TY - JOUR
T1 - Assessing feasibility of real-time ultrasound monitoring in stereotactic body radiotherapyof liver tumors
AU - Zhong, Yahua
AU - Stephans, Kevin
AU - Qi, Peng
AU - Yu, Naichang
AU - Wong, John
AU - Xia, Ping
PY - 2013
Y1 - 2013
N2 - To monitor tumor motion during stereotactic body radiotherapy (SBRT) for patients with liver cancer, an integrated ultrasound and kilo-voltage cone-beam computed tomography (KV-CBCT) system has been proposed. The presence of an ultrasound probe may interfere with the radiation beams. The purpose of this study is to minimize this interference by altering orientations of the ultrasound probe and directions of radiation beams while not compromising the quality of SBRT plans. Ten patients, who received SBRT of liver cancer, were randomly selected for this study. To simulate the presence of an ultrasound probe, a virtual probe was oriented either parallel or vertical to the longitudinal axis of the patient's body and was added on the surface of the patient's body at the nearest location to the tumor. For both the parallel and vertical probe orientations,2 new SBRT (Probe-Para and Probe-Vert) plans that minimize the interference between the probe and radiation beams were created for each patient. These SBRT plans were compared to the original clinically accepted SBRT plans, with a treatment goal of 37.5 Gy to the planning target volume (PTV) in 3 fractions. Specific dosimetric endpoints were evaluated, including doses to 95% (D95), of the PTV plan conformal index (CI), homogeneity index (HI), and relevant end-point doses to organs at risk. For 2 patients with superficially located tumors, no clinically accepable SBRT plans could be produced without the interference between the probe and radiation beams. For the remaining 8 patients, the Probe-Para plans allowed 7 patients to be treated with coplanar radiation beams (without moving the treatment couch during treatment) and 1 patient to be treated with non-coplanar beams (by moving the treatment couch during treatment). The Probe-Vert plans allowed 2 patients to be treated with coplanar beams and 6 patients to be treated with non-coplanar beams. The average D95 of the PTV were 38.63 Gy ± 0.14 (p=0.65) for Probe-Para plans, 38.48 Gy ± 0.31 (p=0.33) for Probe-Vert plans, and 38.72 Gy ± 0.14 for clinical SBRT plans. There were no significant differences (p > 0.05) in CI and HI of all SBRT plans. The endpoint doses to the liver, heart, esophagus, right kidney, and stomach also had no significant differences (p > 0.05). Except for superficial lesions, real-time ultrasound monitoring during liver SBRT is clinically feasible. Placing the ultrasound probe parallel to the longitudinal axis of the patient allows a greater probability of utilizing preferred coplanar beams.
AB - To monitor tumor motion during stereotactic body radiotherapy (SBRT) for patients with liver cancer, an integrated ultrasound and kilo-voltage cone-beam computed tomography (KV-CBCT) system has been proposed. The presence of an ultrasound probe may interfere with the radiation beams. The purpose of this study is to minimize this interference by altering orientations of the ultrasound probe and directions of radiation beams while not compromising the quality of SBRT plans. Ten patients, who received SBRT of liver cancer, were randomly selected for this study. To simulate the presence of an ultrasound probe, a virtual probe was oriented either parallel or vertical to the longitudinal axis of the patient's body and was added on the surface of the patient's body at the nearest location to the tumor. For both the parallel and vertical probe orientations,2 new SBRT (Probe-Para and Probe-Vert) plans that minimize the interference between the probe and radiation beams were created for each patient. These SBRT plans were compared to the original clinically accepted SBRT plans, with a treatment goal of 37.5 Gy to the planning target volume (PTV) in 3 fractions. Specific dosimetric endpoints were evaluated, including doses to 95% (D95), of the PTV plan conformal index (CI), homogeneity index (HI), and relevant end-point doses to organs at risk. For 2 patients with superficially located tumors, no clinically accepable SBRT plans could be produced without the interference between the probe and radiation beams. For the remaining 8 patients, the Probe-Para plans allowed 7 patients to be treated with coplanar radiation beams (without moving the treatment couch during treatment) and 1 patient to be treated with non-coplanar beams (by moving the treatment couch during treatment). The Probe-Vert plans allowed 2 patients to be treated with coplanar beams and 6 patients to be treated with non-coplanar beams. The average D95 of the PTV were 38.63 Gy ± 0.14 (p=0.65) for Probe-Para plans, 38.48 Gy ± 0.31 (p=0.33) for Probe-Vert plans, and 38.72 Gy ± 0.14 for clinical SBRT plans. There were no significant differences (p > 0.05) in CI and HI of all SBRT plans. The endpoint doses to the liver, heart, esophagus, right kidney, and stomach also had no significant differences (p > 0.05). Except for superficial lesions, real-time ultrasound monitoring during liver SBRT is clinically feasible. Placing the ultrasound probe parallel to the longitudinal axis of the patient allows a greater probability of utilizing preferred coplanar beams.
KW - Hepatic tumor
KW - Real-time ultrasound
KW - Stereotactic body radiotherapy
UR - http://www.scopus.com/inward/record.url?scp=84877102108&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84877102108&partnerID=8YFLogxK
U2 - 10.7785/tcrt.2012.500323
DO - 10.7785/tcrt.2012.500323
M3 - Article
C2 - 23369158
AN - SCOPUS:84877102108
SN - 1533-0346
VL - 12
SP - 243
EP - 250
JO - Technology in Cancer Research and Treatment
JF - Technology in Cancer Research and Treatment
IS - 3
ER -