Intraoperative Brachytherapy for Central Nervous System Lesions: A Validation Study of a Radioactive Seed Loading Device

The researchers recognized the possible clinical usefulness of a shielded device or jig to help increase the accuracy but decrease the time of loading the seeds into the biocompatible material used intra-operatively. Therefore, the researchers created a prototype of a device called the GammaTile (GT) loader (design patent pending). The reusable device will be made of surgical quality stainless steel of sufficient thickness (greater than 10 half-value layers (HVL) to provide significant staff and user shielding as well as allowing it to be sterilized. It is utilized intraoperatively but off of the operative field and has no direct patient contact. Currently two sizes are planned. The first will accommodate a 2 inch x 2 inch collagen square and the second will accommodate a 1 inch x 1 inch collagen square. These are the most commonly used sizes of lyophilized collagen used in the Barrow Neurosurgical Institute (BNI) operating rooms (OR).

This is a 100 patient observational-design study for the purpose of testing the seed loader device as a method of arranging and securing the seeds in a carrier in a set pattern for the convenient use of the neurosurgeon against the backdrop of a hodgepodge of currently available techniques (seed in suture, seed in mesh, loose seeds), all of which currently need to be secondarily secured with some additional, not currently standardized material, in a cumbersome, time-consuming, and not assuredly accurate manner. An additional primary objective will be an assessment of the loader device as a radiation protection tool for the user and staff during seed placement in the carrier and prior to intracranial carrier placement. Secondary objectives will be conformality of pre- and post-implant dosimetry (expected vs achieved) and post implant stability (seed shift) over time as judged on a routine follow up MRI. An additional proposed endpoint is an economic (cost) comparison to other modalities.

Eligible patients are those deemed appropriate for and scheduled to undergo adjuvant brachytherapy of the central nervous system as determined by the radiation oncologist and neurosurgeon. Potential candidates will have a lesion(s) that may be newly diagnosed or recurrent, in need of gross total or near gross total resection, and such that in the opinion of the operating surgeon it would be both amenable to and in need of the proposed treatment. Informed consent will be obtained. Radiation oncologist and neurosurgeon will determine appropriateness of the proposed procedure and the radiation oncologist and neurosurgeon will determine the volume and configuration of the area to be implanted.

A carrier using currently available material (lyophilized bovine-derived collagen, Duraform or similar) stocked in the BNI OR. The isotope (seeds) are also already approved for use anywhere in the body, are in use and on the hospital's radioactive materials license (RML). Patients will have pre- and post-operative computerized tomography (CT) or magnetic resonance imaging (MRI) as routine care, and post-operative CT's as per routine implant case dosimetry. All applicable radiation safety procedures will continue to be followed. The sterilizable loader(s) will be provided as a non-charge-item, and are anticipated to be classified as a "Class 1" device by the FDA as they are not implanted and have no direct patient contact.

Eligibility Criteria:
Inclusion Criteria:

* Planned for resection of aggressive primary or metastatic brain tumor and appropriate for adjuvant radiotherapy.
* Zubrod Performance Score of 0-2.
* 18 years of age or older.
* Pre-operative stereotactic CT or MRI.
* Life expectancy \>26 weeks.
* History and physical for all patients and detailed neurological exams.
* Signed study-specific informed consent form prior to study entry.

Exclusion Criteria:

* Negative biopsy if presumed diagnosis on imaging.
* External beam therapy is allowed if the implant is being used instead of a boost or cone down treatment.
* Life expectancy \< 26 weeks.
* Inability to undergo post-operative CT for implant assessment, or postoperative follow-up imaging.
* Major medical or psychiatric illness, which, in the investigator's opinion, would prevent completion of treatment and/or interfere with follow-up.
* Inability or refusal to provide informed consent.
* Prior radiation therapy in excess of 100Gy to site of implant.
* Patients in which there is no cranium in place (for example, bone flap removed for infection).