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Invasive frame-based: immobilization

10

l

Image-guidance

g

Quantification of intrafraction motion

g

Frame-based system

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.

!

2010 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 95 (2010) 109–115

Radiosurgery has an important role in the treatment of primary

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

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

patients wearing head frames creates a clinical resource burden

Radiotherapy and Oncology 95 (2010) 109–115

Contents lists available at

ScienceDirect

Radiotherapy and Oncology

journal homepage: www.thegreenjournal.c m

Passive verifica,on of 102 frame-­‐based set-­‐ups

Radiotherapy and Oncology 2010;95:109–115