Technical notesComprehensive quality assurance phantom for the small animal radiation research platform (SARRP)
Introduction
The small animal radiation research platform (SARRP) is an isocentric irradiation system that combines a micro irradiator, cone beam CT imaging, and a treatment planning system [1]. The SARRP allows for image-guided radiotherapy research to be conducted at preclinical level [2], [3]. By mimicking the clinical system, the SARRP has the capabilities to deliver conformal dose distribution with precision and accuracy to the target volume while minimizing dose to healthy tissue [4].
Use of the SARRP for conducting preclinical research on small animals has become more common over the past years in different institutions across the world. There is, therefore, also increasing need for developing quality assurance tools and protocols with recommended tolerance levels for such small animal radiotherapy systems. In previous work, Ngwa et al. [5] developed a Mosfet phantom, using Mosfet dosimeters for facilitating SARRP QA tasks which may warrant daily evaluation. Other work on the commissioning and calibration of the SARRP using gafchromic (EBT2) film has been reported, covering dosimetry tasks such as: measurements of beam profiles, percent depth dose and isocenter congruency test [6], [7]. The purpose of this work is to develop and test the suitability and performance of a comprehensive QA phantom for the SARRP. This phantom was developed as a tool for carrying out daily, monthly and annual QA tasks including: imaging, dosimetry and treatment planning system (TPS) performance evaluation. The results should provide a useful reference for development of a comprehensive quality assurance program with proposed tolerances for the SARRP and potentially other small animal irradiators.
Section snippets
SARRP
A SARRP (Gulmay Medical Inc, 480 Brodgon Rd, Suwanee, GA USA) consists of an x-ray tube mounted on a gantry, with a robotic stage serving as a couch on which the animal is placed. This robotic stage has four degree of freedom x, y z, and φ (couch angle). In imaging mode an SARRP typically operates at 60–80 kVp and 0.5 mA using 1 mm of Al filtration. In therapy mode, it typically operates at 175–220 kVp with 0.15 mm of Cu filtration. The SARRP uses isocentric design in both modes and employs a
Results
The output constancy QA results for different field sizes (Fig. 3) showed maximum differences of 2.5%, 2.3%, 2.01%, and 1.89%, respectively, for open field (20 × 20 cm2), 3 × 3 mm, 5 × 5 mm2, and 12 mm fields. The results are within the tolerances (3% for daily QA) recommended by AAPM Task report 40 and 142 [14], [15].
Figure 4 shows the lateral profile for field size of 5 × 5 mm2 and 12 mm at two depths (0 mm and 10 mm). Analyzed results (Table 1) show the beam flatness results between 1.78%
Discussion
The investigated QA phantom provides an effective comprehensive QA tool for performing daily, monthly, and annual SARRP QA. The results for output check and beam profile (flatness, symmetry, and penumbra) are consistent with the expected reference values. Based on our results over many months using different dosimeters, a recommended tolerance for output measurements could be 3% similar to clinical systems. Results using film (EBT3) showed good 2D dosimetry; however, use of film is laborious
Conclusion
As the use of the SARRP and other small animal irradiators continues to increase across the globe, the need for tools to facilitate different QA tasks or comprehensive QA are also increasing. The QA phantom developed in this work provides one such tool. The results serve as a useful reference for development of a comprehensive quality assurance program, with proposed tolerances and frequency of required tests.
References (25)
- et al.
Anti-PD-1 blockade and stereotactic radiation produce long-term survival in mice with intracranial gliomas
Int J Radiat Oncol Biol Phys
(2013) - et al.
A fast analytic dose calculation method for arc treatments for kilovoltage small animal irradiators
Phys Med
(2013) - et al.
High throughput film dosimetry in homogeneous and heterogeneous media for a small animal irradiator
Phys Med
(2014) - et al.
Development and validation of a treatment planning system for small animal radiotherapy: SmART-Plan
Radiother Oncol
(2013) - et al.
Image-guided small animal radiation research platform: calibration of treatment beam alignment
Phys Med Biol
(2009) - et al.
SU-D-BRB-05: small animal lung compliance imaging: assessment system for tissue sensitivity to radiation induced lung injury
Med Phys
(2012) - et al.
Small animal radiotherapy research platforms
Phys Med Biol
(2011) - et al.
A multipurpose quality assurance phantom for the small animal radiation research platform (SARRP)
Phys Med Biol
(2012) - et al.
A comprehensive system for dosimetric commissioning and Monte Carlo validation for the small animal radiation research platform
Phys Med Biol
(2009) - et al.
Small animal radiation research platform: imaging, mechanics, control and calibration
Comparison of Gafchromic EBT2 and EBT3 films for clinical photon and proton beams
Med Phys
AAPM protocol for 40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology
Med Phys
Cited by (21)
Novel platform for subcutaneous tumor irradiation in mice
2023, Methods in Cell BiologyA comprehensive and efficient quality assurance program for an image-guided small animal irradiation system
2022, Zeitschrift fur Medizinische PhysikCitation Excerpt :Therefore, comprehensive quality assurance (QA) programs have to be established and run routinely/regularly (similar to QA programs for human radiotherapy). There are suggestions for simple QA programs [10], for geometric QA [11], for specific phantoms [12], and for image quality [6]. To our knowledge, there is neither a published comprehensive QA program that covers all involved subsystems, namely imaging, treatment planning, and the irradiation system (in terms of geometric accuracy and dosimetric aspects), nor any guideline to create such a comprehensive program.
Increased carcinoembryonic antigen expression on the surface of lung cancer cells using gold nanoparticles during radiotherapy
2020, Physica MedicaCitation Excerpt :Dosimetry was performed using radiochromic films calibrated at the SARRP using an ionization chamber following the Task Group 61 report by the American Association of Physicists in Medicine (AAPM) [38]. Calibration was performed under same conditions and energy range as the irradiation described in previous studies [39]. Dose rate delivered on the SARRP is verified on a monthly basis.
3D printing for dosimetric optimization and quality assurance in small animal irradiations using megavoltage X-rays
2020, Zeitschrift fur Medizinische PhysikCitation Excerpt :Preclinical in vivo studies using small animals are routinely performed in radiation therapy (RT) to test new therapeutic applications or to evaluate the biological effect of ionizing radiation on either tissues or molecular components. For these experiments, a variety of dedicated equipment, often produced in-house, has been developed to perform small-scale irradiations and quality assurance (QA) [1–5]. However, in order to avoid important capital investments, standard linear accelerators (LINAC) routinely employed for RT treatment of humans with mega-voltage (MV) beams can be used to irradiate small animals as well [6].
The Need for Accurate Reporting of Dosimetric Conditions in Radiobiology Studies
2020, International Journal of Radiation Oncology Biology PhysicsToward a pre-clinical irradiator using clinical infrastructure
2019, Physica MedicaCitation Excerpt :Similarly, the latest X-RAD products are capable of producing beams of 1 mm diameter. Both systems come with image guidance capabilities, and a tool for platform QA has been developed for the SARRP [21]. In this work we describe methods for the delivery of very compact radiation fields using clinical infrastructure, with beam collimation provided by a high-definition MLC.