65 year old male with stage IVA NSCLC (large cell carcinoma) with single right 3.5cm symptomatic occipital metastasis status post subtotal resection for linac based FSRT to post-op cavity.
Rx: The patient received LINAC-based, fractionated stereotactic radiotherapy to a single post-operative brain metastasis cavity.
Simulation/Planning:
Case contributed by Queen's University
GTV/HTV:
CTV (per Soliman IJROBP 2018, Mahajan Lancet Oncol 2017, Minniti Radiation Oncology 2021)
Post-op FSRT Prescription Alliance A071801 trial |
|
PTV Volume |
Dose / Fractionation |
<30cc |
27 Gy / 3 fractions |
≥ 30 cc to <5cm |
30 Gy / 5 fractions |
Plan Specification: The dose should be prescribed to the highest isodose line encompassing the PTV (surgical cavity plus 2mm), which can range from 45-95% of the maximum dose Dose Uniformity, Conformity, and Dose Spillage: Conformity Index CI = V100%/PTV should be between 1-2, for lesions less than 5mm up to 3.0 is acceptable |
Structure |
3 fractions |
5 fractions |
Brainstem |
V18 Gy ≤ 0.5cc; Maximum point dose ≤ 23.1 Gy |
V23Gy ≤ 0.5 cc; Maximum point dose < 28 Gy |
Optic Pathway |
V13.8 Gy < 0.2cc; Maximum point dose < 17.4 Gy |
V20 Gy < 0.2cc; Maximum point dose < 23 Gy |
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