Evaluation of different set-up error corrections on dose-volume metrics in prostate IMRT using CBCT images.

We investigated the effect of different set-up error corrections on dose-volume metrics in intensity-modulated radiotherapy (IMRT) for prostate cancer under different planning target volume (PTV) margin settings using cone-beam computed tomography (CBCT) images. A total of 30 consecutive patients who underwent IMRT for prostate cancer were retrospectively analysed, and 7-14 CBCT datasets were acquired per patient. Interfractional variations in dose-volume metrics were evaluated under six different set-up error corrections, including tattoo, bony anatomy, and four different target matching groups. Set-up errors were incorporated into planning the isocenter position, and dose distributions were recalculated on CBCT images. These processes were repeated under two different PTV margin settings. In the on-line bony anatomy matching groups, systematic error (∑) was 0.3 mm, 1.4 mm, and 0.3 mm in the left-right, anterior-posterior (AP), and superior-inferior directions, respectively. ∑ in three successive off-line target matchings was finally comparable with that in the on-line bony anatomy matching in the AP direction. Although doses to the rectum and bladder wall were reduced for a small PTV margin, averaged reductions in the volume receiving 100% of the prescription dose from planning were within 2.5% under all PTV margin settings for all correction groups, with the exception of the tattoo set-up error correction only (≥ 5.0%). Analysis of variance showed no significant difference between on-line bony anatomy matching and target matching. While variations between the planned and delivered doses were smallest when target matching was applied, the use of bony anatomy matching still ensured the planned doses.

Hirose Y ，Nakamura M ，Tomita T ，Kitsuda K ，Notogawa T ，Miki K ，Nakamura K ，Ishigaki T ... -  《-》

Superiority of a soft tissue-based setup using cone-beam computed tomography over a bony structure-based setup in intensity-modulated radiotherapy for prostate cancer.

Sato H ，Abe E ，Utsunomiya S ，Kaidu M ，Yamana N ，Tanaka K ，Ohta A ，Obinata M ，Liu J ，Kawaguchi G ，Maruyama K ，Ayukawa F ，Aoyama H ... -  《Journal of Applied Clinical Medical Physics》

PTV margin analysis for prostate patients treated with initial pelvic nodal IMRT and prostate proton boost.

Su Z ，Li Z ，Henderson R ，Hoppe B ，Nichols RC ，Bryant C ，Mendenhall W ，Mendenhall N ... -  《-》

Determining optimal planning target volume and image guidance policy for post-prostatectomy intensity modulated radiotherapy.

Bell LJ ，Cox J ，Eade T ，Rinks M ，Herschtal A ，Kneebone A ... -  《-》

The potential failure risk of the cone-beam computed tomography-based planning target volume margin definition for prostate image-guided radiotherapy based on a prospective single-institutional hybrid analysis.

Hirose K ，Sato M ，Hatayama Y ，Kawaguchi H ，Komai F ，Sohma M ，Obara H ，Suzuki M ，Tanaka M ，Fujioka I ，Ichise K ，Takai Y ，Aoki M ... -  《Radiation Oncology》