Absorption spectra time evolution of EBT‐2 model GAFCHROMIC™ film

267

243

Radiochromic film has become an important tool to verify dose distributions in highly conformal radiation therapy such as IMRT. Recently, a new generation of these films, EBT3, has become available. EBT3 has the same composition and thickness of the sensitive layer of the previous EBT2 films, but its symmetric layer configuration allows the user to eliminate side orientation dependence, which is reported for EBT2 films. The most important EBT3 characteristics have been investigated, such as response at high‐dose levels, sensitivity to scanner orientation and postirradiation coloration, energy and dose rate dependence, and orientation dependence with respect to film side. Additionally, different IMRT fields were measured with both EBT3 and EBT2 films and evaluated using gamma index analysis. The results obtained show that most of the characteristics of EBT3 film are similar to the EBT2 film, but the orientation dependence with respect to film side is completely eliminated in EBT3 films. The study confirms that EBT3 film can be used for clinical practice in the same way as the previous EBT2 film.PACS number: 87.56.Fc

Section: Introductionmentioning

confidence: 99%

Dosimetric characterization and use of GAFCHROMIC EBT3 film for IMRT dose verification

Borca

Pasquino

Russo

et al. 2013

267

243

“…The properties of these EBT films have been reported in several publications, based on investigations conducted by using several types of photon, electron, and proton beams 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 . Their energy response 7 , 8 , 11 absorption spectra (9) scanning orientation dependence 10 , 11 film homogeneity (12) temperature dependence 10 , 13 ambient light sensitivity (10) postexposure coloration 10 , 11 and variations among different lot numbers (14) were analyzed. The use of EBT3 films is limited to doses below 1000 cGy, owing to the optimality constraint on the film's red channel (10) .…”

Section: Introductionmentioning

confidence: 99%

Gafchromic EBT‐XD film: Dosimetry characterization in high‐dose, volumetric‐modulated arc therapy

Miura¹,

Ozawa

Hosono³

et al. 2016

Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT‐XD films have been designed for optimal performance in the 40–4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose‐response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high‐dose volumetric‐modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0–4,000 cGy range. Postexposure coloration was analyzed at postirradiation times ranging from several minutes to 48 h. The films were also irradiated with 6 MV (dose rate (DR): 600 MU/min), 6 MV flattening filter‐free (FFF) (DR: 1,400 MU/ min), and 10 MV FFF (DR: 2,400 MU/min) beams to determine the energy and dose‐rate dependence. For clinical examinations, we compared the dose distribution measured with EBT‐XD films and calculated by the planning system for four VMAT cases. The red channel of the EBT‐XD film exhibited a wider dynamic range than the green and blue channels. Scanner orientation yielded a variation of ∼3% in the net optical density (OD). The difference between the film front and back scan orientations was negligible, with variation of ∼1.3% in the net OD. The net OD increased sharply within the first 6 hrs after irradiation and gradually afterwards. No significant difference was observed for the beam energy and dose rate, with a variation of ∼1.5% in the net OD. The gamma passing rates (at 3%, 3 mm) between the film‐ measured and treatment planning system (TPS)‐calculated dose distributions under a high dose VMAT plan in the absolute dose mode were more than 98.9%.PACS number(s): 87.56 Fc

“…For MV beams, EBT, EBT2, and EBT3 GAFCHROMIC film models were used extensively to measure therapeutic doses over wide dose range and the same dosimetry protocols apply for imaging. The dosimetric properties of these films were tested widely in the literature in terms of absorption spectra, (24) postirradiation waiting time, 24 , 25 scanning mode and exposure to light, 25 , 26 high temperature behavior, (25) performance in water, (27) depth dose measurements, (28) and energy dependence 29 , 30 …”

Section: Introductionmentioning

confidence: 99%

Radiochromic film based dosimetry of image‐guidance procedures on different radiotherapy modalities

Nobah

Aldelaijan

Dević

et al. 2014

Self Cite

In this work we compare doses from imaging procedures performed on today's state‐of‐the‐art integrated imaging systems using a reference radiochromic film dosimetry system. Skin dose and dose profile measurements from different imaging systems were performed using radiochromic films at different anatomical sites on a humanoid RANDO phantom. EBT3 film was used to measure imaging doses from a TomoTherapy MVCT system, while XRQA2 film was used for dose measurements from kilovoltage imaging systems (CBCT on 21eX and TrueBeam Varian linear accelerators and CyberKnife stereoscopic orthogonal imagers). Maximum measured imaging doses in cGy at head, thorax, and pelvis regions were respectively 0.50, 1.01, and 4.91 for CBCT on 21eX, 0.38, 0.84, and 3.15 for CBCT on TrueBeam, 4.33, 3.86, and 6.50 for CyberKnife imagers, and 3.84, 1.90, and 2.09 for TomoTherapy MVCT. In addition, we have shown how an improved calibration system of XRQA2 film can achieve dose uncertainty level of better than 2% for doses above 0.25 cGy. In addition to simulation‐based studies in literature, this study provides the radiation oncology team with data necessary to aid in their decision about imaging frequency for image‐guided radiation therapy protocols.PACS number: 87.53.Bn, 87.55.Qr, 87.56.Fc