The dose of the pelvic EBRT was 45–50.4 Gy, with a 1.8–2 Gy/fraction. Some patients were treated with concurrent or sequential therapy with a total lymph node boost dose of 57.5–65 Gy. The EBRT techniques included three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), or volume modulated radiotherapy (VMAT). In Arm 1 and Arm 2, 52 (82.5%) and 49 (86.0%) of the patients received concurrent platinum-based chemotherapy, and 11 (17.5%) and 8 (14.0%) of the patients received radiotherapy only. All the patients received treatment by using the MRI-guided 192Ir HDR after-loading the therapy equipment (Micro-Selectron HDR V2), and the BT was performed after completion of the EBRT.
The implantation of the BT applicator and needle was performed as described below: the applicator was selected before the surgery, according to the disease conditions of patients. The tumor location, size, shape, para-uterine invasion, and relationship with surrounding organs were verified from the MRI images before and after the EBRT, as well as gynecological examination. The bowel preparation was performed on the day before the operation, and vaginal irrigation was performed on the day of operation. Combined intravenous and inhalation anesthesia was administered to the patients, then the patients were disinfected routinely, and the Foley urethral catheter was placed, with the balloon at the site of the vesical neck. The color ultrasound-assisted implantation of the applicator and needle was performed. The applicators used included the Utrecht interstitial Fletcher CT/MRI applicator set, interstitial ring CT/MRI applicator set, vaginal CT/MRI multi-channel applicator set, and self-made 3D-printed applicator. In patients that the para-uterine invasion has reached the pelvic wall, trans-perineal manual implantation was performed in addition to the above-mentioned applicators to meet the demands of dose distribution, and the depth of the needle was guided under the assistance of ultrasound. After the completion of the implantation, the applicator and needles were fixed. For one BT fraction in one application and two BT fractions every other day in one application, the fixation method of the applicator and needles remained the same. First, the needles were fixed on the applicator using the guiding tube, which was assembled on the applicator. Next, the applicator was filled with gauze for internal fixation, and then it was externally fixed on the patient's body with a T-shaped fixing belt. And then the rectum was pushed by the rectal pressure plate. The MRI was performed after the patient has been awakened. The application of analgesic drugs was decided based on the level of pain in patients. The analgesic drugs included were as follows: patient-controlled intravenous analgesia (PCIA), subcutaneous injection of opiates, and/or anti-inflammatory analgesics. The analgesic drugs were used in the recovery and treatment periods according to the requirements.
T2W MRI of each BT fraction was used for the delineation of target volume and OARs, as referred to in the GEC-ESTRO recommendations [4 (link)]. The high-risk clinical target volume (HR-CTV) was applied for the range of tumors that showed by the MRI and physical examinations following the EBRT, as well as the overall uterine cervix examination. The intermediate-risk clinical target volume (IR-CTV) was applied for the range of cervical cancer before the EBRT and for the extension of HR-CTV. The OARs included the bladder, small intestine, sigmoid colon, and rectum.
All the patients received the HDR-IGABT treatment at the 28 Gy/4f. The MRI was performed on the day when the operation has been completed. The patients in Arm 1 have received one BT fraction, and then the applicator or needles have been removed, while the patients in Arm 2 have received the first BT fraction. CT has been performed 16–24 h later to verify the locations of the applicator and needles. The second BT fraction was performed after confirmation.
All the patients received routine medical nursing, and stretch socks were worn to prevent deep venous thrombosis (DVT). Continuous electrocardiogram (ECG), blood pressure, and blood oxygen saturation were monitored during the waiting period. Antiemetics and anxiolytics were provided based on patient assessment. For the patients who received BT fractions every other day in one application, the segmental pressing massager was used in the waiting period, and corresponding nursing practices were also adopted during the waiting period to maintain the patients in the supine position. In addition, one doctor and two nurses were assigned for nursing and closely monitoring the continuous BT patients.
The implantation of the BT applicator and needle was performed as described below: the applicator was selected before the surgery, according to the disease conditions of patients. The tumor location, size, shape, para-uterine invasion, and relationship with surrounding organs were verified from the MRI images before and after the EBRT, as well as gynecological examination. The bowel preparation was performed on the day before the operation, and vaginal irrigation was performed on the day of operation. Combined intravenous and inhalation anesthesia was administered to the patients, then the patients were disinfected routinely, and the Foley urethral catheter was placed, with the balloon at the site of the vesical neck. The color ultrasound-assisted implantation of the applicator and needle was performed. The applicators used included the Utrecht interstitial Fletcher CT/MRI applicator set, interstitial ring CT/MRI applicator set, vaginal CT/MRI multi-channel applicator set, and self-made 3D-printed applicator. In patients that the para-uterine invasion has reached the pelvic wall, trans-perineal manual implantation was performed in addition to the above-mentioned applicators to meet the demands of dose distribution, and the depth of the needle was guided under the assistance of ultrasound. After the completion of the implantation, the applicator and needles were fixed. For one BT fraction in one application and two BT fractions every other day in one application, the fixation method of the applicator and needles remained the same. First, the needles were fixed on the applicator using the guiding tube, which was assembled on the applicator. Next, the applicator was filled with gauze for internal fixation, and then it was externally fixed on the patient's body with a T-shaped fixing belt. And then the rectum was pushed by the rectal pressure plate. The MRI was performed after the patient has been awakened. The application of analgesic drugs was decided based on the level of pain in patients. The analgesic drugs included were as follows: patient-controlled intravenous analgesia (PCIA), subcutaneous injection of opiates, and/or anti-inflammatory analgesics. The analgesic drugs were used in the recovery and treatment periods according to the requirements.
T2W MRI of each BT fraction was used for the delineation of target volume and OARs, as referred to in the GEC-ESTRO recommendations [4 (link)]. The high-risk clinical target volume (HR-CTV) was applied for the range of tumors that showed by the MRI and physical examinations following the EBRT, as well as the overall uterine cervix examination. The intermediate-risk clinical target volume (IR-CTV) was applied for the range of cervical cancer before the EBRT and for the extension of HR-CTV. The OARs included the bladder, small intestine, sigmoid colon, and rectum.
All the patients received the HDR-IGABT treatment at the 28 Gy/4f. The MRI was performed on the day when the operation has been completed. The patients in Arm 1 have received one BT fraction, and then the applicator or needles have been removed, while the patients in Arm 2 have received the first BT fraction. CT has been performed 16–24 h later to verify the locations of the applicator and needles. The second BT fraction was performed after confirmation.
All the patients received routine medical nursing, and stretch socks were worn to prevent deep venous thrombosis (DVT). Continuous electrocardiogram (ECG), blood pressure, and blood oxygen saturation were monitored during the waiting period. Antiemetics and anxiolytics were provided based on patient assessment. For the patients who received BT fractions every other day in one application, the segmental pressing massager was used in the waiting period, and corresponding nursing practices were also adopted during the waiting period to maintain the patients in the supine position. In addition, one doctor and two nurses were assigned for nursing and closely monitoring the continuous BT patients.
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