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Background and Aim: Modern radiotherapy modalities, such as Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy involve complex dose delivery. The dose delivery is complex as it involves beam modulation, hence, manual dose calculations for these techniques are not possible. Film dosimetry is commonly used method of dose verification for these modalities because of the advantages associated with it. The quantification of uncertainty associated with a film dosimetry system under clinical use becomes important for accurate dosimetry. The spread in the distribution of the pixel values (PV) of the irradiated film contributes to the uncertainty. The probability distribution (PD) of the PV was studied for the clinical photon beam energies of 6, 10, and 15 MV. Methods and Materials: Gafchromic EBT3 film and EPSON 10000XL flatbed scanner were used for this purpose and using the resulting PD, the uncertainty budgets for these energies in the red, green and blue color channels were estimated. Results: The PV of exposed films for the energies studied follows t-distribution, the sum of the squares of the deviation of the measured data from the fitted value was of the order of 10−7, this indicates the goodness of fit. The “t” value corrected combined standard uncertainty (CSU) at 1σ confidence level for exposed film and dose measurement at 200 cGy were 1.42%, 1.48%, and 1.63% and 1.99%, 3.23%, and 5.08% for 6, 10, and 15 MV energies, respectively, in the red colour channel. Conclusion: In the case of the limited number of measurements of a quantity, the SU values must be corrected using the “t” value to get the correct CSU.

Background and Aim: Modern radiotherapy modalities, such as Intensity Modulated Radiotherapy and Volumetric Modulated Arc Therapy involve complex dose delivery. The dose delivery is complex as it involves beam modulation, hence, manual dose calculations for these techniques are not possible. Film dosimetry is commonly used method of dose verification for these modalities because of the advantages associated with it. The quantification of uncertainty associated with a film dosimetry system under clinical use becomes important for accurate dosimetry. The spread in the distribution of the pixel values (PV) of the irradiated film contributes to the uncertainty. The probability distribution (PD) of the PV was studied for the clinical photon beam energies of 6, 10, and 15 MV. Methods and Materials: Gafchromic EBT3 film and EPSON 10000XL flatbed scanner were used for this purpose and using the resulting PD, the uncertainty budgets for these energies in the red, green and blue color channels were estimated. Results: The PV of exposed films for the energies studied follows t distribution, the sum of the squares of the deviation of the measured data from the fitted value was of the order of 10-7, this indicates the goodness of fit. The "t" value corrected combined standard uncertainty (CSU) at 1σ, confidence level for exposed film and dose measurement at 200 cGy were 1.42%, 1.48%, and 1.63% and 1.99%, 3.23%, and 5.08% for 6, 10, and 15 MV energies, respectively, in the red colour channel. Conclusion: In the case of the limited number of measurements of a quantity, the SU values must be corrected using the "t" value to get the correct CSU. [ABSTRACT FROM AUTHOR]

Highlights • The use of the Munsell system to assess soil color has evolved over the past century. • 60% of Munsell color chips have duplicates. • The MSC color range is sufficient for only 52% of the studied soil samples. • The reliability of MSC color reproduction is high. • MSC coupled with scanners can quadruple the precision of soil color estimation. Abstract This article considers the evolution of the use of the Munsell system for assessing soil color. In the 1920s, Munsell color disks were recommended for soil color measurement. Munsell soil color charts (MSCs) were introduced in the 1940s. In 1942, the American Standards Association recommended that spectrophotometers be used for quantitative measurements and the Munsell system be used only for the psychological characterization of color. Despite this recommendation, soil scientists have continued using MSCs to measure soil color semi-quantitatively. The utility of MSCs for color determination depends on three qualities: ambiguity, adequacy and reliability. Quantitative color was measured with a spectrophotometer. Chip colors were compared using the CIELAB color difference (Δ E ab ∗). To examine ambiguity, we calculated the Δ E ab ∗ for every possible MSC color chip pair. Considerable ambiguity was found; 60% of the chips had duplicates. Chips were considered duplicates if the color difference was barely perceptible visually (Δ E ab ∗ < 3). To investigate adequacy, the color difference between 161 soil samples and their closest MSC chips was calculated. Only 52% of the samples had Δ E ab ∗ < 3. This indicated that the color range of the MSC does not adequately cover the range of natural soil colors. To study the reliability of MSCs, an old and a new MSC were compared. The identically designated chips in the old and new MSC generally had color differences of less than 3. Only 16% had Δ E ab ∗ > 3. In addition, chips within a chart or even within a sheet can fade over time in a non-uniform way. On the 2.5Y sheet, a stable group of color chips (∼63%) occurred. This stable group consisted of the chips that were the least prone to discoloration (Δ E ab ∗ < 3). This study determined that the inadequacy and ambiguity of MSCs can be overcome by using MSCs in combination with flatbed scanners. MSCs can be used to calibrate flatbed scanners for the purpose of soil color measurement. A procedure is proposed. The procedure calibrates the scanner using 7 chips from the stable group of the 2.5Y sheet. This procedure enables the measurement of soil color inexpensively and efficiently. The high efficiency of the method was confirmed by testing the accuracy of the soil color determinations for 20 soil samples, covering a wide color range. The calibration procedure quadruples the precision of color estimation compared to solely using MSCs and results in soil color measurements close to those achievable with spectrophotometers. [ABSTRACT FROM AUTHOR]

During the past decade a few artists and even fewer entomologists discovered flatbed scanning technology, using extreme resolution graphical arts scanners for acquiring high magnification digital images of plants, animals and inanimate objects. They are not just for trip receipts anymore. The special attributes of certain scanners, to image thick objects is discussed along with the technical features of the scanners including magnification, color depth and shadow detail. The work of pioneering scanner artist, Joseph Scheer from New York’s Alfred University is highlighted. Representative flatbed-scanned images of moths are illustrated along with techniques to produce them. Collecting and preparing moths, and other objects, for scanning are described. Highlights of the Fulbright sabbatical year of professor Scheer in Arizona and Sonora, Mexico are presented, along with comments on moths in science, folklore, art and pop culture. The use of flatbed scanners is offered as a relatively new method for visualizing small objects while acquiring large files for creating archival inkjet prints for display and sale.

Purpose When comparing different scans of the same radiochromic film, several patterns can be observed. These patterns are caused by different sources of uncertainty, which affect the repeatability of the scanner. The purpose of this work was to study these uncertainties. Methods The variance of the scanner noise, as a function of the pixel position, was studied for different resolutions. The inter-scan variability of the scanner response was analyzed taking into account spatial discrepancies. Finally, the distance between the position of the same point in different scans was examined. Results The variance of noise follows periodical patterns in both axes, causing the grid patterns. These patterns were identified for resolutions of 50, 72 and 96 dpi, but not for 150 dpi. Specially recognizable is the sinusoidal shape with a period of 8.5 mm that is produced with 72 dpi. Inter-scan variations of the response caused systematic relative dose deviations larger than 1% in 5% of the red channel images, 9% of the green and 51% of the blue. No systematic deviation larger than 1% was found after applying response corrections. The initial positioning and the speed of the scanner lamp vary between scans. Conclusions Three new sources of uncertainty, which influence radiochromic film dosimetry with flatbed scanners, have been identified and analyzed in this work: grid patterns, spatial inter-scan variations and scanning reading repeatability. A novel correction method is proposed, which mitigates spatial inter-scan variations caused by deviations in the autocalibration of the individual Charge Coupled Device detectors. [ABSTRACT FROM AUTHOR]

Purpose s : To assess performance of FilmQA Pro software for pre-treatment patient-specific quality assurance (QA), using radiochromic films and two commercial flatbed scanners. To evaluate a novel multichannel approach compared to the classical red channel evaluation. Material and methods Patient films (mostly EBT2 films, one box of EBT3) were digitalized using successively two flatbed scanners: the A4-size Epson V750 and the A3-size Epson 10000XL. Prior to patient dose verification, basic characteristics of films and scanners were investigated. Patient films were analyzed using FilmQA Pro software, which enables to use the signal from all three colour channels (Red, Green, Blue). Results Compared to the red channel evaluation, multichannel evaluation presents better passing rates with regard to local gamma index. As expected, we obtained better results using A3-size scanner compared to A4-size scanner, especially when considering large region of interest. An observation of great interest was made for both scanners: after intensive use, a tilting in the blue transmittance profiles appeared in the lamp direction, making multichannel analysis unsuitable for accurate dose evaluation. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is the correction of the lateral scanner artifact, i.e., the effect that, on a large homogeneously exposed EBT3 film, a flatbed scanner measures different optical densities at different positions along the x axis, the axis parallel to the elongated light source. At constant dose, the measured optical densitiy profiles along this axis have a parabolic shape with significant dose dependent curvature. Therefore, the effect is shortly called the parabola effect. The objective of the algorithm developed in this study is to correct for the parabola effect. Any optical density measured at given position x is transformed into the equivalent optical density c at the apex of the parabola and then converted into the corresponding dose via the calibration of c versus dose. Methods: For the present study EBT3 films and an Epson 10000XL scanner including transparency unit were used for the analysis of the parabola effect. The films were irradiated with 6 MV photons from an Elekta Synergy accelerator in a RW3 slab phantom. In order to quantify the effect, ten film pieces with doses graded from 0 to 20.9 Gy were sequentially scanned at eight positions along the x axis and at six positions along the z axis (the movement direction of the light source) both for the portrait and landscape film orientations. In order to test the effectiveness of the new correction algorithm, the dose profiles of an open square field and an IMRT plan were measured by EBT3 films and compared with ionization chamber and ionization chamber array measurement. Results: The parabola effect has been numerically studied over the whole measuring field of the Epson 10000XL scanner for doses up to 20.9 Gy and for both film orientations. The presented algorithm transforms any optical density at position x into the equivalent optical density that would be measured at the same dose at the apex of the parabola. This correction method has been validated up to doses of 5.2 Gy all over the scanner bed with 2D dose distributions of an open square photon field and an IMRT distribution. Conclusions: The algorithm presented in this study quantifies and corrects the parabola effect of EBT3 films scanned in commonly used commercial flatbed scanners at doses up to 5.2 Gy. It is easy to implement, and no additional work steps are necessary in daily routine film dosimetry. [ABSTRACT FROM AUTHOR]

During the past decade a few artists and even fewer entomologists discovered flatbed scanning technology, using extreme resolution graphical arts scanners for acquiring high magnification digital images of plants, animals and inanimate objects. They are not just for trip receipts anymore. The special attributes of certain scanners, to image thick objects is discussed along with the technical features of the scanners including magnification, color depth and shadow detail. The work of pioneering scanner artist, Joseph Scheer from New York's Alfred University is highlighted. Representative flatbed-scanned images of moths are illustrated along with techniques to produce them. Collecting and preparing moths, and other objects, for scanning are described. Highlights of the Fulbright sabbatical year of professor Scheer in Arizona and Sonora, Mexico are presented, along with comments on moths in science, folklore, art and pop culture. The use of flatbed scanners is offered as a relatively new method for visualizing small objects while acquiring large files for creating archival inkjet prints for display and sale. [ABSTRACT FROM AUTHOR]