Background and purpose
A patient with a left lower tarsal conjunctival melanoma was treated at the Nelune Comprehensive Cancer Centre in July 2020 using High Dose Rate (HDR) Brachytherapy (BT) with Iridium-192. The 79 year old patient had previously undergone excision of the lesion and local reconstruction which resulted in tethering of the eye. As a consequence, plaque brachytherapy was not a viable treatment option. There was a positive margin and the disease involved the inferior conjunctival fornix.
We designed a novel technique using a single channel source placed along the medial reconstructed eyelid. The source channel was stabilised with a hydraulic clamp that is attached to the treatment couch. The tip of the channel was secured flushed with the medial canthus. The patient underwent CT Simulation and a HDR Brachytherapy treatment plan was generated using the Oncentra Brachy Treatment Planning System (Elekta, AB, Stockholm, Sweden), delivering 36 Gy in 6 fractions, every second day. The dose limiting structure was the adjacent cornea.
The treatment was uneventful and well tolerated by the patient. There was only grade 1 conjunctival irritation with no other acute toxicity. The patient will continue to be followed up for late toxicities and disease outcome.
Soo Min Heng – Medical Physics Specialist Nelune Comprehensive Cancer Centre, Prince Of Wales HospitalSoo Min Heng is a Medical Physics Specialist at the NCCC. She loves QA and has a coffee addiction.
Simon Downes – Director of Medical Physics Nelune Comprehensive Cancer Centre, Prince Of Wales HospitalSimon Downes is the Chief Physicist at the NCCC. He is also the chair of the Asia Pacific Special Interest Group and has previously accompanied a new Co-60 teletherapy source to PNG.