Comparison of three high-resolution digitizers for radiochromic film dosimetry.

A recently introduced radiographic film scanner from Howtek is evaluated and compared to two other commercially available densitometry systems for its use in radiochromic (RC) film dosimetry in the clinical dose range 0-100 Gy. It has a high-intensity red LED light-source centered at 662 nm (near the major absorption peak for RC film), and is coupled to a CCD linear array detector. This new densitometry system is directly compared to two high-resolution film scanners commonly employed in RC film dosimetry, namely the Lumiscan 75 digitizer (He-Ne laser light source) and the Vidar VXR-16 digitizer (fluorescent light source).

The use of an inexpensive red acetate filter to improve the sensitivity of GAFChromic dosimetry.

The sensitivity of GAFChromic dosimetry using a conventional broad band light source densitometer has significantly been improved twofold using an inexpensive red acetate filter overlay during the densitometric measurements. This thin sheet of red acetate enhances the dosimetric analysis of radiochromic blue image distributions recorded on GAFChromic films. The combination provides higher sensitivity in the optical density measurements than the more expensive He-Ne laser-scanning densitometers.

A rapid colour stabilization technique for radiochromic film dosimetry.

Various forms of GAFChromic film have been used for several years as radiographic media for measuring dose distributions of brachytherapy sources and small radiation fields. Upon irradiation the film changes colour and darkens with time post-irradiation. The darkening is most rapid in the first 24 h, and it has been suggested that for accurate dosimetry a waiting period of 24 h should occur before any optical density (OD) measurements are taken.