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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4624_Библиотеки_им_академика_М_И_Перельмана
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F. Bussu et al.
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Fig. 13.3
extensive invasion of the skin of the nose tip, multiple tubes are placed. Yellow line: 100% Isodose.
Patients 2 and 3: Nose vestibule SCC spreading between alar and lateral cartilages. Plastic tubes
follow the same path as the tumors themselves. Red line: 100% isodose. Patient 4: SCC of the
medial wall (septum and columella). Violet line: 100% isodose. Patient 5: SCC of the lateral wall
spreading between the lateral cartilage and the bone. Red line: 100% isodose. Patient 6: SCC of
the medial wall (septum and columella). Red line: 100% isodose. Patient 7: SCC of the inferior
wall. Red line: 100% isodose
A series of tumors, implants, and resulting clinical target volumes are shown. Patient 1:
13.4 Specific Considerations About Interstitial, Intracavitary,
or Surface Dose Delivery
The above principles apply perfectly to the interstitial implantation: the CTV is
covered by applicators placed inside and around the tumor, along the abovedescribed planes, and the active part of the tubes is intramural (“buried”), a fundamental point for stabilization of the implant. The implants’ geometry must be stable
for the duration of the treatment—usually lasting at least 7days in case of exclusive
IRT for nose vestibule primaries (Chap. 12). The stability of the implant is of utmost
importance for the reliability of the treatment plan, and it can be increased by keeping the plastic tubes’ entrance and exit (“burial”) points as far as possible from the
CTV itself. This trick avoids changes of the entrance/exit points of the tubes and
therefore their displacement, a probable event when they are very close or within the
tumor, which can shrink or get ulcerated during the treatment, extruding the
catheter(s). This is also one of the reasons why, in case of extensive involvement of
the superior lip, we sometimes place tubes completely outside the subperichondral
planes, yet fully interstitial, inside the superior lip itself, perpendicular to the main
axis of the subperichondal route (Fig.13.4). Another reason to follow this route is
sometimes to warrant an adequate coverage and dose to the inferior nasal sill and to
the area below and posterior to the anterior nasal spine, which could be more difcult to obtain with tubes following the subperichondal route.
In general, stability of the tubes and therefore reliability of the treatment plan as
well as the low local toxicity rates are the main advantages of interstitial delivery,
which, when feasible, in our opinion should be preferred for nose vestibule.
Nonetheless, in some situations, the CTV cannot be fully covered by an interstitial implant.
Among these situations, there is the event of a bulky, exophytic skin component.
Supercial molds, which, in our opinion, have a limited role in nose vestibule IRT,
may have a role in such an event. For the same goal, we also resort to contact delivery, mainly using tubes, in selected cases of exophytic skin involvements (Fig.13.5).
Anyway, the most common situation when it can be impossible to cover the target volume with fully interstitial implants is a lesion extending beyond the plane
tangential to the piriform opening (which we propose as a landmark both for the
denition of the nose vestibule subsite, Chap. 1, and for the novel T classication,
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ab c
d e
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Fig. 13.4 A bulky lesion of the inferior wall of the vestibule extensively invaded the superior lip
(a). Catheters were placed both along the “classical” subperichondral paths and perpendicular to
them along the coronal main axis of the superior lip (b, c). This allowed to completely cover the
target volume with a fully interstitial implant (d, e)
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a b
Fig. 13.5 The bulky skin component (a) could not be covered by “buried” subperichondral tubes.
cheel and of the nasal dorsum
Chap. 5). In these cases, it must be kept in mind that the needles currently used for
interstitial plastic tube placement badly tolerate bending and are to be considered
practically straight (Fig.13.6a). Therefore, the interstitially placed tubes, even if
slightly bent, can barely overcome the plan of the pyriform opening (Fig.13.6b).
For tumors approaching such a plane, we use “combined” implants in which some
tubes follow an interstitial route and others are endocavitary. A new standard for
endocavitary nose and paranasal IRT implantation is the “endoscopy guided brachytherapy” (IGBRT) [17] which allows more precise, targeted, and reliable tube placement and should be used, in case of posterior lesions of the nose vestibule, in
combination with the interstitial implantation.
Nevertheless, the main issue of the endocavitary delivery in nose vestibule
brachytherapy is stabilization of the catheters, which is always less reliable than in
the interstitial one. Several tricks can be used to improve the stability and so the
reliability of endocavitary implants. The most frequently used is the xation to
sponge packing of blind end tubes (Fig.13.7), this is a simple and non-traumatic
procedure, and the presence of the packing in the nasal cavity has the additional
advantage to improve dose delivery by eliminating the interface with air.
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Fig. 13.6 Metal guides are provided straight and can be only slightly bended for the application
of the plastic tubes (a). This implies that interstitial implants can only cover lesions conned to the
nasal vestibule (considering the plane tangential to the pyriform opening as the posterior boundary
of the nasal vestibule itself) (b)
Fig. 13.7 Plastic tubes
are preliminarily xed on
nasal packing
The administration of the dose through catheters xed to nasal swabs is however
affected by the following problems:
1. Fixation by stitches is not completely stable because tying is limited by the soft-
ness and friableness of sponge itself.
2. An overly tight stitch can “choke” the tube itself and compromise the passage of
the source.
3. The placement under direct vision requires endoscopic aid [17], but the packing
can move after retraction of the endoscope with unexpected paths (Fig.13.8).
Another trick is to x the tubes on the skin of the lip and nose using buttons to
reduce the residual mobility (Fig.13.9).
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a
b
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Fig. 13.8 (a) Endocavitary implant for a left septal primary involving the septum up to the level
of ethmoid lamina. Septal deviation pushed the left packing towards the inferior choana, so that the
CTV had to be covered exploiting the right nostril implant. This allowed local control with currently NED but required an increased dose on the right nasal fossa with turbinoseptal sinechas in
the nasal fossa not originally affected by the tumor (see Fig.13.12). (b) Inferior wall primary
needed a mixed (interstitial and endocavitary) implant for an adequate coverage of the CTV, but
the packing led the endocavitary tubes cranially, with dosimetric issues luckily solved through
intensity modulation and adequate exploiting of all the implants, also in this case the local control
has been obtained, and the patient is currently free of disease
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Fig. 13.9 Stabilization of
implants through suture to
the packing and buttons
sutured to the skin, in an
endocavitary implant for a
septal primary extending
beyond the piriform
opening
F. Bussu et al.
Suturing the tubes to a silicon plate, which can be easily xed on the nose/superior lip, is an alternative/additional method for implant stabilization. Such strategy
(contrary to the packing) does not determine a complete nasal obstruction
(Fig.13.10).
All the above tricks can be variously combined according to the specic case to
allow the optimal coverage of the target and the maximum stability of the tubes,
privileging the interstitial modality as much as possible (Fig.13.11).
The use of endocavitary molds has been suggested by Haynes [18] back in 1974,
but poorly exploited, probably also for the lack of fast reliable polymers best suited
for the scope and tolerable in the nasal cavity, which could allow tailoring of personalized molds.
We are currently evaluating such a hypothesis and in particular the feasibility of
removable endocavitary molds made by polymers to be placed in the cavity
de
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Fig. 13.10 A nose vestibule primary of the lateral wall showed a spread toward the nasal bones
and the plane of the piriform opening (a) raising concerns about the possibility of a complete coverage of the CTV through a fully interstitial implant. In order to reach posteriorly at the level of the
internal mucosal coverage of the nasal bones, plastic tubes were xed on a silicon plate bended to
adapt to the nasal wall itself (b). After the interstitial implant of four plastic tubes, placement of the
silicon plate with two additional catheters allowed for the complete coverage of the CTV (c). Both
the interstitial and endocavitary plastic tubes (d, e) were then further stabilized through buttons and
stitches
immediately after the implant of interstitial tubes under endoscopic guidance. Such
strategy could drastically improve reliability and stability of endocavitary implants
and even lead to an enlargement of the indications to IRT for more posterior/nasal
cavity proper lesions.
Also, the toxicity associated with endocavitary implants is higher, in fact we
observed, as a typical sequela in correspondence to the hotspots on the mucosal
surfaces, nasal wall synechiae, which are anyway easily treated by revision surgery
1month after the end of irradiation (Fig.13.12), but were never observed after fully
interstitial dose delivery.
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F. Bussu et al.
a
Fig. 13.11 An SCC arising from the inferior and medial (septal) walls of the nose vestibule
showed a posterior spread, which made impossible a complete coverage of the target through
interstitial tubes. Therefore, after placing interstitial tubes both along the nasal axis and in the
superior lip to reach as much posterior as possible, other tubes were xed on nasal packing, placed
under endoscopic guidance and further stabilized with buttons on the skin (a). This allowed an
optimal coverage of the target as shown on the axial (b), coronal, and sagittal (c) scans
ab
cd
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Fig. 13.12 Typical toxicity after endocavitary implant with the high dose on the mucosal surfaces, which may merge to form a synechia or synechiae, mostly turbinoseptal (a, b). These problems are easily treated by endoscopic approach using cold lysis and positioning of a silastic plate,
with excellent anatomical and functional results (c, d)
13.5 Anesthesiology andOperating Theater Setting
The implants are best applied under general anesthesia, with orotracheal intubation
being preferred, and laryngeal masks should be avoided to minimize the hindrance
by the anesthesiology tube, which should be stabilized as far away as possible from
the operating eld. The implantation must be performed by the nose surgeon at the
presence of experienced IRT radiation oncologists.
In selected cases of small anterior lesions, implantation can be performed under
local anesthesia. Inltration with local anesthetics, with or without adrenaline, of
the subperichondrial planes, as in functional nose surgery, is fundamental to obtaining analgesia in case of local anesthesia and is helpful in facilitating the optimal
catheter path along the planes also in general anesthesia.
The interaction between the surgeon and the IRT radiation oncologist at the
implantation phase in the surgical theater is always recommended, also to improve
the following cooperation in the CTV delineation and planning.
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