9 Reporting in Brachytherapy: Dose and Volume Specification

Reporting in Brachytherapy 188

Fig 6.19 A,B: Large diameter applicator in a wide oesophageal lumen with moderate stenosis

Fig 6.19A: Large diameter applicator (15mm) in a wide oesophageal lumen with moderate stenosis and tumour load. Dose is prescribed at 5 mm from the applicator/lumen surface (100%). Dose prescription is identical with the dose to be reported. The dose at the applicator surface is 180%. Higher isodose lines are inside the applicator i.e. outside the tissue. The dose at the mucosa/tumour surface is evenly distributed (180%), because the applicator surface and mucosa/tumour are directly attached to each other. Dose variation within the oesopohageal wall (thickness 4 - 5 mm) is from ~100% to 180% (factor of 1.8).

Fig. 6.19B: Large diameter applicator (15mm) in a wide oesophageal lumen with moderate stenosis and tumour load. Dose is prescribed at 10 mm from the source axis (100%). The dose to be reported at 5 mm from the applicator/lumen surface is 80% of the prescribed dose; the dose at the applicator surface is 140% of the prescribed dose i.e. 180% of the reported dose. The dose at the mucosa/tumour is 140%, the variation within the oesophageal wall (thickness 4 - 5 mm) is from ~90% to 140% (factor of 1.8).

Fig 6.19C,D Small diameter applicator in a narrow oesophageal lumen with extensive stenosis

Fig 6.19C: Small diameter applicator (6 mm) in a narrow oesophageal lumen with extensive stenosis and tumour load (tumour thickness as measured from the lumen surface maximum 16 mm). The applicator is directly attached to the mucosa and the tumour surface. Dose is prescribed at 5 mm from the applicator/lumen surface (100%). Doses to be

Fig 6.19D: Small diameter applicator (6 mm) in a narrow oesophageal lumen with extensive stenosis and tumour load (see above). Dose is prescribed at 10 mm from the source axis (100%). The dose to be reported at 5 mm from the applicator surface is 130%, and at the applicator surface (tumour/mucosa) 370%.