The authors retract this article due to an error in the data used in Figure 6. The authors have concluded that the data in Figure 6 cannot be used to support the conclusions of the article. This decision has been approved by Alexandre Detappe, Rajiv Kumar, Thomas Ireland, Lisa Cameron, Douglas E. Biancur, Vincent Motto-Ros, Lucie Sancey, Srinivas Sridhar, G. Mike Makrigiorgos, and Ross I. Berbeco. Sijumon Kunjachan did not respond.
The original letter was published on September 29, 2015. A correction was issued on August 10, 2020 to address figure assembly errors, specifically in Figure 6. This article was retracted on November 2, 2022.