bluuebunny/crossref_metadata_2025 huggingface dataset:
SU‐D‐204‐05: Fitting Four NTCP Models to Treatment Outcome Data of Salivary Glands Recorded Six Months After Radiation Therapy for Head and Neck Tumors
Authors: Mavroidis P , Price A , Kostich M , Amdur R , Mendenhall W , Sheets N , Green R , Das S , Marks L , Chera B
Published: July 2016

Purpose:

To estimate the radiobiological parameters of four popular NTCP models that describe the dose‐response relations of salivary glands to the severity of patient reported dry mouth 6 months post chemo‐radiotherapy. To identify the glands, which best correlate with the manifestation of those clinical endpoints. Finally, to evaluate the goodness‐of‐fit of the NTCP models.

Methods:

Forty‐three patients were treated on a prospective multiinstitutional phase II study for oropharyngeal squamous cell carcinoma. All the patients received 60 Gy IMRT and they reported symptoms using the novel patient reported outcome version of the CTCAE. We derived the individual patient dosimetric data of the parotid and submandibular glands (SMG) as separate structures as well as combinations. The Lyman‐Kutcher‐Burman (LKB), Relative Seriality (RS), Logit and Relative Logit (RL) NTCP models were used to fit the patients data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC) and the Odds Ratio methods.

Results:

The AUC values were highest for the contralateral parotid for Grade ≥ 2 (0.762 for the LKB, RS, Logit and 0.753 for the RL). For the salivary glands the AUC values were: 0.725 for the LKB, RS, Logit and 0.721 for the RL. For the contralateral SMG the AUC values were: 0.721 for LKB, 0.714 for Logit and 0.712 for RS and RL. The Odds Ratio for the contralateral parotid was 5.8 (1.3–25.5) for all the four NTCP models for the radiobiological dose threshold of 21Gy.

Conclusion:

It was shown that all the examined NTCP models could fit the clinical data well with very similar accuracy. The contralateral parotid gland appears to correlated best with the clinical endpoints of severe/very severe dry mouth. An EQD2Gy dose of 21Gy appears to be a safe threshold to be used as a constraint in treatment planning.
SU‐D‐204‐07: Retrospective Correlation of Dose Accuracy with Regions of Local Failure for Early Stage Lung Cancer Patients Treated with Stereotactic Body Radiotherapy
Authors: Devpura S , Li H , Liu C , Fraser C , Ajlouni M , Movsas B , Chetty I
Published: July 2016

Purpose:

To correlate dose distributions computed using six algorithms for recurrent early stage non‐small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT), with outcome (local failure).

Methods:

Of 270 NSCLC patients treated with 12Gyx4, 20 were found to have local recurrence prior to the 2‐year time point. These patients were originally planned with 1‐D pencil beam (1‐D PB) algorithm. 4D imaging was performed to manage tumor motion. Regions of local failures were determined from follow‐up PET‐CT scans. Follow‐up CT images were rigidly fused to the planning CT (pCT), and recurrent tumor volumes (Vrecur) were mapped to the pCT. Dose was recomputed, retrospectively, using five algorithms: 3‐D PB, collapsed cone convolution (CCC), anisotropic analytical algorithm (AAA), AcurosXB, and Monte Carlo (MC). Tumor control probability (TCP) was computed using the Marsden model (1,2). Patterns of failure were classified as central, in‐field, marginal, and distant for Vrecur ≥95% of prescribed dose, 95–80%, 80–20%, and ≤20%, respectively (3).

Results:

Average PTV D95 (dose covering 95% of the PTV) for 3‐D PB, CCC, AAA, AcurosXB, and MC relative to 1‐D PB were 95.3±2.1%, 84.1±7.5%, 84.9±5.7%, 86.3±6.0%, and 85.1±7.0%, respectively. TCP values for 1‐D PB, 3‐D PB, CCC, AAA, AcurosXB, and MC were 98.5±1.2%, 95.7±3.0, 79.6±16.1%, 79.7±16.5%, 81.1±17.5%, and 78.1±20%, respectively. Patterns of local failures were similar for 1‐D and 3D PB plans, which predicted that the majority of failures occur in centraldistal regions, with only ∼15% occurring distantly. However, with convolution/superposition and MC type algorithms, the majority of failures (65%) were predicted to be distant, consistent with the literature.

Conclusion:

Based on MC and convolution/superposition type algorithms, average PTV D95 and TCP were ∼15% lower than the planned 1‐D PB dose calculation. Patterns of failure results suggest that MC and convolution/superposition type algorithms predict different outcomes for patterns of failure relative to PB algorithms.

Work supported in part by Varian Medical Systems, Palo Alto, CA
SU‐D‐201‐01: A Multi‐Institutional Study Quantifying the Impact of Simulated Linear Accelerator VMAT Errors for Nasopharynx
Authors: Pogson E , Hansen C , Blake S , Arumugam S , Juresic J , Ochoa C , Yakobi J , Haman A , Trtovac A , Holloway L , Thwaites D
Published: July 2016

Purpose:

To quantify the impact of differing magnitudes of simulated linear accelerator errors on the dose to the target volume and organs at risk for nasopharynx VMAT.

Methods:

Ten nasopharynx cancer patients were retrospectively replanned twice with one full arc VMAT by two institutions. Treatment uncertainties (gantry angle and collimator in degrees, MLC field size and MLC shifts in mm) were introduced into these plans at increments of 5,2,1,−1,−2 and −5. This was completed using an in‐house Python script within Pinnacle3 and analysed using 3DVH and MatLab. The mean and maximum dose were calculated for the Planning Target Volume (PTV1), parotids, brainstem, and spinal cord and then compared to the original baseline plan. The D1cc was also calculated for the spinal cord and brainstem. Patient average results were compared across institutions.

Results:

Introduced gantry angle errors had the smallest effect of dose, no tolerances were exceeded for one institution, and the second institutions VMAT plans were only exceeded for gantry angle of ±5° affecting different sided parotids by 14–18%. PTV1, brainstem and spinal cord tolerances were exceeded for collimator angles of ±5 degrees, MLC shifts and MLC field sizes of ±1 and beyond, at the first institution. At the second institution, sensitivity to errors was marginally higher for some errors including the collimator error producing doses exceeding tolerances above ±2 degrees, and marginally lower with tolerances exceeded above MLC shifts of ±2. The largest differences occur with MLC field sizes, with both institutions reporting exceeded tolerances, for all introduced errors (±1 and beyond).

Conclusion:

The plan robustness for VMAT nasopharynx plans has been demonstrated. Gantry errors have the least impact on patient doses, however MLC field sizes exceed tolerances even with relatively low introduced errors and also produce the largest errors. This was consistent across both departments.

The authors acknowledge funding support from the NSW Cancer Council.
SU‐D‐201‐04: Evaluation of Elekta Agility MLC Performance Using Statistical Process Control
Authors: Meyers SM , Balderson MJ , Letourneau D
Published: July 2016

Purpose:

to evaluate the performance and stability of the Elekta Agility MLC model using an automated quality control (QC) test in combination with statistical process control tools.

Methods:

Leaf positions were collected daily for 11 Elekta units over 5–19 months using the automated QC test, which analyzes 23 MV images to determine the location of MLC leaves relative to the radiation isocenter. The leaf positions are measured at 5 nominal positions, and images are acquired at collimator 0° and 180° to capture all MLC leaves in the field‐of‐view. Leaf positioning accuracy was assessed using individual and moving range control charts. Control limits were recomputed following MLC recalibration (occurred 1–2 times for 4 units). Specification levels of ±0.5, ±1 and ±1.5mm were tested. The mean and range of duration between out‐of‐control and out‐of‐specification events were determined.

Results:

Leaf position varied little over time, as confirmed by very tight individual control limits (mean ±0.19mm, range 0.09–0.44). Mean leaf position error was −0.03mm (range −0.89–0.83). Due to sporadic out‐of‐control events, the mean in‐control duration was 3.3 days (range 1–23). Data stayed within ±1mm specification for 205 days on average (range 3–372) and within ±1.5mm for the entire date range. Measurements stayed within ±0.5mm for 1 day on average (range 0–17); however, our MLC leaves were not calibrated to this level of accuracy.

Conclusion:

The Elekta Agility MLC model was found to perform with high stability, as evidenced by the tight control limits. The in‐specification durations support the current recommendation of monthly MLC QC tests with a ±1mm tolerance. Future work is on‐going to determine if Agility performance can be optimized further using high‐frequency QC test results to drive recalibration frequency. Factors that can affect leaf positioning accuracy, including beam spot motion, leaf gain calibration, drifting leaves, and image artifacts, are under investigation.
SU‐D‐201‐06: Remote Dosmetric Auditing of VMAT Deliveries for Clinical Trials Using EPID
Authors: Legge K , Lehmann J , Vial P , Miri N , Greer P
Published: July 2016

Purpose:

To develop a method for remote dosimetric auditing the delivery of VMAT using EPID which allows for simple, inexpensive and time efficient dosimetric credentialing for clinical trials.

Methods:

Remote centers are provided with CT datasets and planning guidelines to produce VMAT plans for a head and neck and a post‐prostatectomy treatment. Plans are transferred in the planning system to two virtual water equivalent phantoms, one flat and one cylindrical. Cine images are acquired during VMAT delivery to the EPID in air with gantry angle recorded in image headers. Centers also deliver provided calibration plans to enable EPID signal to dose conversion, determination of the central axis, and correction of EPID sag prior to analysis. EPID images and planned doses are sent to the central site. EPID cine images are converted to dose in the virtual phantoms using an established backprojection method (King et al., Med.Phys. 2012) with EPID backscatter correction. Individual arcs (with gantry angles collapsed to zero) are evaluated at 10 cm depth in the flat phantom using 2D gamma, and total doses are evaluated in the cylindrical phantom using 3D gamma. Results are reported for criteria of 3%,3mm, 3%,2mm and 2%,2mm for all points greater than 10% of global maximum.

Results:

The pilot study for Varian centers has commenced, and three centers have been audited for head and neck plans and two for post‐prostatectomy plans to date. The mean pass rate for arc‐by‐arc 2D analysis at 3%,3mm is 99.5% and for 3D analysis is 95.8%. A method for Elekta linacs using an inclinometer for gantry angle information is under development.

Conclusion:

Preliminary results for this new method are promising. The method takes advantage of EPID equipment available at most centers and clinically established software to provide a feasible, low cost solution to credentialing centers for clinical trials.

Funding has been provided from Calvary Mater Newcastle Department of Radiation Oncology, TROG Cancer Research and the University of Newcastle. Kimberley Legge is the recipient of an Australian Postgraduate Award. Narges Miri is a recipient of a University of Newcastle postgraduate scholarship.
SU‐D‐BRC‐04: Development of Proton Tissue Equivalent Materials for Calibration and Dosimetry Studies
Authors: Olguin E , Flampouri S , Lipnharski I , Bolch W
Published: July 2016

Purpose:

To develop new proton tissue equivalent materials (PTEM), urethane and fiberglass based, for proton therapy calibration and dosimetry studies. Existing tissue equivalent plastics are applicable only for x‐rays because they focus on matching mass attenuation coefficients. This study aims to create new plastics that match mass stopping powers for proton therapy applications instead.

Methods:

New PTEMs were constructed using urethane and fiberglass resin materials for soft, fat, bone, and lung tissue. The stoichiometric analysis method was first used to determine the elemental composition of each unknown constituent. New initial formulae were then developed for each of the 4 PTEMs using the new elemental compositions and various additives. Samples of each plastic were then created and exposed to a well defined proton beam at the UF Health Proton Therapy Institute (UFHPTI) to validate its mass stopping power.

Results:

The stoichiometric analysis method revealed the elemental composition of the 3 components used in creating the PTEMs. These urethane and fiberglass based resins were combined with additives such as calcium carbonate, aluminum hydroxide, and phenolic micro spheres to achieve the desired mass stopping powers and densities. Validation at the UFHPTI revealed adjustments had to be made to the formulae, but the plastics eventually had the desired properties after a few iterations. The mass stopping power, density, and Hounsfield Unit of each of the 4 PTEMs were within acceptable tolerances.

Conclusion:

Four proton tissue equivalent plastics were developed: soft, fat, bone, and lung tissue. These plastics match each of the corresponding tissue's mass stopping power, density, and Hounsfield Unit, meaning they are truly tissue equivalent for proton therapy applications. They can now be used to calibrate proton therapy treatment planning systems, improve range uncertainties, validate proton therapy Monte Carlo simulations, and assess in‐field and out‐of‐field organ doses.
SU‐D‐BRC‐05: Effects of Motion and Variable RBE in a Lung Patient Treated with Passively Scattered Protons
Authors: Mirkovic D , Titt U , Yepes P , Mohan R
Published: July 2016

Purpose:

To evaluate effects of motion and variable relative biological effectiveness (RBE) in a lung cancer patient treated with passively scattered proton therapy using dose volume histograms associated with patient dose computed using three different methods.

Methods:

A proton treatment plan of a lung cancer patient optimized using clinical treatment planning system (TPS) was used to construct a detailed Monte Carlo (MC) model of the beam delivery system and the patient specific aperture and compensator. A phase space file containing all particles transported through the beam line was collected at the distal surface of the range compensator and subsequently transported through two different patient models. The first model was based on the average CT used by the TPS and the second model included all 10 phases of the corresponding 4DCT. The physical dose and proton linear energy transfer (LET) were computed in each voxel of two models and used to compute constant and variable RBE MC dose on average CT and 4D CT. The MC computed doses were compared to the TPS dose using dose volume histograms for relevant structures.

Results:

The results show significant differences in doses to the target and critical structures suggesting the need for more accurate proton dose computation methods. In particular, the 4D dose shows reduced coverage of the target and higher dose to the spinal cord, while variable RBE dose shows higher lung dose.

Conclusion:

The methodology developed in this pilot study is currently used for the analysis of a cohort of ∼90 lung patients from a clinical trial comparing proton and photon therapy for lung cancer. The results from this study will help us in determining the clinical significance of more accurate dose computation models in proton therapy.
SU‐D‐BRC‐07: System Design for a 3D Volumetric Scintillation Detector Using SCMOS Cameras
Authors: Darne C , Robertson D , Alsanea F , Beddar S
Published: July 2016

Purpose:

The purpose of this project is to build a volumetric scintillation detector for quantitative imaging of 3D dose distributions of proton beams accurately in near real‐time.

Methods:

The liquid scintillator (LS) detector consists of a transparent acrylic tank (20×20×20 cm3) filled with a liquid scintillator that when irradiated with protons generates scintillation light. To track rapid spatial and dose variations in spot scanning proton beams we used three scientific‐complementary metal‐oxide semiconductor (sCMOS) imagers (2560×2160 pixels). The cameras collect optical signal from three orthogonal projections. To reduce system footprint two mirrors oriented at 45° to the tank surfaces redirect scintillation light to cameras for capturing top and right views. Selection of fixed focal length objective lenses for these cameras was based on their ability to provide large depth of field (DoF) and required field of view (FoV). Multiple cross‐hairs imprinted on the tank surfaces allow for image corrections arising from camera perspective and refraction.

Results:

We determined that by setting sCMOS to 16‐bit dynamic range, truncating its FoV (1100×1100 pixels) to image the entire volume of the LS detector, and using 5.6 msec integration time imaging rate can be ramped up to 88 frames per second (fps). 20 mm focal length lens provides a 20 cm imaging DoF and 0.24 mm/pixel resolution. Master‐slave camera configuration enable the slaves to initiate image acquisition instantly (within 2 µsec) after receiving a trigger signal. A computer with 128 GB RAM was used for spooling images from the cameras and can sustain a maximum recording time of 2 min per camera at 75 fps.

Conclusion:

The three sCMOS cameras are capable of high speed imaging. They can therefore be used for quick, high‐resolution, and precise mapping of dose distributions from scanned spot proton beams in three dimensions.
SU‐F‐E‐04: A Paris System‐Based Implant Approach to Hyperthermia Cancer Tumor with Gold Seeds and Ultrasound
Authors: Austerlitz C , Barros A , Gkigkitzis I , Haranas I , Zhu D , Campos D
Published: July 2016

Purpose:

To apply the Paris system‐based implant for an uniform bio‐heat distribution from implanted gold rods in tissue insonated with ultrasound.

Methods:

Experiments with single‐plane implants using parallel equidistant 1.018 ± 0.015 cm height and 0.136 ± 0.001 cm diameter 24‐K gold rods) arranged in triangular and square shapes were performed in Mus Musculus white mice (medial dorsal region). The mice were anesthetized and gold rods were implanted by means of a trocar needle and the implanted region was insonated with a 4‐cm diameter transducer oscillating with a nominal frequency of 1 MHz and power of about 75 W. Intramuscular tissue temperature measurements were taken using implantable needle type thermocouples affixed to a portable Fluke thermometer. Superficial tissue temperature profile was also measured with a FLIR infrared camera and thermographic analysis were performed using the ImageJ computer software. In both cases, the central implant planes have been assigned to that approximately bisects all the implanted rods.

Results:

Measured with the needle type thermistor, for the triangular implant, the percentage deviation between the maximum and minimum temperature within the triangular plane was 5%. For a square shape, this percentage deviation was 6%. The thermographic analysis have shown a deviation of 3% and 5% for the triangular and square shapes, respectively.

Conclusion:

Based on the temperature measurements with needle type thermistor and thermographic analysis, the Paris system‐based implant approach for gold rods implanted in tissue and exposed to ultrasound may greatly improve the bio‐heat propagation and sustain a constant temperature profile inside triangular and square patterns formed by gold rods implants. Additionally, the Paris system may minimize ablations areas and treatment length in hyperthermia if used in cancer tumor treatment.
SU‐F‐E‐06: Dosimetric Characterization of Small Photons Beams of a Novel Linear Accelerator
Authors: Almonte A , Polanco G , Sanchez E
Published: July 2016

Purpose:

The aim of the present contribution was to measure the main dosimetric quantities of small fields produced by UNIQUE and evaluate its matching with the corresponding dosimetric data of one 21EX conventional linear accelerator (Varian) in operation at the same center. The second step was to evaluate comparative performance of the EDGE diode detector and the PinPoint micro‐ionization chamber for dosimetry of small fields.

Methods:

UNIQUE is configured with MLC (120 leaves with 0.5 cm leaf width) and a single low photon energy of 6 MV. Beam data were measured with scanning EDGE diode detector (volume of 0.019 mm3), a PinPoint micro‐ionization chamber (PTW) and for larger fields (≥ 4×4cm2) a PTW Semi flex chamber (0.125 cm3) was used. The scanning system used was the 3D cylindrical tank manufactured by Sun Nuclear, Inc. The measurement of PDD and profiles were done at 100 cm SSD and 1.5 depth; the relative output factors were measured at 10 cm depth.

Results:

PDD and the profile data showed less than 1% variation between the two linear accelerators for fields size between 2×2 cm2 and 5×5cm2. Output factor differences was less than 1% for field sizes between 3×3 cm2 and 10×10 cm2 and less of 1.5 % for fields of 1.5×1.5 cm2 and 2×2 cm2 respectively. The dmax value of the EDGE diode detector, measured from the PDD, was 8.347 mm for 0.5×0,5cm2 for UNIQUE. The performance of EDGE diode detector was comparable for all measurements in small fields.

Conclusion:

UNIQUE linear accelerator show similar dosimetrics characteristics as conventional 21EX Varian linear accelerator for small, medium and large field sizes.EDGE detector show good performance by measuring dosimetrics quantities in small fields typically used in IMRT and radiosurgery treatments.
SU‐F‐E‐12: Elective International Rotations in Medical Physics Residency Programs
Authors: Brown D , Mundt A , Einck J , Pawlicki T
Published: July 2016

Purpose:

The purpose of this educational program is to motivate talented, intelligent individuals to become stakeholders in the global effort to improve access to radiotherapy.

Methods:

The need to improve global access to radiotherapy has been clearly established and several organizations are making substantial progress in securing funding and developing plans to achieve this worthwhile goal. The incorporation of elective international rotations in residency programs may provide one possible mechanism to promote and support this future investment. We recently incorporated an elective 1‐month international rotation into our CAMPEP accredited Medical Physics residency program, with our first rotation taking place in Vietnam. A unique aspect of this rotation was that it was scheduled collaboratively with our Radiation Oncology residency program such that Radiation Oncology and Medical Physics residents traveled to the same clinic at the same time.

Results:

We believe the international rotation substantially enhances the educational experience, providing additional benefits to residents by increasing cross‐disciplinary learning and offering a shared learning experience. The combined international rotation may also increase benefit to the host institution by modeling positive multidisciplinary working relationships between Radiation Oncologists and Medical Physicists. Our first resident returned with several ideas designed to improve radiotherapy in resource‐limited settings – one of which is currently being pursued in collaboration with a vendor.

Conclusion:

The elective international rotation provides a unique learning experience that has the potential to motivate residents to become stakeholders in the global effort to improve access to radiotherapy. What better way to prepare the next generation of Medical Physicists to meet the challenges of improving global access to radiotherapy than to provide them with training experiences that motivate them to be socially conscious and equip them with the clinical and problem solving skills required to deliver effective treatments in resource limited settings?
SU‐F‐E‐14: Global Radiation Oncology Education and Training in Medical Physics Powered by Information and Communication Technologies
Authors: Ngwa W , Sajo E , Ngoma T , Dachi J , Julius Mwaiselage J , Kenton O , Avery S
Published: July 2016

Purpose:

Recent publications have highlighted the potential of Information and Communication Technologies (ICTs) to catalyze collaborations in cancer care, research and education in global radiation oncology. This work reports on the use of ICTs for global Medical Physics education and training across three countries: USA, Tanzania and Kuwait

Methods:

An online education platform was established by Radiation Oncology Faculty from Harvard Medical School, and the University of Pennsylvania with integrated Medical Physics Course modules accessible to trainees in Tanzania via partnership with the Muhimbili University of Health and Allied Sciences, and the Ocean Road Cancer Institute. The course modules incorporated lectures covering Radiation Therapy Physics with videos, discussion board, assessments and grade center. Faculty at Harvard Medical School and the University of Massachusetts Lowell also employed weekly Skype meetings to train/mentor three graduate students, living out‐of‐state and in Kuwait for up to 9 research credits per semester for over two semesters towards obtaining their graduate degrees

Results:

Students were able to successfully access the Medical Physics course modules and participate in learning activities, online discussion boards, and assessments. Other instructors could also access/co‐teach the course modules from USA and Tanzania. Meanwhile all three graduate students with remote training via Skype and email made major progress in their graduate training with each one of them submitting their research results as abstracts to be presented at the 2016 AAPM conference. One student has also published her work already and all three are developing these abstracts for publication in peer‐reviewed journals.

Conclusion:

Altogether, this work highlights concrete examples/model on how ICTs can be used for capacity building in Medical Physics across continents, for both education and research training needed for Masters/PhD degrees. The developed modules and model will be scaled to benefit many more trainees and other developing countries.
SU‐F‐P‐01: Changing Your Oncology Information System: A Detailed Process and Lessons Learned
Authors: Abing C
Published: July 2016

Purpose:

Radiation Oncology departments are faced with many options for pairing their treatment machines with record and verify systems. Recently, there is a push to have a single‐vendor‐solution. In order to achieve this, the department must go through an intense and rigorous transition process. Our department has recently completed this process and now offer a detailed description of the process along with lessons learned.

Methods:

Our cancer center transitioned from a multi‐vendor department to a single‐vendor department over the 2015 calendar year. Our staff was partitioned off into superuser groups, an interface team, migration team, and go‐live team. Six months after successful implementation, a detailed survey was sent to the radiation oncology department to determine areas for improvement as well as successes in the process.

Results:

The transition between record and verify systems was considered a complete success. The results of the survey did point out some areas for improving inefficiencies with our staff; both interactions between each other and the vendors.

Conclusion:

Though this process was intricate and lengthy, it can be made easier with careful planning and detailed designation of project responsibilities. Our survey results and retrospective analysis of the transition are valuable to those wishing to make this change.
SU‐F‐P‐02: A New Framework for the Equipment Donation Program
Authors: Brown D , Court L , Hudson A , Odom A , Pipman Y
Published: July 2016

Purpose:

The Equipment Donation Sub‐Committee has developed a new, formalized process for both donating and requesting donated equipment. The purpose of the framework is to increase the likelihood that available, working‐order equipment is put to good use at functional, deserving clinics.

Methods:

A consensus approach was used to develop a fresh approach to equipment donation and requesting equipment for donation. The committee developed specific forms for people who wish to donate equipment and for those who are seeking specific donated equipment. The forms include a summary of the equipment as well as questions designed to inform the committee with respect to the condition of the equipment, the resources of the clinic that is requesting equipment, the specific need for requested equipment, whether or not additional components or software are required for its proper functioning, and ancillary considerations such as regulatory and import rules that may affect the donation. Following submission of the forms the equipment, or request, are entered into a database, reviewed by the committee, and compatibility matches are proposed.

Results:

This is the first time a formalized, consensus‐based approach has been used by the Equipment Donation Sub‐Committee. Forms are available on the aapm.org website and should be emailed to equipment.donation@aapm.org. The first applications using this new process will be summarized and discussed.

Conclusion:

We anticipate this process will facilitate and expedite the process of equipment donation and will serve as a tool for assessing and improving the program.
SU‐F‐P‐03: Management of Time to Treatment Inititation: Case for An Electronic Whiteboard
Authors: Adnani N
Published: July 2016

Purpose:

To determine if data mining of an electronic whiteboard improves the management of the Time to Treatment Initiation (TTI) in radiation oncology.

Methods:

An electronic whiteboard designed to help in managing the planning workflow and improves communication regarding patient planning progress was used to record the dates at which each phase of the planning process began or completed. These are CT Sim date, Plan Start, Physician Review, Physicist Review, Approval for Treatment Delivery, Setup or Verification of Simulation.

Results:

During clinical implementation, the electronic whiteboard was able to fulfill its primary objective of providing a transparent account of the planning progress of each patient. Peer pressure also meant that individual tasks, such as contouring, were easily brought to the attention of the responsible party and prioritized accordingly. Data mining to analyze the electronic whiteboard per patient (figure 1), per diagnosis (figure 2), per treatment modality (figure 3), per physician (figure 4), per planner (figure 5), etc., added another sophisticated tool in the management of Time to Treatment Initiation without compromising quality of the plans being generated. A longer than necessary time between CT Sim and Plan Start can be discussed among the members of the treatment team as an indication of inadequate/outdated CT Simulator, Contouring Tools, Image Fusion Tools, Other Imaging Studies (MRI, PET/CT) performed, etc. The same for the Plan Start to Physician Review where an extended time than expected may be due unrealistic planning goals, limited planning system features, etc.

Conclusion:

An Electronic Whiteboard in radiation oncology is not only helping with organizing planning workflow, it is also a potent tool that can be used to reduce the Time to Treatment Initiation by providing the clinic with hard data about the duration of each phase treatment planning as a function of different variable affecting the planning process.

The work is supported by the Global Medical Physics Institute.
SU‐F‐P‐10: A Web‐Based Radiation Safety Relational Database Module for Regulatory Compliance
Authors: Rosen C , Ramsay B , Konerth S , Roller D , Ramsay A
Published: July 2016

Purpose:

Maintaining compliance with Radioactive Materials Licenses is inherently a time‐consuming task requiring focus and attention to detail. Staff tasked with these responsibilities, such as the Radiation Safety Officer and associated personnel must retain disparate records for eventual placement into one or more annual reports. Entering results and records in a relational database using a web browser as the interface, and storing that data in a cloud‐based storage site, removes procedural barriers. The data becomes more adaptable for mining and sharing.

Methods:

Web‐based code was written utilizing the web framework Django, written in Python. Additionally, the application utilizes JavaScript for front‐end interaction, SQL, HTML and CSS. Quality assurance code testing is performed in a sequential style, and new code is only added after the successful testing of the previous goals. Separate sections of the module include data entry and analysis for audits, surveys, quality management, and continuous quality improvement. Data elements can be adapted for quarterly and annual reporting, and for immediate notification of user determined alarm settings.

Results:

Current advances are focusing on user interface issues, and determining the simplest manner by which to teach the user to build query forms. One solution has been to prepare library documents that a user can select or edit in place of creation a new document. Forms are being developed based upon Nuclear Regulatory Commission federal code, and will be expanded to include State Regulations.

Conclusion:

Establishing a secure website to act as the portal for data entry, storage and manipulation can lead to added efficiencies for a Radiation Safety Program. Access to multiple databases can lead to mining for big data programs, and for determining safety issues before they occur. Overcoming web programming challenges, a category that includes mathematical handling, is providing challenges that are being overcome.
SU‐F‐P‐12: Leveraging a Communication Tool to Assess IMRT Planning Process Efficiency and Identify Improvement Opportunities
Authors: Evans J
Published: July 2016

Purpose:

To utilize an existing patient‐specific IMRT QA communication tool to quantify our department's compliance with existing IMRT planning policies and to identify opportunities for improvement.

Methods:

A centralized network‐based spreadsheet is utilized by our dosimetrists to communicate to the physics team when an IMRT plan is ready for patient‐specific QA measurement. Since Feb. 2014, the dosimetrists and physicists track additional date information for each case including treatment start, contour approval, plan approval, and QA measurement. Since Jan. 2015, our team also tracks if, and why, a patient plan requires more than one QA measurement. Two time periods were analyzed: Feb. 2014 to Dec. 2014 and Jan. 2015 to Dec. 2015. The Excel “networkdays” function was used to calculate the number of days between process steps for each case. Histogram analysis was used to quantify environmental hazards created by compressed timelines for QA. The rate of and the reasons for QA re‐measurement was also quantified.

Results:

In 2014, 27.3% of QA measurements were performed the day before treatment start. From this, we modified our QA policies and staffing. In 2015, this day before start QA rate was reduced to 20%, but is ultimately limited by physician plan approval. In 2014, 29% of cases were approved by the physician within 2 or fewer days of treatment start. In 2015, this rate increased to 38% of cases. In 2015, 16.4% of QA measurements were a re‐measurement. The 2 most common themes for a re‐measurement were clinical reasons (re‐sim, re‐plan, contours modified) or a measurement setup error, e.g. the MatrixX ion chamber plane being left in a high dose gradient region.

Conclusion:

Leveraging an existing communication tool has allowed us to quantify our IMRT process performance, identify bottlenecks for improvement, and quantify improvement following policy changes.
SU‐F‐P‐13: NRG Oncology Medical Physics Manpower Survey Quantifying Support Demands for Multi Institutional Clinical Trials
Authors: Monroe J , Boparai K , Xiao Y , Followill D , Galvin J , Sohn J
Published: July 2016

Purpose:

A survey was taken by NRG Oncology to assess Full Time Equivalent (FTE) contributions to multi institutional clinical trials by medical physicists.No current quantification of physicists’ efforts in FTE units associated with clinical trials is available. The complexity of multi‐institutional trials increases with new technologies and techniques. Proper staffing may directly impact the quality of trial data and outcomes. The demands on physics time supporting clinical trials needs to be assessed.

Methods:

The NRG Oncology Medical Physicist Subcommittee created a sixteen question survey to obtain this FTE data. IROC Houston distributed the survey to their list of 1802 contact physicists.

Results:

After three weeks, 363 responded (20.1% response). 187 (51.5%) institutions reporting external beam participation were processed. There was a wide range in number of protocols active and supported at each institution. Of the 187 clinics, 134 (71.7%) participate in 0 to 10 trials, 28 (15%) in 11 to 20 trials, 10 (5.3%) in 21 to 30 trials, 9 (4.8%) had 40 to 75 trials. On average, physicist spent 2.7 hours (SD: 6.0) per week supervising or interacting with clinical trial staff. 1.25 hours (SD: 3.37), 1.83 hours (SD: 4.13), and 0.64 hours(SD: 1.13) per week were spent on patient simulation, reviewing treatment plans, and maintaining a DICOM server, respectively. For all protocol credentialing activities, physicist spent an average of 37.05 hours (SD: 96.94) yearly. To support dosimetrists, clinicians, and therapists, physicist spend on average 2.07 hours (SD: 3.52) per week just reading protocols. Physicist attended clinical trial meetings for on average 1.13 hours (SD: 1.85) per month.

Conclusion:

Responding physicists spend a nontrivial amount of time: 8.8 hours per week (0.22 FTE) supporting, on average, 9 active multi‐institutional clinical trials.
SU‐F‐P‐14: Oxygen Inhalation Should Be the Conventional Approach in the Treatment of Thoracic and Abdominal Cancer by Radiotherapy with Active Breathing Control (ABC)
Authors: Gong G , Guo Y , Yin Y
Published: July 2016

Purpose:

To investigate the feasibility and potential benefit of oxygen inhalation (OI) during radiotherapy applying an active breathing control (ABC) device, by analyzing the blood oxygen saturation (SpO2) and the instantaneous heart rate (IHR) variation in breath holding with OI and oxygen non‐inhalation (ONI).

Methods:

The 27 healthy volunteers (16 males, 11 females) who were involved in this trial were all required to hold their breath for 10 times, non‐inhaling and inhaling oxygen successively. The breath‐holding time (BHT), rest time (RT), SpO2 and IHR under different oxygen status were recorded and compared.

Results:

The volunteers were divided into two groups according to SpO2 variations in breath‐holding: group A (12 cases), with less than2% decline of SpO2; group B (15 cases), with a decline that surpassed 2%, and which could reach 3–6%. The BHT of group A, without inhaling oxygen, was significantly longer than that of group B (mean 33.77s Vs 30.51s, p<0.05); and was extended by 26.6% and 27.85%, after inhaling oxygen, in groups A and B, respectively. The SpO2 decreased in all volunteers during RT with ONI, to an extent that could reach up to 6%. The IHR of all volunteers showed the fast‐slow‐fast variation rule, and the oxygen had little effect. More than 70% of the volunteers stated that oxygen made them feel more comfortable and were more cooperative when ABC was used.

Conclusion:

The SpO2 declines during breath holding and RT could not be ignored while applying ABC, oxygen inhalation should become a conventional method with lengthening BHT and shortening RT, which yielded the benefit of improving the stability and reproducibility.
SU‐F‐P‐21: Study of Dosimetry Accuracy of Small Passively Scattered Proton Beam Fields
Authors: Li Y , Gautam A , Kerr M , Martin C , Poenisch F , Zhang X , Li H , Wu R , Zhu X , Gillin M , Sahoo N
Published: July 2016

Purpose:

To study the accuracy of the dose distribution of very small irregular fields of passively scattered proton beams calculated by the analytical pencil beam model of the Eclipse treatment planning system (TPS).

Methods:

An irregular field with a narrow region (width < 1 cm) that was used for the treatment of a small volume adjacent to a previously treated area were chosen for this investigation. Point doses at different locations inside the field were measured with a small volume ion chamber (A26, Standard Imaging). 2‐D dose distributions were measured using a 2‐D ion chamber array (MatriXX, IBA). All the measurements were done in plastic water phantom. The measured dose distributions were compared with the verification plan dose calculated in a water like phantom for the patient treatment field without the use of the compensator.

Results:

Point doses measured with the ion chamber in the narrowest section of the field were found to differ as much as 10% from the Eclipse calculated dose at some of the points. The 2‐D dose distribution measured with the MatriXX which was validated by comparison with limited film measurement, at the proximal 95%, center of the spread out Bragg Peak and distal 90% depths agreed reasonably well with the TPS calculated dose distribution with more than 92% of the pixels passing the 2% / 2 mm dose distance agreement.

Conclusion:

The dose calculated by the pencil beam model of the Eclipse TPS for narrow irregular fields may not be accurate within 5% at some locations of the field, especially at the points close to the field edge due to the limitation of the dose calculation model. Overall accuracy of the calculated 2‐D dose distribution was found to be acceptable for the 2%/2 mm dose/distance agreement with the measurement.
SU‐F‐P‐32: A Phantom Study of Accuracy of Four‐Dimensional Cone‐Beam CT (4D‐CBCT) Vs. Three‐Dimensional Cone Beam CT (3D‐CBCT) in Image Guided Radiotherapy
Authors: He R , Morris B , Duggar N , Markovich A , Standford J , Lu J , Yang C
Published: July 2016

Purpose:

SymmetryTM 4D IGRT system of Elekta has been installed at our institution, which offers the 4D CBCT registration option. This study is to evaluate the accuracy of 4D CBCT system by using the CIRS 4D motion phantom and to perform a feasibility study on the implementation of 4D‐CBCT as image guidance for SBRT treatment.

Methods:

The 3D and 4D CT image data sets are acquired using the CIRS motion phantom on a Philips large bore CT simulator. The motion was set as 0.5 cm superior and inferior directions with 6 seconds recycle time. The 4D CT data were sorted as 10 phases. One identifiable part of the 4D CT QA insert from CIRS phantom was used as the target. The ITV MIP was drawn based on maximum intensity projection (MIP) and transferred as a planning structure into 4D CBCT system. Then the 3D CBCT and 4D CBCT images were taken and registered with the free breath (3D), MIP (4D) and average intensity projection (AIP)(4D) reference data sets. The couch shifts (X, Y, Z) are recorded and compared.

Results:

Table 1 listed the twelve couch shifts based on the registration of MIP, AIP and free breath CT data sets with 3D CBCT and 4D CBCT for both whole body and local registration. X, Y and Z represent couch shifts in the direction of the right‐left, superior‐inferior and anterior‐posterior. The biggest differences of 0.73 cm and 0.57 cm are noted in the free breath CT data with 4D CBCT and 3D CBCT data registration. Fig. 1 and Fig. 2 are the shift analysis in diagram. Fig. 3 shows the registration.

Conclusion:

Significant differences exist in the shifts corresponding with the direction of target motion. Further investigations are ongoing.
SU‐F‐P‐35: A Multi‐Institutional Plan Quality Checking Tool Built On Oncospace: A Shared Radiation Oncology Database System
Authors: Bowers M , Robertson S , Moore J , Wong J , Phillips M , Hendrickson K , Evans K , McNutt T
Published: July 2016

Purpose:

Late toxicity from radiation to critical structures limits the possible dose in Radiation Therapy. Perfectly conformal treatment of a target is not realizable, so the clinician must accept a certain level of collateral radiation to nearby OARs. But how much? General guidelines exist for healthy tissue sparing which guide RT treatment planning, but are these guidelines good enough to create the optimal plan given the individualized patient anatomy? We propose a means to evaluate the planned dose level to an OAR using a multi‐institutional data‐store of previously treated patients, so a clinician might reconsider planning objectives.

Methods:

The tool is built on Oncospace, a federated data‐store system, which consists of planning data import, web based analysis tools, and a database containing:1) DVHs: dose by percent volume delivered to each ROI for each patient previously treated and included in the database.2) Overlap Volume Histograms (OVHs): Anatomical measure defined as the percent volume of an ROI within a given distance to target structures.Clinicians know what OARs are important to spare. For any ROI, Oncospace knows for which patients’ anatomy that ROI was harder to plan in the past (the OVH is less). The planned dose should be close to the least dose of previous patients. The tool displays the dose those OARs were subjected to, and the clinician can make a determination about the planning objectives used.Multiple institutions contribute to the Oncospace Consortium, and their DVH and OVH data are combined and color coded in the output.

Results:

The Oncospace website provides a plan quality display tool which identifies harder to treat patients, and graphically displays the dose delivered to them for comparison with the proposed plan.

Conclusion:

The Oncospace Consortium manages a data‐store of previously treated patients which can be used for quality checking new plans.

Grant funding by Elekta.
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
Authors: Salinas Aranda F , Suarez V , Arbiser S , Sansogne R
Published: July 2016

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.