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

or “recovery” seed implantation can be done immediately. 9. Advantages of RSI-BT as stereotactic
The unique, whole-body BT-TPS was issued a license in ablative BT (SABT)
China in 2004 and connected to a CT simulator in 2012.
During the past two decades, dramatic developments/
7.3. 3D-PT assistance improvements and innovations in technology have taken
The 3D-PNCT has been commonly used for I-125 place in China in the field of I-125 RSI-BT. The significant
RSI-BT in specific lesions such as intracranial, head developments of RSI-BT have concentrated on image
and neck, thoracic, abdomen, pelvic, spinal cord, and guidance with advances from ultrasound to CT, 3D printing
retroperitoneal carcinomas. The unique I-125 BT-TPS of individual templates, intra-operative real-time BT-TPS,
system has multiple functions, such as 3D-PNCT and post-plan seed and dosimetry verification, stabilization
3D-PCT assistant I-125 RSI-BT plan design, which could assistance, navigator system, and patient immobilization
meet approximately 80%–90% of patients’ treatments. techniques. The quality of RSI-BT under 3D-PT supported
BT-TPS has built-in features to design and directly by CT guidance has greatly improved and realized tumor
communicate with a 3D printer. As soon as the pre- ablation effects at present.
plan of I-125 RSI-BT is described, it is transferred to a 9.1. Image-guidance
commercial-grade 3D printer for construction of the
3D-PT, with the whole process expected to be completed The whole process of I-125 RSI-BT is performed based
within 24 h in China. on CT guidance, including pre-planning, real-time dose
optimization, and post-plan evaluation. The CT scan is the
8. Basic requirements of I-125 RSI-BT best image-guidance technique for RT, with resolution and
I-125 RSI-BT performance technique is more similar to time efficiency the best at present. Most of the pre-plans are
surgery or interventional medicine than conventional based on CT-scan imaging datasets that were transferred
radiation therapy. The operation requires the patient into BT-TPS to design the 3D needle arrangement into the
to be administered local, spinal, or general anesthesia patient and the target, simultaneously avoiding the OARs.
to keep the patient immobilized and avoid pain during MRI or PET-CT scans can also be fused with the CT scan,
the operation. In China, at the end of the procedure, the making the targets’ margins more clearly identified.
doctors, physicists, technicians, and nurses review and The intra-operative and real-time dose optimization
finish the I-125 RSI-BT operation together. also depends on CT-scan images and imaging during the
It takes more time for patients to prepare for I-125 operation and confirmation and evaluation after needle
RSI-BT, such as cooperation in body positioning to insertion. Due to the changes in tumor shape and contour,
ensure that the operators can create a convenient setup tumor necrosis, organ movement, swelling, or bleeding
and that the patients are comfortable. For all I-125 RSI-BT associated with a needle puncture, real-time, and intra-
procedures, it is suggested and preferred that the setups operative treatment planning may require that a fine
and procedures are performed in the CT simulator room, adjustment be made to the needle’s position making the
which is a better option, rather than in the diagnostic CT procedure more adaptive and precise during the actual
room. The CT simulator has a flat plane couch, external process.
positioning lasers, and a large bore which is more After I-125 RSI-BT, CT scans are again performed for
convenient for RSI-BT operative procedures. The patient’s the post-plan evaluation, determination of the distribution
body is stabilized and fixed with a vacuum pad, and the and placement of the seeds, and the calculation of D90 of
head and neck are fixed with a mask or with a stabilization the targets on the BT-TPS, allowing the quality of seed
frame which provides a double-immobilization assuring implantation to be known immediately. If the post-plan D90
that there are no patients movements during the RSI-BT of targets did not reach the pre-PD requirements, “salvage”
operation, but the patient can be moved in and out on or “rescue” measures can be performed immediately
the CT-simulator couch smoothly and without changing based on real-time dose optimization until the optimal
positions. dose is achieved. This flexibility, ease of optimization, and

If necessary, ECG monitoring, oxygen, intravenous accuracy cannot be realized for EBRT, SBRT, or IGRT.
infusion, and anesthesia are required to monitor the Quality assurance of all procedures based on CT guidance
patient’s vital signs during the RSI-BT operation. After ensures that RSI-BT significantly improves the success of
RSI-BT, the patients may return to their wards or rooms each procedure which is impossible for EBRT as there is no
and receive antibiotics, and hemostasis is monitored for real-time intraprocedure TPS for EBRT and no post-plan
one day with discharge 24 h later. dose evaluation up to now.

Volume 1 Issue 1 (2023) 11 https://doi.org/10.36922/arnm.0907