Ir-192 pellet source HDR brachytherapy using wax surface mould applicators in head and neck cancer: A single institute experience.

Abstract

e17029 Background: Surface mould brachytherapy is suitable for radiation treatment of superficial lesions in head and cancer and it is the choice of radiotherapy technique. Various isotopes viz, Radium, Cs-137, Ir-192 wire, co-60, Sr-90 has been used. Earlier customized acrylic mould with hollow needle or catheters were used. With the advent of Ir-192 HDR pellet source we used tissue equivalent thermo malleable wax surface moulds. Single plane was used but in lips, pinna and ala of nose double planar sandwich technique was used with good dosimitry and cosmetic effect. BED is calculated by using LQ model. Methods: A retrospective analysis of 20 cases superficial H & N epithelial cancers treated with surface mould Brachytherapy using wax mould during 2008 to 2010 at RIMS is retrieved from the archive. HDR Ir-192 pellet source surface mould was used by positioning the flexible catheters in proper positions without distortion of geometry. The mould is made with wax plates by warming upto 70 degree Celsius in thermal water bath. The thickness of the slab is 1 cm and catheters embedded on surface and kept 1 to 1.5 cm gap and parallel to each other which can be bent or curved according to the surface contour. The fixation is reinforced with transpore /cellotapes. The dose delivered varies 500cgy 6 to 8 doses or daily 300 cgy for 5 to 7 fractions with BED calculated for LDR 2500cgy to 3000 cgy. Results: 20 cases were analysed: 8 Basal cell ca on face. SCC inner canthus 2, lips 2, pinna 1, ala nasi 2, alveolus 1, 1 hard palate, and 4 cheeks. One lip and one cheek has undergone resection with margin not free. All had disease less than 4 cm size and infiltration less than .5 cm. and clinically Node negative. At median follow up of 30 months 18 had no evidence of disease with good cosmesis and one patient with Ca. hard palate had local failure and one upper eyelid has recurrence after 9 months. Conclusions: The study though small in number indicates practicability and satisfactory results of using locally available tissue equivalent wax surface mould application therapy of HDR pellet source for very superficial T1 N0 lesions as primary mode or adjuvant radiotherapy in head and neck areas.