G. Kawaguchi

Salvage endoscopic submucosal dissection in patients with local failure after chemoradiotherapy for esophageal squamous cell carcinoma.

Abstract Objective. For locoregional failure after chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC), salvage esophagectomy and endoscopic mucosal resection have disadvantages, such as a high morbidity rate and a high local recurrence rate, respectively. The aim of this study was to clarify the efficacy of salvage endoscopic submucosal dissection (ESD) for locoregional failure of CRT. Methods. A total of 19 lesions in 19 patients were treated with salvage ESD; 15 lesions were local recurrences at the primary site and 4 lesions were residual. All lesions were intramucosal or submucosal tumors without metastases. A case-control study was retrospectively evaluated to clarify whether the clinical outcomes of salvage ESD were equivalent to those of control primary ESD. Results. No significant differences were observed between salvage ESD and primary ESD in short-term outcomes, including procedure time. For salvage ESD, the complete en bloc resection rate was 94.7% (18 of 19), and no severe complications were observed. At a median follow up of 54.6 (range: 5–98) months after salvage ESD, the local recurrence rate was 0%. However, three patients (15.8%) died due to lymph node and distant metastases and six patients (31.5%) died from other diseases, including radiation pneumonitis, pyothorax or respiratory failure with no recurrence of ESCC. The 3-year overall survival rate for all 19 patients was 74%. Conclusions. ESD represents an acceptable treatment option for recurrent or residual ESCC because of its improvement in local control, when local failure after CRT is limited to the submucosal layer without metastases.

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.

The purpose of this study was to test the superiority of a soft tissue‐based setup using cone‐beam computed tomography (CBCT) to a bony structure‐based setup using the ExacTrac system in intensity‐modulated radiotherapy (IMRT) for prostate cancer. We studied 20 patients with localized prostate cancer who received IMRT between November 2010 and February 2012. After the initial setup, the pelvic bony structure‐based setup and ExacTrac system were applied. After that, CBCT and a soft tissue‐based setup were used. A shift in the isocenter between the ExacTrac‐based and CBCT‐based setup was recorded in the anterior–posterior (AP), superior–inferior (SI), and left–right (LR) axes. The shift was considered an interfractional prostate shift. Post‐treatment CBCT was also taken once a week to measure the intrafractional prostate shift, based on the coordinates of the isocenter between pre‐ and post‐treatment CBCT. The planning target volume (PTV) margins were determined using van Herks method. We measured the elapsed time required for soft tissue matching and the entire treatment time using CBCT. The means±standard deviation(SD) of the inter‐ and intrafractional shifts were 0.9±2.8 mm and −0.3±1.4 mm in the AP, 0.9±2.2 mm and −0.1±1.2 mm in the SI, and 0.1±0.7 mm and −0.1±0.7 mm in the LR directions. The PTV margins in the cases of bony structure‐based and soft tissue‐based setups were 7.3 mm and 2.7 mm in the AP, 5.8 mm and 2.3 mm in the SI, and 1.9 mm and 1.2 mm in the LR directions. Even though the median elapsed time using CBCT was expanded in 5.9 min, the PTV margins were significantly reduced. We found the calculated PTV margins in the soft tissue‐based setup using CBCT were small, and this arrangement was superior to the bony structure‐based setup in prostate IMRT. PACS numbers: 87.19.ru, 87.55.T‐

Clinical commissioning of a new patient positioning system, SyncTraX FX4, for intracranial stereotactic radiotherapy

Abstract Background & Aims A new real‐time tracking radiotherapy (RTRT) system, the SyncTraX FX4 (Shimadzu, Kyoto, Japan), consisting of four X‐ray tubes and four ceiling‐mounted flat panel detectors (FPDs) combined with a linear accelerator, was installed at Uonuma Kikan Hospital (Niigata, Japan) for the first time worldwide. In addition to RTRT, the SyncTraX FX4 system enables bony structure‐based patient verification. Here we provide the first report of this systems clinical commissioning for intracranial stereotactic radiotherapy (SRT). Materials & Methods A total of five tests were performed for the commissioning: evaluations of (1) the systems image quality; (2) the imaging and treatment coordinate coincidence; and (3) the localization accuracy of cone‐beam computed tomography (CBCT) and SyncTraX FX4; (4) the measurement of air kerma; (5) an end‐to‐end test. Results & Discussion The tests revealed the following. (1) All image quality evaluation items satisfied each acceptable criterion in all FPDs. (2) The maximum offsets among the centers were ≤0.40 mm in all combinations of the FPD and X‐ray tubes (preset). (3) The isocenter localization discrepancies between CBCT and preset #3 in the SyncTraX FX4 system were 0.29 ± 0.084 mm for anterior‐posterior, −0.19 ± 0.13 mm for superior‐inferior, 0.076 ± 0.11 mm for left‐right, −0.11 ± 0.066° for rotation, −0.14 ± 0.064° for pitch, and 0.072±0.058° for roll direction. the Pearsons product‐moment correlation coefficient between the two systems was >0.98 in all directions. (4) The mean air kerma value for preset #3 was 0.11 ± 0.0002 mGy in predefined settings (80 kV, 200 mA, 50 msec). (5) For 16 combinations of gantry and couch angles, median offset value in all presets was 0.31 mm (range 0.14–0.57 mm). Conclusion Our results demonstrate a competent performance of the SyncTraX FX4 system in terms of the localization accuracy for intracranial SRT.