Fiducial markers for stereotactic lung radiation therapy: review of the transthoracic, endovascular and endobronchial approaches

Abstract

Stereotactic body radiation therapy is an alternative to surgery for early-stage, inoperable peripheral non-small cell lung cancer. As opposed to linear accelerator (linac)-based (e.g. gating) and free-breathing techniques, CyberKnife® with Synchrony® technology allows accurate radiation delivery by means of a real-time respiratory motion tracking system using, in most cases, metal fiducial markers (FMs) placed in the vicinity of the target. The aims of this review are as follows. First, to describe the safety and efficacy of the transthoracic, endovascular and endobronchial FM insertion techniques for peripheral pulmonary lesions (PPLs). Second, to analyse performance in terms of the migration and tracking rates of different FM types. Recent developments in FM tracking for central lesions will also be reviewed. In conclusion, for PPLs, the endobronchial approach provides a low rate of pneumothorax, offers the possibility of concurrent diagnostic sampling for both the PPL and the lymph nodes, and, finally, reduces the intervention time compared to other techniques. In this context, coil-tailed and coil-spring FMs have shown the lowest migration rate with a consequently high tracking rate.

Endoscopic Technologies for Peripheral Pulmonary Lesions: From Diagnosis to Therapy

“…These pathologies may both exclude eligibility for surgery or worsen postoperative survival outcomes, a matter still neglected in the medical literature [ 145 , 146 ]. The only other option remaining with a radical intent is stereotaxic body radiation therapy, which, despite its effectiveness, bears significant adverse effects [ 147 , 148 , 149 , 150 ]. For all these reasons, endoscopic approaches have progressively become more investigated due to the reduced risk of short-term and long-term complications [ 151 ].…”

“…Potential uses for bronchoscopy include pleural dye marking of PPLs for surgical resection [ 152 , 153 , 154 , 155 ], placement of fiducial markers for radiotherapy [ 149 , 156 , 157 ], and direct ablation [ 158 ]. The latter is mainly an active research field, currently distant from clinical practice but rapidly progressing and supported by a large IP community.…”

“…Fiducial markers (FMs) for radiotherapy may be positioned with EMN or RP-EBUS guidance [ 149 , 156 ]. Generally, they are composed of a nitinol filament attached to a gold seed.…”

“…Generally, they are composed of a nitinol filament attached to a gold seed. Different types of FM are available: linear, coil-tailed, coil-spring, and two-band [ 149 ]. The main adverse event related to this procedure is the migration of the positioned marker [ 166 , 167 ].…”

End‐to‐end validation of fiducial tracking accuracy in robotic radiosurgery using MRI‐only simulation imaging

“…The clinical implementation of MRI‐only simulation imaging for robotic radiosurgery relies on the compatibility of MRI‐simulation images and IGRT‐based fiducial marker tracking systems. Clinical treatments using robotic radiosurgery for sites such as the abdomen, lung, and prostate can use fiducial markers for tumor tracking 12–16 . Robotic radiosurgery platforms use fiducial tracking algorithms to detect fiducial markers for tumor localization on orthogonal X‐ray images for IGRT‐based tracking 14,17 .…”