Giant cell tumour of the tendon sheath (GCTTS) is the second most common tumour of the hand. Despite surgery, local recurrence after excision has been reported in up to 45% of cases. Post-operative radiotherapy (PORT) has been found to be promising in preventing these recurrences in high-risk group. One of the reservations of PORT is secondary effects of radiation which may cause a decreased range of motion of the affected joint, sensory changes and nail changes. Surface mould brachytherapy can provide a high dose to target volume with a rapid fall of dose to surrounding structures. Despite this, it is less used, the possible reason can be less technical proficiency.

We have technically illustrated surface mould brachytherapy in a case of GCTTS of the left index finger, and compared dosimetrically with more widely used conventional photon and electron external beam radiotherapy.

The 6-MV photon treatment plan with a bolus plan provided the least dose to skin (106%) and phalanges (103%). It has a Homogeneity index (1·06) closest to 1, whereas the Conformity index of all plans was similar. The dose coverage was adequate in all plans. The second-best plan dosimetrically was the surface mould brachytherapy.