Real-time measurement of ICD lead motion during stereotactic body radiotherapy of ventricular tachycardia

Abstract

background: here we aimed to evaluate the respiratory and cardiac-induced motion of a IcD lead used as surrogate in the heart during stereotactic body radiotherapy (sBrT) of ventricular tachycardia (VT). Data provides insight regarding motion and motion variations during treatment. Materials and methods:We analyzed the log files of surrogate motion during sBrT of ventricular tachycardia performed in 20 patients. evaluated parameters included the IcD lead motion amplitudes; intrafraction amplitude variability; correlation error between the IcD lead and external markers; and margin expansion in the superior-inferior (sI), latero-lateral (LL), and anterior-posterior (ap) directions to cover 90% or 95% of all amplitudes. results: In the sI, LL, and ap directions, respectively, the mean motion amplitudes were 5.0 ± 2.6, 3.4. ± 1.9, and 3.1 ± 1.6 mm. The mean intrafraction amplitude variability was 2.6 ± 0.9, 1.9 ± 1.3, and 1.6 ± 0.8 mm in the sI, LL, and ap directions, respectively. The margins required to cover 95% of IcD lead motion amplitudes were 9.5, 6.7, and 5.5 mm in the sI, LL, and ap directions, respectively. The mean correlation error was 2.2 ± 0.9 mm. conclusions: Data from online tracking indicated motion irregularities and correlation errors, necessitating an increased cTV-pTV margin of 3 mm. In 35% of cases, the motion variability exceeded 3 mm in one or more directions. We recommend verifying the correlation between cTV and surrogate individually for every patient, especially for targets with posterobasal localization where we observed the highest difference between the lead and cTV motion.

Cardiac motion and its dosimetric impact during radioablation for refractory ventricular tachycardia

“…This is consistent with the findings of Knybel et al, who employed online tracking during treatment delivery and found that target motion exceeded 3 mm in 35% of their cases. 25 A central limitation of this study is reliance on DIR.DIR performance assessment is a subjective process which is dependent on user experience and can be subject to error without quality assurance (QA). The registration QA also needs to be specific to the underlying goal of the DIR.…”

“…Our study suggests that motion is often non‐uniform, and it is reasonable to surmise a cardiac lead may either over or under‐estimate movement. Knybel et al have also shown that the lead can exhibit larger motion than the target area, and that the correlation between lead motion and target motion vary from patient to patient 25 . Both cardiac gating under voluntary breath hold and combined cardio‐respiratory gating have been shown to be feasible in preclinical studies, 26,27 and further investigation of these techniques may offer a way to reduce total cardio‐respiratory positioning uncertainty.…”

Stereotactic Ablative Radiotherapy of Ventricular Tachycardia Using Tracking: Optimized Target Definition Workflow

“…For our technology, it is, namely, LED marker correlation uncertainty. However, since in GDM-based volume, cardiac motion should be included, the same factor causing the increase in the correlation uncertainty ( 7 ) should not be included again. Again, for this reason, we decided to use a 2-mm isotropic margin overall.…”

“…Our treatment planning and delivery procedure have been described in detail previously ( 4 , 7 – 9 ). After initial development, the original target definition workflow was established as follows:…”

Cardiac radioablation for ventricular tachycardia: Which approach for incorporating cardiorespiratory motions into the planning target volume?

“…Mean target displacements induced by respiration have been reported as 3.9 mm left/right, 4.1 mm anterior/posterior, and 4.7 mm superior/inferior. Additionally, these motions are highly patient-specific, depending on the location of the target in the heart and the respiration amplitude [4,5]. The main target motion management technique used in CR, especially when using a C-arm linear accelerator, is the generation of a cardiorespiratory internal target volume (ITV) based on cardiac-gated and/or respiration-gated four-dimensional computed-tomography (4D-CT) scans [3].…”