Shooting and assessing the portfilm in radiation therapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To discuss how to practise and consummate to shoot and assess the portfilm for radiotherapy. Methods Double radiography technique was used to take a portfilm. The reference mark points (plumbum points) were added into the field at the first exposure and the cross lines drawn based on the plumbum point images were definited as the reference coordinate to the actual field. Then, the portfilm was compared and analyzed with the simulator planning film. Results The images of both plumbum points and block boundaries were distinct in the portfilm, but the resolution and contrast of the tissue structure image was inferior to the ordinary film from simulator. However, all different structures and positions could be identified in order to assess if the actual field coincided with the radiation planning. Conclusions Although the real-time property of the portfilm is inferior to the electric portal image device (EPID), the double radiography portfilm is feasible as an important quality control method in radiation therapy due to its lower price and easier performance. The design of reference points is the key point in this technique.