Volumetric modulated arc therapy for spine SBRT patients to reduce treatment time and intrafractional motion

Volumetric modulated arc therapy (VMAT) is an efficient technique to reduce the treatment time and intrafractional motion to treat spine patients presented with severe back pain. Five patients treated with spine stereotactic body radiation therapy (SBRT) using 9 beams intensity modulated radiation therapy (IMRT) were retrospectively selected for this study. The patients were replanned using two arcs VMAT technique. The average mean dose was 104% ± 1.2% and 104.1% ± 1.0% in IMRT and VMAT, respectively (p = 0.9). Accordingly, the average conformal index (CI) was 1.3 ± 0.1 and 1.5 ± 0.3, respectively (p = 0.5). The average dose gradient (DG) distance was 1.5 ± 0.1 cm and 1.4 ± 0.1 cm, respectively (p = 0.3). The average spinal cord maximum dose was 11.6 ± 1.0 Gy and 11.8 ± 1.1 Gy (p = 0.8) and V10Gy was 7.4 ± 1.4 cc and 8.6 ± 1.7 cc (p = 0.4) for IMRT and VMAT, respectively. Accordingly, the average number of monitor units (MUs) was 6771.7 ± 1323.3 MU and 3978 ± 576.7 MU respectively (p = 0.02). The use of VMAT for spine SBRT patients with severe back pain can reduce the treatment time and intrafractional motion

Volumetric modulated arc therapy for spine SBRT patients to reduce treatment time and intrafractional motion

Volumetric modulated arc therapy (VMAT) is an efficient technique to reduce the treatment time and intrafractional motion to treat spine patients presented with severe back pain. Five patients treated with spine stereotactic body radiation therapy (SBRT) using 9 beams intensity modulated radiation therapy (IMRT) were retrospectively selected for this study. The patients were replanned using two arcs VMAT technique. The average mean dose was 104% ± 1.2% and 104.1% ± 1.0% in IMRT and VMAT, respectively (p = 0.9). Accordingly, the average conformal index (CI) was 1.3 ± 0.1 and 1.5 ± 0.3, respectively (p = 0.5). The average dose gradient (DG) distance was 1.5 ± 0.1 cm and 1.4 ± 0.1 cm, respectively (p = 0.3). The average spinal cord maximum dose was 11.6 ± 1.0 Gy and 11.8 ± 1.1 Gy (p = 0.8) and V10Gy was 7.4 ± 1.4 cc and 8.6 ± 1.7 cc (p = 0.4) for IMRT and VMAT, respectively. Accordingly, the average number of monitor units (MUs) was 6771.7 ± 1323.3 MU and 3978 ± 576.7 MU respectively (p = 0.02). The use of VMAT for spine SBRT patients with severe back pain can reduce the treatment time and intrafractional motion

Potential systematic uncertainties in IGRT when FBCT reference images are used for pancreatic tumors

The purpose of this study was to quantify the systematic uncertainties resulting from using free breathing computed tomography (FBCT) as a reference image for image-guided radiation therapy (IGRT) for patients with pancreatic tumors, and to quantify the associated dosimetric impact that resulted from using FBCT as refer-ence for IGRT. Fifteen patients with implanted fiducial markers were selected for this study. For each patient, a FBCT and an average intensity projection computed tomography (AIP) created from four-dimensional computed tomography (4D CT) were acquired at the simulation. The treatment plan was created based on the FBCT. Seventy-five weekly kilovoltage (kV) cone-beam computed tomography (CBCT) images (five for each patient) were selected for this study. Bony align-ment without rotation correction was performed 1) between the FBCT and CBCT, 2) between the AIP and CBCT, and 3) between the AIP and FBCT. The contours of the fiducials from the FBCT and AIP were transferred to the corresponding CBCT and were compared. Among the 75 CBCTs, 20 that had> 3 mm differences in centers of mass (COMs) in any directions between the FBCT and AIP were chose