Effect of applicator materials on absorbed dose in water from afterloading 92Ir source / 中华放射医学与防护杂志

ABSTRACT

Objective:To measure the effect of applicator materials on absorbed dose in water from HDR afterloading 192Ir source by using three-dimensional printed holder (3DPH) and synthetic single-crystal diamond detector (SSCDD). Methods:SSCDD and plastic implants were fixed on the 3DPH in turn. The central axis of SSCDD was perpendicular to that of plastic implant needle on the same plane. The actual residence dwell position measured using source position simulator was 248 mm, which was consistent with the maximum response dwell position measured in a point by point way. The materials for measurement included 304 stainless steel, polyphenylene sulfone resins (PPSU), polymethyl methacrylate (PMMA) and 3-D printed polylactic acid (PLA), respectively. The attenuation of absorbed dose in water with different thickness or filling ratio was measured.Results:The linear fitting formula of relative dose varying with thickness (mm) for 304 stainless steel and PPSU materials were y=-0.029 7 x+ 1.000 3 and y=-0.002 3 x + 1.010 2, respectively. And the goodness-of-fits were 0.925 3 and 0.722 2, respectively. The effect on dose of PMMA materials within 10 mm was less than 1%. The linear fitting formula of relative dose varying with filling ratio (%) for PLA materials with 10 mm thickness was y=-0.000 4 x+ 1.024 6, with a goodness-of-fit of 0.854 5. Conclusions:The effect of applicator materials on the absorbed dose arising from afterloading 192Ir source should attract enough attention of both developers and clinical users, especially with regard to high-density materials like 304 stainless steel and new technology materials such as 3D printed polylactic acid.