PURPOSE: Single four-dimensional CT (4DCT) scans reliably capture intrafractional tumor mobility for radiotherapy planning, but generating internal target volumes (ITVs) requires the contouring of gross tumor volumes (GTVs) in up to 10 phases of a 4DCT scan, as is routinely performed in our department. We investigated the use of maximum intensity projection (MIP) protocols for rapid generation of ITVs. METHODS AND MATERIALS: 4DCT data from a mobile phantom and from 12 patients with Stage I lung cancer were analyzed. A single clinician contoured GTVs in all respiratory phases of a 4DCT, as well as in three consecutive phases selected for respiratory gating. MIP images were generated from both phantom and patient data, and ITVs were derived from encompassing volumes of the respective GTVs. RESULTS: In the phantom study, the ratio between ITVs generated from all 10 phases and those from MIP scans was 1.04. The corresponding center of mass of both ITVs differed by less than 1 mm. In scans from patients, good agreement was observed between ITVs derived from 10 and 3 (gating) phases and corresponding MIPs, with ratios of 1.07 +/- 0.05 and 0.98 +/- 0.05, respectively. In addition, the center of mass of the respective ITVs differed by only 0.4 and 0.5 mm. CONCLUSION: MIPs are a reliable clinical tool for generating ITVs from 4DCT data sets, thereby permitting rapid assessment of mobility for both gated and nongated 4D radiotherapy in lung cancer.
PURPOSE: Single four-dimensional CT (4DCT) scans reliably capture intrafractional tumor mobility for radiotherapy planning, but generating internal target volumes (ITVs) requires the contouring of gross tumor volumes (GTVs) in up to 10 phases of a 4DCT scan, as is routinely performed in our department. We investigated the use of maximum intensity projection (MIP) protocols for rapid generation of ITVs. METHODS AND MATERIALS: 4DCT data from a mobile phantom and from 12 patients with Stage I lung cancer were analyzed. A single clinician contoured GTVs in all respiratory phases of a 4DCT, as well as in three consecutive phases selected for respiratory gating. MIP images were generated from both phantom and patient data, and ITVs were derived from encompassing volumes of the respective GTVs. RESULTS: In the phantom study, the ratio between ITVs generated from all 10 phases and those from MIP scans was 1.04. The corresponding center of mass of both ITVs differed by less than 1 mm. In scans from patients, good agreement was observed between ITVs derived from 10 and 3 (gating) phases and corresponding MIPs, with ratios of 1.07 +/- 0.05 and 0.98 +/- 0.05, respectively. In addition, the center of mass of the respective ITVs differed by only 0.4 and 0.5 mm. CONCLUSION: MIPs are a reliable clinical tool for generating ITVs from 4DCT data sets, thereby permitting rapid assessment of mobility for both gated and nongated 4D radiotherapy in lung cancer.
Authors: David A Zamora; Adam C Riegel; Xiaojun Sun; Peter Balter; George Starkschall; Osama Mawlawi; Tinsu Pan Journal: Med Phys Date: 2010-11 Impact factor: 4.071
Authors: Min Li; Sarah Joy Castillo; Richard Castillo; Edward Castillo; Thomas Guerrero; Liang Xiao; Xiaolin Zheng Journal: Int J Comput Assist Radiol Surg Date: 2017-02-14 Impact factor: 2.924
Authors: Markus Oechsner; Barbara Chizzali; Michal Devecka; Stefan Münch; Stephanie Elisabeth Combs; Jan Jakob Wilkens; Marciana Nona Duma Journal: Strahlenther Onkol Date: 2017-07-19 Impact factor: 3.621