TY - JOUR
T1 - Do we need daily image-guided radiotherapy by megavoltage computed tomography in head and neck helical tomotherapy? the actual delivered dose to the spinal cord
AU - Duma, Marciana Nona
AU - Kampfer, Severin
AU - Schuster, Tibor
AU - Aswathanarayana, Nandana
AU - Fromm, Laura Sophie
AU - Molls, Michael
AU - Andratschke, Nicolaus
AU - Geinitz, Hans
PY - 2012/9/1
Y1 - 2012/9/1
N2 - Purpose: To quantify the actual delivered dose to the cervical spinal cord with different image-guided radiotherapy (IGRT) approaches during head and neck (HN) cancer helical tomotherapy. Methods and Materials: Twenty HN patients (HNpts) treated with bilateral nodal irradiation were analyzed. Daily megavoltage computed tomography MVCT) scans were performed for setup purposes. The maximum dose on the planning CT scan (plan-Dmax) and the magnitude and localization of the actual delivered Dmax (a-Dmax) were analyzed for four scenarios: daily image-guided radiotherapy (dIGRT), twice weekly IGRT (2×WkIGRT), once weekly IGRT (1×WkIGRT), and no IGRT at all (non-IGRT). The spinal cord was recontoured on 236 MVCTs for each scenario (total, 944 fractions), and the delivered dose was recalculated for each fraction (fx) separately. Results: Fifty-one percent of the analyzed fx for dIGRT, 56% of the analyzed fx for the 2×WkIGRT, 62% of the analyzed fx for the 1×WkIGRT, and 63% of the analyzed fx for the non-IGRT scenarios received a higher a-Dmax than the plan-Dmax. The median increase of dose in these fx was 3.3% more for dIGRT, 5.8% more for 2×WkIGRT, 10.0% more for 1×WkIGRT, and 9.5% more for non-IGRT than the plan-Dmax. The median spinal cord volumes receiving a higher dose than the plan-Dmax were 0.02 cm 3 for dIGRT, 0.11 cm 3 for 2×WkIGRT, 0.31 cm 3 for 1×WkIGRT, and 0.22 cm 3 for non-IGRT. Differences between the dIGRT and all other scenarios were statistically significant (p < 0.05). Conclusions: Compared to the Dmax of the initial plan, daily IGRT had the smallest increase in dose. Furthermore, daily IGRT had the lowest proportion of fractions and the smallest volumes affected by a dose that was higher than the planned dose. For patients treated with doses close to the tolerance dose of the spinal cord, we recommend daily IGRT. For all other cases, twice weekly IGRT is sufficient.
AB - Purpose: To quantify the actual delivered dose to the cervical spinal cord with different image-guided radiotherapy (IGRT) approaches during head and neck (HN) cancer helical tomotherapy. Methods and Materials: Twenty HN patients (HNpts) treated with bilateral nodal irradiation were analyzed. Daily megavoltage computed tomography MVCT) scans were performed for setup purposes. The maximum dose on the planning CT scan (plan-Dmax) and the magnitude and localization of the actual delivered Dmax (a-Dmax) were analyzed for four scenarios: daily image-guided radiotherapy (dIGRT), twice weekly IGRT (2×WkIGRT), once weekly IGRT (1×WkIGRT), and no IGRT at all (non-IGRT). The spinal cord was recontoured on 236 MVCTs for each scenario (total, 944 fractions), and the delivered dose was recalculated for each fraction (fx) separately. Results: Fifty-one percent of the analyzed fx for dIGRT, 56% of the analyzed fx for the 2×WkIGRT, 62% of the analyzed fx for the 1×WkIGRT, and 63% of the analyzed fx for the non-IGRT scenarios received a higher a-Dmax than the plan-Dmax. The median increase of dose in these fx was 3.3% more for dIGRT, 5.8% more for 2×WkIGRT, 10.0% more for 1×WkIGRT, and 9.5% more for non-IGRT than the plan-Dmax. The median spinal cord volumes receiving a higher dose than the plan-Dmax were 0.02 cm 3 for dIGRT, 0.11 cm 3 for 2×WkIGRT, 0.31 cm 3 for 1×WkIGRT, and 0.22 cm 3 for non-IGRT. Differences between the dIGRT and all other scenarios were statistically significant (p < 0.05). Conclusions: Compared to the Dmax of the initial plan, daily IGRT had the smallest increase in dose. Furthermore, daily IGRT had the lowest proportion of fractions and the smallest volumes affected by a dose that was higher than the planned dose. For patients treated with doses close to the tolerance dose of the spinal cord, we recommend daily IGRT. For all other cases, twice weekly IGRT is sufficient.
KW - Head and neck
KW - Helical tomotherapy
KW - IGRT
KW - IMRT
KW - Spinal cord
UR - http://www.scopus.com/inward/record.url?scp=84865686362&partnerID=8YFLogxK
U2 - 10.1016/j.ijrobp.2011.10.073
DO - 10.1016/j.ijrobp.2011.10.073
M3 - Article
C2 - 22417803
AN - SCOPUS:84865686362
SN - 0360-3016
VL - 84
SP - 283
EP - 288
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -
