Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

Abstract

The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily. There are several challenges in using the new RCFs, readout systems and validation of the results depending on their applications. Accurate RCF dosimetry requires understanding of RCF selection, handling and calibration methods, calibration curves, dose conversion methods, correction methodologies as well as selection, operation and quality assurance (QA) programs of the readout systems. Acquiring this level of knowledge is not straight forward, even for some experienced users. This Task Group report addresses these issues and provides a basic understanding of available RCF models, dosimetric characteristics and properties, advantages and limitations, configurations, and overall elemental compositions of the RCFs that have changed over the past 20 yr. In addition, this report provides specific guidelines for data processing and analysis schemes and correction methodologies for clinical applications in radiation therapy.

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

“…[197][198][199][200][201] In view of this controversy, it is advisable to strictly adopt all the precautions needed for radiochromic film dosimetry. 123,192…”

“…126,231,232 However, the parallel irradiation of the Gafchromic™ EBT films is discouraged by Fontanarosa et al 233 who observed unacceptable under dosage in PDD at depths greater than 15 cm (about 5% at 20 cm). In general, the detectors that have smallest k f clin, f msr Q clin, Q msr factor (microdiamond, microslicon, plastic scintillator, EBT film) 78,85,97,123,156,158,[186][187][188]192,[234][235][236] are preferred to avoid the need to correct the PDD. If the institution is unable to justify acquisition of at least one of these systems, the method described by Francescon et al 237 and as described in Figure 5 could be adopted.…”

A protocol for accurate radiochromic film dosimetry using Radiochromic.com

“…However, for doses larger than 10 Gy and up to 40 Gy, EBT-XD films are preferred. 10 EBT3 and EBT-XD films are considered energy independent for MV photon beams. However, they under-respond to photon energies lower than 100 keV 8 , and exhibit LET dependence for protons.…”

Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications

“… 9 , 10 More recently, sensitive self-developing films such as GAFchromicExternal Beam Therapy (EBT) have been developed by Ashland that are based on the lithium salt of PCDA (Li-PCDA) 11 − 18 and span dose ranges of 0.01–40 Gy. 1 , 2 , 19 As the more recent models of GAFchromic EBT films (especially EBT3 and EBT-XD) exhibit high spatial resolutions, 20 , 21 near-tissue equivalence, 21 , 22 and dose rate and energy dependence 23 , 24 along with being insensitive to visible light, 25 they are routinely employed in low-dose gradient (e.g., a quality assurance tool in intensity-modulated radiation therapy) 25 − 28 and high-dose gradient settings (e.g., brachytherapy 29 , 30 ). 18 , 23 , 31 Therefore, continued research into photoactive ingredients with a tunable reactivity is very important to improve dosimetry technologies for different therapeutic uses.…”