Australasian Brachytherapy Group

30th Annual
Scientific Meeting

25 - 27 February 2021
A Virtual Event

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Using surface brachytherapy to treat circumferential progression of mycosis fungoides of both forearms, feasibility and technical considerations

Mycosis fungoides is an uncommon and incurable disease, associated with a long natural history of relapses necessitating multiple lines of therapy. The significant symptom burden experienced by these patients is associated with high rates of morbidity and negatively impacts quality of life. Here, we report the first Australian case of a patient with mycosis fungoides, with technically challenging volumes, treated with skin brachytherapy for symptom control.
This 77 year old gentleman had a long history of multi-relapsed mycoses fungoides, first diagnosed in 2007. Previous treatments included multiple lines of systemic therapies, total skin electron irradiation, plus localised fields of electron and superficial radiation therapy. Most recently, the patient presented with symptomatic circumferential involvement of both forearms. After multi-disciplinary consultation in the Cutaneous Lymphoma Clinic, the patient was offered re-irradiation to his forearms for symptom control.
At the time of CT-simulation numerous radiation therapy techniques, including both VMAT and skin-brachytherapy, were considered. Technical challenges included patient positioning and a desire to avoid full limb irradiation in a heavily-pre-treated patient. Ultimately, patient positioning and dose distribution favoured skin-brachytherapy.
Technical considerations such as catheter stand-off, catheter spacing and mould thickness were customised by the planner to 7 mm, 10 mm – 15 mm, and 5 mm respectively. Variations of these parameters were evaluated to achieve optimal coverage of the areas. The devised plan achieved excellent conformity to skin surface, and relative sparing to deeper tissues.
Using 3D printing, personalised moulds were made from a flexible thermoplastic urethane material. Technical considerations included determining the density of material used, the cut line of the mould so it could be placed around the forearms in two pieces, accuracy of catheter channel lumens and consistency of mould thickness.
The patient was re-scanned in treatment position wearing the forearm moulds with the catheters in-situ. The fit was assessed and the treatment plan was recreated. Extensive QA was undertaken on the moulds which included creating multiple plans to check indexer lengths, active length of dwell positions in relation to field borders, and ensuring any catheter curvature did not obstruct the source.
The patient was successfully treated with skin brachytherapy to his forearms to a total dose of 8 Gy in 2 fractions prescribed to 2 mm depth from skin surface. The patient obtained a complete clinical response with durable symptom relief.

Presenters

Angelo Tzovaras Brachytherapist Peter MacCallum Cancer Centre

Brachytherapist at Peter MacCallum Cancer Centre

Sylvia van Dyk Brachytherapist Peter MacCallum Cancer Centre

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Li Zhu Medical Physicist Peter MacCallum Cancer Centre

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Hayley Nisi Brachytherapist Peter MacCallum Cancer Centre

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Ashley Uhm Brachytherapist Peter MacCallum Cancer Centre

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Cate Sproston Brachytherapist Peter MacCallum Cancer Centre

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Margaret Garth Brachytherapist Peter MacCallum Cancer Centre

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Kurian George Medical Physicist Peter MacCallum Cancer Centre

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Tomas Kron Medical Physicist Peter MacCallum Cancer Centre

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Belinda Campbell Radiation Oncologist Peter MacCallum Cancer Centre

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