30. Paediatric malignancies - The GEC-ESTRO Handbook of Brachytherapy

Paediatric malignancies

10

THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/09/2023

Figure 9. Recurrent para-pharyngeal tumour, excised and implanted with a mould for the AMORE technique. Prescribed dose 40 Gy 5 mm from the mould surface. Planning Target Volume is indicated with a red broken line structure

Figure 7. Parapharyngeal space filled with thermoplastic mould pieces containing brachytherapy catheters.

A

B

Figure 8. (A) Excisional area. (B) Muscle flap to cover surgical and irradiated cavity

structures need to be removed because of bone infiltration, e.g., in case of the mandible, the defect is reconstructed with a bone graft. For tumours of the oral cavity, oropharynx, or oral mucosa, interstitial treatments as per adult patients are performed, following Paris system rules (see chapters 11, 12, 13, and 14) [18].

term adverse side effects, in particular minimizing functional and cosmetic impairment. Therefore, computer assisted dose calculation is always performed and treatment planning is systematically based on sectional images, preferably MRI. Specific issues on dose and fractionation are detailed in the next paragraph. Each treatment should be individualized, and computerized treatment planning is mandatory. After implantation, CT is performed, with scan acquisition in the supine position with applicator and/or interstitial catheters in place, slice thickness usually 1.5 mm. A T2-weighted MRI is useful to guide target delineation, especially for patients treated with in situ tumour (e.g., BP RMS, gynaecological RMS, perineal RMS). Catheters are localized and active source dwell positions are decided according to the target volume, that is delineated taking into account clinical findings,

9. TREATMENT PLANNING

General requirements The main goals of paediatric BT must be carefully considered in treatment planning. These are to achieve local control and preserve the function of the organ involved at the same time as reducing long