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Table 2 Target volume definitions

From: Early palliative radiation versus observation for high-risk asymptomatic or minimally symptomatic bone metastases: study protocol for a randomized controlled trial

Target volume Definition MSKCC Standard Approach
GTV Gross tumor in the bone, including soft tissue extension Consider fusing diagnostic imaging including PET. MRI is recommended for spinal metastases.
Consider reviewing diagnostic and/or simulation imaging with a diagnostic radiologist.
CTV Margin for microscopic extension of tumor GTV + 5 mm but not extending beyond the bone unless direct extension with adjacent tissue invasion is present.
NOTE: For lesions in the spine undergoing SBRT, published guidelines will be followed [24]
PTV Margin for setup error (patient positioning and treatment delivery) CTV + 3 mm (if using daily CBCT)