Details

Autor(en) / Beteiligte

• Noble, David J.
• Yeap, Ping-Lin
• Seah, Shannon Y.K.
• Harrison, Karl
• Shelley, Leila E.A.
• Romanchikova, Marina
• Bates, Amy M.
• Zheng, Yaolin
• Barnett, Gillian C.
• Benson, Richard J.
• Jefferies, Sarah J.
• Thomas, Simon J.
• Jena, Raj
• Burnet, Neil G.

Titel

Anatomical change during radiotherapy for head and neck cancer, and its effect on delivered dose to the spinal cord

Ist Teil von

• Radiotherapy and oncology, 2019-01, Vol.130, p.32-38

Ort / Verlag

Ireland: Elsevier B.V

Erscheinungsjahr

2019

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• •A cohort of 133 head & neck cancer patients treated with TomoTherapy was examined.•Differences between planned and delivered maximum spinal cord dose were small.•Substantial weight loss and anatomical change during treatment was observed.•No link between weight loss or anatomical change, and dose differences was seen. The impact of weight loss and anatomical change during head and neck (H&N) radiotherapy on spinal cord dosimetry is poorly understood, limiting evidence-based adaptive management strategies. 133 H&N patients treated with daily mega-voltage CT image-guidance (MVCT-IG) on TomoTherapy, were selected. Elastix software was used to deform planning scan SC contours to MVCT-IG scans, and accumulate dose. Planned (DP) and delivered (DA) spinal cord D2% (SCD2%) were compared. Univariate relationships between neck irradiation strategy (unilateral vs bilateral), T-stage, N-stage, weight loss, and changes in lateral separation (LND) and CT slice surface area (SSA) at C1 and the superior thyroid notch (TN), and ΔSCD2% [(DA – DP) D2%] were examined. The mean value for (DA – DP) D2% was −0.07 Gy (95%CI −0.28 to 0.14, range −5.7 Gy to 3.8 Gy), and the mean absolute difference between DP and DA (independent of difference direction) was 0.9 Gy (95%CI 0.76–1.04 Gy). Neck treatment strategy (p = 0.39) and T-stage (p = 0.56) did not affect ΔSCD2%. Borderline significance (p = 0.09) was seen for higher N-stage (N2-3) and higher ΔSCD2%. Mean reductions in anatomical metrics were substantial: weight loss 6.8 kg; C1LND 12.9 mm; C1SSA 12.1 cm2; TNLND 5.3 mm; TNSSA 11.2 cm2, but no relationship between weight loss or anatomical change and ΔSCD2% was observed (all r2 < 0.1). Differences between delivered and planned spinal cord D2% are small in patients treated with daily IG. Even patients experiencing substantial weight loss or anatomical change during treatment do not require adaptive replanning for spinal cord safety.