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Advances in Radiotherapy
& Nuclear Medicine Single-channel applicators for cervical cancer

Radiotherapy, which involves the optimal integration of A B C
brachytherapy and external-beam radiotherapy, represents
a critical treatment option for cervical cancer at any stage.
Brachytherapy plays an important role in treating all-
invasive cervical cancer, mainly using afterloading devices
for intracavitary treatment. The majority of currently
available applicators have been prepared following the
Manchester method [6-8] , characterized by the use of
intrauterine sources along with vaginal sources (one
tandem plus two ovoids). However, each brachytherapy D
fraction shows significant variation due to the geometric
displacement of the left ovoid, right ovoid, and tandem.
Furthermore, we often encounter patients with narrow
vaginas or sensitivity to surgical stress, making applicator
placement difficult for them. As a result, these patients
often need to undergo applicator placement under spinal
or general anesthesia. E
Accordingly, we aimed to challenge the existing method
used for source placement by hypothesizing that a single
tube (single-channel applicator [SCA]) could proximately
represent a fletcher applicator set (FAS). In the present study,
we modified the tandem with asymmetrical shielding on
the channel and verified that this SCA could generate flat,
pear-shaped, and isodose curves similar to those obtained Figure 1. The structure of our single-patient applicator. (A) FAS;
using the FAS. This modification effectively reduced the (B) SCA; (C) and (D) SCA appearance; and (E) SCA cross-sectional view.
irradiation along the bladder-rectum axis, as measured Schematic diagram shows different thicknesses of 1.41 mm and 0.65 mm
considering the physical and dosimetric characteristics. at the sagittal and coronal axes, respectively. Finished SCA with an added
The SCA is a simple, and easy-to-use structure used for trocar sheath for surgery, with a maximum diameter of 0.68 cm.
Abbreviations: FAS: Fletcher applicator set; SCA: Single-channel applicator.
implant surgery; it causes limited autologous geometric
displacement. Despite having a single-tube structure, it The Hospital Ethics Committee conducted a thorough
functions similarly to nearly three tubes. Accordingly, we inspection and assessment to ensure the least possible
believe that the SCA warrants further clinical investigation. harm and maximum benefit for the patients (approval no.

2. Materials and methods K22012004). All patients provided informed consent by
signing consent forms for participation.
2.1. Key instruments and materials
2.3. Planar physical dosimetry
We used the SCA (Chinese patent no., 200710050108.1,
State Intellectual Property Office of the PRC; the concise Films were irradiated with 2 Gy using the SCA and
depiction of the structure is shown in Figure 1). We also tandem in the coronal, sagittal, and sectional planes. To
used the FAS and a micro-electron Ir afterloading system compare the differences between the SCA and tandem,
192
(Nucletron, the Netherlands), Oncentra 4.3 treatment the irradiated films were then analyzed with a RIT113 film
planning software (Elekta Brachytherapy, Veenendaal, dosimeter using version 4.2 software (RIT, Chicago, USA).
the Netherlands), GafChromic EBT2 films (ISP, Wayne,

NJ, U.S.A.), RIT113 film dosimeter software, version 4.2 2.4. Dosimetry of the SCA on the Chinese female
(Radiological Imaging Technology, Inc., U.S.A), an RGD-3B anthropomorphic phantom (CFAP)
thermoluminescent dosimeter (TLD), and related-element The applicators were inserted to a depth of 5 cm into the
LiF: Mg Cu andP (GR-200A, standard treatment indicated phantom, and the inferential reference points (A, cervix;

,
,
by the National Institute of Metrology, Luzhou, China). B, bladder; and R, rectum) were determined according to
the ICRU 38 definitions. Point A was defined as a point
2.2. Patients and ethical considerations located 2 cm superior to the lateral vaginal fornix and 2 cm
A total of 48 patients with stage IIB to IIIB cervical cancer lateral to the cervical canal. The posterior vaginal wall
were selected for this trial from our department until 2008. was visualized on computed tomography images with the

Volume 1 Issue 2 (2023) 2 https://doi.org/10.36922/arnm.0322