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Purpose: To quantify the clinical practice of respiratory motion management in radiation oncology. Methods: A respiratory motion management survey was designed and conducted based on clinician survey guidelines. The survey was administered to American Association of Physicists in Medicine (AAPM) members on 17 August 2020 and closed on 13 September 2020. Results: A total of 527 respondents completed the entire survey and 651 respondents completed part of the survey, with the partially completed surveys included in the analysis. Overall, 84% of survey respondents used deep inspiration breath hold for left-sided breast cancer. Overall, 83% of respondents perceived respiratory motion management for thoracic and abdominal cancer radiotherapy patients to be either very important or required. Overall, 95% of respondents used respiratory motion management for thoracic and abdominal sites, with 36% of respondents using respiratory motion management for at least 90% of thoracic and abdominal patients. The majority (60%) of respondents used the internal target volume method to treat thoracic and abdominal cancer patients, with 25% using breath hold or abdominal compression and 13% using gating or tracking. Conclusions: A respiratory motion management survey has been completed by AAPM members. Respiratory motion management is generally considered very important or required and is widely used for breast, thoracic, and abdominal cancer treatments.

Current available secondary dose calculation software for Gamma Knife radiosurgery falls short in situations where the target is shallow in depth or when the patient is positioned with a gamma angle other than 90°. In this work, we evaluate a new secondary calculation software which utilizes an innovative method to handle nonstandard gamma angles and image thresholding to render the skull for dose calculation. 800 treatment targets previously treated with our GammaKnife Icon system were imported from our treatment planning system (GammaPlan 11.0.3) and a secondary dose calculation was conducted. The agreement between the new calculations and the TPS were recorded and compared to the original secondary dose calculation agreement with the TPS using a Wilcoxon Signed Rank Test. Further comparisons using a Mann‐Whitney test were made for targets treated at a 90° gamma angle against those treated with either a 70 or 110 gamma angle for both the new and commercial secondary dose calculation systems. Correlations between dose deviations from the treatment planning system against average target depth were evaluated using a Kendall’s Tau correlation test for both programs. The Wilcoxon Signed Rank Test indicated a significant difference in the agreement between the two secondary calculations and the TPS, with a P‐value

The field of radiation oncology has recently experienced a period of remarkable transformation of our technical capabilities. These technical and computational advancements have resulted in a tremendous improvement in our ability to precisely and accurately deliver radiation dose. However, this increased emphasis on technical capabilities may be inadvertently diverting attention and funding from scientific developments in other areas, even at a time when exciting new advances are occurring in cancer biology. Much of our recent technical development has been promoted and subsidized by the manufacturers of radiation oncology equipment. The question now becomes “who will encourage and subsidize the research needed to bring our recent biological advances to clinical fruition?” In a recent commentary which inspired this debate, Brown and Adler suggest that we “…are in a golden age of radiation and cancer biology” and that “…the industry's current focus on equipment development alone is undermining significant potential clinical advances in radiation oncology.”3 This is the subject of this month's 3DCRT debate. Arguing for the proposition will be Drs. Leonard Kim, Stephanie Markovina, and Samantha Van Nest. Dr. Leonard Kim has worked on defining microscopic disease target volumes for breast cancer radiotherapy at William Beaumont Hospital and Rutgers Cancer Institute of New Jersey. He is currently Chief Medical Physicist at the MD Anderson Cancer Center at Cooper. Dr. Stephanie Markovina is interested in improving therapeutic response to radiation in cervical cancer and other solid tumors by better understanding molecular mechanisms of radiation induced tumor cell death and survival. She is an Assistant Professor of Radiation Oncology and Cancer Biology at Washington University in St Louis where she specializes primarily in the treatment of patients with gynecologic cancers. Dr. Samantha Van Nest has worked to establish spectroscopic techniques for the personalization of radiation therapy. She is currently a Postdoctoral Associate at Weill Cornell Medicine in New York, where her research investigates the effects of radiation on tumor immunity, with a particular focus on improving our understanding of the abscopal effect. Arguing against the proposition will be Drs. Subarna Eisaman, Lakshmi Santanam, and Julie Sullivan. Dr. Subarna Hamid Eisaman is the clinical director and assistant professor at the University of Pittsburgh Medical Center (UPMC) Hillman Cancer Center Department of Radiation Oncology at the J. Murtha Pavilion in Johnstown, Pennsylvania. She serves as co‐chair of the Radiation Oncology Lung and Lymphoma Via Oncology Pathways Physician Advisory Committee. Her clinical practice includes treatment of breast, GYN, lung, CNS, head and neck, skin and musculoskeletal malignancies. Dr. Lakshmi Santanam is an attending medical physicist at Memorial Sloan Kettering Cancer Center. Her primary interests include motion management and patient safety. She currently serves as vice chair for the AAPM Working Group on RO‐ILS and the Task Group on the Management of Respiratory Motion in Radiation Oncology. Dr. Julie Sullivan is a biologist at the U.S. Food and Drug Administration's (FDA) Center for Devices and Radiological Health. Her scientific interests include the use of radiation‐emitting medical devices in clinical trials and the medical planning for and response to radiological and nuclear incidents.

Purpose Characterize the intra‐fraction motion management (IFMM) system found on the Gamma Knife Icon (GKI), including spatial accuracy, latency, temporal performance, and overall effect on delivered dose. Methods A phantom was constructed, consisting of a three‐axis translation mount, a remote motorized flipper, and a thermoplastic sphere surrounding a radiation detector. An infrared marker was placed on the translation mount secured to the flipper. The spatial accuracy of the IFMM was measured via the translation mount in all Cartesian planes. The detector was centered at the radiation focal point. A remote signal was used to move the marker out of the IFMM tolerance and pause the beam. A two‐channel electrometer was used to record the signals from the detector and the flipper when motion was signaled. These signals determined the latency and temporal performance of the GKI. Results The spatial accuracy of the IFMM was found to be

Purpose We describe the acceptance testing, commissioning, periodic quality assurance, and workflow procedures developed for the first clinically implemented magnetic resonance imaging-guided radiation therapy (MR-IGRT) system for real-time tracking and beam control. Methods The system utilizes real-time cine imaging capabilities at 4 frames per second for real-time tracking and beam control. Testing of the system was performed using an in-house developed motion platform and a commercially available motion phantom. Anatomical tracking is performed by first identifying a target (a region of interest that is either tissue to be treated or a critical structure) and generating a contour around it. A boundary contour is also created to identify tracking margins. The tracking algorithm deforms the anatomical contour (target or a normal organ) on every subsequent cine frame and compares it to the static boundary contour. If the anatomy of interest moves outside the boundary, the radiation delivery is halted until the tracked anatomy returns to treatment portal. The following were performed to validate and clinically implement the system: (a) spatial integrity evaluation; (b) tracking accuracy; (c) latency; (d) relative point dose and spatial dosimetry; (e) development of clinical workflow for gating; and (f) independent verification by an outside credentialing service. Results The spatial integrity of the MR system was found to be within 2 mm over a 45-cm diameter field-of-view. The tracking accuracy for geometric targets was within 1.2 mm. The average system latency was measured to be within 394 ms. The dosimetric accuracy using ionization chambers was within 1.3% ± 1.7%, and the dosimetric spatial accuracy was within 2 mm. The phantom irradiation for the outside credentialing service had satisfactory results, as well. Conclusions The first clinical MR-IGRT system was validated for real-time tracking and gating capabilities and shown to be reliable and accurate. Patient workflow methods were developed for efficient treatment. Periodic quality assurance tests can be efficiently performed with commercially available equipment to ensure accurate system performance.

A substantial barrier to the single-and multi-institutional aggregation of data to supporting clinical trials, practice quality improvement efforts, and development of big data analytics resource systems is the lack of standardized nomenclatures for expressing dosimetric data. To address this issue, the American Association of Physicists in Medicine (AAPM) Task Group 263 was charged with providing nomenclature guidelines and values in radiation oncology for use in clinical trials, data-pooling initiatives, population-based studies, and routine clinical care by standardizing: (1) structure names across image processing and treatment planning system platforms; (2) nomenclature for dosimetric data (eg, doseevolume histogram [DVH]-based metrics); (3) templates for clinical trial groups and users of an initial subset of software platforms to facilitate adoption of the standards; (4) formalism for nomenclature schema, which can accommodate the addition of other structures defined in the future. A multisociety, multidisciplinary, multinational group of 57 members representing stake holders ranging from large academic centers to community clinics and vendors was assembled, including physicists, physicians, dosimetrists, and vendors. The stakeholder groups represented in the membership included the AAPM, American Society for Radiation Oncology (ASTRO), NRG Oncology, European Society for Radiation Oncology (ESTRO), Radiation Therapy Oncology Group (RTOG), Children's Oncology Group (COG), Integrating Healthcare Enterprise in Radiation Oncology (IHE-RO), and Digital Imaging and Communications in Medicine working group (DICOM WG); A nomenclature system for target and organ at risk volumes and DVH nomenclature was developed and piloted to demonstrate viability across a range of clinics and within the framework of clinical trials. The final report was approved by AAPM in October 2017. The approval process included review by 8 AAPM committees, with additional review by ASTRO, European Society for Radiation Oncology (ESTRO), and American Association of Medical Dosimetrists (AAMD). This Executive Summary of the report highlights the key recommendations for clinical practice, research, and trials. (C) 2017 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The purpose of this study is to describe the comprehensive commissioning process and initial clinical experience of the Mevion S250 proton therapy system, a gantry‐mounted, single‐room proton therapy platform clinically implemented in the S. Lee Kling Proton Therapy Center at Barnes‐Jewish Hospital in St. Louis, MO, USA. The Mevion S250 system integrates a compact synchrocyclotron with a C‐inner gantry, an image guidance system and a 6D robotic couch into a beam delivery platform. We present our commissioning process and initial clinical experience, including i) CT calibration; ii) beam data acquisition and machine characteristics; iii) dosimetric commissioning of the treatment planning system; iv) validation through the Imaging and Radiation Oncology Core credentialing process, including irradiations on the spine, prostate, brain, and lung phantoms; v) evaluation of localization accuracy of the image guidance system; and vi) initial clinical experience. Clinically, the system operates well and has provided an excellent platform for the treatment of diseases with protons. PACS number(s): 87.55.ne, 87.56.bd

Purpose: To determine the feasibility of automating mechanical quality assurance measurements on the Varian Truebeam LINAC.Methods: Using the XML coding capability of the Varian Truebeam Research Mode, the LINAC was programmed to mimic the beams delivered for the following mechanical tests. These tests included: Field size accuracy, jaw positions for asymmetric fields, collimator rotation isocenter, and MLC positional‐accuracy. Images for these beams were acquired with the EPID. The images were analyzed using an analysis code written in MATLAB. Tests for gantry and couch rotation isocenters and radiation and mechanical isocenter coincidence are being developed. Results: For field‐sizes ranging from 4×4cm2 to 15×15cm2, the measured matched the nominal field sizes to within 1mm. The collimator rotation isocenter and the overall accuracy for asymmetric field matched to within 1mm. No positional error 〉1mm was seen in the 33 MLC pairs visible in the MLC positional‐accuracy images.Conclusions: A large portion of the time required to make mechanical QA measurements using film is spent placing, processing, and scanning the film. Complete automation in performing these mechanical tests results in a significant time gain compared to film. A majority of the mechanical tests suggested by TG‐142 have been performed using this technique, and an automated mechanical QA process has been established in our clinic.

Purpose To quantify the potential impact of the Integrating the Healthcare Enterprise–Radiation Oncology Quality Assurance with Plan Veto (QAPV) on patient safety of external beam radiation therapy (RT) operations. Methods and Materials An institutional database of events (errors and near-misses) was used to evaluate the ability of QAPV to prevent clinically observed events. We analyzed reported events that were related to Digital Imaging and Communications in Medicine RT plan parameter inconsistencies between the intended treatment (on the treatment planning system) and the delivered treatment (on the treatment machine). Critical Digital Imaging and Communications in Medicine RT plan parameters were identified. Each event was scored for importance using the Failure Mode and Effects Analysis methodology. Potential error occurrence (frequency) was derived according to the collected event data, along with the potential event severity, and the probability of detection with and without the theoretical implementation of the QAPV plan comparison check. Failure Mode and Effects Analysis Risk Priority Numbers (RPNs) with and without QAPV were compared to quantify the potential benefit of clinical implementation of QAPV. Results The implementation of QAPV could reduce the RPN values for 15 of 22 (71%) of evaluated parameters, with an overall average reduction in RPN of 68 (range, 0-216). For the 6 high-risk parameters (>200), the average reduction in RPN value was 163 (range, 108-216). The RPN value reduction for the intermediate-risk (200 > RPN > 100) parameters was (0-140). With QAPV, the largest RPN value for “Beam Meterset” was reduced from 324 to 108. The maximum reduction in RPN value was for Beam Meterset (216, 66.7%), whereas the maximum percentage reduction was for Cumulative Meterset Weight (80, 88.9%). Conclusion This analysis quantifies the value of the Integrating the Healthcare Enterprise–Radiation Oncology QAPV implementation in clinical workflow. We demonstrate that although QAPV does not provide a comprehensive solution for error prevention in RT, it can have a significant impact on a subset of the most severe clinically observed events.

Purpose Systems to ensure patient safety are of critical importance. The electronic incident reporting systems (IRS) of 2 large academic radiation oncology departments were evaluated for events that may be suitable for submission to a national reporting system (NRS). Methods and Materials All events recorded in the combined IRS were evaluated from 2007 through 2010. Incidents were graded for potential severity using the validated French Nuclear Safety Authority (ASN) 5-point scale. These incidents were categorized into 7 groups: ( 1 ) human error, ( 2 ) software error, ( 3 ) hardware error, ( 4 ) error in communication between 2 humans, ( 5 ) error at the human-software interface, ( 6 ) error at the software-hardware interface, and ( 7 ) error at the human-hardware interface. Results Between the 2 systems, 4407 incidents were reported. Of these events, 1507 (34%) were considered to have the potential for clinical consequences. Of these 1507 events, 149 (10%) were rated as having a potential severity of ≥2. Of these 149 events, the committee determined that 79 (53%) of these events would be submittable to a NRS of which the majority was related to human error or to the human-software interface. Conclusions A significant number of incidents were identified in this analysis. The majority of events in this study were related to human error and to the human-software interface, further supporting the need for a NRS to facilitate field-wide learning and system improvement.

Purpose To evaluate whether planning 4-dimensional computed tomography (4DCT) can adequately represent daily motion of abdominal tumors in regularly fractionated and stereotactic body radiation therapy (SBRT) patients. Methods and Materials Intrafractional tumor motion of 10 patients with abdominal tumors (4 pancreas-fractionated and 6 liver-stereotactic patients) with implanted fiducials was measured based on daily orthogonal fluoroscopic movies over 38 treatment fractions. The needed internal margin for at least 90% of tumor coverage was calculated based on a 95th and fifth percentile of daily 3-dimensional tumor motion. The planning internal margin was generated by fusing 4DCT motion from all phase bins. The disagreement between needed and planning internal margin was analyzed fraction by fraction in 3 motion axes (superior-inferior [SI], anterior-posterior [AP], and left-right [LR]). The 4DCT margin was considered as an overestimation/underestimation of daily motion when disagreement exceeded at least 3 mm in the SI axis and/or 1.2 mm in the AP and LR axes (4DCT image resolution). The underlying reasons for this disagreement were evaluated based on interfractional and intrafractional breathing variation. Results The 4DCT overestimated daily 3-dimensional motion in 39% of the fractions in 7 of 10 patients and underestimated it in 53% of the fractions in 8 of 10 patients. Median underestimation was 3.9 mm, 3.0 mm, and 1.7 mm in the SI axis, AP axis, and LR axis, respectively. The 4DCT was found to capture irregular deep breaths in 3 of 10 patients, with 4DCT motion larger than mean daily amplitude by 18 to 21 mm. The breathing pattern varied from breath to breath and day to day. The intrafractional variation of amplitude was significantly larger than intrafractional variation (2.7 mm vs 1.3 mm) in the primary motion axis (ie, SI axis). The SBRT patients showed significantly larger intrafractional amplitude variation than fractionated patients (3.0 mm vs 2.1 mm, P Conclusions It may not be appropriate to use 4DCT without monitoring of patient motion on a regular basis for patients with abdominal tumors, especially SBRT patients.

Purpose To evaluate respiratory gating accuracy and intrafractional consistency for abdominal cancer patients treated with respiratory gated treatment on a regular linear accelerator system. Methods and Materials Twelve abdominal patients implanted with fiducials were treated with amplitude-based respiratory-gated radiation therapy. On the basis of daily orthogonal fluoroscopy, the operator readjusted the couch position and gating window such that the fiducial was within a setup margin (fiducial-planning target volume [f-PTV]) when RPM indicated “beam-ON.” Fifty-five pre- and post-treatment fluoroscopic movie pairs with synchronized respiratory gating signal were recorded. Fiducial motion traces were extracted from the fluoroscopic movies using a template matching algorithm and correlated with f-PTV by registering the digitally reconstructed radiographs with the fluoroscopic movies. Treatment was determined to be “accurate” if 50% of the fiducial area stayed within f-PTV while beam-ON. For movie pairs that lost gating accuracy, a MATLAB program was used to assess whether the gating window was optimized, the external-internal correlation (EIC) changed, or the patient moved between movies. A series of safety margins from 0.5 mm to 3 mm was added to f-PTV for reassessing gating accuracy. Results A decrease in gating accuracy was observed in 44% of movie pairs from daily fluoroscopic movies of 12 abdominal patients. Three main causes for inaccurate gating were identified as change of global EIC over time (∼43%), suboptimal gating setup (∼37%), and imperfect EIC within movie (∼13%). Conclusions Inconsistent respiratory gating accuracy may occur within 1 treatment session even with a daily adjusted gating window. To improve or maintain gating accuracy during treatment, we suggest using at least a 2.5-mm safety margin to account for gating and setup uncertainties.

Purpose We have created an automated process using real-time tracking data to evaluate the adequacy of planning target volume (PTV) margins in prostate cancer, allowing a process of adaptive radiotherapy with minimal physician workload. We present an analysis of PTV adequacy and a proposed adaptive process. Methods and Materials Tracking data were analyzed for 15 patients who underwent step-and-shoot multi-leaf collimation (SMLC) intensity-modulated radiation therapy (IMRT) with uniform 5-mm PTV margins for prostate cancer using the Calypso® Localization System. Additional plans were generated with 0- and 3-mm margins. A custom software application using the planned dose distribution and structure location from computed tomography (CT) simulation was developed to evaluate the dosimetric impact to the target due to motion. The dose delivered to the prostate was calculated for the initial three, five, and 10 fractions, and for the entire treatment. Treatment was accepted as adequate if the minimum delivered prostate dose (D min ) was at least 98% of the planned D min . Results For 0-, 3-, and 5-mm PTV margins, adequate treatment was obtained in 3 of 15, 12 of 15, and 15 of 15 patients, and the delivered D min ranged from 78% to 99%, 96% to 100%, and 99% to 100% of the planned D min . Changes in D min did not correlate with magnitude of prostate motion. Treatment adequacy during the first 10 fractions predicted sufficient dose delivery for the entire treatment for all patients and margins. Conclusions Our adaptive process successfully used real-time tracking data to predict the need for PTV modifications, without the added burden of physician contouring and image analysis. Our methods are applicable to other uses of real-time tracking, including hypofractionated treatment.

The transfer of radiation therapy data among the various subsystems required for external beam treatments is subject to error. Hence, the establishment and management of a data transfer quality assurance program is strongly recommended. It should cover the QA of data transfers of patient specific treatments, imaging data, manually handled data and historical treatment records. QA of the database state (logical consistency and information integrity) is also addressed to ensure that accurate data are transferred. PACS numbers: 87.56.bd, 87.55.D, 87.55.Gh, 87.55.km, 87.55.Qr, 87.55.T

A procedure for periodic quality assurance of a video surface imaging system is introduced. AlignRT is a video camera‐based patient localization system that captures and compares images of a patient's topography to a DICOM‐formatted external contour, then calculates shifts required to accurately reposition the patient. This technical note describes the tools and methods implemented in our department to verify correct and accurate operation of the AlignRT hardware and software components. The procedure described is performed monthly and complements a daily calibration of the system. PACS number: 87.56Fc

Udgivelsesdato: 2009-Jun-1 PURPOSE: We report on an integrated system for real-time adaptive radiation delivery to moving tumors. The system combines two promising technologies-three-dimensional internal position monitoring using implanted electromagnetically excitable transponders and corresponding real-time beam adaptation using a dynamic multileaf collimator (DMLC). METHODS AND MATERIALS: In a multi-institutional academic and industrial collaboration, a research version of the Calypso position monitoring system was integrated with a DMLC-based four-dimensional intensity-modulated radiotherapy delivery system using a Varian 120-leaf multileaf collimator (MLC). Two important determinants of system performance-latency (i.e., elapsed time between target motion and MLC response) and geometric accuracy-were investigated. Latency was quantified by acquiring continuous megavoltage X-ray images of a moving phantom (with embedded transponders) that was tracked in real time by a circular MLC field. The latency value was input into a motion prediction algorithm within the DMLC tracking system. Geometric accuracy was calculated as the root-mean-square positional error between the target and the centroid of the MLC aperture for patient-derived three-dimensional motion trajectories comprising two lung tumor traces and one prostate trace. RESULTS: System latency was determined to be approximately 220 milliseconds. Tracking accuracy was observed to be sub-2 mm for the respiratory motion traces and sub-1 mm for prostate motion. CONCLUSION: We have developed and characterized a research version of a novel four-dimensional delivery system that integrates nonionizing radiation-based internal position monitoring and accurate real-time DMLC-based beam adaptation. This system represents a significant step toward achieving the eventual goal of geometrically ideal dose delivery to moving tumors.

Purpose To describe a more aggressive treatment technique allowing dose escalation to positive para-aortic lymph nodes (PALN) in patients with cervical cancer, by means of positron emission tomography (PET)/computed tomography (CT)–guided intensity-modulated radiation therapy (IMRT). Here, we describe methods for simulation and planning of these treatments and provide objectives for target coverage as well as normal tissue sparing to guide treatment plan evaluation. Methods and Materials Patients underwent simulation on a PET/CT scanner. Treatment plans were generated to deliver 60.0 Gy to the PET-positive PALN and 50.0 Gy to the PALN and pelvic lymph node beds. Treatment plans were optimized to deliver at least 95% of the prescribed doses to at least 95% of each target volume. Dose–volume histograms were calculated for normal structures. Results The plans of 10 patients were reviewed. Target coverage goals were satisfied in all plans. Analysis of dose–volume histograms indicated that treatment plans involved irradiation of approximately 50% of the bowel volume to at least 25.0 Gy, with less than 10% receiving at least 50.0 Gy and less than 1% receiving at least 60.0. With regard to kidney sparing, approximately 50% of the kidney volume received at least 16.0 Gy, less than 5% received at least 50.0 Gy, and less than 1% received at least 60.0 Gy. Conclusions We have provided treatment simulation and planning methods as well as guidelines for the evaluation of target coverage and normal tissue sparing that should facilitate the more aggressive treatment of cervical cancer.

Purpose This prospective study investigates gynecologic malignancy online treatment setup error corrections using planar kilovoltage/megavoltage (KV/MV) imaging and helical MV computed tomography (MVCT) imaging. Methods and Materials Twenty patients were divided into two groups. The first group (10 patients) was imaged and treated using a conventional linear accelerator (LINAC) with image-guidance capabilities, whereas the second group (10 patients) was treated using tomotherapy with MVCT capabilities. Patients treated on the LINAC underwent planar KV and portal MV imaging and a two-dimensional image registration algorithm was used to match these images to digitally reconstructed radiographs (DRRs). Patients that were treated using tomotherapy underwent MVCT imaging, and a three-dimensional image registration algorithm was used to match planning CT to MVCT images. Subsequent repositioning shifts were applied before each treatment and recorded for further analysis. To assess intrafraction motion, 5 of the 10 patients treated on the LINAC underwent posttreatment planar imaging and DRR matching. Based on these data, patient position uncertainties along with estimated margins based on well-known recipes were determined. Results The errors associated with patient positioning ranged from 0.13 cm to 0.38 cm, for patients imaged on LINAC and 0.13 cm to 0.48 cm for patients imaged on tomotherapy. Our institutional clinical target volume-PTV margin value of 0.7 cm lies inside the confidence interval of the margins established using both planar and MVCT imaging. Conclusion Use of high-quality daily planar imaging, volumetric MVCT imaging, and setup corrections yields excellent setup accuracy and can help reduce margins for the external beam treatment of gynecologic malignancies.

Purpose To demonstrate that fiducial tracking during pretreatment Cone-Beam CT (CBCT) can accurately measure tumor motion and that this method should be used to validate 4-dimensional CT (4DCT) margins before each treatment fraction. Methods and Materials For 31 patients with abdominal tumors and implanted fiducial markers, tumor motion was measured daily with CBCT and fluoroscopy for 202 treatment fractions. Fiducial tracking and maximum-likelihood algorithms extracted 3-dimensional fiducial trajectories from CBCT projections. The daily internal margin (IM) (ie, range of fiducial motion) was calculated for CBCT and fluoroscopy as the 5th-95th percentiles of displacement in each cardinal direction. The planning IM from simulation 4DCT (IM 4DCT ) was considered adequate when within ±1.2 mm (anterior–posterior, left–right) and ±3 mm (superior–inferior) of the daily measured IM. We validated CBCT fiducial tracking as an accurate predictive measure of intrafraction motion by comparing the daily measured IM CBCT with the daily IM measured by pretreatment fluoroscopy (IM pre-fluoro ); these were compared with pre- and posttreatment fluoroscopy (IM fluoro ) to identify those patients who could benefit from imaging during treatment. Results Four-dimensional CT could not accurately predict intrafractional tumor motion for ≥80% of fractions in 94% (IM CBCT ), 97% (IM pre-fluoro ), and 100% (IM fluoro ) of patients. The IM CBCT was significantly closer to IM pre-fluoro than IM 4DCT ( P t CBCT was in agreement with IM fluoro for 93% of fractions (superior–inferior), compared with 63% for the t > 7.5 minutes group, demonstrating the need for patient-specific intratreatment imaging. Conclusions Tumor motion determined from 4DCT simulation does not accurately predict the daily motion observed on CBCT or fluoroscopy. Cone-beam CT could replace fluoroscopy for pretreatment verification of simulation IM 4DCT , reducing patient setup time and imaging dose. Patients with treatment time t > 7.5 minutes could benefit from the addition of intratreatment imaging.

To identify deficiencies with simulation and treatment planning orders and to develop corrective measures to improve safety and quality.At Washington University, the DMAIIC formalism is used for process management, whereby the process is understood as comprising Define, Measure, Analyze, Improve, Implement, and Control activities. Two complementary tools were used to provide quantitative assessments: failure modes and effects analysis and reported event data. The events were classified by the user according to severity. The event rates (ie, number of events divided by the number of opportunities to generate an event) related to simulation and treatment plan orders were determined.We analyzed event data from the period 2008-2009 to design an intelligent SIMulation and treatment PLanning Electronic (SIMPLE) order system. Before implementation of SIMPLE, event rates of 0.16 (420 of 2558) for a group of physicians that were subsequently used as a pilot group and 0.13 (787 of 6023) for all physicians were obtained. An interdisciplinary group evaluated and decided to replace the Microsoft Word-based form with a Web-based order system. This order system has mandatory fields and context-sensitive logic, an ability to create templates, and enables an automated process for communication of orders through an enterprise management system. After the implementation of the SIMPLE order, the event rate decreased to 0.09 (96 of 1001) for the pilot group and to 0.06 (145 of 2140) for all physicians (P.0001). The average time to complete the SIMPLE form was 3 minutes, as compared with 7 minutes for the Word-based form. The number of severe events decreased from 10.7% (45 of 420) and 12.1% (96 of 787) to 6.2% (6 of 96) and 10.3% (15 of 145) for the pilot group and all physicians, respectively.There was a dramatic reduction in the total and the number of potentially severe events through use of the SIMPLE system. In addition, the order process has become more efficient and reliable.

Purpose The aim of this study was to report on the development of a standardized target and organ-at-risk naming convention for use in radiation therapy and to present the nomenclature for structure naming for interinstitutional data sharing, clinical trial repositories, integrated multi-institutional collaborative databases, and quality control centers. This taxonomy should also enable improved plan benchmarking between clinical institutions and vendors and facilitation of automated treatment plan quality control. Materials and Methods The Advanced Technology Consortium, Washington University in St. Louis, Radiation Therapy Oncology Group, Dutch Radiation Oncology Society, and the Clinical Trials RT QA Harmonization Group collaborated in creating this new naming convention. The International Commission on Radiation Units and Measurements guidelines have been used to create standardized nomenclature for target volumes (clinical target volume, internal target volume, planning target volume, etc.), organs at risk, and planning organ-at-risk volumes in radiation therapy. The nomenclature also includes rules for specifying laterality and margins for various structures. The naming rules distinguish tumor and nodal planning target volumes, with correspondence to their respective tumor/nodal clinical target volumes. It also provides rules for basic structure naming, as well as an option for more detailed names. Names of nonstandard structures used mainly for plan optimization or evaluation (rings, islands of dose avoidance, islands where additional dose is needed [dose painting]) are identified separately. Results In addition to its use in 16 ongoing Radiation Therapy Oncology Group advanced technology clinical trial protocols and several new European Organization for Research and Treatment of Cancer protocols, a pilot version of this naming convention has been evaluated using patient data sets with varying treatment sites. All structures in these data sets were satisfactorily identified using this nomenclature. Conclusions Use of standardized naming conventions is important to facilitate comparison of dosimetry across patient datasets. The guidelines presented here will facilitate international acceptance across a wide range of efforts, including groups organizing clinical trials, Radiation Oncology Institute, Dutch Radiation Oncology Society, Integrating the Healthcare Enterprise, Radiation Oncology domain (IHE-RO), and Digital Imaging and Communication in Medicine (DICOM).

Udgivelsesdato: 2009-Jul-1 PURPOSE: Continuous tumor position measurement coupled with a tumor tracking system would result in a highly accurate radiation therapy system. Previous internal position monitoring systems have been limited by fluoroscopic radiation dose and low delivery efficiency. We aimed to incorporate a continuous, electromagnetic, three-dimensional position tracking system (Calypso 4D Localization System) with a dynamic multileaf collimator (DMLC)-based dose delivery system. METHODS AND MATERIALS: A research version of the Calypso System provided real-time position of three Beacon transponders. These real-time three-dimensional positions were sent to research MLC controller with a motion-tracking algorithm that changed the planned leaf sequence. Electromagnetic transponders were embedded in a solid water film phantom that moved with patient lung trajectories while being irradiated with two different plans: a step-and-shoot intensity-modulated radiation therapy (S-IMRT) field and a dynamic IMRT (D-IMRT) field. Dosimetric results were recorded under three conditions: no intervention, DMLC tracking, and a spatial gating system. RESULTS: Dosimetric accuracy was comparable for gating and DMLC tracking. Failure rates for gating/DMLC tracking are as follows: +/-3 cGy 10.9/ 7.5% for S-IMRT, 3.3/7.2% for D-IMRT; gamma (3mm/3%) 0.2/1.2% for S-IMRT, 0.2/0.2% for D-IMRT. DMLC tracking proved to be as efficient as standard delivery, with a two- to fivefold efficiency increase over gating. CONCLUSIONS: Real-time target position information was successfully integrated into a DMLC effector system to modify dose delivery. Experimental results show both comparable dosimetric accuracy as well as improved efficiency compared with spatial gating.

Purpose: This study investigates the enhanced conformality of neutron dose distributions obtainable through the application of intensity modulated neutron radiotherapy (IMNRT) to the treatment of prostate adenocarcinoma. Methods and Materials: An in-house algorithm was used to optimize individual segments for IMNRT generated using an organ-at-risk (OAR) avoidance approach. A number of beam orientation schemes were investigated in an attempt to approach an optimum solution. The IMNRT plans were created retrospectively for 5 patients previously treated for prostate adenocarcinoma using fast neutron therapy (FNT), and a comparison of these plans is presented. Dose distributions and dose–volume histograms (DVHs) were analyzed and plans were evaluated based on percentage volumes of rectum and bladder receiving 95%, 80%, and 50% (V 95 , V 80 , V 50 ) of the prescription dose, and on V 60 for both the femoral heads and GM muscle group. Results: Plans were normalized such that the IMNRT DVHs for prostate and seminal vesicles were nearly identical to those for conventional FNT plans. Use of IMNRT provided reductions in rectum V 95 and V 80 of 10% (2–27%) and 13% (5–28%), respectively, and reductions in bladder V 95 and V 80 of 12% (3–26%) and 4% (7–10%), respectively. The average decrease in V 60 for the femoral heads was 4.5% (1–18%), with no significant change in V 60 for the GM muscle group. Conclusions: This study provides the first analysis of the application of intensity modulation to neutron radiotherapy. The IMNRT technique provides a substantial reduction in normal tissue dose in the treatment of prostate cancer. This reduction should result in a significant clinical advantage for this and other treatment sites.

Purpose: Traditional manual quality assurance checks of a patient treatment plan beam parameters transfer involve visually checking the information printed from the treatment planning system against the record‐and verify system for one‐to‐one correspondence. To provide the efficiency and accuracy of data transfer check, we have utilized the Varian TrueBeam log files which contain the complete delivery parameters. Methods: The approved plans are transferred to the Record and Verify (R&V) system, and the beams are delivered in the Truebeam Linac. The expected and actual status of TrueBeam delivery parameters are recorded during the delivery. Compared to traditional dynalog files from Varian, TrueBeam log files offer complete delivery parameters, which enable complete data transfer QA. An automatic program was designed to read the planned parameters from TPS and delivered parameters from Linac workstation. The program can verify the delivered parameters for all the external deliveries, including 3D conformal, EDW delivery, IMRT, VMAT, and electrons treatments. Results: The patient ID, beam ID, photon or electron energy, beam MU, gantry angle, couch angle, cough positions, collimator angle, jaw positions, EDW wedge angle and orientations, MLC positions, number of segments, gantry speed, dose rate, applicator size are all checked. The data transfer and/or delivery errors are flagged in the report for each type of delivery. Conclusion: The end‐to‐end data transfer check using TrueBeam log files provides an efficient, reliable and complete beam parameter plan check process for variety of radiation delivery technique. It is more efficient than human chart checking and improves the robustness and quality of chart checking.

1A 330 1A 49 100.0 % 0.022 ± 0.033 (0.259) mu Pass Pass Pass Pass 1B 300 1B 79 100.0 % 0.035 ± 0.058 (0.391) mu Pass Pass Pass Pass 1C 270 1C 66 100.0 % 0.032 ± 0.077 (0.398) mu Pass Pass Pass Pass 1D 240 1D 108 100.0 % 0.045 ± 0.078 (0.516) mu Pass Pass Pass Pass 1E 210 1E 44 100.0 % 0.018 ± 0.037 (0.276) mu Pass Pass Pass Pass 1F 210 1F 42 100.0 % 0.013 ± 0.013 (0.158) mu Pass Pass Pass Pass 1 - Pass Rate = the percentage of the number of pixels with error less than the 2 percent of the maximal fluence (in mu) of the

Results: A decrease in gating accuracy was observed in 44% of movie pairs, with 17 out of 40 movie pairs in Fractionated-pancreas patients and 7 out of 15 movie pairs in SBRT-Liver patients. Three main causes for decreased gating accuracy were identified as non-optimized gating window (52%), change of EIC over time (42%) and patient motion (6%). The extra 2 mm margin between set-up and treatment aperturewas able to compensate for most of gating uncertainty for both SBRTand fractionated patients. Whena 5mm f-ptvwas modeled, gatingaccuracyimproved from 77%±14%to 95%±5% for all 24 post-treatment movies with decreased accuracy, except for one SBRT movie whose accuracy still below 50%. Conclusions: Quantitative analysis of respiratory gating accuracy indicated that i) inconsistent correlation between external and internalmotionisinherentforfreebreathingpatients,butdoesnotnecessarilyrelatetodecreaseofgatingaccuracy;andii)thereis a limitation in choosing gating window manually based on real-time fluoroscopic movies. In order to improve/maintain gating accuracy during treatment, we suggest using at least a 2mm or greater difference between the f-PTVand CTV-PTVexpansion to account for residual error. Author Disclosure: J. Ge: None. L. Santanam: None. P.J. Parikh: B. Research Grant; Varian Medical Systems.