Page 12 - ARNM-1-1

Advances in Radiotherapy
& Nuclear Medicine Seed implantation head-and-neck carcinoma

ultrasound for real-time BT-treatment planning system slices through the area of interest; (iv) marks the patient
(BT-TPS) for whole body RSI-BT and other sites. Fast and with X-, Y-axis laser lines on patient’s skin showing the
convenient operations are the advantages of ultrasound tumor center location according to CT scan; (v) transfers
guidance. Due to these advantages, ultrasound guidance is CT scan slices into the BT-TPS, identifying the target and
recognized as a reliable guidance technique in RSI-BT and organ at risk (OAR); (vi) definines and delineates the PD at
prioritized in applications, especially for superficial and 110 – 160 Gy, expands clinical target volume (CTV) from
small-sized tumors, such as liver metastasis or lymphatic gross target volume (GTV) to 5 – 6 mm in 3D; (vii) designs
metastasis/masses. It is wise to continue seeking more the needle arrangements on pre-plan with the activity of
improvements in using the equipment. I-125 seeds, which is usually 0.4 – 0.7 mCi; (viii) after
1 – 2 days, set up the patients with the vacuum stabilization
4. Percutaneous CT-guided I-125 RSI-BT for pad on the CT-simulator couch with a CT scan again for
HNC the BT procedure performed preoperatively to locate
4.1. Advantages of percutaneous CT-guided I-125 the central puncture point on the skin for each needle
RSI-BT insertion one by one according to pre-plan; (ix) performs
the CT scan again to visualize and confirm each needles’
The first CT-guided I-125 RSI-BT was introduced for position before placement (if a deviation in the needles’
spinal cancer in 2002 in China. From then on, CT-guided position of more than 2 mm is observed, a fine adjustment
RSI-BT has been applied to HNC, thoracic, abdomen, is made to the needle’s position until the deviation error is
retroperitoneal, pelvic, and metastatic cancers adjacent to less than 2 mm); (x) repeats a CT scan again immediately
the spinal cord [28,29] . The applications of RSI-BT have been before radioactive seed placement to confirm each needles’
expanded and enriched greatly.
position after a fine adjustment); (xi) once confirmed,
The CT guidance for RSI-BT has a lot of advantages the radioactive seeds are implanted according to the pre-
compared with that of ultrasound guidance. The advantages plan; and (xii) after the seeds are implanted, a CT scan is
of CT guidance are that: (i) CT imaging is widely utilized performed and images are transferred into BT-TPS to do
in the clinical diagnosis of carcinomas with reconstructed, the final calculation of the doses to the targets.
high precision, and high-resolution 3D-images; (ii) the
target and normal tissue margins are more clearly identified 4.3. CT-guided I-125 RSI-BT for HNC
in contrasted CT scans; (iii) no air or bony interference Zhou et al. evaluated the efficacy of utilizing I-125
[30]
compared to that with ultrasound; (iv) real-time CT scan RSI-BT alone for the treatment of advanced parotid gland
imaging can better visualize the positioning of the needles carcinoma (n = 23). All patients were in clinical stage
intraoperatively as well as radioactive seed distribution IV disease. The PD was 60 – 160 Gy. Of the 23 patients
in the tumor targets during the operation, then adjust included in the study, six experienced local failure, and 11
needles’ position or salvage seed repositioning during the died during the follow-up period. The 1-, 3-, and 5-year
implantation immediately if the needles position or post- OS rates were 87.0%, 55.4%, and 47.5%, respectively. The
plan doses evaluation is determined to be suboptimal; 1-, 3-, and 5-year PFS rates were 73.9%, 47.0%, and 39.2%,
and (v) the CT can be connected with BT-TPS which is respectively. The 1-, 3-, and 5-year LC rates were 82.1%,
convenient and fast for doses calculation, optimization, 73.9%, and 73.9%, respectively. The use of I-125 RSI-BT
and evaluation during and after the operation. alone for the treatment of primary parotid gland carcinoma

The limitations of 3D printing template (3D-PT)- provided good short-term results without causing any
[14]
assisted 125I RSI-BT may include radiation exposure severe side effects. Ji et al. reported 101 patients treated
risks for the medical staff and relatives of the patient, as with CT-guided I-125 RSI for rHNC after EBRT. The
well as the invasive nature of the procedure. High-quality median D90 after I-125 RSI was 117 Gy. The 5-year LC rate
clinical studies are also needed for evidence-based medical was 26.6%, and the 5-year OS rate was 15.5%. Univariate
application of this technique. analysis showed that the 5-year LC rate was 11.5% (2-year)
if D90 was <120 Gy and 44.2% if D90 was ≥120 Gy. Skin
4.2. Workflow of percutaneous CT-guided I-125 RSI-BT or mucosa ulceration accounted for 26 cases (25.7%). The
The Chinese CT-Guided I-125 RSI-BT Workflow Consensus study concluded that CT-guided RSI-BT was safe with low
recommended steps as follows : (i) prepares and collects toxicity and could be used as a salvage treatment modality
[29]
patients’ indication, eligibility, and selection criteria; (ii) set for rHNC. Jiang et al. reported 113 patients with
[16]
up the patients in a body stabilization and immobilization recurrent head-and-neck cancer after surgery and EBRT
equipments with vacuum pad on CT-simulator couch; in multiple centers. The 1-, 2-, 3-, and 5-year LC rates were
(iii) obtains a contrast CT scan with 5 mm thickness 57.4%, 41.8%, 29.3%, and 15.2%, respectively. The 1-, 2-, 3-,

Volume 1 Issue 1 (2023) 4 https://doi.org/10.36922/arnm.0907