scanners

Currently the variety of scanners film is very broad. In the medical field and with the introduction of the film Radiochromic expensive laser scanners and Vidar type are no longer needed, and is more desktops are what give best answer for this type of color film.

This document pretend to collect the characteristics of most scanners used in radio physics departments and their response to clinical dosimetry film Radiochromic.

scanners

Note: Curves obtained by subtracting the Optical Density (FROM) film to OGy.

Source:BT Baker, LE Reinstein y GR Gluckman. Dept of Rad Onc, University Hospital, Stony Brook, NEW 11794-7028

Epson scanners planes

Desktop flatbed scanners are now one of the best alternatives for digitization of medical imaging and especially for the film Radiochromic.

Epson Expression 1640XL scanner with transparency adapter is used in both mode grayscale and color (individual color channels are extracted to create a grayscale image in the red channel, green and blue) Hardware and supports images 14 bits but is made through software 16bits.

Epson scanners V700 and its successor V850 (A4) with transparency module is an economical and good solution for EBT film dosimetry. Its disadvantage compared to Epson 12000 XL is that its effect is greater edge having lower surface, it does not allow the film to scan in landscape format, which is recommended.

A) Yes, the scanner is recommended Epson 12000 XL.

Laser scanners (Lumisys, Molecular Dynamics,…)

Laser scanners due to the high degree of polarizacón of its light, show artifacts and nonuniform responses when used with radiochromic film EBT.

the Lumisys (Kodak currently) LS75 (He-Ne source) is the scanner on the market with the most appropriate wave length for the film (633nm) but because these devices is not the most advisable.

It is a scanner 12 bits.

For users of EBT film with an LS75 cuentenn diffusers they are sticking to the light source, that depolarize light, thereby reducing the effect of artefacts.

Howtek MultiRAD 460

This scanner uses an LED light source centered 660 nm and a spectrum of approximately 50nm.

It is not recommended for film Radiochromic

Vidar

The Vidar scanners tell a fluorescent tube as a light source.

The Vidar scanners work perfectly with the film Radiochromic, although not optimally.

To work with EBT in a Vidar is recommended to use a yellow or orange filter.

The orientation (portrait or landscape) Radiochromic scanning of film is very important to always keep the same, and it is recommended to do it in portrait mode always, but scan the film at a particularly important Vidar scan in portrait mode.

The latest model VXR-16 Dosimetry Pro is a scanner 16 bits.

Experience: Compare Epson 1680 con Vidar VXR-16

Comparison of the Epson Expresion 1680 flatbed and the Vidar VXR 16 Dosimetry PRO: Ellen Wilcox, Ph.D., george Daskalov, Ph.D., Lucy Nedialkova, Ph.D.

 

objective:

Verification of treatment planning has often been done with conventional film and a scanner Vidar. But nevertheless, many hospitals are moving to filmless technology and processing are already disappearing.

Thus, we have investigated the Gafchromic® EBT film for IMRT dosimetry.

Planar IMRT dose distributions were carried gafchromic EBT film and Kodak EDR2 and were scanned with Vidar VXR-16 and the flatbed scanner Epson Expression 1680. Metered dose distributions were compared with those calculated by the scheduler Pinnacle.

 

Materials and methods:

IMRT plans consisting of 7 a 9 6MV fields prostate treatment, head and neck and other organs, They were calculated using the Pinnacle TPS.

Each specific patient was recalculated for our dummy sheets of solid water and obtained a planar dose distribution to 10cm deep in the mannequin.

The dose distribution was made into a film using EBT dummy and EDR2 with a maximum dose in the range of 125 a 225cGy, which it was typical for a fraction of treatment.

The films were subsequently scanned in the Epson 1680 and Vidar VXR-16 and analyzed using the FilmQA ™ software (3Cognition LLC).

Comparisons between dose distributions measured and calculated were reported:

  • Unlike dose (pixels within ± 5%
  • Distance to agreement (3mm)
  • gamma function (dose = ±3%, dist.=2 mm)

results:

Using EDR2 with Vidar scanner is an established technique and gives good results.

However EBT with the film was not as good Vidar. This is due to the way the film is moved inside the scanner. The Vidar scanners have a diffuse fluorescent white light source. As the film moves past the measuring gap, changes direction and hence the light strikes the film at a slightly different angle and thus the proportion of incident light reflected from the film surface changes.

This causes artifacts in the scanning EBT but not appear to affect the film EDR2.

EPSON scanner in both films are rigidly immobilized and the light source scans over the film. It was found that the Epson scanner worked equally well for both types of film.

conclusions:

While it is possible to use EBT film with the Vidar scanner, you can get a much better resolution and according to the calculation when digitized using a flatbed scanner. EDR2 for both scanners were successful.

The film properties tissue equivalence EBT, high spatial resolution, energy independence, and autorevelado make this film the most desirable choice for IMRT, instead of conventional. However, we recommend a scanner in transmissive mode to give optimal results with this type of film.

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