Development and evaluation of an end‐to‐end test for head and neck IMRT with a novel multiple‐dosimetric modality phantom

Abstract

A comprehensive end‐to‐end test for head and neck IMRT treatments was developed using a custom phantom designed to utilize multiple dosimetry devices. Initial end‐to‐end test and custom H&N phantom were designed to yield maximum information in anatomical regions significant to H&N plans with respect to: (i) geometric accuracy, (ii) dosimetric accuracy, and (iii) treatment reproducibility. The phantom was designed in collaboration with Integrated Medical Technologies. The phantom was imaged on a CT simulator and the CT was reconstructed with 1 mm slice thickness and imported into Varian's Eclipse treatment planning system. OARs and the PTV were contoured with the aid of Smart Segmentation. A clinical template was used to create an eight‐field IMRT plan and dose was calculated with heterogeneity correction on. Plans were delivered with a TrueBeam equipped with a high definition MLC. Preliminary end‐to‐end results were measured using film, ion chambers, and optically stimulated luminescent dosimeters (OSLDs). Ion chamber dose measurements were compared to the treatment planning system. Films were analyzed with FilmQA Pro using composite gamma index. OSLDs were read with a MicroStar reader using a custom calibration curve. Final phantom design incorporated two axial and one coronal film planes with 18 OSLD locations adjacent to those planes as well as four locations for IMRT ionization chambers below inferior film plane. The end‐to‐end test was consistently reproducible, resulting in average gamma pass rate greater than 99% using 3normal%/3 mm analysis criteria, and average OSLD and ion chamber measurements within 1% of planned dose. After initial calibration of OSLD and film systems, the end‐to‐end test provides next‐day results, allowing for integration in routine clinical QA. Preliminary trials have demonstrated that our end‐to‐end is a reproducible QA tool that enables the ongoing evaluation of dosimetric and geometric accuracy of clinical head and neck treatments.PACS number(s): 87.55.Qr

Dose calculation validation of a convolution algorithm in a solid water phantom

“…For end-to-end test verifications, systematic error in dose calculation will be interpreted as geometric misalignment. Snyder et al have adapted a custom phantom to ensure dosimetry accuracy and then perform a relevant end-to-end verification [22]. The dose calculation accuracy is of great importance when checking dose distributions in targets and organs at risk.…”

End-to-End QA in Radiation Therapy Quality Management

“…Some specific developments and applications for E2E QA to evaluate specific clinical treatment protocols are referenced in Table 1 below (which presents a list of vendors that supply various commercial tools and services to aid in-house E2E testing) and in the most recent IC3Ddose proceedings from the virtual meeting in 2021 [99][100][101][102][103]. These and other [21,53,96,[104][105][106][107][108][109][110][111][112] clinical reports span a range of investigations into the feasibility of RT E2E testing, nonetheless they do make some common observations. The papers indicate that clinically relevant E2E QA can be performed with a wide range of phantom designs that may contain various point, 2D or 3D dosimetry systems (see discussion below).…”

“…If the delivery under evaluation involves motion management, then the phantom will have to be able to be integrated into some commercial or in-house built motion testing system [129,130,178,179]. For some RT deliveries the E2E QA phantoms may need to be more anthropomorphic in external appearance (e.g., if the delivery requires phantom set-up in some patient immobilization system with set-up validation and repositioning) or to simulate internal structure heterogeneity with organ mimicking structures (e.g., if the E2E testing is being applied to RT delivery to specific anatomy and the assessment includes target conformity) [89,102,104,106,111,180,181]. The material for the phantom need not be exactly tissue or water equivalent although it should be similar to any organs of interest and should be well characterised by CT, and perhaps MR imaging, before use [174].…”

Human Body Anthropomorphic Phantom Utilisation for the Complex Testing of Radiation Therapy Technological Process

“…Идейно дозиметрические аудиты берут свое начало в стандартных программах менеджмента качества. В обоих случаях все действия направлены на проверку двух основных аспектов лучевой терапии: соответствие плана лечения клиническим требованиям и адекватность представления лечебным планом тех дозовых нагрузок, которые будет получать реальный пациент в течение всего курса лечения [7].…”

“…Кроме того, эти фантомы не только точно повторяют анатомические контуры тела человека, но и содержат различные гетерогенности, а также позволяют использовать разнообразное дозиметрическое оборудование: радиохромные и радиографические пленки, термолюминесцентные дозиметры, ионизационные камеры и т. д. [7,8].…”