Increased brachytherapy safety with 3D printing

A total of 252 treatments were performed, with 24 patients in the IMRT combined with 3D-printed brachytherapy group undergoing 125 treatments. In this group, a total of 443 implantation needles were used, averaging 3.5 needles per treatment, and an average of one CT scan was performed per procedure. The complication rate was 5.6% (7 cases). In contrast, 25 patients in the IMRT combined with free hand insertion brachytherapy group underwent 127 treatments. A total of 255 implantation needles were used in this group, averaging 2 needles per treatment, and an average of 1.2 CT scans were performed per procedure. The complication rate was higher at 11.0% (14 cases) (Table 2).

The coverage of the clinical target volume (CTV) was limited by the constraints on the bladder and rectum (D1cc and D2cc) in the IMRT combined with free hand insertion brachytherapy group, resulting in a lower CTV coverage compared to the IMRT combined with 3D-printed brachytherapy group. Moreover, the doses received by the bladder and rectum were lower in the 3D-printed brachytherapy group than in the free hand insertion group (Table 2).

Table 2 Comparison of radiotherapy operation between IMRT combined with 3D postloading radiotherapy group and IMRT combined with freehand insertion postloading radiotherapy groupEnhanced safety of 3D-printed brachytherapy in large tumors

The application of 3D-printed brachytherapy significantly improved the safety of radiation therapy operations for large tumors (≥ 30 mm) compared to smaller tumors (Tables 3 and 4). In the group receiving 3D-printed brachytherapy for large tumors, CTV D90 is set at 60 Gy for all patients. the mean doses for CTV-D95, CTV-D98, and CTV-D100 were 53.08 Gy, 46.91 Gy, and 33.92 Gy, respectively, demonstrating higher accuracy in targeting the tumor area. The dose-volume ratios (CTV-v100, CTV-v150, and CTV-v200) were also superior in the 3D printing-BT, indicating better preservation of the target volume while minimizing exposure to surrounding tissues.

Table 3 Comparison of effective target areas and organ damage in radiotherapy for small tumoursTable 4 Comparison of effective target areas and organ damage in radiotherapy for large tumours

Furthermore, the organ-damaging doses (bladder irradiation dose D1CC and D2CC, rectal irradiation dose D1CC and D2CC) were significantly lower in the 3D printed-BT, highlighting the enhanced safety profile of 3D-printed brachytherapy in large tumors. These results underscore the importance of 3D-printed brachytherapy in improving the therapeutic outcomes of radiation therapy for patients with large cervical tumors.

Additionally, it is important to note that the 3D-printed BT approach typically involves the use of more needles compared to the free-hand procedure. This increased use of needles allows for more precise dose distribution and better targeting of the tumor, while minimizing exposure to surrounding healthy tissues. This aspect of 3D-printed BT contributes to its trend towards improved safety results and lower doses to organs at risk (OAR) when compared to free-hand BT.

Lower complication rates with 3D printing in brachytherapy

The incidence of radiation-induced cystitis and proctitis was evaluated using the RTOG/EORTC grading standards [19]. In the 3D printing-BT, 70.8% of patients had no radiation enteritis, compared to 12.0% in the Freehand implant-BT (P < 0.001). Acute and combined acute and chronic radiation enteritis were significantly less frequent in the 3D group compared to the freehand group (Table 5).

The complication rate was 5.6% for 3-printed and 11% for freehand implant. There were no significant differences between the two groups in terms of radiation cystitis, rectovaginal fistula, abdominal infection, vesicovaginal fistula, and intestinal obstruction (Table 5).

Table 5 Comparison of radiotherapy complication rates between the IMRT combined with 3D postloading radiotherapy group and IMRT combined with freehand insertion postloading radiotherapy groupShort-term efficacy and survival outcomes of 3D-printed brachytherapy in cervical Cancer patients

In the group receiving intensity-modulated radiation therapy (IMRT) combined with 3D-printed brachytherapy, the proportions of patients achieving CR and PR were equal (50% vs. 50%). In contrast, in the group receiving IMRT combined with freehand insertion brachytherapy, the proportion of patients achieving CR was slightly lower than that of patients achieving PR (48% vs. 52%) (Fig. 4). In terms of survival outcomes, The median follow-up period in this study was 22.5 months [IQR 18–29], and overall, there were no significant differences in the therapeutic responses between the two groups, indicating that both treatment modalities provide comparable outcomes in terms of clinical response. Kaplan-Meier analysis revealed no significant difference in overall survival between the two groups of patients (P > 0.05) (Fig. 5). This indicates that while 3D-printed brachytherapy may enhance the immediate therapeutic response, it does not significantly impact the overall survival of cervical cancer patients when compared to traditional brachytherapy techniques.

Fig. 4

Short-Term Efficacy of 3D-Printed Brachytherapy in Cervical Cancer Patients

Fig. 5

Survival Outcomes of 3D-Printed Brachytherapy in Cervical Cancer Patients