Epson Scanner Research Articles

Effect of mirror system and scanner bed of a flatbed scanner on lateral response artefact in radiochromic film dosimetry.

Radiochromic film, evaluated with flatbed scanners, is used for practical radiotherapy QA dosimetry. Film and scanner component effects contribute to the Lateral Response Artefact (LRA), which is further enhanced by light polarisation from both. This study investigates the scanner bed's contribution to LRA and also polarisation from the mirrors for widely used EPSON scanners, as part of broader investigations of this dosimetry method aiming to improve processes and uncertainties. Alternative scanner bed materials were compared on a modified EPSON V700 scanner. Polarisation effects were investigated for complete scanners (V700, V800, on- and off-axis, and V850 on-axis), for a removed V700 mirror system, and independently using retail-quality single mirror combinations simulating practical scanner arrangements, but with varying numbers (0-5) and angles. Some tests had no film present, whilst others included films (EBT3) irradiated to 6 MV doses of 0-11.3 Gy. For polarisation analysis, images were captured by a Canon 7D camera with 50 mm focal length lens. Different scanner bed materials showed only small effects, within a few percent, indicating that the normal glass bed is a good choice. Polarisation varied with scanner type (7-11%), increasing at 10cm lateral off-axis distance by around a further 6%, and also with film dose. The V700 mirror system showed around 2% difference to the complete scanner. Polarization increased with number of mirrors in the single mirror combinations, to 14% for 4 and 5 mirrors, but specific values depend on angles and mirror quality. Novel film measurement methods could reduce LRA effect corrections and associated uncertainties.

Correlations between appearance traits and internal quality of Bupleurum scorzonerifolium roots based on theory of "quality evaluation through morphological identification"

It is generally believed that high-quality Bupleurum scorzonerifolium roots possess specific morphological characteristics, being red, robust, and long with strong odor. However, the scientific connotation of these characteristics has not been elucidated. According to the theory of "quality evaluation through morphological identification", we studied the correlations between appearance traits(the RGB value of root surface, root length, root diameter, dry weight, and ratio of phloem to xylem) and content of main chemical components(volatile oils, total saponins, total flavonoids, total polysaccharides, and seven saikosaponins) of B. scorzonerifolium roots. Epson Scanner and ImageJ were used to scan the root samples and measure the appearance traits. Ultraviolet spectrophotometry and HPLC were employed to determine the content of chemical components. The correlation, regression, and cluster analyses were performed to study the correlations between the appearance traits and the content of chemical components. The results showed that the content of volatile oils and saikosaponins were significantly correlated with RGB value, root length, and root diameter, indicating that within a certain range, the roots being redder, longer, and thicker had higher content of volatile oils and saikosaponins. According to the appearance traits and chemical component content, the 14 samples from different producing areas were classified into four grades, and the differences in morphological traits and chemical component content were consistent among different grades. The findings in this study demonstrate that appearance traits(RGB value, root length, and root diameter) can be used to evaluate the quality of B. scorzonerifolium roots. Meanwhile, this study lays a foundation for establishing an objective quality evaluation method for B. scorzonerifolium roots.

Effect of scanner lens on lateral response artefact in radiochromic film dosimetry

Radiochromic film is a good dosimeter choice for patient QA for complex treatment techniques because of its near tissue equivalency, high spatial resolution and established method of use. Commercial scanners are typically used for film dosimetry, with Epson scanners being the most common. Radiochromic film dosimetry is not straightforward having some well-defined problems which must be considered, one of the main ones being the Lateral Response Artefact (LRA) effect. Previous studies showed that the contributing factors to LRA are from the structure of the active ingredients of the film and the components and construction of the flatbed scanner. This study investigated the effect of the scanner lens on the LRA effect, as part of a wider investigation of scanner design effects and uncertainties. Gafchromic EBT3 films were irradiated with 40 × 40 cm2 field size 6 MV beams. Films were analysed using images captured by a Canon 7D camera utilising 18 mm, 50 mm and 100 mm focal length lenses compared to images scanned with a conventional Epson V700 scanner. The magnitude of the LRA was observed to be dependent on the focal length of the lens used to image the film. A substantial reduction in LRA was seen with the use of the 50 mm and 100 mm lenses, by factors of 3–5 for the 50 mm lens and 4–30 for the 100 mm lens compared to conventional desktop scanner techniques. This is expected to be from the longer focal length camera lens system being able to collect more light from distant areas compared to the scanner-based system. This provides an opportunity to design film dosimetry systems that minimise this artefact.

Digital Seed Morphometric Analysis of Nigerian Cultivated Rice (<i>Oryza sativa</i> L.) Varieties Grown Under Guinea Savannah Agro-ecology

This study investigated the varietal differences for morphometric properties among Nigerian cultivated rice varieties. Twenty-two rice varieties were grown under rain fed conditions in guinea agro-ecology at National Agricultural Seed Council, Abuja, Nigeria in 2017 and 2018. After 30 days of harvest, seed samples were collected for morphometric evaluation. The seed samples were evaluated in laboratory of the Department of Plant Breeding and Seed Technology, Federal University of Agriculture, Abeokuta in 2017 and 2018 using completely randomized design in three replicates. Seeds obtained from the 22 varieties in two years were assessed for: six morphometric (physical) characters: seed projected area, seed straight length (mm), seed curve length (mm), seed straight width (mm), seed curved width (mm), seed width length (mm) and seed perimeter (mm) using an Epson Scanner connected to a computer device to acquire image of the seeds. A reagent instrument from Reagent Instrument Inc. Canada was used for the digital image analysis by running the custom written software WinSEEDLETM (Pro Version). Data obtained were subjected to Analysis of Variance and means were separated using Tukey’s HSD at 5% probability level. Pearson’s correlation coefficient and principal component analyses were also used. Significant varietal differences were observed for all seed physical characters evaluated. Seed physical characters (projected area, curve length, seed width, seed length and perimeters) were higher in 2018 compared to 2017. WAB 189 had superior physical characters. FARO 62 and FARO 22 had the least values for most of the seed physical characters. Most of the seed morphometric characteristics were strongly associated with one another. PC1 with seed projected area, straight length, seed straight width, seed curved width and seed perimeter contributed to the total variation observed. The study concluded that WAB 189 and FARO 50 with superior seed physical characters should be used for future seed improvement programme.

Development of a method for rapid evaluation of the color of flour and pasta made from wheat of different species

Purpose. Develop a simplified method for estimating the color of flour and pasta using Adobe Photo Shop® software.Methods. The research material was grain of varieties and selection lines of wheat species Triticum durum, T. dicoccum, T. timopheevii bred in the Рlant Production Institute nd. a. V. Ya. Yuryev and samples of the National Center for Genetic Resources of Plants of Ukraine, 2018–2020 harvest. Batch of flour and pieces of dough were scanned using EPSON Scanner 010 F. Color was evaluated using Adobe PhotoShop®. The level of carotenoids was determined by spectrophotometric method.Results. Visual assessments of flour and pasta color, presented by different researchers, differ significantly (up to 2–3 points on a 9-point scale). At the same time, the use of the developed method of express color evaluation of flour and pasta samples in Adobe PhotoShop® with the color evaluation system L*a*b*, used in modern reflectometers, allows to obtain data in numerical value and provides high accuracy. In the case of the developed me­thod, correlations were established between the content of carotenoids and the index b* of flour (r = 0.41 / ≤ 0.05) and pasta (r = 0.60 / p ≤ 0.001) and allowed to select the best in flour color selection lines 10-56, 10-65, 14-153, sample T. durum var. falcatomelanopus, in pasta color – lines 10-56, 10-65, 11-29, 12-3.Conclusions. The developed method provides high accuracy and can be used to evaluate the color of pasta and wheat flour, simplifies the evaluation of test samples, standardizes the parameters of agricultural products and avoids subjective judgment. The established weak correlation between the carotenoid content and the b* value of flour indicates the effect on the color of flour not only orange but also yellow and red pigments, and the ave­rage correlation between the carotenoid content and the b* value of pasta indicates the influence of the products of polyphenols oxidation reactions of wheat grain. The best in color flour and pasta lines were selected for breeding work to increase the content of carotenoid pigments in grain.

RE-REDUCTION OF THE OLD PHOTOGRAPHIC OBSERVATIONS OF INTERAMNIA (704) BASED ON GAIA DR2 REFERENCE CATALOGUE

A new astrometric reduction of oldphotographic astroplates benefiting from integration ofmodern technologies such as the high precision digitizingmachines and the high precision Gaia DR2 cataloguecould be useful to study the orbital motion of Solar systemminor bodies. Based on the newly released Gaia DR2 starcatalogue, the scans of the photographic plates containingimages of Interamnia (704) taken by the Zonal Astrographof Mykolaiv Astronomical Observatory (MAO) in 1974-1985 were re-reduced. For our investigation we used 29plates from the UkrVO archive digitized by commercialEPSON scanner with 1600 dpi resolutions. Besides for 2of them were digitized by the high precision digitizingmachine of Shanghai Astronomical Observatory of theChinese Academy of Sciences (ShAO) with 2540 dpiresolution. Almost all the plates have 3 exposures with asmall shift. Each of 29 plates was scanned 6 times byEPSON scanner in 0° direction. The ShAO digitizingmachine scanned 2 plates also 6 times but 3 times in 0°direction and 3 times in 90° direction. Totally, 85 asteroidpositions taken from 29 plates were derived. Only 5asteroid positions were calculated from ShAO scans.The full identification was conducted andcoordinates of all objects were obtained with usage ofdifferent options of astrometric reductions. The meaninner accuracy of obtained asteroid positions is 0.03″ inRA and 0.14″ in DEC for EPSON scanner and 0.014″ inRA and 0.013″ in DEC for the ShAO digitizing machinein 0° direction and 0.010″ in RA and 0.011″ in DEC in90° direction. The comparison of the new topocentricasteroid positions with Horizons ephemeris was made forcalculation (O-C) residuals and their RMS. The meanresidual differences between the scan obtained positionsand JPL calculated positions were (0.09 ± 0.16)″ in RAand (-0.09 ± 0.25)″ in DEC for the MAO digitized plates;the calculated differences for the ShAO scans are close tozero. Comparison of the results obtained with previousreductions of these observations with Tycho2 and UCAC4reference catalogues showed that the use of the Gaia DR2reference catalogue does not lead to a significantimprovement in the random and systematic component ofthe residual differences (O-C) for scans with EPSONscanner from the UkrVO archive. The results obtained byprocessing images with the ShAO digitizing machinesuggest that in this case, the re-reduction of allphotographic observations based on the Gaia DR2 couldimprove the accuracy of old photographic observations tothe level of modern ground-based CCD observations.

Development and characterization of urethane substituted diacetylene based radiochromic films for medical radiation dosimetry

In this work urethane substituted diacetylene compound was synthesized to prepare its radiochromic films which can be sensitive to therapeutic radiation doses. The developed radiochromic films showed significant color change from white to blue in 0–16 Gy dose range. The colorimetric spectral response of the developed films was studied and a maximum absorption at 624 nm was observed which increased with the radiation doses. The change in the morphology of the films pre and post irradiation was analyzed by acquiring their SEM images. The radiation induced color changes were studied quantitatively in terms of optical density by using high resolution Epson scanner along with MATLAB software. The dose response of the developed films was compared with the commercially available Gafchromic EBT3 films. Both the films showed similar dose response with an uncertainty of less than 2%. The post irradiation stability and environmental stability of the films were also analyzed. The films were found to be highly stable under normal environmental conditions with only 1.67% and 1.19% variation in optical density due to the change in temperature and light intensity, respectively. The developed radiochromic films were tissue equivalent and possessed promising characteristics for a potential film dosimeter for medical applications.

A comparison between EPSON V700 and EPSON V800 scanners for film dosimetry.

Radiochromic film is a good dosimeter choice for patient QA for complex treatment techniques (IMRT, VMAT, SABR, SBRT) because of its near tissue equivalency, very high spatial resolution and established method of use. Commercial scanners are usually used for film dosimetry, among which EPSON scanners are the most common. NCCI have used an EPSON V700 scanner, but recently acquired a new model EPSON V800 scanner. The purpose of this work was to evaluate any differences between these two scanners to consider whether they can be used interchangeably or not. Different aspects of film dosimetry, e.g. lateral response artefact (LRA) effect, orientation effect, scanner response etc., were compared. EBT3 films were irradiated with 40 × 40cm2 field size 6MV beams and scanned in both the scanners. The scanned images were read in ImageJ V1.49 software. The data obtained was then copied in MS Excel to compare the scanners. The V800 scanner causes more polarisation, which results in more LRA effect than for the V700 scanner. The responses of the scanners in all three colour channels are not the same for the same film and irradiation. The V800 scanner shows an increase of response of up to 1.6% compared to 3.7% increase in the V700 scanner after scanning a piece of irradiated film 20 times. The scanners cannot be used interchangeably. The correction factors for LRA effect and the calibration curves are different. Further characterisation, evaluation and commissioning is required before clinical use.

Dose-response linearization in radiochromic film dosimetry based on multichannel normalized pixel value with an integrated spectral correction for scanner response variations.

To introduce a model that reproducibly linearizes the response from radiochromic film (RCF) dosimetry systems at extended dose range. To introduce a correction method, generated from the same scanned images, which corrects for scanner temporal response variation and scanner bed inhomogeneity. Six calibration curves were established for different lot numbers of EBT3 GAFCHROMIC™ film model based on four EPSON scanners [10000XL (2 units), 11000XL, 12000XL] at three different centers. These films were calibrated in terms of absorbed dose to water based on TG51 protocol or TRS398 with dose ranges up to 40Gy. The film response was defined in terms of a proposed normalized pixel value ( ) as a summation of first-order equations based on information from red, green, and blue channels. The fitting parameters of these equations are chosen in a way that makes the film response equal to dose at the time of calibration. An integrated set of correction factors (one per color channel) was also introduced. These factors account for the spatial and temporal changes in scanning states during calibration and measurements. The combination of and this "fingerprint" correction formed the basis of this new protocol and it was tested against net optical density ( ) single-channel dosimetry in terms of accuracy, precision, scanner response variability, scanner bed inhomogeneity, noise, and long-term stability. Incorporating multichannel features (RGB) into the normalized pixel value produced linear response to absorbed dose (slope of 1) in all six RCF dosimetry systems considered in this study. The "fingerprint" correction factors of each of these six systems displayed unique patterns at the time of calibration. The application of to all of these six systems could achieve a level of accuracy of±2.0% in the dose range of interest within modeled uncertainty level of 2.0%-3.0% depending on the dose level. Consistent positioning of control and measurement film pieces and integrating the multichannel correction into the response function formalism mitigated possible scanner response variations of as much as±10% at lower doses and scanner bed inhomogeneity of±8% to the established level of uncertainty at the time of calibration. The system was also able to maintain the same level of accuracy after 3 and 6months post calibration. Combining response linearity with the integrated correction for scanner response variation lead to a sustainable and practical RCF dosimetry system that mitigated systematic response shifts and it has the potential to reduce errors in reporting relative information from the film response.

Monte Carlo uncertainty analysis of dose estimates in radiochromic film dosimetry with single-channel and multichannel algorithms

PurposeTo provide a multi-stage model to calculate uncertainty in radiochromic film dosimetry with Monte-Carlo techniques. This new approach is applied to single-channel and multichannel algorithms. Material and methodsTwo lots of Gafchromic EBT3 are exposed in two different Varian linacs. They are read with an EPSON V800 flatbed scanner. The Monte-Carlo techniques in uncertainty analysis provide a numerical representation of the probability density functions of the output magnitudes. From this numerical representation, traditional parameters of uncertainty analysis as the standard deviations and bias are calculated. Moreover, these numerical representations are used to investigate the shape of the probability density functions of the output magnitudes. Also, another calibration film is read in four EPSON scanners (two V800 and two 10000XL) and the uncertainty analysis is carried out with the four images. ResultsThe dose estimates of single-channel and multichannel algorithms show a Gaussian behavior and low bias. The multichannel algorithms lead to less uncertainty in the final dose estimates when the EPSON V800 is employed as reading device. In the case of the EPSON 10000XL, the single-channel algorithms provide less uncertainty in the dose estimates for doses higher than four Gy. ConclusionA multi-stage model has been presented. With the aid of this model and the use of the Monte-Carlo techniques, the uncertainty of dose estimates for single-channel and multichannel algorithms are estimated. The application of the model together with Monte-Carlo techniques leads to a complete characterization of the uncertainties in radiochromic film dosimetry.

Modeling and predicting of the color changes of wood surface during CO2 laser modification

Abstract To adopt a greener approach, a novel thermal treatment for wood was proposed. Poplar wood surface was treated by CO2 laser and the surface color changes were evaluated by CIELAB color space. The treated and untreated surface were scanned by Epson scanner to measure lightness difference (ΔL*), red-green index difference (Δa*) and yellow-blue index difference (Δb*), then the total color difference (ΔE*) was calculated. The laser energy load on wood surface caused characteristic changes in the chemical component, which were determined by means of Fourier infrared spectrometer (FTIR). Response surface methodology (RSM) was used for modelling and to establish a relationship between color changes and laser modification parameters. The results showed that the feed speed, sweep width and laser power had significant effects on color changes of wood surface. The ΔE* increased with the increasing of laser power, however it decreased with increasing of feed speed and sweep width, because of the amount of heat transferring decreased with the increasing of feed speed and sweep width. The results of FTIR revealed chemical structure in the wood components, which is one of the reasons to the color changes of the wood surfaces. The established quadratic mathematical model applied to describe the relationship between color changes and laser modification parameters had a good prediction. It will be useful for selecting appropriate modification parameters to achieve desired color changes.

SU-F-T-581: The Effect of Scanning Orientation On New EBT-XD Film Using Vidar and Epson Scanners

Purpose: To study the effect of film scanning orientation for new EBT-XD film using Vidar and Epson scanners, compared with EBT3 films. Methods: The EBT-XD (lot#01081501) and EBT3 films (lot#11031501) were cut into 4cm×7cm pieces and each film piece was uniformly exposed to a 6MV photon beam (15×15cm2) at 5 cm depth and 100cm SAD in polystyrene phantom, one at a time. The doses delivered were 0,2.5,5,10,20,30,40 and 50 Gy for EBT-XD films, and 0,0.5,1,2,4,8,12 and 16 Gy for EBT3 films, respectively. All films were scanned at least 16 hours after irradiation, one at a time, in portrait or landscape orientation, using a Vidar DosimetryPro Advantage Red and an Epson 10000XL scanner (red channel). Each film piece was positioned at the center of a frame (36cm×36cm) with a cutout slightly larger than the film size for scanning. The scanned data (71 dpi), were analyzed using ImageJ and the average in the ROI (3cm×3cm) of each film at the center was obtained. Results: Dose response curves (netOD vs. dose) were established and compared with EBT-XD and EBT3 film in portrait or landscape orientation using these two scanners. The portrait to landscape (P/L) ratio for each film/scanner combination was determined. The EBT-XD film is about three times less sensitive than EBT3 film. The netOD is higher for portrait than landscape orientation for all the film/scanner combinations. For EBT-XD and EBT3, the average P/L ratios are 1.02 and 1.03 using Vidar scanner, and 1.03 and 1.05 using Epson scanner (red channel), respectively. Conclusion: The effect of film scanning orientation for new EBT-XD film using Vidar Advantage Red and Epson 10000XL scanners has been studied, in comparison with EBT3 film. The portrait/landscape ratios are the lowest for EBT-XD film using Vidar Advantage Red scanner among the four film/scanner combinations.

Practical IMRT QA dosimetry using Gafchromic film: a quick start guide.

This work outlines a method for using Gafchromic film for dosimetry purposes, by scanning it with currently available commercial scanners. The scanners used were: Epson V800, Epson V700, Epson V37 series, specifically a V370 and a Canon multi-function office printer/scanner. The Epson scanners have 16 bit RGB resolution, the Canon has 8 bit RGB (Red Green Blue) resolution, and the V800 and V700 allow scanning in transmission mode. The V700 uses an Epson White Cold Cathode Florescent Lamp; the recently released V800 uses an Epson light emitting diode (LED) light source, while the V37 series uses a reflective mode and the Epson LED light source. The Epson V37 series scanners are designed for non-professional use so the cost has been kept at a low "entry level" point, so they would be a suitable option for a department wanting to use Gafchromic film or with limited needs that did not justify a more sophisticated and expensive unit. Note that the V800 or V700 scanners are not expensive in context, costing approximately the same as a 25 sheet box of Gafchromic film. The Canon was included to demonstrate that a scanner with 8 bit RGB resolution can be used for dosimetry. These general multi-function units are available in most departments, and they would allow Gafchromic film to be evaluated as a dosimetry tool without a significant investment. Furthermore, they are generally capable of scanning large format film (425×350mm) in one part. Although this is not necessary for dosimetry, it is often useful for machine QA, where dividing the film into two parts to ensure accurate measurements is not practical. Moreover, this analytical method uses software that is freely or commonly available, particularly the image processing package ImageJ. Note ImageJ v1.48 was the version used. The results demonstrate that this method used with the scanners evaluated is a practical method of using Gafchromic film as a dosimeter for IMRT QA.

Dosimetry verification on VMAT and IMRT radiotherapy techniques: In the case of prostate cancer

Radiotherapy treatment depends on the accuracy of the dose delivery to patients, the purpose of the study is to verify the dose in IMRT and VMAT technique in prostate cancer cases correspond to TPS dose using phantom base on ICRU No.50. The dose verification of the target and OAR was performed by placing the TLD Rod LiF100 and EBT2 Gafchromic film at slab hole of pelvic part of the Alderson RANDO phantom for prostate cancer simulation. The Exposed TLDs was evaluated using the TLD Reader Harshaw while EBT2 film was scanned using Epson scanner. The point dose measurements were compared between planned dose and measured dose at target volume and OAR. The result is the dose difference at target volume, bladder and rectum for IMRT and VMAT are less than 5%. On the other hand, the dose difference at the Femoral head is more than 5% for both techniques because the location of OAR already in low gradient dose. Furthermore, the difference dose of the target volume for IMRT technique tends to be smaller than VMAT either for TLD and EBT2 film detectors. From the measurement showed that the delivered dose on the phantom simulation match with ICRU No.50 criteria.

SU‐E‐T‐778: Use of the 2D MatriXX Detector for Measuring Scanned Ion Beam Parameters

Purpose:The quality assurance (QA) procedure has to check the most relevant beam parameters to ensure the delivery of the correct dose to patients. Film dosimetry, which is commonly used for scanned ion beam QA, does not provide immediate results. The purpose of this work is to answer whether, for scanned ion beam therapy, film dosimetry can be replaced with the 2D MatriXX detector as a real‐time tool.Methods:MatriXX, equipped with 32×32 parallel plate ion‐chambers, is a commercial device intended for pre‐treatment verification of conventional radiation therapy.The MatriXX, placed at the isocenter, and GAFCHROMIC films, positioned on the MatriXX entrance, were exposed to 131.44 MeV proton and 221.45 MeV/u Carbon‐ion beams.The OmniPro‐I'mRT software, applied for the data taking of MatriXX, gives the possibility of acquiring consecutive snapshots. Using the NI LabVIEW, the data from snapshots were logged as text files for further analysis. Radiochromic films were scanned with EPSON scanner and analyzed using software programs developed in‐house for comparative purposes.Results:The field dose uniformity, flatness, beam position and beam width were investigated. The field flatness for the region covering 6×6 cm2 square field was found to be better than 2%. The relative standard deviations, expected to be constant over 2×2, 4×4 and 6×6 pixels from MatriXX measurement gives a uniformity of 1.5% in good agreement with the film results.The beam center position is determined with a resolution better than 200 µm for Carbon and less than 100 µm for proton beam.The FWHM determination for a beam wider than 10 mm is satisfactory, whilst for smaller beams the determination is uncertain.Conclusion:Precise beam position and fast 2D dose distribution can be determined in real‐time using MatriXX detector. The results show that MatriXX is quick and accurate enough to be used in charged‐particle therapy QA.

SU‐E‐T‐699: Simulation of Bone Tissue Interface to Study Perturbation Effect in Gamma Knife Radiosurgery

Purpose:To study perturbing effect of bone tissue interface in Gamma Knife dose distribution.Methods:PAGAT polymer gel was manufactured in‐house and poured into two PET cylinders for 3D measurement. Small vials were used for calibration.For 2D measurement EBT2 film was placed in mid portion of third gel filled PET cylinder. A bone material (+1400HU) of length 7cm and width 1.3cm was placed in the path of radiation beam at a distance of 4.5cm from measurement region to investigate its influence on dose distribution. For treatment planning each gel cylinder was fixed in Leksell frame and imaged in X‐Ray CT with scanning parameters: Tube Voltage — 120kVp, Tube Current — 130mAs, Slice Thickness — 1mm. Acquired images were transferred to Leksell Gamma Plan TPS (LGP Version 10.1). A treatment plan consisting of single 16mm collimator with coordinates x=100, y=100, z=100 was generated using convolution algorithm based planning (CABP). Each cylinder was positioned in treatment table and exposed to time calculated by the TPS. Irradiated gel was imaged with MRI (GE Medical Systems) to extract dose information from R2 maps and to determine subtle influence of bone material in the radiation path. Scanning parameter used: TE — 13.6ms, TR — 5000ms, slice thickness — 1.2mm, no of echoes — 8, FOV — 256×256mm2. Similarly exposed EBT2 film was scanned with EPSON scanner (Expression 10000XL) to measure dose.Results:3D and 2D measurement showed altered dose distribution in profile measurement, isodose overlay and dose volume histogram (DVH) comparison. For a gamma pass criteria of 1%/1mm voxel pass rate was around 76%.Conclusion:Presence of bone material in the radiation path perturbed the dose distribution unnoticeable in TPS calculation. Any HU value above +1024 is truncated by CABP hence need to incorporate higher HU values for accurate dose calculation in Gamma Knife TPS.The scientific resources used in this work were from the completed project N‐964 provided by AERB, Mumbai.

EP-1419: Portal dosimetry verification of stereotactic intensity modulated fields

Images from Vidar scans were directly analyzed on a Tomotherapy DQA station. Images from the EPSON scanner were acquired and processed using FilmQAPro software with and without corrections for the characteristic response nonuniformity normal to the scan direction and transferred back to Tomotherapy DQA station for plan-film analysis. Gamma factor maps for five treatment plans (brain, abdomen, vulva and two prostates) were visually compared for EDR2 and EBT3 films scanned on Vidar as well as EBT3 films scanned on EPSON using the FilmQAPro software with and without the nonuniformity corrections 1. C. Fiandra, et al., Med. Phys. 33 4314-9

EP-1420: Comparison of AAA and collapsed cone algorithms for treatment planning of lung SABR

Images from Vidar scans were directly analyzed on a Tomotherapy DQA station. Images from the EPSON scanner were acquired and processed using FilmQAPro software with and without corrections for the characteristic response nonuniformity normal to the scan direction and transferred back to Tomotherapy DQA station for plan-film analysis. Gamma factor maps for five treatment plans (brain, abdomen, vulva and two prostates) were visually compared for EDR2 and EBT3 films scanned on Vidar as well as EBT3 films scanned on EPSON using the FilmQAPro software with and without the nonuniformity corrections 1. C. Fiandra, et al., Med. Phys. 33 4314-9

Correcting lateral response artifacts from flatbed scanners for radiochromic film dosimetry.

A known factor affecting the accuracy of radiochromic film dosimetry is the lateral response artifact (LRA) induced by nonuniform response of a flatbed scanner in the direction perpendicular to the scan direction. This work reports a practical solution to eliminate such artifacts for all forms of dose QA. EBT3 films from a single production lot (02181401) cut into rectangular 4 × 5 cm(2) pieces, with the long dimension parallel to the long dimension of the original 20.3 × 25.4 cm(2) sheets, were exposed at a depth of 5 cm on a Varian Trilogy at the center of a 20 × 20 cm(2) open field at seven doses between 50 and 1600 cGy using 6 MV photons. These films together with an unexposed film from the same production lot were lined one next to the other on an Epson 10000 XL or 11000 XL scanner in portrait orientation with their long dimension parallel to the scan direction. Scanned images were then obtained with the line of films positioned at seven discrete lateral locations perpendicular to the scan direction. The process was repeated in landscape orientation and on three other Epson scanners. Data were also collected for three additional production lots of EBT3 film (11051302, 03031401, and 03171403). From measurements at the various lateral positions, the scanner response was determined as a function of the lateral position of the scanned film. For a given color channel X, the response at any lateral position L is related to the response at the center, C, of the scanner by Response(C, D, X) = A(L,X) + B(L,X) ⋅ Response(L, D, X), where D is dose and the coefficients A(L,X) and B(L,X) are determined from the film measurements at the center of the scanner and six other discrete lateral positions. The values at intermediate lateral positions were obtained by linear interpolation. The coefficients were determined for the red, green, and blue color channels, preserving the ability to apply triple-channel dosimetry once corrections were applied to compensate for the lateral position response artifact. To validate this method, corrections were applied to several films that were exposed to 15 × 15 cm(2) open fields and large IMRT and VMAT fields and scanned at the extreme edges of the scan window in addition to the central location. Calibration and response data were used to generate dose maps and perform gamma analysis using single- or triple-channel dosimetry with FilmQAPro 2014 software. The authors' study found that calibration curves at the different lateral positions could be correlated by a simple two-point rescaling using the response for unexposed film as well as the response of film exposed at high doses between 800 and 1600 cGy. The coefficients A(L,X) and BL,X for each color channel X were found to be independent of dose at each lateral location L. This made it possible to apply the relationship Response(C, D, X) = A(L,X) + B(L,X) ⋅ Response(L, D, X), to the raw film responses, permitting correction of the response values at any lateral position to an equivalent response, as if that part of the film was located at the center of the scanner. This correction method was validated for several films exposed to open as well as large IMRT and VMAT fields. The work reported elaborates on the process using the correction procedures to eliminate the lateral response artifact and demonstrates improvements in the accuracy of radiochromic film dosimetry for the radiation therapy quality assurance applications.

SU-E-T-121: Dosimetric Characterization of Gafchromic Film EBT3 Using Vidar DosimetryPro Advantage RED and EPSON Expression 10000XL Scanners

Purpose: The purpose of this paper is to characterize EBT3 using two types of scanner, analyzing the factors of influence of each dosimetry system. Methods: The film used in this study was GAFCHROMIC EBT3, the films were exposed at a dose range between 0Gy a 9Gy in a solid water phantom, SSD=100cm, 5cm depth and perpendicularly to the 6MV photon beam generated by a Novalis TX linear accelerator equipped with an HDMLC. A Farmer type ion chamber TN30013 (PTW) was used to determine the dose delivered to the film. The films were digitized with a scanner EPSON expression 10000XL and the VIDAR DosimetryPro Adventage RED. Software RIT113v6.1 was used for construction of the calibration curve and analysis. The film characteristics investigated were: response at different dose levels, sensitivity to orientation and side and resolution through the results of the spatial response function by analyzing a step pattern. Additionally, 20 IMRT treatment fields were measured with both scanner and compared with calculated dose using gamma index analysis (3%-3mm). Results: The OD obtained for dose level 2Gy in the orientation portrait of the film on the scanner EPSON is (0,222±0,19) and for Vidar RED (0,252±0,10) and landscape is for EPSON (0,211±0,25) and for Vidar RED (0,250±0,11) . The orientation dependence with respect to film side is about 0,09% for EPSON and about 0.03% for VIDAR. The spatial response function increase in response to the Gaussian function FWHM EPSON scanner (0.18mm) compared with VIDAR scanner function (less than 0.06mm) was observed. We analyzed 20 total plan dose distributions the number of pixels with gamma>1 (3%-3mm) was 0.7%±1.2 [0.1%; 2.82%] for EBT3-VIDAR y 2%±2.9 [0.2%; 3.5%] for EBT3-EPSON. Conclusion: VIDAR scanner shows better sensitivity. EBT3 film shows a different response between portrait and landscape orientation. Step pattern is better reproduce by VIDAR scanner.