bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐T‐486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)
Authors: Herchko S , Ding G 
Published: July 2016

Purpose:To develop an accurate, straightforward, and user‐independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily‐accessible materials, and a free software program.Methods:A simple phantom consisting of a blocking tray, graph paper, and high‐density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images.Results:The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm.Conclusion:Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.
SU‐F‐T‐488: Comparison of the TG‐51 and TG‐51 Addendum Calibration Protocols
Authors: McCaw T , Hwang M , Jang S , Huq M 
Published: July 2016

Purpose:To quantify differences between the TG51 and TG51 addendum calibration protocols.Methods:Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose‐to‐water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm2 radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume‐averaging correction was applied based on crossline and inline dose profiles. For the TG51 procedure, the collimating jaws were set to 10×10cm2 according to the digital readout, and a lead foil was used for kQ measurements of energies greater than 10MV.Results:For beam energies with a flattening filter, absorbed dose‐to‐water determined by the two protocols differed by 0.1%–0.3%. For FFF beam energies, differences between the protocols were up to 0.2% and 0.8% for the scanning and Farmer ionization chambers, respectively. Differences between the protocols were due to kQ determination, volume‐averaging correction, and measurement of raw ionization. Differences in kQ values between the two protocols were up to 0.4% and 0.2% for the scanning and Farmer ionization chambers, respectively. Volume‐averaging corrections were less than 0.1% for the scanning ionization chamber, and up to 0.4% and 0.6% for the Farmer ionization chamber in beams with a flattening filter and FFF beams, respectively. Raw ionization measurements differed up to 0.3%±0.07% due to differences in jaw settings.Conclusion:The TG51 and TG51 addendum calibration protocols differed less than 0.3% for the scanning ionization chamber. For the Farmer chamber in FFF energies, volume‐averaging corrections of up to 0.6% contributed to calibration differences of up to 0.8%. Failure to verify the radiation field size can produce calibration differences of up to 0.3%.
SU‐F‐T‐490: Separating Effects Influencing Detector Response in Small MV Photon Fields
Authors: Wegener S , Sauer O 
Published: July 2016

Purpose:Different detector properties influence their responses especially in field sizes below the lateral electron range. Due to the finite active volume, the detector density and electron perturbation at other structural parts, the response factor is in general field size dependent. We aimed to visualize and separate the main effects contributing to detector behavior for a variety of detector types. This was achieved in an experimental setup, shielding the field center. Thus, effects caused by scattered radiation could be examined separately.Methods:Signal ratios for field sizes down to 8 mm (SSD 90 cm, water depth 10 cm) of a 6MV beam from a Siemens Primus LINAC were recorded with several detectors: PTW microDiamond and PinPoint ionization chamber, shielded diodes (PTW P‐60008, IBA PFD and SNC Edge) and unshielded diodes (PTW E‐60012 and IBA SFD). Measurements were carried out in open fields and with an aluminum pole of 4 mm diameter as a central block. The geometric volume effect was calculated from profiles obtained with Gafchromic EBT3 film, evaluated using FilmQA Pro software (Ashland, USA).Results:Volume corrections were 1.7% at maximum. After correction, in small open fields, unshielded diodes showed a lower response than the diamond, i.e. diamond detector over‐response seems to be higher than that for unshielded diodes. Beneath the block, this behavior was amplified by a factor of 2. For the shielded diodes, the overresponse for small open fields could be confirmed. However their lateral response behavior was strongly type dependent, e.g. the signal ratio dropped from 1.02 to 0.98 for the P‐60008 diode.Conclusion:The lateral detector response was experimentally examined. Detector volume and density alone do not fully account for the field size dependence of detector response. Detector construction details play a major role, especially for shielded diodes.
SU‐F‐T‐491: Photon Beam Matching Analysis at Multiple Sites Up to Twelve Years Post Installation
Authors: Able C , Zakikhani R , Yan K , Sha D , Chopra A 
Published: July 2016

Purpose:To determine if the photon beams associated with several models of accelerators are matched with ‘Golden Beam’ data (VGBD) to assess treatment planning modeling and delivery.Methods:Six accelerators’ photon beams were evaluated to determine if they matched the manufacturer's (Varian Medical Systems, Inc.) VGBD. Additional direct comparisons of the 6X and 18X beams using the manufacturer's specification of Basic and Fine beam matching were also performed. The Cseries accelerator models were 21 EX (3), IX (2), and a IX Trilogy, ranging from three to twelve years post installation. Computerized beam scanning was performed (IBA Blue Phantom 2) with 2 CC13 ion chambers in water at 100 cm SSD. Dmax (10 cm2 field size), percentage depth dose (6 cm2, 10 cm2, 20 cm2, and 30 cm2 field sizes) and beam uniformity (10 cm2, 30 cm2 and 40 cm2 field sizes) were evaluated.Results:When comparing the beams with VGBD using the ‘Basic’ matching criteria, all beams were within the specifications (1.5mm at dmax, 1% PDD, and 2% Profiles). When considering the “Fine” matching criteria (1.5mm at dmax, 0.5% PDD, and 2% Profiles), only three of six 6MV beams and two of six high energy (five 18MV & one 15MV) beams passed. Direct comparisons between accelerators using the Clinac IX (installed 2012) as the reference beam datasets resulted in all 6 MV and 18MV beams meeting both the “Basic” and “Fine” criterion with the exception of two accelerators.Conclusion:Linear accelerators installed up to nine years apart are capable of meeting the manufacturers beam matching criteria for “Basic” matching. Without any adjustments most beams, when evaluated, may meet the “Fine” match criteria. The use of a single dataset (VGBD or designated accelerator reference data) for treatment planning commissioning is acceptable and can provide quality treatment delivery.
SU‐F‐T‐493: An Investigation Into the Feasibility of Using PipsPro Software with Film for Linac QA
Authors: Underwood R 
Published: July 2016

Purpose:To determine the feasibility of using radiochromic and radiographic film with Pipspro software for quality assurance of linear accelerators with no on‐board imaging.Methods:The linear accelerator being used is a Varian Clinac 21EX. All IGRT is performed using the BrainLab ExacTrac system. Because of the lack of on board imaging, certain monthly and annual TG‐142 quality assurance tests are more difficult to perform and analyze to a high degree of accuracy. Pipspro was not designed to be used with hard film, and to our knowledge its use with film had not been investigated. The film used will be GafChromic EBT3 film and Kodak EDR2 film, scanned with an Epson V700 scanner. The following routine tests will be attempted: MLC picket fence, light vs. radiation field coincidence, starshots, and MLC transmission.Results:The only tests that gave accurate and reliable results were the couch, gantry, and collimator starshots. Typical MV and kV images are acquired with a much higher level of contrast between the irradiated and non‐irradiated areas when compared to film. Pipspro relies on this level of contrast to be able to automatically detect the fiducial points from its phantom devices, leaf edges for picket fence and transmission tests, and jaw edges for light vs. radiation field tests. Because of this, certain tests gave erroneous results and others were not able to be performed in the software at all, with either type of film. The number of monitor units delivered to the film, the experimental setup, and the scan settings was not able to rectify the problem.Conclusion:For linear accelerators with no on‐board imaging, it is not recommended to use hard film with PipsPro to perform TG‐142 quality assurance tests. Other software or methods should instead be investigated.
SU‐F‐T‐494: A Multi‐Institutional Study of Independent Dose Verification Using Golden Beam Data
Authors: Itano M , Tachibana R , Yamashita M , Shimizu H , Sugawara Y , Kotabe K , Kamima T , Takahashi R , Ishibashi S , Uchida Y , Yamazaki T , Tachibana H 
Published: July 2016

Purpose:In general, beam data of individual linac is measured for independent dose verification software program and the verification is performed as a secondary check. In this study, independent dose verification using golden beam data was compared to that using individual linac's beam data.Methods:Six institutions were participated and three different beam data were prepared. The one was individual measured data (Original Beam Data, OBD) .The others were generated by all measurements from same linac model (Model‐GBD) and all linac models (All‐GBD). The three different beam data were registered to the independent verification software program for each institute. Subsequently, patient's plans in eight sites (brain, head and neck, lung, esophagus, breast, abdomen, pelvis and bone) were analyzed using the verification program to compare doses calculated using the three different beam data.Results:1116 plans were collected from six institutes. Compared to using the OBD, the results shows the variation using the Model‐GBD based calculation and the All‐GBD was 0.0 ± 0.3% and 0.0 ± 0.6%, respectively. The maximum variations were 1.2% and 2.3%, respectively. The plans with the variation over 1% shows the reference points were located away from the central axis with/without physical wedge.Conclusion:The confidence limit (2SD) using the Model‐GBD and the All‐GBD was within 0.6% and 1.2%, respectively. Thus, the use of golden beam data may be feasible for independent verification. In addition to it, the verification using golden beam data provide quality assurance of planning from the view of audit.This research is partially supported by Japan Agency for Medical Research and Development(AMED)
SU‐F‐T‐496: An Investigation of Two Novel Devices for Testing Linac Clearance During CT Simulation
Authors: Morrow A , Massingill B 
Published: July 2016

Purpose:This work's objective is to determine the efficacy of two newly patented devices termed the Mor‐O rings, Mark1 and Mark2, developed to predict collisions between the patient and a linac at the time of CT simulation.Methods:Mark1: A ring with an inner radius equal to the distance between the isocenter and the nearest portion of a linac head(diso) was made. This is mounted to a stand that allows vertical repositioning. The ring is placed around the patient on the CT table and aligned with isocenter. The patient is moved through the ring. If the ring touches the patient, a collision is predicted. To test this device, predicted collisions were marked on a phantom. The phantom was then repositioned on the linac table where the collisions were verified. Mark2: An arc with the radius diso was created with a re‐locatable half‐linac head wire‐frame. The Mark2 is positioned in the same way as the Mark1 but can additionally mimic couch and gantry angulations. The Mark2 was tested with a volunteer using multiple couch, gantry and isocenter positions. The volunteer was then repositioned on the linac table to verify the angles of collisions.Results:Mark1: One isocenter out of ten showed negative clearance (0.9mm) on the linac table. All other collisions were predicted with 1 to 36mm of additional clearance. Mark2: All collisions were prevented with an additional 1.3 to 14.8 degrees of clearance.Conclusion:The Mark1 prototype is able to predict all collisions when no couch angulation is used. This device takes less than a minute to setup and is simple to use. The Mark2, when testing beam geometries used for noncoplanar SBRT, was able to prevent all collisions with 1.3 to 14.8 degrees additional clearance. Improvements in construction for both devices could increase accuracy and usability.Andrew Morrow owns Morrow Physics, LLC and Brian Massingill owns Spur Physics, LLC. We are both listed on the patent for the devices investigated in this work (patent 9220922). Our current employer, Baylor Scott and White, is also on the patent.
SU‐F‐T‐497: Spatiotemporally Optimal, Personalized Prescription Scheme for Glioblastoma Patients Using the Proliferation and Invasion Glioma Model
Authors: Kim M , Rockhill J , Phillips M 
Published: July 2016

Purpose:To investigate a spatiotemporally optimal radiotherapy prescription scheme and its potential benefit for glioblastoma (GBM) patients using the proliferation and invasion (PI) glioma model.Methods:Standard prescription for GBM was assumed to deliver 46Gy in 23 fractions to GTV1+2cm margin and additional 14Gy in 7 fractions to GTV2+2cm margin. We simulated the tumor proliferation and invasion in 2D according to the PI glioma model with a moving velocity of 0.029(slow‐move), 0.079(average‐move), and 0.13(fast‐move) mm/day for GTV2 with a radius of 1 and 2cm. For each tumor, the margin around GTV1 and GTV2 was varied to 0–6 cm and 1–3 cm respectively. Total dose to GTV1 was constrained such that the equivalent uniform dose (EUD) to normal brain equals EUD with the standard prescription. A non‐stationary dose policy, where the fractional dose varies, was investigated to estimate the temporal effect of the radiation dose. The efficacy of an optimal prescription scheme was evaluated by tumor cell‐surviving fraction (SF), EUD, and the expected survival time.Results:Optimal prescription for the slow‐move tumors was to use 3.0(small)‐3.5(large) cm margins to GTV1, and 1.5cm margin to GTV2. For the average‐ and fast‐move tumors, it was optimal to use 6.0cm margin for GTV1 suggesting that whole brain therapy is optimal, and then 1.5cm (average‐move) and 1.5–3.0cm (fast‐move, small‐large) margins for GTV2. It was optimal to deliver the boost sequentially using a linearly decreasing fractional dose for all tumors. Optimal prescription led to 0.001–0.465% of the tumor SF resulted from using the standard prescription, and increased tumor EUD by 25.3–49.3% and the estimated survival time by 7.6–22.2 months.Conclusion:It is feasible to optimize a prescription scheme depending on the individual tumor characteristics. A personalized prescription scheme could potentially increase tumor EUD and the expected survival time significantly without increasing EUD to normal brain.
SU‐F‐T‐498: A Comparative Evaluation of 6MV Flatten Beam and Flattening Filter Free Photon Beam in Carcinoma Breast
Authors: Tamilarasu Suresh , Saminathan Madeswaran 
Published: July 2016

Purpose:Aim of the current study is to look plan quality, treatment beam ON time for IMRT using 6MV FB (Flatten Beam) and FFFB (Flattening Filter Free Beam) in left breast cancer cases.Methods:Ten left breast cancer patients treated with breast conserving surgical (BCS) procedure approach and adjuvant radiotherapy were selected from the department database. Simultaneous Integrated boost (SIB) technique was used to irradiate the total left breast (PTV) to a dose of 50.40Gy with concomitant enhance to the lumpectomy cavity known as gross tumour volume (GTV) to a dose of 59.40Gy in 28 fractions. Plans 6MV FB IMRT and 6MV FFFB IMRT had been generated to achieve dose to 95% target volume (TV) and spare Organ at risks (OAR's). Homogeneity index (HI), conformity index (CI), treatment monitor unit (MU),normal tissues integral dose (NTID) and low dose volume of normal tissue were compared.Results:There was no statistically huge difference among the plans with respect to target volume coverage, CI HI, Ipsilateral Lung and Breast. But statistically significant difference (p< 0.05) as observed in Heart, V5Gy of Contralateral Lung, MU's NTID and low dose volume of normal tissue.Conclusion:6MV FB and FFF beam produce almost equivalent plans in IMRT modality with admire to target volume coverage, HI, CI. Beam on time and NTID was determined to be much less in 6MV FFFB IMRT. FFF beam leads to a time saving treatment delivery and fewer NTID in cancer of left breast cases
SU‐F‐T‐499: Anatomic Features for Selection of Electronic Tissue Compensation Radiotherapy in Early‐Stage Breast Cancer Patients After Breast‐Conserving Surgery
Authors: Song Y , Zhang M , Yue N , Gan L , Chen X , Zhang T , Ren G 
Published: July 2016

Purpose:To explore the correlations between anatomic features and dose‐volumetric parameters in 3DCRT and eComp whole breast irradiation and identify the feasibility of anatomic parameters to predict the planning method selection.Methods:We compared the effectiveness between conventional three‐dimensional conformal radiotherapy (3DCRT) and electronic tissue compensation (eComp) for whole breast irradiation. 3DCRT and eComp planning techniques were used to generate treatment plans for 60 whole breast patients, respectively. The planning goal was to cover 95% of the planning target volume (PTV) with 95% of the prescription dose while minimizing dose to lung, heart, and skin. Statistical analyses were performed between critical organ doses and patient anatomic features, i.e., central lung distance (CLD), maximal heart distance (MHD), maximal heart length (MHL) and breast separation (BS).Results:Comparing to 3DCRT plans, on the average, eComp treatment planning process was about 7 minutes longer, but resulted in lower lung V20Gy, lower mean skin dose, with similar heart dose. The benefits were more pronounced for larger breast patients. To keep the lung V20Gy lower than 20% and mean skin dose lower than 85% of the prescription dose, eComp was the preferred method for patients with more than 2.3 cm CLD or larger than 22.5 cm BS.Conclusion:The study results may be useful in providing a handy criterion in clinical practice allowing us to easily choose between different planning techniques to satisfy the planning goal with minimal increase in complexity and cost.This study was supported by National Natural Science Foundation of China (NO. 31420103915) and Chongqing Health and Family Planning Commission Project (2015MSXM012).
SU‐F‐T‐501: Dosimetric Comparison of Single Arc‐Per‐Beam and Two Arc‐Per‐Beam VMAT Optimization in the Monaco Treatment Planning System
Authors: Kalet A , Richardson H , Cao N , Meyer J , Dempsey C 
Published: July 2016

Purpose:The purpose of this study was to evaluate the dosimetric and practical effects of the Monaco treatment planning system “max arcs‐per‐beam” optimization parameter in pelvic radiotherapy treatments.Methods:A total of 17 previously treated patients were selected for this study with a range of pelvic disease site including prostate(9), bladder(1), uterus(3), rectum(3), and cervix(1). For each patient, two plans were generated, one using a arc‐per‐beam setting of ‘1’ and another with setting of ‘2’. The setting allows the optimizer to add a gantry direction change, creating multiple arc passes per beam sequence. Volumes and constraints established from the initial clinical treatments were used for planning. All constraints and dose coverage objects were kept the same between plans, and all plans were normalized to 99.7% to ensure 100% of the PTV received 95% of the prescription dose. We evaluated the PTV conformity index, homogeneity index, total monitor units, number of control points, and various dose volume histogram (DVH) points for statistical comparison (alpha=0.05).Results:We found for the 10 complex shaped target volumes (small central volumes with extending bilateral ‘arms’ to cover nodal regions) that the use of 2 arcs‐per‐beam achieved significantly lower average DVH values for the bladder V20 (p=0.036) and rectum V30 (p=0.001) while still meeting the high dose target constraints. DVH values for the simpler, more spherical PTVs were not found significantly different. Additionally, we found a beam delivery time reduction of approximately 25%.Conclusion:In summary, the dosimetric benefit, while moderate, was improved over a 1 arc‐per‐beam setting for complex PTVs, and equivalent in other cases. The overall reduced delivery time suggests that the use of multiple arcs‐per‐beam could lead to reduced patient on table time, increased clinical throughput, and reduced medical physics quality assurance effort.