Lung

Lung tumors move during breathing, and tumor motion of more than 3 cm has been seen for tumors located near the diaphragmatic domes. Breathing-adapted radiotherapy, such as respiratory beam gating or tumor tracking, compensates for tumor motion by only irradiating during a prespecified part of the breathing cycle or by letting the treatment beam follow the tumor motion. Both approaches rely on the ability to determine and predict the breathing-related tumor motion based on an external or internal surrogate for tumor motion. The prediction of the correlation between the tumor and the surrogate positions must be verified throughout the treatment; the verification can be performed with repeated kV imaging of the tumor. However, not all lung tumors are well defined on kV images and, therefore, radio-opaque markers implanted in or close to the tumor have been used as a surrogate for tumor position. When the position of the radio-opaque markers is used as surrogate for tumor position during radiotherapy, it is important that the position of the markers relative to the tumor is stable throughout the course of radiotherapy.

The ™ 3D fiducial Markers can be surgically implanted directly at the perimeter of the tumor site or tumor and will remain sewn into place throughout the tissue healing process until the absorbable suture is re-absorbed by the body. From then on, the sutures are held in place by the healed tissue and will be less likely to migrate from their original implantation site for the length of the radiation therapy and much longer after.