13 Head and Neck - Oropharynx

Head and Neck - Oropharynx

13

THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 15/02/2021

middle line, through the uvula. Then a loop is made joining the two lateral lines. Before making the loop, a larger piece of plastic tube is placed over the implantation tubes, to fix the loop to the central tube, which will perforate the piece of plastic. Loading of the sources may be extended to the hard palate region. In that case it is advised tomake a customisedmould, covering the hard palate and with predrilled holes in it, to contain the sources close against the hard- and soft palate mucosa. It is also possible to build in a layer of lead protection caudal to the tube level to minimize normal tissue irradiation (Figure 21). 8.5 Tonsil For tumours of the tonsil the entire tonsillar fossa on the involved side is considered as the target. The most posterior needle which is positioned in the posterior tonsillar pillar is inserted first. A hollow slightly curved or straight needle is used. The needle is inserted below the hyoid and is guided with bimanual palpation into the posterior tonsillar pillar. The needle is pushed until it reaches the junction of posterior tonsillar pillar and soft palate where it exits. Nylon tube with a button at the closed end is used. The thin end of the nylon tube is inserted into the needle and taken out through the neck. The tube is pulled out in the neck until the button sits on the soft palate.

Tonsillar fossa needle is slightly deeper and hence is inserted posteriorly in the neck. Care has to be taken while inserting this needle palpating the carotid and keeping the needle anterior to it. The needle is inserted with bimanual palpation. The needle is pushed into the fossa until it reaches the upper pole of the tonsil where it exits into the oropharyngeal cavity. This needle is then replaced with the nylon tube with a button at the closed end. Third needle is inserted above the hyoid bone. This needle goes into the anterior tonsillar pillar. With bimanual palpation the needle is guided into the anterior tonsillar pillar and is pushed until it reaches the junction of the anterior tonsillar pillar with the soft palate. The bevelled edge of the tube is then taken out into the oropharyngeal cavity. The needle is replaced with a button tube (Figure 22). Typically, three tubes form a triangle in the neck with the most anterior needle being the tube for the anterior tonsillar pillar. For tumours extending to the base of the tongue using additional loop or non-looping loops with or without modification or a straight tube can be used to cover that region (Figure 22). Figure 23 shows 3D CT based planning for tonsillar brachytherapy.

Figure 23: Axial, Coronal, sagital and 3D dose distribution for right tonsillar tumour with extension to tonsillolingual sulcus. Please note the additional base of tongue needles for improved coverage.