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KMID : 1038720130240030145
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Progress in Medical Physics
2013 Volume.24 No. 3 p.145 ~ p.153
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Comparison of IMRT and VMAT Techniques in Spine Stereotactic Radiosurgery with International Spine Radiosurgery Consortium Consensus Guidelines
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Oh Se-An
Kang Min-Kyu
Kim Sung-Kyu
Yea Ji-Woon
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Abstract
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Stereotactic body radiation therapy (SBRT) is increasingly used to treat spinal metastases. To achieve the highest
steep dose gradients and conformal dose distributions of target tumors, intensity-modulated radiation therapy
(IMRT) and volumetric-modulated arc therapy (VMAT) techniques are essential to spine radiosurgery. The purpose
of the study was to qualitatively compare IMRT and VMAT techniques with International Spine Radiosurgery
Consortium (ISRC) contoured consensus guidelines for target volume definition. Planning target volume (PTV)
was categorized as TB, TBPT and TST depending on sectors involved; TB (vertebral body only), TBPT (vertebral body+
pedicle+transverse process), and TST (spinous process+transverse process). Three patients treated for spinal
tumor in the cervical, thoracic, and lumbar region were selected. Eacg tumor was contoured by the definition
from the ISRC guideline. Maximum spinal cord dose were 12.46 Gy, 12.17 Gy and 11.36 Gy for TB, TBPT and
TST sites, and 11.81 Gy, 12.19 Gy and 11.99 Gy for the IMRT, RA1 and RA2 techniques, respectively. Average
fall-off dose distance from 90% to 50% isodose line for TB, TBPT, and TST sites were 3.5 mm, 3.3 mm and
3.9 mm and 3.7 mm, 3.7 mm and 3.3 mm for the IMRT, RA1 and RA2 techniques, respectively. For the most
complicated target TBPT sites in the cervical, thoracic and lumbar regions, the conformity index of the IMRT, RA1
and RA2 is 0.621, 0.761 and 0.817 and 0.755, 0.796 and 0.824 for rDHI. Both IMRT and VMAT techniques
delivered high conformal dose distributions in spine stereotactic radiosurgery. However, if the target volume
includes the vertebral body, pedicle, and transverse process, IMRT planning resulted in insufficient conformity
index, compared to VMAT planning. Nevertheless, IMRT technique was more effective in reducing the maximum
spinal cord dose compared to RA1 and RA2 techniques at most sites.
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KEYWORD
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Stereotactic body radiation therapy (SBRT), International Spine Radiosurgery Consortium (ISRC), Intensity-modulated radiation therapy (IMRT), Volumetric-modulated arc therapy (VMAT)
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