American Association Of Physicists In Medicine Research Articles

Verification of SuperMC for simulation of a high-dose-rate brachytherapy source

In this study, SuperMC (Super Monte Carlo simulation program for nuclear and radiation simulation) was tested and verified for simulation of a high-dose-rate brachytherapy source. The Monte Carlo simulation includes calculations of the air kerma strength, dose rate constant, radial dose function and anisotropy function as recommended by the American Association of Physicists in Medicine (AAPM) in Task Group reports 43 and 43U1 (TG-43, TG-43U1). The air kerma strength, dose rate constant, radial dose function and anisotropy function were compared with previously published Monte Carlo simulation results and experimental data. The calculated parameters were found to be in good agreement with published Monte Carlo and measured data. The value obtained from the SuperMC simulation for the air kerma strength was 9.779 × 10−8 U·Bq−1 and the dose rate constant was 1.1092 ± 0.02% cGy·h−1·U−1. The time to transport 5 × 107 photons showed SuperMC to be relatively faster than MCNP. The results show that SuperMC can be used for fast and accurate simulations and dosimetric calculations of HDR brachytherapy sources.

AAPM medical physics practice guideline 6.a.: Performance characteristics of radiation dose index monitoring systems.

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States.The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner.Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized.The following terms are used in the AAPM practice guidelines: •Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. •Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.

9th International Conference on 3D Radiation Dosimetry

IC3DDose 2016 - 9th International Conference on 3D Radiation DosimetryPrefaceIt was a great pleasure to welcome participants to IC3DDose 2016, the 9th International Conference on 3D Radiation Dosimetry, held from 7–10 November 2016 in Galveston, Texas.The series of conferences has evolved considerably during its history. At the first conference, DOSGEL’99, the discussion centered around gel dosimetry. Held in Lexington, Kentucky in 1999, it was timed to coincide with the American Association of Physicists in Medicine (AAPM) Annual Meeting in Nashville, Tennessee. It was my honour to organize that first conference, and it was once again my honour to organize the 9th conference in the series now known as IC3DDose which was held in Galveston, Texas.As was the case with recent IC3DDose conferences, the topic has broadened considerably beyond gel dosimetry. Not only have newer 3D volumetric dosimeters appeared on the scene, but novel electronic dosimetry systems and software that generate quasi-3D dose information have also. These changes have tracked advances in radiation oncology as techniques such as IMRT, VMAT, and IGRT have become almost ubiquitous. At the same time, dynamic treatments including gating and tracking now enjoy widespread use. Novel treatment technologies have appeared with perhaps the most disruptive being combined MR imaging-treatment units such as the ViewRay MR-cobalt unit and the Elekta/Philips MR-Linac.The potential benefits offered by 3D dosimetry were explored, compared and evaluated during IC3DDose 2016. Novel and improved readout techniques, some of which take advantage of the contemporary treatment environment and new QA systems and procedures, as well as other aspects of clinical dosimetry were well represented in the program.Over the past several years, the importance of safety in radiation therapy has been highlighted. The benefits of 3D dosimetry in contributing to safe and accurate treatments cannot be overstated. The implementation of new dosimetry procedures also requires careful attention to safety, accuracy and thorough validation. Therefore, the aims of IC3DDose 2016 were similar to those from previous conferences:• to enhance the quality and accuracy of radiation therapy treatment through improved clinical dosimetry;• to investigate and understand the dosimetric challenges of modern radiation treatment techniques;• to provide a forum to discuss the latest research and developments in 3D and advanced radiation dosimetry; and,• to energize and diversify dosimetry research and clinical practice by encouraging interaction and synergy among advanced, 3D and semi-3D dosimetry techniques.IC3DDose 2016 was a stimulating and exciting conference and the program included substantial contributions to scientific progress in the field.Thanks are offered to those who helped make the conference possible. The Scientific Committee, led by Sam Beddar, conducted thorough peer reviews of submitted papers in a timely manner and made valuable and thoughtful suggestions for improvements. The Committee also contributed to the planning of the meeting and to the organization of the program. The distinguished invited speakers who agreed to present are thanked for the extra work they performed to design and prepare educational and timely talks. My colleagues at MD Anderson Cancer Center are also thanked for their contributions to the planning of the meeting, managing the logistics, and generally helping to make sure that the conference was a success.Geoff IbbottMD Anderson Cancer CenterINTERNATIONAL SCIENTIFIC COMMITTEESam Beddar (Chair) (USA)Claus Andersen (Sweden)Sven Back (Sweden)Clive Baldock (Conference Proceedings Editor) (Australia)Crister Ceberg (Sweden)Yves de Deene (Australia)Simon Doran (United Kingdom)Anna Karlsson Hauer (Sweden)Andrew Jirasek (Canada)Kevin Jordan (Canada)Martin Lepage (Canada)Daniel Low (USA)Mark Oldham (USA)John Schreiner (Canada)Cheng-Shie Wuu (USA)LOCAL ORGANIZING COMMITTEEGeoffrey Ibbott (Chair)Dana GarrisonKayla WhiteHannah LeeYvonne RoedMitchell CarrollSam Beddar

Dosimetric evaluation of IMRT plan for homogenous and inhomogeneous medium using AAPM TG-119 protocol

The American Association of Physicists in Medicine (AAPM) TG-119 protocol has been applied for dose verification in IMRT technique. However, some criteria in the protocol need to be verified for inhomogeneous medium and small volume targets. Hence, the purpose of this study was to verify the assessment criteria of dose verification in AAPM TG-119 for inhomogeneous medium and small volume targets. The work has been conducted by dose verification for homogeneous (phantom A) and inhomogeneous phantoms (phantom B and C) on two geometrical targets: C-shape and circular targets. The targets were simulated using 7 static dMLC IMRT fields at two different depths of 5 g/cm2 and 10 g/cm2. The dose optimisation and calculation were done by using Pinnacle3 for 6 MV photons beam. The planning objectives were set according to AAPM TG-119 parameters. The plan analysis was conducted by Conformity Index and Homogeneity Index. The point dose measurements were conducted with Exradin A16, Semiflex 0.125cc, and Gafchromic EBT3. The plan results show that CI for C-shape target is in the range of 0.710-0.999 at 10 g/cm2 depth and 0.691–1.613 at 5 g/cm2. In addition, HI for C-shape and circular were in the range of 6.3%-58.7% and 5.4%-87.1% for 10 g/cm2 depth. The measurement results show that the dose measurement at inhomogeneous medium and small volume targets are much lower than the criteria in AAPM TG-119. In conclusion, the criteria in the AAPM TG-119 cannot be fully implemented for inhomogeneous medium and small volume targets.

EFFECTIVE DOSES RADIATION TO THE PATIENTS IN EXAMINATIONS PERFORMED IN THREE CT SCANNERS IN BRAZIL†

This work aimed to analyze the effective doses radiation, estimated from the dose-length product, in 4821 examinations carried out in three CT scanners (named as A, B and C) during the period of December 1st 2013 to 30th November 2014 and compare them, with 95% confidence interval, with typical values for the CT practice described in the American Association of Physicists in Medicine (AAPM) Report # 96 (2008). The mean values of effective doses found in the A, B and C equipments were, respectively, 1.55, 2.09 and 1.30 mSv, in head; 7.75, 9.01 and 10.45 mSv in abdomen/pelvis; and 3.87, 7.94 and 3.92 mSv in chest examinations. There were significantly different among each service, except between the A and C equipments in the chest examinations (p = 0.7148). Only the B equipment performed CT scans with effective doses above the US typical values, for head and chest examinations.

Development and testing of a database of NIH research funding of AAPM members: A report from the AAPM Working Group for the Development of a Research Database (WGDRD).

To produce and maintain a database of National Institutes of Health (NIH) funding of the American Association of Physicists in Medicine (AAPM) members, to perform a top-level analysis of these data, and to make these data (hereafter referred to as the AAPM research database) available for the use of the AAPM and its members. NIH-funded research dating back to 1985 is available for public download through the NIH exporter website, and AAPM membership information dating back to 2002 was supplied by the AAPM. To link these two sources of data, a data mining algorithm was developed in Matlab. The false-positive rate was manually estimated based on a random sample of 100 records, and the false-negative rate was assessed by comparing against 99 member-supplied PI_ID numbers. The AAPM research database was queried to produce an analysis of trends and demographics in research funding dating from 2002 to 2015. A total of 566 PI_ID numbers were matched to AAPM members. False-positive and -negative rates were respectively 4% (95% CI: 1-10%, N=100) and 10% (95% CI: 5-18%, N=99). Based on analysis of the AAPM research database, in 2015 the NIH awarded $USD 110M to members of the AAPM. The four NIH institutes which historically awarded the most funding to AAPM members were the National Cancer Institute, National Institute of Biomedical Imaging and Bioengineering, National Heart Lung and Blood Institute, and National Institute of Neurological Disorders and Stroke. In 2015, over 85% of the total NIH research funding awarded to AAPM members was via these institutes, representing 1.1% of their combined budget. In the same year, 2.0% of AAPM members received NIH funding for a total of $116M, which is lower than the historic mean of $120M (in 2015 USD). A database of NIH-funded research awarded to AAPM members has been developed and tested using a data mining approach, and a top-level analysis of funding trends has been performed. Current funding of AAPM members is lower than the historic mean. The database will be maintained by members of the Working group for the development of a research database (WGDRD) on an annual basis, and is available to the AAPM, its committees, working groups, and members for download through the AAPM electronic content website. A wide range of questions regarding financial and demographic funding trends can be addressed by these data. This report has been approved for publication by the AAPM Science Council.

Quality Assurance and Average Glandular dose Measurement in Mammography Units.

To ensure the safe operation of mammography units, acceptance tests and quality assurance (QA) protocols have been developed by the American Association of Physicists in Medicine (AAPM), Engineers Registration Board, and International Atomic Energy Agency. Eight mammography units manufactured by five different manufacturers located in hospitals in our region were investigated following the AAPM and Atomic Energy Regulatory Board (AERB) protocols using a solid-state dosimeter-based PTW-NOMEX Multimeter and a metal-oxide-semiconductor field-effect transistor. This study evaluated different operating parameters through mechanical test, accelerating voltage (kVp) accuracy test, machine output measurement, half-value layer measurement, calibration of compression device, image quality assessment, measurement of leakage radiation, radiation survey, and average glandular dose (AGD) measurements using stereotactic needle biopsy phantom. The results show that out of eight mammography units, only a single mammography unit (U-1) passed all QA tests and 2 units passed 7 tests, 2 units passed 6 tests, and 3 units passed 5 tests out of 8 QA tests. In unit 5, the AGD value was 4 and 1.93 mGy before and after service, respectively. QA programs as recommended by AAPM and AERB should be carried out periodically to ensure safety in breast cancer screening. This work points to the importance of the regulation and effective compliance and also help in both improving the QA and reduce the glandular dose received by the patients.

Validation of Treatment Planning Dose Calculations: Experience Working with Medical Physics Practice Guideline 5.a.

Recently published Medical Physics Practice Guideline 5.a. (MPPG 5.a.) by American Association of Physicists in Medicine (AAPM) sets the minimum requirements for treatment planning system (TPS) dose algorithm commissioning and quality assurance (QA). The guideline recommends some validation tests and tolerances based primarily on published AAPM task group reports and the criteria used by IROC Houston. We performed the commissioning and validation of the dose algorithms for both megavoltage photon and electron beams on three linacs following MPPG 5.a. We designed the validation experiments in an attempt to highlight the evaluation method and tolerance criteria recommended by the guideline. It seems that comparison of dose profiles using in-water scan is an effective technique for basic photon and electron validation. IMRT/VMAT dose calculation is recommended to be tested with some TG-119 and clinical cases, but no consensus of the tolerance exists. Extensive validation tests have provided the better understanding of the accuracy and limitation of a specific dose calculation algorithm. We believe that some tests and evaluation criteria given in the guideline can be further refined.

Evaluation of Intensity Modulated Radiation Therapy Delivery System using a Volumetric Phantom on the Basis of the Task Group 119 Report of American Association of Physicists in Medicine.

The current work describes the implementation of the American Association of Physicists in Medicine (AAPM)'s Task Group 119 report on a volumetric phantom (Delta4, Scandidos, Uppsala, Sweden) following the stated dose goals, to evaluate the step-and-shoot intensity modulated radiation therapy (IMRT) system. Delta4 consists of diode detectors, lying on two crossed planes, measuring the delivered dose, and providing two-dimensional dosimetric information. Seven plans of different goals and complexity were performed, with individual structure sets. TG199 structure sets and plans were transferred and implemented on the Delta4 phantom taking into account its cylindrical geometry. All plans were delivered with a 6 MV linear accelerator equipped with multileaf collimator of 1 cm thickness. Plan results for each test met the recommended dose goals. The evaluation was performed in terms of dose deviation, distance to agreement, and gamma index passing rate. In all test cases, the gamma index passing rate was measured >90%. Delta4 phantom has proven to be fast, applicable, and reliable for the step-and-shoot IMRT commissioning following TG119's recommended tests. Although AAPM's TG119 report is referring to the implementation of test plans that do not correspond to patient plans, it could be used as an evaluation tool of various IMRT systems, considering the local treatment planning system and the delivery system.

A Study to Determine Whether the Volume-Weighted Computed Tomography Dose Index Gives Reasonable Estimates of Organ Doses for Thai Patients Undergoing Abdomen and Pelvis Computed Tomography Examinations.

Introduction:Values for the CTDIvol, which is displayed on scanner consoles, give doses relative to a phantom much larger than most Thai patients, and the CTDIvol does not take account of differences in patient size, which affect organ doses.Objective:The purpose of this study was to evaluate relationships for size specific dose estimate (SSDE) and volume weighted computed tomography (CT) dose index (CTDIvol) with patient size for CT scanners operating under automatic tube current modulation (ATCM).Methods:Retrospective data from 244 patients who had undergone abdomen and pelvis examination on GE and Siemens CT scanners were included in this study. The combination of anteroposterior (AP) and lateral dimensions at the level of the first lumbar vertebra (L1) was used to represent patient size. Image noise within the liver was measured, and values of the absorbed dose for organs covered by the primary beam such as the liver, stomach and kidney were calculated using methods described in the literature. Values of CTDIvol were recorded and SSDE calculated according to the American Association of Physics in Medicine (AAPM) Report No.204. Linear regression models were used to evaluate the relationship between SSDE, CTDIvol, image noise and patient size.Results:SSDE is 20%-50% larger than the CTDIvol, with values for larger patients being more representative. Both the CTDIvol and image noise decreased with patient size for Siemens scanners, but the decline in SSDE was less significant. For the GE scanner, the CTDIvol was a factor of 3-4 lower in small patients compared to larger ones, while the SSDE only decreased by a factor of two. Noise actually decreased slightly with patient size.Conclusion:Values of SSDE were similar to the doses calculated for the liver, stomach and kidney, which are covered by the primary beam, confirming that it provides a good estimate of organ-absorbed dose.

A survey on table tolerances and couch overrides in radiotherapy.

The purpose of this study was to survey current departmental policies on treatment couch overrides and the values of table tolerances used clinically. A 25‐question electronic survey on couch overrides and tolerances was sent to full members of the American Association of Physicists in Medicine (AAPM). The first part of the survey asked participants if table overrides were allowed at their institution, who was allowed to perform these overrides, and if imaging was required with overrides. The second part of the survey asked individuals to provide table tolerance data for the following treatment sites: brain/head and neck (H&N), lung, breast, abdomen/pelvis and prostate. Each site was further divided into IMRT/VMAT and 3D conformal techniques. Spaces for free‐text were provided, allowing respondents to enter any table tolerance data they were unable to specify under the treatment sites listed. A total of 361 individuals responded, of which approximately half participated in the couch tolerances portion of the survey. Overall, 86% of respondents’ institutions allow couch tolerance overrides at treatment. Therapists were the most common staff members permitted to perform overrides, followed by physicists, dosimetrists, and physicians, respectively. Of the institutions allowing overrides, 34% reported overriding daily. More than half of the centers document the override and/or require a setup image to radiographically verify the treatment site. With respect to table tolerances, SRS/SBRT table tolerances were the tightest, while clinical setup table tolerances were the largest. There were minimal statistically significant differences between IMRT/VMAT and 3D conformal table tolerances. Our results demonstrated that table overrides are relatively common in radiotherapy despite being a potential safety concern. Institutions should review their override policy and table tolerance values in light of the practices of other institutions. Careful attention to these matters is crucial in ensuring the safe and accurate delivery of radiotherapy.PACS number(s): 87.55.N‐, 87.55.Qr, 87.55.T‐

Radiation dose in cardiac SPECT/CT: An estimation of SSDE and effective dose

AimsThe dose levels for Computed Tomography (CT) localization and attenuation correction of Single Photon Emission Computed Tomography (SPECT) are limited and reported as Volume Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP). This work presents CT dose estimation from Cardiac SPECT/CT based on new American Association of Physicists in Medicine (AAPM) Size Specific Dose Estimation (SSDE) parameter, effective dose, organ doses and also emission dose from nuclear issue. Material and methodsMyocardial perfusion SPECT/CT for 509 patients was included in the study. SSDE, effective dose and organ dose were calculated using AAPM guideline and Impact-Dose software. Data were analyzed using R and SPSS statistical software. Spearman-Pearson correlation test and linear regression models were used for finding correlations and relationships among parameters. ResultsThe mean CTDIvol was 1.34 mGy±0.19 and the mean SSDE was 1.7 mGy±0.16. The mean±SD of effective dose from emission, CT and total dose were 11.5±1.4, 0.49±0.11 and 12.67±1.73 (mSv) respectively. The mean±SD of effective dose from emission, CT and total dose were 11.5±1.4, 0.49±0.11 and 12.67±1.73 (mSv) respectively. The spearman test showed that correlation between body size and organ doses is significant except thyroid and red bone marrow. CTDIvol was strongly dependent on patient size, but SSDE was not. Emission dose was strongly dependent on patient weight, but its dependency was lower to effective diameter. ConclusionThe dose parameters including CTDIvol, DLP, SSDE, effective dose values reported here are very low and below the reference level. This data suggest that appropriate CT acquisition parameters in SPECT/CT localization and attenuation correction are very beneficial for patients and lowering cancer risks.

Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study.

The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8-40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2% for phantom diameters ≥11.2cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111.

Monte Carlo calculations and experimental measurements of the TG-43U1-recommended dosimetric parameters of 125I (Model IR-Seed2) brachytherapy source.

A new design of I125 (Model IR‐Seed2) brachytherapy source has been manufactured recently at the Applied Radiation Research School, Nuclear Science and Technology Research Institute in Iran. The source consists of six resin beads (0.5 mm diameter) that are sealed in a cylindrical titanium capsule of 0.7 mm internal and 0.8 mm external diameters. This work aims to evaluate the dosimetric parameters of the newly designed I125 source using experimental measurements and Monte Carlo (MC) simulations. Dosimetric characteristics (dose rate constant, radial dose function, and 2D and 1D anisotropy functions) of the IR‐Seed2 were determined using experimental measurements and MC simulations following the recommendations by the Task Group 43 (TG‐43U1) report of the American Association of Physicists in Medicine (AAPM). MC simulations were performed using the MCNP5 code in water and Plexiglas, and experimental measurements were carried out using thermoluminescent dosimeters (TLD‐GR207A) in Plexiglas phantoms. The measured dose to water in Plexiglas data were used for verification of the accuracy of the source and phantom geometry in the Monte Carlo simulations. The final MC simulated data to water in water were recommended for clinical applications. The MC calculated dose rate constant (Λ) of the IR‐Seed2 I125 seed in water was found to be 0.992±0.025 cGy h−1U−1. Additionally, its radial dose function by line and point source approximations, gL(r) and gp(r), calculated for distances from 0.1 cm to 7 cm. The values of gL(r) at radial distances from 0.5 cm to 5 cm were measured in a Plexiglas phantom to be between 1.212 and 0.413. The calculated and measured of values for 2D anisotropy function, F(r,θ), were obtained for the radial distances ranging from 1.5 cm to 5 cm and angular range of 0°‐90° in a Plexiglas phantom. Also, the 2D anisotropy function was calculated in water for the clinical application. The results of these investigations show that the uncertainty of the experimental data is within ±7% between the measured and simulated data in Plexiglas. Based on these results, the MC‐simulated dosimetric parameters of the new I125 source model in water are presented for its clinical applications in brachytherapy treatments.PACS number(s): 87.56.bg

TU‐D‐201‐04: Veracity of Data Elements in Radiation Oncology Incident Learning Systems

Purpose:Incident learning systems encompass volumes, varieties, values, and velocities of underlying data elements consistent with the V's of big data. Veracity, the 5th V however exists only if there is high inter‐rater reliability (IRR) within the data elements. The purpose of this work was to assess IRR in the nationally deployed RO‐ILS: Radiation Oncology‐Incident Learning System (R) sponsored by the American Society for Radiation Oncology (ASTRO) and the American Association of Physicists in Medicine (AAPM).Methods:Ten incident reports covering a wide range of scenarios were created in standardized narrative and video formats and disseminated to 67 volunteers of multiple disciplines from 26 institutions along with two published narratives from the International Commission of Radiological Protection to assess IRR on a nationally representative level. The volunteers were instructed to independently enter the associated data elements in a test version of RO‐ILS over a 3‐week period. All responses were aggregated into a spreadsheet to assess IRR using free‐marginal kappa metrics.Results:48 volunteers from 21 institutions completed all reports in the study period. The average kappa score for all raters across all critical data elements was 0.659 [range 0.326–1.000]. Statistically significant differences (p <0.05) were noted between reporters of different disciplines and raters with varying levels of experience. Kappa scores were high for event classification (0.781) and contributory factors (0.777) and low for likelihood‐of‐harm (0.326). IRR was highest among AAPM‐ASTRO members (0.672) and lowest among trainees (0.463).Conclusion:A moderate‐to‐substantial level of IRR in RO‐ILS was noted in this study. Although the number of events reviewed in this study was small, opportunities for improving the taxonomy for the lower scoring data elements as well as specific educational targets for training were identified by assessing data veracity quantitatively. This is expected to improve the quality of the data garnered from RO‐ILS.

SU‐F‐T‐270: A Technique for Modeling a Diode Array Into the TPS for Lung SBRT Patient Specific QA

Purpose:To accurately match the treatment planning system (TPS) with the measurement environment, where quality assurance (QA) devices are used to collect data, for lung Stereotactic Body Radiation Therapy (SBRT) patient specific QA. Incorporation of heterogeneities is also studied.Methods:Dual energy computerized tomography (DECT) and single energy computerized tomography (SECT) were used to model phantoms incorporating a 2‐D diode array into the TPS. A water‐equivalent and a heterogeneous phantom (simulating the thoracic region of a patient) were studied. Monte Carlo and pencil beam planar dose distributions were compared to measured distributions. Composite and individual fields were analyzed for normally incident and planned gantry angle deliveries. γ‐ analysis was used with criteria 3% 3mm, 2% 2mm, and 1% 1mm.Results:The Monte Carlo calculations for the DECT resulted in improved agreements with the diode array for 46.4% of the fields at 3% 3mm, 85.7% at 2% 2mm, and 92.9% at 1% 1mm.For the SECT, the Monte Carlo calculations gave no agreement for the same γ‐analysis criteria. Pencil beam calculations resulted in lower agreements with the diode array in the TPS. The DECT showed improvements for 14.3% of the fields at 3% 3mm and 2% 2mm, and 28.6% at 1% 1mm.In SECT comparisons, 7.1% of the fields at 3% 3mm, 10.7% at 2% 2mm, and 17.9% at 1% 1mm showed improved agreements with the diode array.Conclusion:This study demonstrates that modeling the diode array in the TPS is viable using DECT with Monte Carlo for patient specific lung SBRT QA. As recommended by task groups (e.g. TG 65, TG 101, TG 244) of the American Association of Physicists in Medicine (AAPM), pencil beam algorithms should be avoided in the presence of heterogeneous materials, including a diode array.

TU‐D‐201‐03: Results of a Survey On the Implementation of the TG‐51 Protocol and Associated Addendum On Reference Dosimetry of External Beams

Purpose:The working group on the review and extension of the TG‐51 protocol (WGTG51) collected data from American Association of Physicists in Medicine (AAPM) members with respect to their current TG‐51 and associated addendum usage in the interest of considering future protocol addenda and guidance on reference dosimetry best practices. This study reports an overview of this survey on dosimetry of external beams.Methods:Fourteen survey questions were developed by WGTG51 and released in November 2015. The questions collected information on reference dosimetry, beam quality specification, and ancillary calibration equipment.Results:Of the 190 submissions completed worldwide (U.S. 70%), 83% were AAPM members. Of the respondents, 33.5% implemented the TG‐51 addendum, with the maximum calibration difference for any photon beam, with respect to the original TG‐51 protocol, being <1% for 97.4% of responses. One major finding is that 81.8% of respondents used the same cylindrical ionization chamber for photon and electron dosimetry, implying that many clinics are foregoing the use of parallel‐plate chambers. Other evidence suggests equivalent dosimetric results can be obtained with both cylindrical and parallel‐plate chambers in electron beams. This, combined with users comfort with cylindrical chambers for electrons will likely impact recommendations put forward in an upcoming electron beam addendum to the TG‐51 protocol. Data collected on ancillary equipment showed 58.2% (45.0%) of the thermometers (barometers) in use for beam calibration had NIST traceable calibration certificates, but 48.4% (42.7%) were never recalibrated.Conclusion:This survey provides a snapshot of TG‐51 external beam reference dosimetry practice in radiotherapy centers. Findings demonstrate the rapid take‐up of the TG‐51 photon beam addendum and raise issues for the WGTG51 to focus on going forward, including guidelines on ancillary equipment and the choice of chamber for electron beam dosimetry.

The effect of time in use on the display performance of the iPad

The aim of this study was to evaluate changes to the luminance, luminance uniformity and conformance to the digital imaging and communication in medicine greyscale standard display function (GSDF) as a function of time in use for the iPad. Luminance measurements of the American Association of Physicists in Medicine (AAPM) Group 18 task group (TG18) luminance uniformity and luminance test patterns (TG18-UNL and TG18-LN8) were performed using a calibrated near-range luminance meter. Nine sets of measurements were taken, where the time in use of the iPad ranged from 0 to 2500 h. The maximum luminance (Lmax) of the display decreased (367-338 cdm(-2)) as a function of time. The minimum luminance remained constant. The maximum non-uniformity coefficient was 11%. Luminance uniformity decreased slightly as a function of time in use. The conformance of the iPad deviated from the GSDF curve at commencement of use. Deviation did not increase as a function of time in use. This study has demonstrated that the iPad display exhibits luminance degradation typical of liquid crystal displays. The Lmax of the iPad fell below the American College of Radiology-AAPM-Society of Imaging Informatics in Medicine recommendations for primary displays (>350 cdm(-2)) at approximately 1000 h in use. The Lmax recommendation for secondary displays (>250 cdm(-2)) was exceeded during the entire study. The maximum non-uniformity coefficient did not exceed the recommendations for either primary or secondary displays. The deviation from the GSDF exceeded the recommendations of the TG18 for use as either a primary or secondary display. The brightness, uniformity and contrast response are reasonably stable over the useful lifetime of the device; however, the device fails to meet the contrast response standard for either a primary or secondary display.

Quality Assurance of Sterile, Single Use Savi(TM) Applicators at the Time of Simulation to Verify That Channel Positions Do Not Deviate from Their Expected Locations

Quality Assurance of Sterile, Single Use Savi(TM) Applicators at the Time of Simulation to Verify That Channel Positions Do Not Deviate from Their Expected Locations

Best practices for safety improvement through high-volume institutional incident learning: lessons learned from 2 years

Incident learning systems (ILSs) are a key component of improving patient safety in radiation oncology, but the practicalities of ILS implementation can present major challenges. We describe the implementation and best practices derived from 2 years of experience with institutional incident learning, with details on root cause analysis (RCA), a list of key process improvements, and operational aspects of ILS use. The structure of the ILS is consistent with recommendations from the American Association of Physicists in Medicine (AAPM). Workflow is analyzed for incident reports from initial reporting to analysis and feedback to the reporter, including staffing required. A system for incident categorization is shown, as well as sample events selected for root cause analysis, and suggestions for providing feedback to users of ILS. In the first 2 years of the ILS implementation from 2012 to 2014, 1897 near-miss incidents were reported. There is widespread participation in the ILS program across all professional groups inside the department, with at least 75 % of clinical staff having filed at least one report. Total workload for the ILS program is estimated to be approximately one full-time employee, shared by approximately eight team members. Fifteen events were selected for RCA during this period. Eighteen major process improvement projects are described, ranging from issues related to process standardization, automation, staffing, new organization structures, and equipment purchase. A unique high reporting volume institutional ILS has successfully resulted in numerous improvements in process, safety, and quality. Details for implementation and best practices for incident learning have been presented to allow adaptation in other practices.