TY - JOUR
T1 - Parotid Gland Dose in Intensity-Modulated Radiotherapy for Head and Neck Cancer
T2 - Is What You Plan What You Get?
AU - O'Daniel, Jennifer C.
AU - Garden, Adam S.
AU - Schwartz, David L.
AU - Wang, He
AU - Ang, Kian K.
AU - Ahamad, Anesa
AU - Rosenthal, David I.
AU - Morrison, William H.
AU - Asper, Joshua A.
AU - Zhang, Lifei
AU - Tung, Shih Ming
AU - Mohan, Radhe
AU - Dong, Lei
PY - 2007/11/15
Y1 - 2007/11/15
N2 - Purpose: To quantify the differences between planned and delivered parotid gland and target doses, and to assess the benefits of daily bone alignment for head and neck cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eleven head and neck cancer patients received two CT scans per week with an in-room CT scanner over the course of their radiotherapy. The clinical IMRT plans, designed with 3-mm to 4-mm planning margins, were recalculated on the repeat CT images. The plans were aligned using the actual treatment isocenter marked with radiopaque markers (BB) and bone alignment to the cervical vertebrae to simulate image-guided setup. In-house deformable image registration software was used to map daily dose distributions to the original treatment plan and to calculate a cumulative delivered dose distribution for each patient. Results: Using conventional BB alignment led to increases in the parotid gland mean dose above the planned dose by 5 to 7 Gy in 45% of the patients (median, 3.0 Gy ipsilateral, p = 0.026; median, 1.0 Gy contralateral, p = 0.016). Use of bone alignment led to reductions relative to BB alignment in 91% of patients (median, 2 Gy; range, 0.3-8.3 Gy; 15 of 22 parotids improved). However, the parotid dose from bone alignment was still greater than planned (median, 1.0 Gy, p = 0.007). Neither approach affected tumor dose coverage. Conclusions: With conventional BB alignment, the parotid gland mean dose was significantly increased above the planned mean dose. Using daily bone alignment reduced the parotid dose compared with BB alignment in almost all patients. A 3- to 4-mm planning margin was adequate for tumor dose coverage.
AB - Purpose: To quantify the differences between planned and delivered parotid gland and target doses, and to assess the benefits of daily bone alignment for head and neck cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eleven head and neck cancer patients received two CT scans per week with an in-room CT scanner over the course of their radiotherapy. The clinical IMRT plans, designed with 3-mm to 4-mm planning margins, were recalculated on the repeat CT images. The plans were aligned using the actual treatment isocenter marked with radiopaque markers (BB) and bone alignment to the cervical vertebrae to simulate image-guided setup. In-house deformable image registration software was used to map daily dose distributions to the original treatment plan and to calculate a cumulative delivered dose distribution for each patient. Results: Using conventional BB alignment led to increases in the parotid gland mean dose above the planned dose by 5 to 7 Gy in 45% of the patients (median, 3.0 Gy ipsilateral, p = 0.026; median, 1.0 Gy contralateral, p = 0.016). Use of bone alignment led to reductions relative to BB alignment in 91% of patients (median, 2 Gy; range, 0.3-8.3 Gy; 15 of 22 parotids improved). However, the parotid dose from bone alignment was still greater than planned (median, 1.0 Gy, p = 0.007). Neither approach affected tumor dose coverage. Conclusions: With conventional BB alignment, the parotid gland mean dose was significantly increased above the planned mean dose. Using daily bone alignment reduced the parotid dose compared with BB alignment in almost all patients. A 3- to 4-mm planning margin was adequate for tumor dose coverage.
KW - Adaptive radiotherapy
KW - Anatomic variation
KW - Image-guided radiotherapy
KW - Parotid gland
KW - Setup uncertainty
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U2 - 10.1016/j.ijrobp.2007.07.2345
DO - 10.1016/j.ijrobp.2007.07.2345
M3 - Article
C2 - 17967319
AN - SCOPUS:35448993585
SN - 0360-3016
VL - 69
SP - 1290
EP - 1296
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -