Fast Megavoltage Computed Tomography: A Rapid Imaging Method for Total Body or Marrow Irradiation in Helical Tomotherapy.
Megavoltage computed tomographic (MVCT) imaging has been widely used for the 3-dimensional (3-D) setup of patients treated with helical tomotherapy (HT). One drawback of MVCT is its very long imaging time, the result of slow couch speeds of approximately 1 mm/s, which can be difficult for the patient to tolerate. We sought to develop an MVCT imaging method allowing faster couch speeds and to assess its accuracy for image guidance for HT.



Three cadavers were scanned 4 times with couch speeds of 1, 2, 3, and 4 mm/s. The resulting MVCT images were reconstructed using an iterative reconstruction (IR) algorithm with a penalty term of total variation and with a conventional filtered back projection (FBP) algorithm. The MVCT images were registered with kilovoltage CT images, and the registration errors from the 2 reconstruction algorithms were compared. This fast MVCT imaging was tested in 3 cases of total marrow irradiation as a clinical trial.



The 3-D registration errors of the MVCT images reconstructed with the IR algorithm were smaller than the errors of images reconstructed with the FBP algorithm at fast couch speeds (2, 3, 4 mm/s). The scan time and imaging dose at a speed of 4 mm/s were reduced to 30% of those from a conventional coarse mode scan. For the patient imaging, faster MVCT (3 mm/s couch speed) scanning reduced the imaging time and still generated images useful for anatomic registration.



Fast MVCT with the IR algorithm is clinically feasible for large 3-D target localization, which may reduce the overall time for the treatment procedure. This technique may also be useful for calculating daily dose distributions or organ motion analyses in HT treatment over a wide area. Automated integration of this imaging is at least needed to further assess its clinical benefits.
Department of Radiological Sciences, Faculty of Health Sciences, Komazawa University, Tokyo, Japan; Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.
Taiki
T
Magome
Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan.
Akihiro
A
Haga
Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota; Department of Radiation Oncology, Osaka University, Osaka, Japan.
Yutaka
Y
Takahashi
Department of Radiology, The University of Tokyo Hospital, Tokyo, Japan.
Keiichi
K
Nakagawa
Department of Therapeutic Radiology, University of Minnesota, Minneapolis, Minnesota.
Kathryn E
KE
Dusenbery
Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota; Department of Therapeutic Radiology, University of Minnesota, Minneapolis, Minnesota; Department of Radiation Oncology and Beckman Research Institute, City of Hope, Duarte, California. Electronic address: shui@coh.org.
Susanta K
SK
Hui
D000328:Adult; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000473:pathology / Q000528:radiation effects*; D002102:Cadaver; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging / Q000379:methods*; D014916:Whole-Body Irradiation / Q000379:methods*
Phys Med Biol. 1999 Oct;44(10):2597-621
10533931
Phys Med Biol. 2001 Mar;46(3):853-66
11277230
Br J Radiol. 2004 Apr;77(916):285-95
15107318
Med Phys. 2005 Aug;32(8):2673-81
16193798
Med Phys. 2005 Oct;32(10):3214-24
16279075
Biol Blood Marrow Transplant. 2006 Mar;12(3):306-15
16503500
Phys Med Biol. 2006 Jul 7;51(13):R427-53
16790916
Acta Oncol. 2007;46(2):250-5
17453378
Med Phys. 2008 Feb;35(2):660-3
18383687
Phys Med Biol. 2008 Sep 7;53(17):4777-807
18701771
Med Phys. 2010 Apr;37(4):1757-60
20443497
Blood. 2011 Jan 6;117(1):309-15
20876852
Med Phys. 2010 Aug;37(8):4068-77
20879568
Clin Cancer Res. 2011 Jan 1;17(1):174-82
21047977
Radiother Oncol. 2011 Mar;98(3):382-6
21339008
Phys Med. 2012 Apr;28(2):94-108
22316498
Int J Radiat Oncol Biol Phys. 2013 Jan 1;85(1):148-56
22592050
Radiother Oncol. 2012 Aug;104(2):249-56
22809588
Radiat Oncol. 2013 Apr 15;8:92
23587349
Int J Radiat Oncol Biol Phys. 2014 May 1;89(1):75-81
24725691
Radiat Oncol. 2014 Nov 28;9:252
25430898
Int J Radiat Oncol Biol Phys. 2015 Jan 1;91(1):30-8
25442340
Med Phys. 2012 Jun;39(6Part20):3857
28517520
Med Phys. 1993 Nov-Dec;20(6):1709-19
8309444