In vivo dosimetry with thermoluminescent dosimeters in external photon beam radiotherapy
Introduction
The ultimate check of the actual dose delivered to a patient in radiotherapy can only be achieved by using in vivo dosimetry (ICRU, 1976). This is perhaps the most obvious way to check the accuracy of patient treatment (Mayles et al., 2000).
In vivo dosimetry can be divided into three classes: entrance dose measurements, exit dose measurements and intracavitary dose measurements.
Entrance dose measurements (Van Dam and Marinello, 1994; Huyskens et al., 2001) are a verification of the output and performance of the treatment unit. Entrance dose measurements can also be used to check the accuracy of patient set-up. Exit dose measurements (Piermattei et al., 2006) serve, in addition, to verify the dose calculation algorithm and to determine the influence of patient's parameters, such as shape, size and tissue inhomogeneities, on the dose calculation procedure. Various methods are available to obtain the target dose from entrance plus exit dose measurements (Venables et al., 2004; Rodríguez et al., 2008).
When detectors can be introduced in readily accessible body cavities, such as esophageal tube, rectum, vagina and bladder, are possible to measure the intracavitary dose (Marcié et al., 2005; Engström et al., 2005).
In vivo dosimetry is applied to assess the delivered dose to critical organs (Kalapurakal et al., 2000) or in difficult geometries where the dose is hard to predict from the treatment plan (Chow and Grigorov, 2008). In vivo dosimetry can also be used to monitor the dose delivered in special treatment techniques (Su et al., 2008).
The principal techniques used for in vivo dosimetry are semiconductor diodes and thermoluminescent dosimetry (Van Dam and Marinello, 1994; Kron, 1999; Mayles et al., 2000; Huyskens et al., 2001). Some other techniques have also been used for in vivo dosimetry, such as metal oxide semiconductor field effect transistors dosimetry, alanine dosimetry, plastic scintillators dosimetry, radiochromic films dosimetry, conventional portal films or electronic portal imaging devices dosimetry and gel dosimetry (Evans and Marinello, 2007). The choice between these techniques may depend on many factors such as availability, intrinsic characteristics of the detector type, measurement type, training of personnel, financial considerations and, of course, personal preference (Van Dam and Marinello, 1994; Evans and Marinello, 2007).
The introduction of thermoluminescent dosimetry in radiotherapy has already a long history and its use for in vivo dose measurements has been well documented in the literature (Cameron et al., 1968; Rudén, 1976; McKinlay, 1981; Van Dam and Marinello, 1994; Kron, 1999; Mayles et al., 2000).
This work reports a pilot study to test the applicability of a thermoluminescent dosimetric system for performing in vivo entrance dose measurements in external photon beam radiotherapy. In vivo dosimetry was applied for treatments of head and neck cancers at a radiotherapy department in a public hospital of Ribeirão Preto, Brazil. The aim is the implementation of in vivo dosimetry as a part of a quality assurance program in radiotherapy.
Presently, in vivo dosimetry is considered as a useful part of a quality assurance program in radiotherapy (Evans and Marinello, 2007). However, in vivo dosimetry as routine verification is still only applied in a small numbers of institutions in Brazil currently (Viegas, 2003).
Section snippets
Materials and methods
A total of 45 thermoluminescent dosimeters (TLD) divided into two batches (one of 17 and the other of 28 TLDs) was used. The thermoluminescent dosimeters are LiF:Mg, Ti (TLD 100) in the form of extruded square ribbons (about 3×3×0.9 mm3) manufactured by Harshaw. Thermoluminescent readouts were performed using Harshaw Model 2000 thermoluminescence (TL) analyzer. The system consists of two components: the Model 2000-B automatic integrating picoammeter and the Model 2000-C TL detector set to a
Results and discussion
The batch of 17 TLDs was found to have an intrinsic precision of ±1.5%. The batch of 28 TLDs was found to have an intrinsic precision of ±1.6%. The thermoluminescent dosimetric system enables individual dose measurements to be made with an expected overall uncertainty lower than ±3%. This overall uncertainty is <±5%, the action level recommended by ICRU (1976).
The TLD response (integrated output current from TLD reader in nanoCoulombs) with dose was plotted versus the dose for each batch. The
Conclusions
The pilot study to test the applicability of a thermoluminescent dosimetric system for performing in vivo entrance dose measurements in external photon beam radiotherapy presented good results. These measurements demonstrated the value of thermoluminescent dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in radiotherapy.
Acknowledgments
The authors acknowledge the partial financial support of the Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP—Brazil, and Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq—Brazil.
References (19)
- et al.
Adverse impact of multileaf collimator field shaping on lens dose in children with acute leukemia receiving cranial irradiation
Int. J. Radiat. Oncol.
(2000) - et al.
In vivo measurements with MOSFET detectors in oropharynx and nasopharynx intensity-modulated radiation therapy
Int. J. Radiat. Oncol.
(2005) - et al.
Implementation of in vivo dosimetry with Isorad™ semiconductor diodes in radiotherapy treatments of the pelvis
Med. Dosim.
(2008) - et al.
Clinical application of GAFCHROMIC® EBT film for in vivo dose measurements of total body irradiation radiotherapy
Appl. Radiat. Isot.
(2008) - et al.
The use of in vivo thermoluminescent dosimeters in the quality assurance programme for the START breast fractionation trial
Radiother. Oncol.
(2004) - et al.
Thermoluminescent Dosimetry
(1968) - et al.
Surface dosimetry for oblique tangential photon beams: a Monte Carlo simulation study
Med. Phys.
(2008) - et al.
In vivo dose verification of IMRT treated head and neck cancer patients
Acta Oncol.
(2005) - et al.
Quality control of treatment delivery
Cited by (20)
Measurement uncertainty analysis of radiophotoluminescent glass dosimeter reader system based on GD-352M for estimation of protection quantity
2022, Nuclear Engineering and TechnologyCitation Excerpt :In addition, Gafchromic EBT3 films have a relatively small dynamic dose range of 0.2–10 Gy compared to other in vivo dosimeters [10]. TLD-100 (Thermo Fisher Scientific, USA) has already been used to determine the absorbed dose in the external audit programs of radiotherapy for several decades [11,12]. TLD-100 contains a reader made of LiF:Mg, Ti in the form of a square (3.2 × 3.2 × 0.38 mm3) manufactured by Harshaw, and the measurable dose ranges are from 1 μGy to 10 Gy.
EPR analysis of the dosimetric properties of sulfamic acid irradiated by different ionizing radiations for radiotherapy and hadrontherapy applications
2021, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsCitation Excerpt :Consequently, the prevention conditions of radiological accidents require the use of a precise technique to measure the prescribed dose [4,5]. Thermo-luminescent dosimeters [6,7], semiconductor components [8,9] and optically stimulated luminescence dosimeters [10] are the dosimetric systems used for this reason. These dosimeters are sensitive and specific.
EPR study of dosimetric properties of glucose irradiated by X-photons and electrons: Analyse of storage effect on produced free radicals
2018, Radiation Physics and ChemistryCitation Excerpt :It provides absorbed dose measurements through the detection and evaluation of the free radicals in the sample under consideration (Regulla, 2000). This technique may detect unpaired electrons of free radicals and it can be considered fast, precise, applicable at large interval dose (few Gy - several kGy) and compared with other dosimetric methods such as thermo-luminescence and optical stimulated luminescence (Costa et al., 2010; Vestad et al., 2004; Jursinic, 2007) it is a non-destructive method that allows to re-read the dosimeter if necessary. Thus, elaborated EPR studies of irradiated organic substances such as amino acid derivatives (Osmanoglu and Sütcü, 2017), alanine (Khoury et al., 2015; Marrale et al., 2016) and table sugar (Ghosne et al., 2011; Mikou et al., 2015), or inorganic ones such as formates, phenol, sulfanic acid and strontium sulphate (Aboelezz et al., 2015; Bartolotta et al., 2001; Maghraby and Tarek, 2006; Marrale et al., 2014; Nor et al., 2016; Rushdi et al., 2015; Waldeland et al., 2011) have revealed that EPR technique coupled with these materials can provide reliable dosimeters in radiotherapy and in radio-sterilization fields.
Performance characteristics of the EPR dosimetry system with table sugar in radiotherapy applications
2015, Applied Radiation and IsotopesCitation Excerpt :Several studies have been performed to develop new in vivo dosimetry systems. Among such passive dosimetry systems are thermoluminescent dosimeters (Venables et al., 2004; Costa et al., 2010) and devices based on semiconductor components (Feygelman et al., 2010; Gopiraj et al., 2008). Of interest are also dosimetry systems based on the physical principle of electron paramagnetic resonance, EPR (Regulla, 2005).
Photon dosimetry methods outside the target volume in radiation therapy: Optically stimulated luminescence (OSL), thermoluminescence (TL) and radiophotoluminescence (RPL) dosimetry
2013, Radiation MeasurementsCitation Excerpt :This enables the possibility of multiple readout of RPL detectors without destroying the signal, which differentiates RPL from TL and OSL. In medicine, radiobiology and especially in modern radiotherapy, small size luminescence dosimeters (TL and OSL dosimeters) are applied for validation of radiotherapy treatment planning systems (Waligórski et al., 2002), for verification of treatment plans in anthropomorphic phantoms (Al-Hallaq et al., 2006; Han et al., 2008) and for in vivo (Costa et al., 2010) and two-dimensional (2-D) (Olko et al., 2008) dosimetry. TLDs find their application as transfer dosimeters during quality audits of the dose delivered by radiotherapy treatment machines (Izewska et al., 2002).