i)–(iv). The system’s user interface and database were designed by a team of physicians, clinical physicists, database experts, and software engineers to ensure usability and robustness for clinical use. Results: The resulting system has been fully integrated within the TPS via a custom script and database. Planning scenario templates, version control, approvals, and logic-based quality control allow this system to fully track and document the planning process as well as physician approval of tradeoffs while improving the consistency of the data. Multiple plans and prescriptions are supported along with non-traditional dose objectives and evaluation such as biologically corrected models, composite dose limits, and management of localization goals. User-specific custom views were developed for the attending physician review, physicist plan checks, treating therapists, and peer review in chart rounds. Conclusion: A method was developed to maintain cohesive information throughout the planning process within one integrated system by using a custom treatment planning management application that interfaces directly with the TPS. Future work includes quantifying the improvements in quality, safety and efficiency that are possible with the routine clinical use of this system. Supported in part by NIH-P01-CA-059827.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

WE-AB-209-12: Quasi Constrained Multi-Criteria Optimization for Automated Radiation Therapy Treatment Planning

Purpose: To introduce quasi-constrained Multi-Criteria Optimization (qcMCO) for unsupervised radiation therapy optimization which generates alternative patient-specific plans emphasizing dosimetric tradeoffs and conformance to clinical constraints for multiple delivery techniques. Methods: For N Organs At Risk (OARs) and M delivery techniques, qcMCO generates M(N+1) alternative treatment plans per patient. Objective weight variations for OARs and targets are used to generate alternative qcMCO plans. For 30 locally advanced lung cancer patients, qcMCO plans were generated for dosimetric tradeoffs to four OARs: each lung, heart, and esophagus (N=4) and 4 delivery techniques (simple 4-field arrangements, 9-field coplanar IMRT, 27-field non-coplanar IMRT, and non-coplanar Arc IMRT). Quasi-constrained objectives included target prescription isodose to 95% (PTV-D95), maximum PTV dose (PTV-Dmax)< 110% of prescription, and spinal cord Dmax<45 Gy. The algorithm’s ability to meet these constraints while simultaneously revealing dosimetric tradeoffs was investigated. Statistically significant dosimetric tradeoffs were defined such that the coefficient of determination between dosimetric indices which varied by at least 5 Gy between different plans was >0.8. Results: The qcMCO plans varied mean dose by >5 Gy to ipsilateral lung for 24/30 patients, contralateral lung for 29/30 patients, esophagus for 29/30 patients, and heart for 19/30 patients. In the 600 plans computed without human interaction, average PTV-D95=67.4±3.3 Gy, PTV-Dmax=79.2±5.3 Gy, and spinal cord Dmax was >45 Gy in 93 plans (>50 Gy in 2/600 plans). Statistically significant dosimetric tradeoffs were evident in 19/30 plans, including multiple tradeoffs of at least 5 Gy between multiple OARs in 7/30 cases. The most common statistically significant tradeoff was increasing PTV-Dmax to reduce OAR dose (15/30 patients). Conclusion: The qcMCO method can conform to quasi-constrained objectives while revealing significant variations in OAR doses including mean dose reductions >5 Gy. Clinical implementation will facilitate patient-specific decision making based on achievable dosimetry as opposed to accept/reject models based on population derived objectives.

60 APPLIED LIFE SCIENCES↗