13 Head and Neck - Oropharynx

Head and Neck - Oropharynx

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

8. TECHNIQUES

8.1 General Aspects In patients who have received EBRT a gap of 1-3 weeks is given for acute reactions to settle down. If possible, it is advisable to minimise the gap to reduce the overall treatment time. Intraoperative implantationwith “boost first “method reduces the overall treatment time. Detailed evaluation of the tumour is done before subjecting patient to anesthesia.This involves information from clinical examination, clinical photographs, diagrams, and imaging withCT scan andMRI. The instruments for brachytherapy are shown in Figure 5. The procedure is done under general anaesthesia in supine position with neck extension (Figure 6). Nasal intubation preferably through the contralateral nostril is done to have access to the oropharynx. Nasogastric tube placement is considered in the majority of the patients to maintain nutrition as swallowing may be affected with implanted tubes. The majority of patients do not require tracheostomy. Especially in the case of base of tongue implants, the anterior positioning and fixation of the base of tongue with the implanted tubes keeps the airways open in the later course of the treatment. However, in rare situations where there is a possibility of airway compromise prophylactic temporary tracheostomy may be considered. After induction and painting and draping of the head and neck region, the mouth is kept opened using a jaw retractor. A tongue tie is placed to pull the tongue which facilitates adequate visualization of the lesion and enables manoeuvring during the implant. Evaluation under anesthesia (EUA) is an important step in which the complete extent of the lesion is palpated in all directions (Figure 7). The size, shape, thickness and distance from bone are noted. A note is also made of any unhealthy mucosa in the surrounding area which may have to be covered. In the case of a boost implant, the response of the lesion is noted and compared to the pre- EBRT volume. Radio-opaque markers are placed at the four corners of the macroscopic tumour wherever feasible. This is helpful in target volume delineation (Figure 3). 8.2 Base of the tongue (BOT) Insertion of the needles for BOT is done with a suprahyoid approach. The approach depends on the tumour extension. If the tumour extends to the glosso-epiglottic sulcus, then the approach can be infrahyoid. The projection of the tumour is marked on the skin of the submental region and a margin of 5-10mm is given. The area to be implanted is decided based on the CTV. While some radiation oncologists consider implantation of the entire base of the tongue, the tumour with 5-10mm margins is considered appropriate by many others. Classic loop technique[30] The posterior branch of the central loop is first implanted. A guide needle is inserted perpendicular in the skin above the hyoid bone. The needle is guided into the pharynx, in most cases into the vallecula, with the index fingertip. One leader of a double leader plastic tube is then introduced intraorally into the needle. Then the

Figure 5: Instruments for brachytherapy of oropharynx

Figure 6: Patient position for head neck brachytherapy

Figure 7: Evaluation under anaesthesia