This document describes a dosimetric feasibility study for using a plastic earbud and stethoscope earpiece as an applicator for brachytherapy to treat early-stage squamous cell carcinoma of the external auditory canal. The plastic earbud is inserted into the ear canal along with an interstitial needle. The earpiece stabilizes the earbud. A simulation was performed and plan was generated to demonstrate the dosimetric viability. The proposed arrangement could provide an effective method of precisely delivering high radiation doses for radical brachytherapy treatment, with potential benefits over surgery such as organ preservation and better cosmetic and functional outcomes. Further studies are still needed to validate this approach.

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How to cite this article: Patro KC, Bhattacharyya PS, Paul S,
Khadanga CR,RajmohonEB,KunduCR,etal. Radicalbrachytherapy
for early-stage external auditory canal squamous cell carcinoma:
A dosimetric feasibility study using plastic earbud as an applicator. J
Curr Oncol 2019;2:49-52.
Original Article
Radical Brachytherapy for Early-stage External Auditory Canal
Squamous Cell Carcinoma: A Dosimetric Feasibility Study
Using Plastic Earbud as an Applicator
Kanhu Charan Patro, P. S. Bhattacharyya, Sayan Paul, Chira Ranjan Khadanga, E. B. Rajmohon, Chitta Ranjan Kundu, Venkata Krishna Readdy P.,
Madhuri Palla, A. C. Prabu, Subhra Das, A. Anil Kumar, Aketi Srinu, Susovan Banerjee, Sanjukta Padhi, Suman Das
Department of Radiation Oncology, Mahatama Gandhi Cancer Hospital, Visakhapatnam, Andhra Pradesh, India
Abstract
Squamous cell carcinoma (SCC) of external auditory canal (EAC) is extremely rare. Although surgery followed by radio (chemo)
therapy is the contemporary standard of care, radical radio (chemo) therapy has been successfully used as an anatomical as well as
functional organ preservation modality. Radical brachytherapy is a promising alternative in early-stage SCC-EAC. We report our
initial experience on the feasibility of using commercially available plastic earbud along with soft flexible earpiece of stethoscope as a
radioactive source career applicator of remote after-loading high-dose rate radioactive sources (Ir192
).
Keywords: Earpiece of stethoscope, external auditory canal, plastic earbud, squamous cell carcinoma
Introduction
Squamous cell carcinoma (SCC) of external auditory
canal (EAC) is extremely rare.[1,2]
Although the established
current standard of care is radical surgery in early-stage
tumors of EAC, radical radio (chemo) therapy has been
attempted with an aim of both anatomical and functional
organ preservation. Traditionally, radiotherapy (RT)
has been delivered either using conventional wedge-pair
portals or three-dimensional (3D) conformal techniques
including intensity-modulated radiation therapy (IMRT).
Recently, there is a growing interest in brachytherapy
(BT) using remote after-loading high-dose rate (HDR)
radioactive sources (Ir192
), which has the advantage
of delivering very high dose of radiation to the target
volume with high conformity as well as precision with
better sparing the surrounding critical structures. Radical
surgery is debilitating and needs plastic reconstruction.
Standard of care remains radical surgery with or without
neck dissection and plastic reconstruction, but for certain
group of patients with very early EAC lesion with deep
infiltration and those who are medically inoperable, BT
can be an alternative for lesions confined to cartilage or
mucosa. Moreover, BT can be delivered in few fractions
over fewer days in comparison with conventional
fractionated RT. Considering all of these above, radical
BT appears to be an attractive alternative to radical
surgery especially in early-stage tumors of EAC with a
comparable tumor-related local control along with much
better acceptable cosmetic as well as functional outcome.
Delivering BT requires a radioactive source placement
within a unique applicator, which is generally placed
within and/or close to the disease site. Here we report our
initial experience on the feasibility of using commercially
available plastic earbud as an applicator of remote
after-loading HDR Ir192
. We selected the plastic earbud as
it is easily available everywhere as well as can be measured,
calibrated, and connected to the source.
Address for correspondence: Dr. Kanhu Charan Patro,
Department of Radiation Oncology, Mahatama Gandhi Cancer Hospital,
Visakhapatnam, Andhra Pradesh, India.
E-mail: drkcpatro@gmail.com
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2. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
50 50 Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019
Mono-institutional Initial Experience
We selected the plastic earbud [Figure 1], which is commonly
available in the market. It has an approximate length
of 5 cm and inner diameter of 3 mm, whose dimensions
are comparable with either the stainless steel needles
[Figures 2 and 3] or nylon catheters available for remote-
after-loading HDR Ir192
. Plastic earbuds are atraumatic
in nature in comparison with stainless steel needles. An
interstitial one-end blind needle with a length of 10 cm is
inserted into an earbud and the assembly is inserted into
the EAC. The distal open end of the plastic earbud is
sealed off by wax, so that the chance of penetrating needle
injury is nullified in the case of needle movement during
the procedure. The position of the plastic earbud in EAC
can further be stabilized using an earpiece of stethoscope
[Figure 4]. This combined arrangement of interstitial
needle stethoscope earpiece along with the plastic earbud
ensures proper reproducible positioning of the radioactive
source during the dwell-time as well as patient comfort,
hence making this arrangement as an effective radioactive
source carrier prosthesis [Figure 5]. After obtaining an
informed consent, we selected a volunteer for an initial
feasibility study. Computed tomographic (CT) simulation
Figure 2: Applicator and dosimetry
Figure 3: Ear bud and applicator attached
Figure 4: Ear bud and applicator attached and stethoscope piece
connected
Figure 5: The total piece inside ear canal
Figure 1: Structure of the applicator
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3. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019 51
scan of slice thickness of 1 mm with marked dummy
radioactive wire inside the source carrier prosthesis of the
temporal bone with 5 cm margin superoinferiorly. A plan
was generated followed by initial dosimetric analysis using
a treatment planning system (Oncentra, Elekta). A linear
array of radioactive source position was activated for
desired length and the plan was optimized. The dose
was prescribed at 5 mm off-axis. If the gross tumor
volume (GTV) is appreciated, a clinical target volume
can be contoured with a margin of 1 cm around the GTV
sparing the brain and tympanic membrane [Figure 6].
The high-dose sleeves in the surface of the applicator can
be dampened by use of wax in the surface of the plastic
earbud.
Inters��al needle
connected to the transfer
tube
Wax coa�ng 5mm
Plas�c ear bud
Co�on plug
Stethoscope ear plug
Ear-bud brachytherapy assembly
Diagram by
dr p s bhattacharyya
Discussion
Tumors of EAC are rare and constitute 0.2% of all
head and neck squamous cell carcinoma (HNSCC).[1,2]
Of these the majority are SCC (85%). A tumor, node,
metastasis staging system is most commonly followed,
which includes histopathologic extent of tumor invasion
and radiological evaluation.[3]
The contemporary
treatment options include either radical surgery with or
without postoperative adjuvant radio (chemo) therapy or
radical radio (chemo) therapy depending upon the stage.
Radical surgery followed by postoperative adjuvant
radio (chemo) therapy is generally used in advanced
disease.[4-7]
Radical surgery includes wide excision of
disease along with removal of middle and/or external
ear results in poor cosmetic and functional outcomes. In
contrast, radical RT that includes either external beam
radiotherapy (EBRT), BT or sequentially combined can
be an alternative with comparable local tumor control
rate and acceptable cosmesis, especially in early-stage
disease (without soft-tissue extension or bony erosion),
although there is paucity of literatures to support this.[8-
11]
Although small-volume lesions can well be treated
with BT alone, there are some technical challenges.
Here, we attempt to deliver a radical BT dose using a
unique source carrier prosthesis that consists of easily
available plastic earbud stabilized with the earpiece of
the stethoscope. It is a dosimetric feasibility study and we
did not treat the patient (volunteer). He was comfortable
throughout the procedure as well as physics-dosimetry to
above arrangement was satisfactory. Our proposed dose
schedule is like other SCC 3 Gy per fraction twice daily
with 6-h gap and biological equivalent dose about more
than 60 Gy over a period of 10 days. The actual dose
is mostly for other SCC. There are no dose criteria for
these organ-at-risk (OAR) structures such as tympanic
membrane and cartilages. When we treat with external
RT, we do not give constraints. As a principle, we should
follow as low as reasonably achievable (ALARA) for
these OAR structures. This is a feasibility study and
in other literature late effects are not mentioned and
reported. Stethoscope ear piece we taken as readymade. It
can be performed also with wax, but it needs expertise to
make it. The stability of this bud and catheter definitely
earbud is more stable. Other things are earbud is cheaper
and easily available.
Conclusion
The combination of commercially available plastic earbud
along with soft flexible earpiece of stethoscope of a 10-cm
17-gauge interstitial needle can be a radioactive source
carrier applicator prosthesis for radical BT of early-stage
SCC-EAC. However, it requires further validations. It is
an attempt to put a bit of innovation into practice for
very early lesions of the EAC confine to the mucosa or
cartilage away from the tympanic membrane for patients
medically inoperable and reluctant for such debilitating
surgery.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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4. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
52 52 Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019
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