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Intrafraction motion:

Frame-based invasive head frame

Immobilization characteristics: Results

Mean 3D of 0.58 mm (SD 0.42 mm)

SBRT set up

A clinical comparison of patient setup and intra-fraction motion using

frame-based radiosurgery versus a frameless image-guided radiosurgery system

for intracranial lesions

Naren Ramakrishna

, Florin Rosca, Scott Friesen, Evrim Tezcanli, Piotr Zygmanszki, Fred Hacker

Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA, USA

a r t i c l e i n f o

Article history:

Received 12 June 2009

Received in revised form 8 December 2009

Accepted 29 December 2009

Available online 28 January 2010

Keywords:

Frameless

Radiosurgery

Image-guided

Stereotactic

a b s t r a c t

Background and purpose:

A comparison of patient positioning and intra-fraction motion using invasive

frame-based radiosurgery with a frameless X-ray image-guided system utilizing a thermoplastic mask

for immobilization.

Materials and methods:

Overall system accuracy was determined using 57 hidden-target tests. Positioning

agreement between invasive frame-based setup and image-guided (IG) setup, and intra-fraction displace-

ment, was evaluated for 102 frame-based SRS treatments. Pre and post-treatment imaging was also

acquired for 7 patients (110 treatments) immobilized with an aquaplast mask receiving fractionated IG

treatment.

Results:

The hidden-target tests demonstrated a mean error magnitude of 0.7 mm (SD = 0.3 mm). For SRS

treatments, mean deviation between frame-based and image-guided initial positioning was 1.0 mm

(SD = 0.5 mm). Fusion failures were observed among 3 patients resulting in aberrant predicted shifts.

The image-guidance system detected frame slippage in one case. The mean intra-fraction shift magnitude

observed for the BRW frame was 0.4 mm (SD = 0.3 mm) compared to 0.7 mm (SD = 0.5 mm) for the frac-

tionated patients with the mask system.

Conclusions:

The overall system accuracy is similar to that reported for invasive frame-based SRS. The

intra-fraction motion was larger with mask-immobilization, but remains within a range appropriate

for stereotactic treatment. These results support clinical implementation of frameless radiosurgery using

the Novalis Body Exac-Trac system.

Radiosurgery has an important role in the treatment of primary

brain tumors, metastases, and functional disorders. Effective radi-

osurgery treatment minimizes normal tissue injury by employing

sharp dose gradients which must be placed accurately at the mar-

infection, and requires pre-medication. Furthermore, the care of

patients wearing head frames creates a clinical resource burden

on the day of care, requiring dedicated nursing and physician sup-

port. Frame-based treatment also requires treatment planning to

Radiotherapy and Oncology 95 (2010) 109–115

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Radiotherapy and Oncology

j ourna l homepage : www. thegreen j ourna l . com

Mean 3D of 0.40 mm (SD 0.30 mm)