Analyzing the Positional uncertainties in 3dcrt ca breast Patients with Free Breathing and Active Breath Coordinator Gating Immobilization Devices

Abstract

Aim: The aim of this study is to rule out the difference in positional setup errors when using immobilization

device such as thermoplastic mould for free breathing and vacloc with ABC gating in ca breast patient

treating with 3DCRT technique.

Objective: The study is to compare the patient setup uncertainties using two different immobilization device,

one with standard thermoplastic mould and other with vacuum cushion with active breath control gating in

our clinical setup.

Methodology: fourteen patients with ca breast are taken for the study. seven patients are undergone

immobilization using standard thermoplastic moulding and remaining seven patients undergone, vacuum

cushion with active breath control DIBH (deep inspiration breath hold) gating. CT was taken and 3dcrt plan

were done according to the standard protocol. Prior to the treatment CBCT was taken, matching was done

in XVI with the reference images, to rule out any positional shifts. Positional Shifts on all 3 axes such x,

y, z is noted with rotational shift. Comparison were done on systematic error (?), random error (?), mean

displacement vector (R), mean setup error (M).

Result: immobilization device used by vacloc with DIBH ABC gating shows very less shifts in all direction,

especially longitudinal direction compared with mould one, which we are using routinely in our department.