RT Journal Article
SR Electronic
T1 Assessment of Planning Target Volume Margin for a Small Number of Vertebral Metastatic Lesions Using Image-guided Intensity-modulated Radiation Therapy by Helical Tomotherapy
JF Anticancer Research
JO Anticancer Res
FD International Institute of Anticancer Research
SP 2453
OP 2456
VO 33
IS 6
A1 NISHIMURA, TAKUYA
A1 YAMAZAKI, HIDEYA
A1 IWAMA, KAZUKI
A1 KOTANI, TOMOYA
A1 OOTA, YOSHITAKA
A1 AIBE, HIRONORI
A1 NAKAMURA, SATOAKI
A1 IKENO, HIROYASU
A1 YOSHIDA, KEN
A1 ISOHASHI, FUMIAKI
A1 OKABE, HARUUMI
YR 2013
UL http://ar.iiarjournals.org/content/33/6/2453.abstract
AB Aim: To evaluate an appropriate planning target volume (PTV) margin in for one to three vertebral metastases using megavolt computed tomography (MVCT) images during the course of image-guided and stereotactic intensity-modulated radiotherapy (IGRT-IMRT) by use of helical tomotherapy. Patients and Methods: A total of 25 lesions in 24 patients with vertebral metastases who received IGRT-IMRT were analyzed. MVCT images were acquired before and after radiation therapy. Intra-fractional movement and PTV margin were calculated by comparing treatment planning images and these 310 MVCT images for right-left (RL), superior-inferior (SI), and anteroposterior (AP) dimensions. Five patients were treated by 35 Gy/5 fractions, 17 by 30 Gy/5 fractions, one by 25 Gy/5 fractions, and one by 60 Gy/30 fractions. A margin to compensate for these variations was calculated with the formula of vanHerk's equation. Results: The intra-fractional motion was 0.02 (−1.3 to 1.4) ± 0.34 mm in the RL direction, −0.09 (−1.8 to 0.28) ± 0.44 mm in the SI direction, and 0.20 (−1.8 to 1.8) ± 0.36 mm in the AP direction. The required PTV margin was 0.98 mm in the RL direction, 0.69 mm in the SI direction, and 1.26 mm in the AP direction. No patient showed a deviation greater than 2 mm. Conclusion: The PTV margin in hypofractionated IGRT–IMRT, using helical tomotherapy for a few vertebral metastases, was 2 mm or less and our tentative PTV margin of 5 mm was sufficient and reducible.