The comparison study of Imaging Plate and Film in treatment field verification in high energy photon beam

Abstract

Backgrounds: Verification images in radiotherapy are usually performed by using the verification film, but film processing is becoming less available in department of radiology. The new tool for treatment field verification needed to be investigated for target location accuracy. Objective: The purpose of this study was to compare the imaging plate and X-omat-V Film in treatment field verification images in high energy photon beam. Materials and methods: Konica Computed Radiography Image Plate (CR IP) and Kodak Ready Pact X-Omat V radiographic film were irradiated in 6 megavoltage photon beam of Primus, Siemens by 1 and 50 MU, respectively. IP was read by Konica Regius Model 110 HQ CR reader. The treatment radiation fields were measured for 2x2, 4x4, 5x5, 10x10, 15x15, 20x20, 25x25 and 30x30 cm2 for both IP and radiographic film. Different phantoms were irradiated to investigate the high and low contrast resolution. The soft-tissue-bony contrast and detail were evaluated and compared in a ranking of the two compared images of the skull phantom. Irradiated by 1 to 4 MU for both IP and Kodak radiographic film, using the EC-L cassettes. Image processing parameters were adjusted to improve the image quality, 2 physicist and 2 radiation technicians visually evaluated the images. Results: The results shown that the radiation field dimensions obtained from imaging plate and radiographic films were found to be in agreement within 2 mm. . For the high and low contrast resolution, the MU used for IP was less than radiographic films. Both IP and radiographic films could not identify line pairs (Lp/mm). For the phantom of human skull image, we can see more detail and contrast in IP than radiographic films with the same MU. Verification image quality of IP was improved by the adjustment of image processing parameters. In general, the quality of the processed IP images was slightly higher than that of the films. Conclusion: The good quality verification images were acquired by an imaging plate. It is suitable for practical use to acquire daily verification images, and it is considered useful for maintaining quality assurance in high energy photon beam. IP may replace the film without any noticeable decrease in image quality thereby reducing processing time.