RGB Mode Research Articles

SU‐FF‐T‐410: The Influence of Scanner Parameters On the Accuracy of Film Dosimetry: A Comparison of the Epson Expression 1680 Flatbed and the Vidar VXR‐16 Dosimetry PRO Film Scanners

Purpose: To investigate the properties of Vidar VXR‐16 Dosimetry PRO™ and Epson Expression 1680 film scanners with Gafchromic EBT and EDR2 radiographic films for dosimetry applications. Method and Materials: The EDR2 and EBT films are irradiated with 10 × 10 cm2 6 MV X‐ray beams in solid water. Dose calibration curves are obtained using an MLC generated stepwedge. Each EDR2 or EBT film is scanned in both vertical and horizontal orientation with Vidar and Epson scanners in transmission mode and analyzed using FilmQA™ (3cognition LLC) software. The RIT (Radiological Imaging Technology, Colorado Springs) software is used with the Vidar only. Epson scans are done without color correction in the 48‐bit RGB mode, resolution 75 dpi. The R channel image is used for analysis. Vidar scans are done with resolution 71 dpi, logarithmic and linear translation tables, and the 16‐bit grayscale image is analyzed. Results: For the EDR2 film no differences are observed for different scan orientations on either Epson or Vidar scanners with both RIT and FilmQA software. The EBT scans show no difference for different scan directions on either scanner. However, artifacts are associated with different translation tables with the Vidar while up to 2% differences are observed in the penumbra with Epson. Scanning measurement, calibration, and background films in the same direction estimates doses on central axis with 2% accuracy for both film types and scanners. However, inconsistent scan directions result in errors up to 10% on Epson and 41%‐45% on Vidar scanner. Conclusion: Calibration curve differences depend on the type of scanner, scanning mode, scanning software, and film orientation. The EDR2 on either scanner reproduces relative profiles and dose to better than 2% regardless of orientation. For the EBT the scanner parameters, orientation, and software corrections become important for accurate dosimetry results and to avoid artifacts.

Topical Application of Photofrin® for Oral Neoplasms in Animal

Early diagnosis improves oral cancer prognosis. Exact demarcation of tumor margins improves surgical outcomes. This study evaluates Photofrin® fluorescence: a new diagnostic procedure for detection of oral neoplasms in animal models. Fourteen male Golden Syrian hamsters were used. 0.5% D.M.B.A (9,10 dimethyl1-1,2-benzanethracene) was brushed onto cheek pouches bilaterally daily for 2,weeks. Hamsters with oral neoplasms received 2.5,mg/ml Photofrin® solution topically. After 3h the neoplasms underwent fluorescence illumination (λex=380–420,nm). A quantitative analysis of the fluorescence contrast between the neoplastic and surrounding tissue was performed using the RGB Mode and the Gray Scale. (GS) Statistical analysis was performed using the ANOVA test. Analysis of the 14 hamsters’ 28 biopsies revealed 4 (14.3%) displayed squamous hyperplasia (1 mild, 3 severe) and 24 (85.7%) displayed squamous cell carcinoma. The sensitivity of neoplasms evaluated using the RGB and GS modes combined resulted in 92.15% (in vivo macroscopic image) and 93.45% (histological). The specificity of neoplasms evaluated via RGB and GS modes combined resulted in 94.78% (in vivo macroscopic image) and 97.30% (histological). The difference between healthy tissue and the lesions as a group is statistically significant. Photofrin® fluorescence provides a sensitive, non-invasive technique for early identification of malignant neoplasms in the oral cavities of animal models.

A study of GafChromic XR Type R film response with reflective-type densitometers and economical flatbed scanners

The GafChromic XR Type R film is a relatively new product for recording high radiation dose in interventional radiological procedures. Means of measuring the film response were studied in this investigation. Two handheld reflective-type densitometers of different models were compared in the range of 0–8 Gy. They were found to be in excellent agreement. Five reflective flatbed scanners of different models were compared by a simple preliminary test. Their widely differed performances suggest the need of testing a scanner before using it for dosimetry measurement. A selected scanner was further tested for its ability to measure radiation in the range of 0–8 Gy and for the development of a scanning protocol. This experiment suggested the inclusion of a calibration pattern with known exposures and a black reference step in the scanning of a film in RGB mode. Then the red component of this image should be used for dosimetry computation. This method was compared to the use of a red acetate filter. The latter was demonstrated to be a possible alternative for measurement below 5 Gy and when there is no software ability to split an image into color components. PACS number(s): 87.66.–a, 87.52.–g

55.4: Super‐multiview Three‐dimensional Display System

AbstractIn this paper, the super multiview 3‐D display method using 24” LCD is introduced. The method is based on a point light source array with a pixel cell plate, which will give full parallax effect. And the resolution of the 24” LCD is 1920 × 1200 in RGB mode. The matrix of source views (from 6×6 to 15×15 views) is built from computer‐generated images or from the natural images taken by a photo‐camera. The multiview image is produced in processing the matrix by specially designed software. To display the resulting 3D multi‐view image, the crossed lenticular sheets are used.

Observation of fluidic behavior in a polymethylmethacrylate-fabricated microchannel by a simple spectroscopic analysis.

An easy-to-use and low cost microreactor made of polymethylmethacrylate was mechanically fabricated with a microchannel (200 microm x 200 microm). The laminar flow behavior was investigated by visualizing the flow of red and green aqueous solutions. Digitized color images from a CCD camera were analyzed by resolving the color in RGB mode. Numeric data from red and green color components in the images could reveal the fluidic behavior in the microchannel because the spatial spectroscopic information corresponds to the color solution flows. Effects of corner shapes in a turn, flow rate and surface roughness were observed on the mixing of the laminar flows. A right angle turn and unevenness of +/-10% of the inner wall surface almost mixed the two color laminar flows.