Page 18 - ARNM-1-1

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

The distribution of I-125 seeds in the target is generally and position to satisfy the target’s dose conformity and
implanted according to a pattern of modified peripheral avoid the OARs.
loading. The needle’s position in BT-TPS for prostate
carcinoma is typically horizontal for all the needles’ 7.2. Pre-plan, real-time plan, and post-plan
arrangement and kept parallelly by plane template The pre-plan is very important for I-125 RSI-BT. The
guidance (Figure 3). objective of the pre-plan is to define and delineate the
targets and OARs, PD, seed activity, and the number of
7.1. Non-co-planar assistance
seeds to be ordered. This is especially the situation where
If the I-125 RSI-BT indications are expanded from the pre-plan meets the PD requirements, and no OAR
prostate cancer to other cancer locations, the BT-TPS interferes with the pathway of the needle. Meanwhile, the
has to overcome and resolve the rigid problems related to BT-TPS can fuse multiple model images such as CT, MRI,
the template. A good BT-TPS should be able to treat and and positron emission tomography (PET)-CT . At the
[48]
satisfy all the carcinomas in the head and neck, thoracic, same time, most I-125 RSI-BT operations are performed in
abdomen, pelvic, and spinal cord anatomic locations for the CT simulator room. The BT-TPS should be connected
I-125 RSI-BT. The arrangements of needles in the head- to the CT simulator, and the CT simulator scan images
and-neck region or complex positions for optimal targets should be transmitted to the BT-TPS fast and conveniently.
dose conformity with all needles in different directions, Real-time and intra-operative dose optimization is required
line by line (even in the same line), and every needle when the needle’s puncture tract deviates due to bleeding,
direction different from each other due to multiple OAR’s necrosis, and shape changes of the tumor. Finally, the
interferences and safety considerations, such as blood evaluation of the post-plan dosimetry can be performed
vessels, bone, nerves, and trachea. The BT-TPS should after seed implantation if the post-plan D90 does not reach
have the flexibility to adjust the needles’ direction, angles, the requirements identified in the pre-plan, and “salvage”

A B

C

Figure 3. Design of 3D printing template. (A) Modeling of 3D printing template on the body surface. (B) Confirming of needle pathway on the bone
window. (C) 3D printing template.

Volume 1 Issue 1 (2023) 10 https://doi.org/10.36922/arnm.0907