Page 14 - ARNM-1-1

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

5. 3D-printed template-assisted I-125 RSI-BT ensure the system’s stabilization and precision, the template
direction, and allow the angles to be adjusted during the
5.1. 3D printing techniques operation according to the requirements of the pre-plan.
The use of 3D printing technology in material fabrication The advantages of 3D-PNCT include: (i) the anatomic
[33]
has recently witnessed significant advancement . Based construction (patient’s anatomy) is immobilized in the
on digital images and documents, a computer-designed head and neck so the template can easily be stabilized;
program controls the 3D printer, which heats and dispenses (ii) all the needles’ channel (position) information on
materials in powdered form layer by layer. The additive the template is designed according to pre-plan on the
process creates a 3D object that matches the calculated and specialized BT-TPS; (iii) the needles are inserted from
[34]
planned original design . different directions (non-co-planar), which permits and
3D printing techniques have made significant ensures the conformity of the target dose distribution
advancements in the medical field, initially expected to to be very good and avoid OAR interferences; (iv) if the
have a broad impact on oral and maxillofacial surgery, stabilization needle’s position deviates from its proposed
plastic surgery, orthopedics, and neurosurgery [35-37] . 3D position when setting up the 3D-PNCT according to CT
printing allows the rapid creation of complex, personalized pre-plan scan, a fine and real-time adjustment can be
constructs, offering a myriad of applications, such as accommodated under CT guidance until the deviation
creating dummy phantoms or applicators for determining error is corrected and less than 1 mm; and (v) 3D-PNCT-
RT doses in HDR-BT and developing individual templates assisted CT guidance for RSI-BT requires significantly less
for RSI-BT . The 3D printing digital software is utilized time than that of sole CT-guidance which often requires
[38]
to program and reconstruct the design in the BT-TPS, and 40 min to 1 h.
subsequently, the design is transferred to the 3D printer The advantages of 3D-PCT-assisted RSI-BT are as
for printing. follows: (i) all the needles are orientated in one direction and
Huang et al. invented the first generation of a planes kept parallel like in a prostate BT template; (ii) the
[38]
3D-individualized template, which was transparent and needles’ arrangements on 3D-PCT meet the targets dose
could be used to stabilize the patient’s head-and-neck conformity, and the needles’ placement has a 5 – 15 mm
anatomic position and ease the observation of whether interval spacing with each other; (iii) the needles’ insertion
bleeding had occurred during RSI-BT. Ji et al. have the sequences are first along the X-axis, and then Y-axis line,
[39]
second to utilize 3D printing techniques and the first to so the time required for needles’ insertion is short; (iv)
invent a template for use in BT, specifically RSI-BT-assisted the systemic stabilization of 3D-PCT is very good because
treatment of body carcinoma. The template introduced the template is connected with a stabilization frame and the
X- and Y-axis coordinate lines at the central position of CT couch; and (v) the price of 3D-PCT is very reasonable.
the tumor, along with needles’ numbering, provided a 3D-PT-assisted CT-guidance RSI-BT is a high-level
new, novel approach for accurate positioning in BT. The standard workflow and a high efficiency and precision
recommendations for 3D-PT classification made for 3D ablation modality, considerably reducing the operative
co-planar template (3D-PCT) and 3D non-co-planar time by almost 80 – 90% for suitable patients (Figure 1).
template (3D-PNCT) were established in the study. The
3D-PNCT coordinate can be aligned with the patient’s 5.2. Accuracy of 3D-PT-assisted CT-guided I-125 RSI-BT
body surface, where laser lines are marked in accordance
with the CT scans. Two to three stabilization needle holes CT-guided puncture is popular in clinical practices such
were designed on the 3D-PNCT template, corresponding as biopsy, radiofrequency ablation, and cryosurgery.
to the tumor location. In addition, “dummy needles” are However, only one or 2 – 3 needles are utilized for
included to create additional approaches and pathways punctures. Given the number of RST-BT needles typically
(more needle holes), allowing for real-time intra-operative averages 20 – 30, maintaining consistent direction,
dose optimization. This approach helps overcome distance, and angle for all needles can be challenging when
deviations caused by organ movements, bleeding, or using the free-hand technique under CT guidance. Hence,
distortion, such as in the lung, liver, or pancreas. Wang exploring a new assistant technique is necessary to help
et al. implemented 3D-PCT, which features the X- and CT guidance become more accurate, fast, and efficient.
[40]
Y-axis coordinate lines at the central point of the tumor. The 3D-PT techniques were born out of this time. 3D-PT-
These coordinate lines also serve as location for needle assisted CT guidance assures systemic stability, precision,
holes, aligning with the laser lines on the patient’s body. and reproducibility.
The stabilization and navigator devices (needles) were Huang et al. first reported the accuracy of RSI-BT on
[18]
necessary to connect with the 3D-PCT and CT couch and 31 patients with recurrent and locally advanced malignant

Volume 1 Issue 1 (2023) 6 https://doi.org/10.36922/arnm.0907