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To evaluate the possibility of dose escalation and reduction of fraction number in cervical brachytherapy using a gel spacer. Twenty patients with uterine cervical cancer treated with image-guided adaptive brachytherapy (IGABT) were selected. Hyaluronic acid gel injection (HGI) was performed in the rectovaginal and vesicouterine septum for 10 patients. The other ten patients were not with HGI. Both groups were treated with IGABT involving tandem/ovoid or cylindrical applicators along with additional interstitial needles. Dose distributions approved by radiation oncologists were retrospectively analyzed, and a dose summation of 45 Gy/25 of external beam radiation therapy and IGABT was performed. Dose constraints for D 2cc of bladder, rectum, and sigmoid were 80, 70, and 70 Gy, respectively. Equivalent dose in 2-Gy fractions calculations used α/β = 10 Gy for high-risk clinical target volume (CTV HR) D 90 and α/β = 3 Gy for organs at risks (OARs). As a planning study, dose distribution rescaling was conducted to deliver as much dose to CTV HR D 90 as possible within the dose constraint limitation for OARs when IGABT was performed for four, three, and two fractions in both groups. The median CTV HR D 90 was >80 Gy in the non-HGI group and >85 Gy in the HGI group for virtual two and three fractions. Rectum D 2cc was significantly lower in the HGI group for three fractions (p < 0.01). In the HGI group, adequate dose delivery to CTV HR could be achieved with a reduced IGABT fraction number while meeting the dose constraints of OARs. [ABSTRACT FROM AUTHOR]

We developed a 3D-printed phantom model for ultrasound-guided caudal block for educational or training purposes because there have been no reports of the 3D-printed phantom model for ultrasound-guided caudal block. This study aimed to identify the needs for the phantom model in a lecture and demonstration at hands-on training (HoT) to promote the use of caudal block for sufficient pain control during high-dose-rate intracavitary/interstitial brachytherapy for gynecological cancers. The sacrum and formwork were designed by computed tomography imaging. A 3D-modeling software program was used to create the sacrum and formwork. The phantom was solidified by injecting a gelatin-based gel. Ultrasonography was performed to visualize the sacral hiatus and puncture needle in the phantom. In October 2023, 10 radiation oncologists who did not perform caudal block in daily clinical practice from ten Japanese facilities participated in HoT on ultrasound-guided caudal block. After the HoT, questionnaires were distributed to each participant, and feedback was obtained through online channels. After receiving a lecture and demonstration on ultrasound-guided caudal block, 90% of the respondents would like to practice the procedure in their daily clinical practice. Moreover, 100% of the respondents would like to use the 3D-printed phantom model for ultrasound-guided caudal block for educational or training purposes. The 3D-printed phantom model for ultrasound-guided caudal block can be used in training and is in demand for facilities introducing caudal block. [ABSTRACT FROM AUTHOR]