Predictive uncertainty in infrared marker‐based dynamic tumor tracking with Vero4DRT^a)

Abstract

Application of IR Tracking substantially reduced the geometric error caused by respiratory motion; however, an intrafractional error due to baseline drift of >3 mm was occasionally observed. To compensate for EBD, the authors recommend checking the target and IR marker positions constantly and updating the 4D model several times during a treatment session.

Simple quality assurance method of dynamic tumor tracking with the gimbaled linac system using a light field

“…The data on the pair of IR markers and on the iron marker was simultaneously obtained to establish the 4D modeling function. The 4D modeling function was a quadratic function of the IR marker position and velocity, 9 , 10 $P_{\text{italicpredict}}=a{P}_{IR}^2+b{P}_{IR}+c+d{v}_{IR}^2+e{v}_{IR},$ where $P_{\text{italicpredict}}$ is the predicted target position, $P_{IR}$ is the IR marker positions, and $v_{IR}$ is the vertical velocity of the IR markers. Parameters a, b, c, d, and e were optimized by minimizing the residual errors between ${\mathrm{normalP}}_{\text{predict}}$ and the predicted target position for each IR marker.…”

“…Several methods were proposed to compensate for breathing‐induced organ motion. Breathing‐induced organ motion‐compensated treatment techniques include delivery techniques such as motion‐encompassing methods, breath holding, (2) forced shallow breathing, (3) respiratory gating, (4) and dynamic tumor tracking (DTT) 5 , 6 , 7 , 8 , 9 , 10 . DTT techniques were realized through reasonably accurate real‐time acquisition of the target motion of a patient using external surrogates (indirect DTT) or an internally implanted marker (direct DTT).…”

Quality assurance of a gimbaled head swing verification using feature point tracking

“…The Vero4DRT™ system (MHI‐TM2000; Mitsubishi Heavy Industries, Ltd., Tokyo, Japan, and BrainLAB, Feldkirchen, Germany) is described elsewhere 6, 7, 8. Briefly, the Vero4DRT™ system is equipped with a gimbaled head for DTT, a system‐specific fixed jaw, multileaf collimator (MLC), IR camera, and image‐guided radiotherapy (IGRT) system.…”

“…The greatest movement is produced in the superior–inferior (SI) direction close to the diaphragm, such as with tumors in the lower lung lobes and upper abdominal tumors, such as liver or pancreatic tumors 1. Several methods have been proposed to compensate for respiratory‐induced organ motion, including forced shallow‐breathing, breath holding, respiratory gating, and dynamic tumor tracking (DTT) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. DTT was realized through reasonably accurate real‐time acquisition of the target motion of a patient using external surrogates (indirect DTT) or an internally implanted marker (direct DTT).…”

Estimation of lung tumor position from multiple anatomical features on 4D‐CT using multiple regression analysis

“…The results in Table 2 show that the explanatory variable of the lung volume had a significant difference in the 3D direction compared with the other explanatory variables, showing that the lung volume had a significant influence on the estimated lung tumor position. In current clinical practice, a single anatomical signal and a correspondence model between a single anatomical signal and a motion of the internal anatomy are typically used to reconstruct 4D-CT 14 and to estimate target position, [15][16][17] respectively. In addition, correspondence models have been used to improve image quality in 4D-CT image reconstruction.…”