Quality of portal verification images using GLP7 film.
ABSTRACT To improve portal verification radiographs, we tested the application of GLP7 film.
The quality of the portal verification radiograph using the XV cassette-GLP7 film combination and the XL cassette-GLP7 film combination was investigated. The XV cassette-XV2 film combination and the SA cassette-GS screen-XTL film combination also were used for comparison.
The characteristic curves showed that the relative speeds were 0.32 and 0.47 for the XV-GLP7 and XL-GLP7 combinations and that the average gradients were 1.93, 2.14, and 1.32 for the XV-GLP7, XL-GLP7, and XV-XV2 combinations, respectively. In the experiment using Burger's phantom, the smallest visible volumes were 11.8, 11.3, 28.7, and 19.6 mm3 for the XV-GLP7, XL-GLP7, XV-XV2, and SA-GS-XTL combinations, respectively. In the lower dosage treatment in the clinic, there were no marked differences between the GLP7 film and XV2 film. However, in the higher dosage treatment, the GLP7 film had a better quality than did the XV2 film.
Portal verification radiographs using GLP7 film are of sufficient quality for clinical use.
Article: Verification imaging using a computed radiography system for high-energy electron beam therapy.[show abstract] [hide abstract]
ABSTRACT: The aim of this study was to examine a method to more conveniently acquire verification images. A computed radiography (CR) system was employed using a photostimulable phosphor plate and diagnostic cassette used for taking diagnostic X-ray photographs. Verification images were acquired using the diagnostic cassette and therapy cassette. Image processing parameters were adjusted to improve the image quality. Verification images were printed using optimum parameters, and 10 radiation technicians visually evaluated the images. The sign test was used, and image quality was evaluated using a two-sided test at a 5% level of significance. To assess its clinical value, a radiation oncologist evaluated patient verification images. Verification image quality was improved by the adjustment of image processing parameters. As a result of the image quality evaluation, there were no significant differences between the two types of cassette (p>0.05). In most of the clinical cases (98%), the verification images were useful. We found that good quality verification images were acquired by a CR system with a diagnostic cassette. This system is suitable for practical use to acquire daily verification images, and it is considered useful for maintaining quality assurance (QA) in high-energy electron beam therapy.Radiation Medicine 12/2005; 23(8):550-6.
Article: Verification Imaging Uging a Computed Radiography System for High-Energy Electron Beam Therapy[show abstract] [hide abstract]
ABSTRACT: The purpose of this study was to develop a convenient method to acquire the verification image in high-energy electron beam therapy. The verification image is important to confirm the treatment field in comparison with the simulation image acquired by treatment planning or the portal-localization image before the treatment is started. Then, the acquisition of verification images was attempted utilizing the computed radiography (CR) system and bremsstrahlung X-rays generated by the irradiation of high-energy electron beams. In the experiment using phantom, verification images were acquired and appeared to be clinically useful at all nominal energies and two kinds of target dose. The cases applied to the clinical examination were useful for verification images. 本論文の目的は, 高エネルギー電子線治療における照合画像の取得を検討することである。照合画像は, 治療計画で得られる位置決め画像または治療開始前の照準画像と対応させて照準野の確認を行う上で重要である。そこで, 高エネルギー電子線の照準時に発生する制動X線とComputed Radiography (CR) システムを利用して照合画像の取得を試みた。ファントム実験の結果, すべてのエネルギーおよび標的線量において臨床適応可能と思われる照合画像が得られた。臨床応用例でも, 4症例すべて臨床的に有用であった。今回利用したCRシステムは, すべて診断X線用のシステムであり, 特殊な装置も必要なく日常的に照合画像の取得に有効であり, 高エネルギー電子線治療の「質の保証」(Quality Assurance; QA)に役立つと考えられる。