A new registration algorithm of electronic portal imaging devices images based on the automatic detection of bone edges during radiotherapy

Abstract

The precision and efficiency of the registration of megavolt-level electronic portal imaging devices (EPID) images with the naked eye in the orthogonal window are reduced. This study aims to develop a new registration algorithm with enhanced accuracy and efficiency. Ten setup errors with different translation and rotation were simulated with the phantom. For each error, one set of simulated computer tomography images and EPID images were acquired and registered with the traditional and the new method. The traditional method was performed by two senior physicists with the Varian Offline Review software. The new method is basing on the comparison of the precise contours of the same bone structure in the digital reconstruction radiography images and the EPID images, and the contours were fitted with an automatic edge detection algorithm based on gradient images. The average error of the new method was decreased by 44.44%, 28.33%, 49.09% in the translation of X, Y, and Z axes (The traditional vs. the new: X axes, 0.45 mm vs. 0.25 mm; Y axes, 0.75 mm vs. 0.35 mm; Z axes, 0.55 mm vs. 0.28 mm), 42.86% and 40.48% in the rotation of X and Z axes (The traditional vs. the new: X axes, 0.49° vs. 0.28°; Z axes, 0.42° vs. 0.25°), respectively. The average elapsed time in the new method was reduced by 11.14% (The traditional vs. the new: 44 s vs. 39.1 s). The new registration method has significant advantages of accuracy and efficiency compared with the traditional method.

A grayscale compression method to segment bone structures for 2D-3D registration of setup images in non-coplanar radiotherapy

“…To the best of our knowledge, this is the first study to examine 2D-3D registration algorithms during non-coplanar radiotherapy. In terms of the registration error for a 0°couch angle, the accuracy of our 2D-3D alignment algorithm is comparable to that of other 2D-3D alignment algorithms proposed in other studies [14,16]. For other couch angles, the maximum translation error along the z-axis (t z ) was less than 1.3 mm.…”

“…In radiation therapy, EPID is widely used as an online verification tool for patient positioning. The advantages of using portal imaging verification include but are not limited to the lower cost of imaging compared to CBCT imaging and the ability to readily combine the imaging dose of portal images with the treatment dose for dosimetry verification of radiotherapy treatments [14]. The lack of 3D patient anatomical information and the low contrast are evident registration limitations of portal images [4].…”

Electronic portal image enhancement based on nonuniformity correction in wavelet domain

“…They found that multiscale enhancement yields better accuracy than top‐hat for lateral views; however, the improvement in performance was low for anterior–posterior (AP) fields. Chen et al 19 . introduced a new method for assessing the registration results of EPID images according to enhanced edge extraction without changing either the photon source or the detector.…”

“…They found that multiscale enhancement yields better accuracy than top-hat for lateral views; however, the improvement in performance was low for anteriorposterior (AP) fields. Chen et al 19 introduced a new method for assessing the registration results of EPID images according to enhanced edge extraction without changing either the photon source or the detector. Cheong claimed that the contrast-limited adaptive histogram equalization (CLAHE) 20 algorithm is the appropriate step for the quality enhancement on the MV EPID image in tumor tracking after assessing the individual contribution of deblurring, contrast improvement, and denoising.…”

Impact of Cold Weather on Setup Errors in Radiotherapy

“…ere will be no benefit for any side if a tiny miscalculation occurs; thus, higher requirements for the setup in radiotherapy are put forward. Scholars have studied the effects of body weight [1][2][3], respiration [4][5][6], body position fixation, molds [7][8][9], registration mode between planning images and CT images [10][11][12], and whether to wear a mask during the epidemic of COVID-19 [13][14][15] on the setup repeatability. To our best knowledge, few studies considered the weather conditions.…”