TY - JOUR
T1 - Use of maximum intensity projections (MIP) for target volume generation in 4DCT scans for lung cancer
AU - Underberg, René W.M.
AU - Lagerwaard, Frank J.
AU - Slotman, Ben J.
AU - Cuijpers, Johan P.
AU - Senan, Suresh
PY - 2005/9/1
Y1 - 2005/9/1
N2 - 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.
AB - 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.
KW - 4DCT scans
KW - Internal target volume
KW - Lung cancer
KW - Maximum intensity projection
UR - http://www.scopus.com/inward/record.url?scp=26944441695&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.ijrobp.2005.05.045
DO - https://doi.org/10.1016/j.ijrobp.2005.05.045
M3 - Article
C2 - 16111596
SN - 0360-3016
VL - 63
SP - 253
EP - 260
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -