Contouring is the most crucial part in the treatment planning. Early ages of radiotherapy people doesn’t have sophisticated treatment planning software and of course the imaging modality also (CT). Because of that they devised the manual method of contouring to plan the patients. After the evolution of the Computerized Tomography (CT) and advanced development in the field of radiation oncology the treatment planning are well pronounced in the treatment. Still, people working on this to increase more and more precisely to contour as well as to calculate the dose in the designated volume.
Devices & Techniques:
A number of devices have been made to obtain patient contours. Some of these are commercially available, while others can be fabricated in the department machine shop.
1. The most common and the simplest of the devices is a solder wire or a lead wire figure (a) embedded in plastic. Because the wire may not faithfully retain the contour dimensions when transferring it from the patient to the paper, one must independently measure anteroposterior and/or lateral diameters of the contour with a caliper.
Figure (a) shows the picture of lead wire used for contouring
2. Another kind of simple device consists of an array of rods, the tips of which are made to touch the patient's skin and then placed on a sheet of paper for contour drawing. Perhaps the most accurate of the mechanical devices is a pantograph-type apparatus (Fig. b) in which a rod can be moved laterally as well as up and down. When the rod is moved over the patient contour, its motion is followed by a pen that records the outline on paper.
Figure (b) shows the view of contour plotter
3. After the CT has discovered taking of patient has become easy for the radiation oncologists. Because of its unique advantage it can be transferred to contouring station. Contouring station is one have the best drawing tools to do the contour. In modern contouring station have technology to fuse the multimodality imaging also for example fusion of MRI and CT is also possible to delineate the contour as precise as possible.
4. PET-CT scan also sometimes used for the contouring the targets and critical structures.
1) Very simple and easily available method to contour is,
1. Contour plotter
2. Contouring stations
3. Lead wires
c) Lead wires
1. The Physics of Radiation Therapy by F. M. Khan