Application of 3D printing technology-assisted standardized applicator in image-guided adaptive brachytherapy of stage Ⅲ B cervical cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective:To explore the application of 3D printing technology-assisted standardized applicator in the image-guided adaptive brachytherapy (IGABT) for cervical cancer.Methods:Twenty-three patients with stage Ⅲ B cervical cancer with extensive paracervical invasion after external irradiation (45 Gy/25f) were treated with IGABT, and the prescription dose was 7 Gy/f×4f. According to the regression of tumor on MRI before and after external irradiation, the range of brachytherapy was determined, and the under dose area of standard intracavitary/interstitial applicator (IC+ IS) was estimated. The virtual transperineal needle channel was inserted in the under dose area, the angle, spacing and depth of implantation were optimized. The auxiliary templates were designed with graphic design software, and 3D printing technology was utilized to print the auxiliary templates. The auxiliary templates were closely combined with the standardized applicator. Under the anesthesia condition, ultrasound-guided applicator was completed, and patients were scanned with MRI image after operation. The MRI images were introduced into treatment planning system (TPS) to delineate the target area and organs at risk, and the treatment plans were optimized to complete the plan evaluation and treatment. Results:The average printing time of templates was (3.5±1.0) h, 382 implant needles were inserted guided by auxiliary templates, (4.2±1.5) template-guided implant needles were used in each fraction and the weight ratio was (16.49±9.50)%. The total dose of HR-CTV D 90% EQD 2Gy, α/ β=10 was (90.45±3.03) Gy, and IR-CTV D 90% EQD 2Gy, α/ β=10 was (66.46±3.68) Gy. The D 2cm 3 EQD 2Gy, α/ β=3 of the bladder, rectum, small intestine and sigmoid colon were (82.69±2.60) Gy, (73.20±2.52) Gy, (69.35±3.32) Gy and (69.39±3.27) Gy, respectively, all of which met the clinical dose requirements. The 1-and 2-year local control rates were 96% and 87%, 87% and 70% for the distant metastasis-free survival rates, and 96% and 78% for thea overall survival rates, respectively. Conclusion:The auxiliary applicators made by 3D printing technology can effectively compensate for the dose insufficiency of the standard applicator in the paracervical and other areas during the clinical brachytherapy in patients with stage Ⅲ B cervical cancer, providing an effective method for the brachytherapy of advanced cervical cancer.