- Email: [email protected]
The use of radiochromic films to measure and analyze the beam profile of charged particle accelerators
ARTICLE IN PRESS Applied Radiation and Isotopes 67 (2009) 2025–2028
Contents lists available at ScienceDirect
Applied Radiation and Isotopes journal homepage: www.elsevier.com/locate/apradiso
Technical note
The use of radiochromic films to measure and analyze the beam profile of charged particle accelerators M.A. Avila-Rodriguez a,b,, J.S. Wilson a, S.A. McQuarrie a a b
Edmonton PET Centre, Cross Cancer Institute, 11560 University Ave, Edmonton, AB T6G 1Z2, Canada ´n, Facultad de Medicina, Universidad Nacional Auto ´noma de Me ´xico, Me ´xico Unidad PET/CT-Ciclotro
a r t i c l e in fo
abstract
Article history: Received 23 June 2008 Received in revised form 8 October 2008 Accepted 14 October 2008
The use of radiochromic films as a simple and inexpensive tool to accurately measure and analyze the beam profile of charged particle accelerators is described. In this study, metallic foils of different materials and thicknesses were irradiated with 17.8 MeV protons and autoradiographic images of the beam strike were acquired by exposing pieces of RCF in direct contact with the irradiated foils. The films were digitalized using a conventional scanner and images were analyzed using DoseLab. Beam intensity distributions, isodose curves and linear beam profiles of the digitalized images were acquired. & 2008 Elsevier Ltd. All rights reserved.
Keywords: Cyclotron beam profile Radiochromic films Proton beam intensity distribution
1. Introduction
2. Materials and methods
Cyclotron production of non-standard PET nuclides such as radiometals and radiohalogens usually involve the irradiation of expensive, isotopically enriched, solid substrates. Accurate assessment of the beam profile to match the target material with the shape of the proton beam is desirable in order to keep the amount of the expensive substrate as low as possible. Other applications where the measurement of the beam profile would be useful are following maintenance service to the cyclotron, change of the stripper foil, beam/target alignment procedures, measurement of beam intensity distribution for modeling and simulations, etc. Beam profiles are commonly measured by an autoradiography technique using either radiographic film or digital radiography with a storage phosphor system. But these techniques require expensive equipment or film development systems that are not available in most cyclotron facilities. The classical ‘‘paper burn’’ technique is useful in beam/target alignment procedures, but is not quantitative. The objective of this work was to explore the feasibility of using radiochromic film (RCF) as a simple and inexpensive tool to accurately measure and qualitatively and quantitatively (intensity distribution) analyze the beam profile of charged particle accelerators.
Irradiations were performed at the Edmonton PET Centre on a TR19/9 cyclotron from Advance Cyclotron Systems Inc (Richmond, BC, Canada). A thick Cu foil (2 mm) and thin foils of Nb and Cu (25 mm) were used as target materials. The thick Cu foil was irradiated using a water-cooled 301 slanted target while the thin foils were irradiated with the proton beam impinging perpendicularly to the front face of the foils. The activation products generated when these foils are irradiated with 17.8 MeV protons are 63Zn (t1/2 ¼ 38 min), 62Zn (9 h) and 65Zn (244 d) for the Cu foil; and 93mMo (6.9 h), 92mNb (10 d) and 89Zr (78 h) for the Nb foil. Only the thick Cu foil was reused following a minimum of 4-days cooling time between irradiations. Gafchromic EBT films (International Specialty Products, Wayne, NJ, USA) consist of two radiosensitive layers (34 mm total thickness) separated by a surface layer (6 mm) and coated on both sides of a polyester base (97 mm on each side). The dose range for this film is 2–800 cGy (linear response up to 600 cGy) and exhibits a weak energy dependence in the 50 kVp–10 MVp X-ray range (Sankar et al., 2005; Bustos et al., 2006; Fuss et al., 2007). The film is colorless, grainless and transparent before exposure to radiation and can be handled and prepared in room light. During exposure to a radiation field, the film develops an instantaneous blue color without requiring latent chemical, optical, or thermal development or amplification and offers a high sensitivity comparable to that of a radiographic film. The color intensity is a function of the absorbed dose with higher doses resulting in a progressively darker blue color. For dosimetry purposes, this color change can
Corresponding author. Unidad PET-Ciclotro´n, Facultad de Medicina, UNAM, Edificio de Investigacio´n P.B, Cd. Universitaria, Circ. Interior, C.P. 04510, Me´xico. Tel.: +55 56232288; fax: +55 56232115 E-mail address: [email protected] (M.A. Avila-Rodriguez).
0969-8043/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2008.10.009
ARTICLE IN PRESS 2026
M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
be measured accurately (with a spectrophotometer, densitometer, or other device that measures optical density or absorbance) to calculate the absorbed dose (Niroomand-Rad et al., 1998). The use of a conventional reflective scanner in an 8-bit grey-scale mode has been also successfully used to get spatial dose distributions with RCF (Avila-Rodriguez et al., 2001). After the irradiation, a piece of RCF which matched the size of the irradiated foil was placed in direct contact with the foil in order to get an autoradiographic image of the proton beam strike. The exposure times were in the range from seconds to hours depending on the amount of activity of the irradiated foils. The exposure was stopped when the beam strike was visible on the film (50–70% of the maximum color intensity developed by the film). The exposed RCF were digitalized (256 grey-levels, 8-bit, 600 dpi, format TIFF) using a conventional flatbed reflective scanner (HP Scanjet 4890). Prior to analysis, a smoothing procedure was applied to the digitalized images using a disk average filter (pixel size 5, sigma 0.5).
The analysis of the digitalized films was performed using DoseLab version 4.00 (created by Nathan Childress, Ph.D., and Isaac Rosen, Ph.D., University of Texas, M.D. Anderson Cancer Center, Houston, TX) which is a set of software programs originally developed for quantitative comparison of measured and computed dose distributions. This program, including the MATLAB source code, is freely distributed and can be downloaded at http://doselab.sourceforge.net/index.html.
3. Results and discussion Although the response of the film is usually expressed in terms of the logarithm of the ratio between the color intensity of the non-irradiated and the irradiated film (Alva et al., 2002), we found that analysis of the irradiated film in terms of color intensity was sufficient to properly define the beam profile. Fig. 1 shows a set of pictures of different pieces of RCF after autoradiographic exposure of a thick Cu foil irradiated on a 301 slanted target (5 min at 10 mA). A 5 min proton irradiation of the thick Cu foil (17.8 MeV) produced 65 Zn, 62Zn and 63Zn in an approximate ratio 1:10:105 at the end of the bombardment, respectively. The RCF illustrated the proton beam strike area when exposed for 30 s, 30 min, and 60 h; after allowing a post-irradiation cooling time of 1 h (mostly 63Zn activity), 10 h (mostly 62Zn) and 100 h (mostly 65Zn), respectively. The 2D beam intensity distributions of these exposures are shown in Fig. 2. The full width at half maximum of the profiles obtained with 63Zn (Fig. 2-left) were determined to be 9.6 mm in the x-axis and 19.7 mm in the y-axis, which are in good agreement with the expected values for a 10 mm collimated beam impinging on 301 slanted target. Even thin foils of Cu and Nb irradiated in stack (Ep ¼ 15 MeV, 5 min at 15 mA) proved to be adequate to get the beam profile following exposure of the RCF for 10 s (front Cu foil) and 10 min (back Nb foil). Beam broadening, originated by scattering processes as the proton beam passes through the different foils in the stack, can be evaluated using this technique. Fig. 3 shows an example of a practical utility of this technique when used to analyze the beam profile of charged particle accelerators. The shape of the beam strike in this figure suggested a damaged stripper foil which was subsequently confirmed and replaced. Spatial calibrations (pixels to distance), beam intensity
Fig. 1. Pieces of Gafchromic EBT film after 10 s (left), 30 s (center) and 60 s (right) autoradiographic exposure on a thick Cu foil irradiated with 17.8 MeV protons (5 min at 10 mA). Exposure took place 1 h post-irradiation.
0
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Fig. 2. Beam profiles of a thick Cu foil irradiated with 17.8 MeV protons. Profiles were acquired at different post-irradiation and exposure times (see text) to get impressions of the different activation products: 63Zn (left), 62Zn (center) and 65Zn (right).
ARTICLE IN PRESS M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
2027
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Fig. 3. Beam profile showing a split proton beam due to a damaged stripper foil. This figure shows the scanned imaged of the RCF (upper left), the correspondent intensity distribution (upper center and bottom right), isodose lines (upper right), and the beam profile along the x-axis (bottom left).
distributions, isodose curves and iterative profiles can be obtained with DoseLab. The use of DoseLab is useful when a detailed analysis of the beam profile is needed or when the 2D distribution of the beam intensity is required. For example, this data can be used as an input source function to simulate, model and optimize the heat transfer process that has aided in the development of our cyclotron targets (Avila-Rodriguez et al., 2007). The use of this autoradiographic technique for practical applications of beam/ target alignment can be performed by means of a simple visual analysis. The price of an 800 1000 sheet of Gafchromic EBT film is on the order of $20 CAD. In this study 50 pieces of 2.5 cm 4 cm, matching the size of the thick Cu foil, were obtained from a single sheet of film. The DoseLab package is distributed free of charge and the digitalization of the films can be done using a conventional flatbed scanner which is commonly available. In this study only foils of Cu and Nb were explored to obtain the proton beam profile, but many other materials could be used with this purpose. These materials include, but are not
restricted to, Ti, V, Fe, Cr, Ni, Zn, Y, Zr, Mo, Ru and Ag. Price and availability of foils of these materials and half life and radiation field of the activated products are parameters that should be taken into account when choosing an appropriate foil material. Experimental thick-target saturated-yields at Ep ¼ 11 Mev for all the metallic materials mentioned above have been previously published (Nickles, 2003). This technique can also be extended to other accelerated particles. The IAEA Technical Document 1211 (IAEA, 2001) provides good examples of monitor reactions for accelerated beams of protons, deuterons, 3He and alpha particles.
4. Conclusions The use of radiochromic films to measure and analyze the beam profile of proton beams was found to be feasible whilst being simpler and more cost effective compared with the
ARTICLE IN PRESS 2028
M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
traditional autoradiography technique using radiographic film or digital radiography with storage phosphor systems.
Acknowledgment The authors are grateful to the staff of the Medical Physics Department at the University of Alberta who kindly provided the radiochromic films used in this study. This work was partially funded by the MicroSystems Technology Research Initiative (MSTRI) at the University of Alberta, Grant 1-2N-3A-Advanced Cyclotron. References Alva, H., Mercado-Uribe, H., Rodrı´guez-Villafuerte, M., Brandan, M.E., 2002. The use of a reflective scanner to study radiochromic film response. Phys. Med. Biol. 47, 2925. Avila-Rodrı´guez, M.A., Rodrı´guez-Villafuerte, M., Dı´az-Perches R., Pe´rezPastenes M.A., 2001. Experimental measurements of spatial dose distributions
in radiosurgery treatments. In: AIP Conference Proceedings vol. 593, pp. 127–132. Avila-Rodriguez, M.A., Sader, J.A., McQuarrie, S.A., 2007. 3D modeling and simulation of the thermal performance of solid cyclotron targets. In: Comsol Conference Proceedings, Boston, MA, pp. 359–363. Bustos, M.J., Cheung, T., Yu, P.K.N., 2006. Weak energy dependence of EBT Gafchromic film dose response in the 50 kVp–10 MVp X-ray range. Appl. Radiat. Isot. 64, 60. Fuss, M., Sturtewagen, E., De Wagter, C., Georg, D., 2007. Dosimetric characterization of GafChromic EBT film and its implications on film dosimetry quality assurance. Phys. Med. Biol. 52, 4211. IAEA, 2001. Charged particle cross-section database for medical radioisotope production: diagnostic radioisotopes and monitor reactions. IAEA-TECDOC1211, Vienna, May 2001. Nickles, R.J., 2003. The production of a broader palette of PET tracers. J. Labelled Compd. Radiopharm. 46, 1. Niroomand-Rad, A., Blackwell, C.R., Coursey, B.M., Gall, K.P., Galvin, J.M., McLaughlin, W.L., Meigooni, A.S., Nath, R., Rodgers, J.E., Soares, C.G., 1998. Radiochromic film dosimetry: recommendations of AAPM radiation therapy committee task group 55. Med. Phys. 25, 2093. Sankar, A., Ayyangar, K.M., Nehru, R.M., Kurup, P.G., Murali, V., Enke, C.A., Velmurugan, J., 2005. Comparison of Kodak EDR2 and Gafchromic EBT films for intensity-modulated radiation therapy dose distribution verification. Med. Dosimetry 31, 273.
Contents lists available at ScienceDirect
Applied Radiation and Isotopes journal homepage: www.elsevier.com/locate/apradiso
Technical note
The use of radiochromic films to measure and analyze the beam profile of charged particle accelerators M.A. Avila-Rodriguez a,b,, J.S. Wilson a, S.A. McQuarrie a a b
Edmonton PET Centre, Cross Cancer Institute, 11560 University Ave, Edmonton, AB T6G 1Z2, Canada ´n, Facultad de Medicina, Universidad Nacional Auto ´noma de Me ´xico, Me ´xico Unidad PET/CT-Ciclotro
a r t i c l e in fo
abstract
Article history: Received 23 June 2008 Received in revised form 8 October 2008 Accepted 14 October 2008
The use of radiochromic films as a simple and inexpensive tool to accurately measure and analyze the beam profile of charged particle accelerators is described. In this study, metallic foils of different materials and thicknesses were irradiated with 17.8 MeV protons and autoradiographic images of the beam strike were acquired by exposing pieces of RCF in direct contact with the irradiated foils. The films were digitalized using a conventional scanner and images were analyzed using DoseLab. Beam intensity distributions, isodose curves and linear beam profiles of the digitalized images were acquired. & 2008 Elsevier Ltd. All rights reserved.
Keywords: Cyclotron beam profile Radiochromic films Proton beam intensity distribution
1. Introduction
2. Materials and methods
Cyclotron production of non-standard PET nuclides such as radiometals and radiohalogens usually involve the irradiation of expensive, isotopically enriched, solid substrates. Accurate assessment of the beam profile to match the target material with the shape of the proton beam is desirable in order to keep the amount of the expensive substrate as low as possible. Other applications where the measurement of the beam profile would be useful are following maintenance service to the cyclotron, change of the stripper foil, beam/target alignment procedures, measurement of beam intensity distribution for modeling and simulations, etc. Beam profiles are commonly measured by an autoradiography technique using either radiographic film or digital radiography with a storage phosphor system. But these techniques require expensive equipment or film development systems that are not available in most cyclotron facilities. The classical ‘‘paper burn’’ technique is useful in beam/target alignment procedures, but is not quantitative. The objective of this work was to explore the feasibility of using radiochromic film (RCF) as a simple and inexpensive tool to accurately measure and qualitatively and quantitatively (intensity distribution) analyze the beam profile of charged particle accelerators.
Irradiations were performed at the Edmonton PET Centre on a TR19/9 cyclotron from Advance Cyclotron Systems Inc (Richmond, BC, Canada). A thick Cu foil (2 mm) and thin foils of Nb and Cu (25 mm) were used as target materials. The thick Cu foil was irradiated using a water-cooled 301 slanted target while the thin foils were irradiated with the proton beam impinging perpendicularly to the front face of the foils. The activation products generated when these foils are irradiated with 17.8 MeV protons are 63Zn (t1/2 ¼ 38 min), 62Zn (9 h) and 65Zn (244 d) for the Cu foil; and 93mMo (6.9 h), 92mNb (10 d) and 89Zr (78 h) for the Nb foil. Only the thick Cu foil was reused following a minimum of 4-days cooling time between irradiations. Gafchromic EBT films (International Specialty Products, Wayne, NJ, USA) consist of two radiosensitive layers (34 mm total thickness) separated by a surface layer (6 mm) and coated on both sides of a polyester base (97 mm on each side). The dose range for this film is 2–800 cGy (linear response up to 600 cGy) and exhibits a weak energy dependence in the 50 kVp–10 MVp X-ray range (Sankar et al., 2005; Bustos et al., 2006; Fuss et al., 2007). The film is colorless, grainless and transparent before exposure to radiation and can be handled and prepared in room light. During exposure to a radiation field, the film develops an instantaneous blue color without requiring latent chemical, optical, or thermal development or amplification and offers a high sensitivity comparable to that of a radiographic film. The color intensity is a function of the absorbed dose with higher doses resulting in a progressively darker blue color. For dosimetry purposes, this color change can
Corresponding author. Unidad PET-Ciclotro´n, Facultad de Medicina, UNAM, Edificio de Investigacio´n P.B, Cd. Universitaria, Circ. Interior, C.P. 04510, Me´xico. Tel.: +55 56232288; fax: +55 56232115 E-mail address: [email protected] (M.A. Avila-Rodriguez).
0969-8043/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2008.10.009
ARTICLE IN PRESS 2026
M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
be measured accurately (with a spectrophotometer, densitometer, or other device that measures optical density or absorbance) to calculate the absorbed dose (Niroomand-Rad et al., 1998). The use of a conventional reflective scanner in an 8-bit grey-scale mode has been also successfully used to get spatial dose distributions with RCF (Avila-Rodriguez et al., 2001). After the irradiation, a piece of RCF which matched the size of the irradiated foil was placed in direct contact with the foil in order to get an autoradiographic image of the proton beam strike. The exposure times were in the range from seconds to hours depending on the amount of activity of the irradiated foils. The exposure was stopped when the beam strike was visible on the film (50–70% of the maximum color intensity developed by the film). The exposed RCF were digitalized (256 grey-levels, 8-bit, 600 dpi, format TIFF) using a conventional flatbed reflective scanner (HP Scanjet 4890). Prior to analysis, a smoothing procedure was applied to the digitalized images using a disk average filter (pixel size 5, sigma 0.5).
The analysis of the digitalized films was performed using DoseLab version 4.00 (created by Nathan Childress, Ph.D., and Isaac Rosen, Ph.D., University of Texas, M.D. Anderson Cancer Center, Houston, TX) which is a set of software programs originally developed for quantitative comparison of measured and computed dose distributions. This program, including the MATLAB source code, is freely distributed and can be downloaded at http://doselab.sourceforge.net/index.html.
3. Results and discussion Although the response of the film is usually expressed in terms of the logarithm of the ratio between the color intensity of the non-irradiated and the irradiated film (Alva et al., 2002), we found that analysis of the irradiated film in terms of color intensity was sufficient to properly define the beam profile. Fig. 1 shows a set of pictures of different pieces of RCF after autoradiographic exposure of a thick Cu foil irradiated on a 301 slanted target (5 min at 10 mA). A 5 min proton irradiation of the thick Cu foil (17.8 MeV) produced 65 Zn, 62Zn and 63Zn in an approximate ratio 1:10:105 at the end of the bombardment, respectively. The RCF illustrated the proton beam strike area when exposed for 30 s, 30 min, and 60 h; after allowing a post-irradiation cooling time of 1 h (mostly 63Zn activity), 10 h (mostly 62Zn) and 100 h (mostly 65Zn), respectively. The 2D beam intensity distributions of these exposures are shown in Fig. 2. The full width at half maximum of the profiles obtained with 63Zn (Fig. 2-left) were determined to be 9.6 mm in the x-axis and 19.7 mm in the y-axis, which are in good agreement with the expected values for a 10 mm collimated beam impinging on 301 slanted target. Even thin foils of Cu and Nb irradiated in stack (Ep ¼ 15 MeV, 5 min at 15 mA) proved to be adequate to get the beam profile following exposure of the RCF for 10 s (front Cu foil) and 10 min (back Nb foil). Beam broadening, originated by scattering processes as the proton beam passes through the different foils in the stack, can be evaluated using this technique. Fig. 3 shows an example of a practical utility of this technique when used to analyze the beam profile of charged particle accelerators. The shape of the beam strike in this figure suggested a damaged stripper foil which was subsequently confirmed and replaced. Spatial calibrations (pixels to distance), beam intensity
Fig. 1. Pieces of Gafchromic EBT film after 10 s (left), 30 s (center) and 60 s (right) autoradiographic exposure on a thick Cu foil irradiated with 17.8 MeV protons (5 min at 10 mA). Exposure took place 1 h post-irradiation.
0
0
0 210
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20
0
2
4
6
8
10 12 14
X distance [mm]
140
0
2
4
6
8
10
12
14
X distance [mm]
Fig. 2. Beam profiles of a thick Cu foil irradiated with 17.8 MeV protons. Profiles were acquired at different post-irradiation and exposure times (see text) to get impressions of the different activation products: 63Zn (left), 62Zn (center) and 65Zn (right).
ARTICLE IN PRESS M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
2027
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ixels]
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tan X dis
Fig. 3. Beam profile showing a split proton beam due to a damaged stripper foil. This figure shows the scanned imaged of the RCF (upper left), the correspondent intensity distribution (upper center and bottom right), isodose lines (upper right), and the beam profile along the x-axis (bottom left).
distributions, isodose curves and iterative profiles can be obtained with DoseLab. The use of DoseLab is useful when a detailed analysis of the beam profile is needed or when the 2D distribution of the beam intensity is required. For example, this data can be used as an input source function to simulate, model and optimize the heat transfer process that has aided in the development of our cyclotron targets (Avila-Rodriguez et al., 2007). The use of this autoradiographic technique for practical applications of beam/ target alignment can be performed by means of a simple visual analysis. The price of an 800 1000 sheet of Gafchromic EBT film is on the order of $20 CAD. In this study 50 pieces of 2.5 cm 4 cm, matching the size of the thick Cu foil, were obtained from a single sheet of film. The DoseLab package is distributed free of charge and the digitalization of the films can be done using a conventional flatbed scanner which is commonly available. In this study only foils of Cu and Nb were explored to obtain the proton beam profile, but many other materials could be used with this purpose. These materials include, but are not
restricted to, Ti, V, Fe, Cr, Ni, Zn, Y, Zr, Mo, Ru and Ag. Price and availability of foils of these materials and half life and radiation field of the activated products are parameters that should be taken into account when choosing an appropriate foil material. Experimental thick-target saturated-yields at Ep ¼ 11 Mev for all the metallic materials mentioned above have been previously published (Nickles, 2003). This technique can also be extended to other accelerated particles. The IAEA Technical Document 1211 (IAEA, 2001) provides good examples of monitor reactions for accelerated beams of protons, deuterons, 3He and alpha particles.
4. Conclusions The use of radiochromic films to measure and analyze the beam profile of proton beams was found to be feasible whilst being simpler and more cost effective compared with the
ARTICLE IN PRESS 2028
M.A. Avila-Rodriguez et al. / Applied Radiation and Isotopes 67 (2009) 2025–2028
traditional autoradiography technique using radiographic film or digital radiography with storage phosphor systems.
Acknowledgment The authors are grateful to the staff of the Medical Physics Department at the University of Alberta who kindly provided the radiochromic films used in this study. This work was partially funded by the MicroSystems Technology Research Initiative (MSTRI) at the University of Alberta, Grant 1-2N-3A-Advanced Cyclotron. References Alva, H., Mercado-Uribe, H., Rodrı´guez-Villafuerte, M., Brandan, M.E., 2002. The use of a reflective scanner to study radiochromic film response. Phys. Med. Biol. 47, 2925. Avila-Rodrı´guez, M.A., Rodrı´guez-Villafuerte, M., Dı´az-Perches R., Pe´rezPastenes M.A., 2001. Experimental measurements of spatial dose distributions
in radiosurgery treatments. In: AIP Conference Proceedings vol. 593, pp. 127–132. Avila-Rodriguez, M.A., Sader, J.A., McQuarrie, S.A., 2007. 3D modeling and simulation of the thermal performance of solid cyclotron targets. In: Comsol Conference Proceedings, Boston, MA, pp. 359–363. Bustos, M.J., Cheung, T., Yu, P.K.N., 2006. Weak energy dependence of EBT Gafchromic film dose response in the 50 kVp–10 MVp X-ray range. Appl. Radiat. Isot. 64, 60. Fuss, M., Sturtewagen, E., De Wagter, C., Georg, D., 2007. Dosimetric characterization of GafChromic EBT film and its implications on film dosimetry quality assurance. Phys. Med. Biol. 52, 4211. IAEA, 2001. Charged particle cross-section database for medical radioisotope production: diagnostic radioisotopes and monitor reactions. IAEA-TECDOC1211, Vienna, May 2001. Nickles, R.J., 2003. The production of a broader palette of PET tracers. J. Labelled Compd. Radiopharm. 46, 1. Niroomand-Rad, A., Blackwell, C.R., Coursey, B.M., Gall, K.P., Galvin, J.M., McLaughlin, W.L., Meigooni, A.S., Nath, R., Rodgers, J.E., Soares, C.G., 1998. Radiochromic film dosimetry: recommendations of AAPM radiation therapy committee task group 55. Med. Phys. 25, 2093. Sankar, A., Ayyangar, K.M., Nehru, R.M., Kurup, P.G., Murali, V., Enke, C.A., Velmurugan, J., 2005. Comparison of Kodak EDR2 and Gafchromic EBT films for intensity-modulated radiation therapy dose distribution verification. Med. Dosimetry 31, 273.