Accuracy evaluation of a six-degree-of-freedom couch using cone beam CT and IsoCal phantom with an in-house algorithm.

Purpose: The accuracy of a six degree of freedom (6DoF) couch was evaluated using a novel method.

Methods: Cone beam CT (CBCT) images of a 3D phantom (IsoCal) were acquired with different, known combinations of couch pitch and roll angles. Pitch and roll angles between the maximum allowable values of 357 and 3 degrees were tested in one degree increments.

Still equivalent for dose calculation in the Monte Carlo era? A comparison of free breathing and average intensity projection CT datasets for lung SBRT using three generations of dose calculation algorithms.

Purpose: Inhomogeneity dose modeling and respiratory motion description are two critical technical challenges for lung stereotactic body radiotherapy, an important treatment modality for small size primary and secondary lung tumors. Recent studies revealed lung density-dependent target dose differences between Monte Carlo (Type-C) algorithm and earlier algorithms. Therefore, this study aimed to investigate the equivalence of the two most popular CT datasets for treatment planning, free breathing (FB) and average intensity projection (AIP) CTs, using Type-C algorithms, and comparing with two older generation algorithms (Type-A and Type-B).

Automated survey of 8000 plan checks at eight facilities.

Purpose: To identify policy and system related weaknesses in treatment planning and plan check work-flows.

Methods: The authors' web deployed plan check automation solution, PlanCheck, which works with all major planning and record and verify systems (demonstrated here for mosaiq only), allows them to compute violation rates for a large number of plan checks across many facilities without requiring the manual data entry involved with incident filings. Workflows and failure modes are heavily influenced by the type of record and verify system used.

Technical Note: Fabricating Cerrobend grids with 3D printing for spatially modulated radiation therapy: A feasibility study.

Purpose: Grid therapy has promising applications in the radiation treatment of large tumors. However, research and applications of grid therapy are limited by the accessibility of the specialized blocks that produce the grid of pencil-like radiation beams. In this study, a Cerrobend grid block was fabricated using the 3D printing technique.

The role of oxygen in the photostimulation luminescence process of europium doped potassium chloride.

A recent suggestion that europium doped potassium chloride (KCl:Eu) has the potential to significantly advance the state-of-the-art in radiation therapy dosimetry has generated a renewed interest in a classic storage phosphor material. The purposes of this work are to investigate the role of oxygen in the photostimulation luminescence (PSL) process and to determine if both increased PSL yield and improved temporal stability could be realized in KCl:Eu by incorporating oxygen in the material fabrication process. Regardless of synthesis atmosphere, air or pure nitrogen, PSL amplitude shows a maximum at 1.

A new variable for SRS plan quality evaluation based on normal tissue sparing: the effect of prescription isodose levels.

Objective: A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.

Methods: 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS.

Two-dimensional high spatial-resolution dosimeter using europium doped potassium chloride: a feasibility study.

Recent research has shown that KCl:Eu²⁺ has great potential for use in megavoltage radiation therapy dosimetry because this material exhibits excellent storage performance and is reusable due to strong radiation hardness. This work reports the authors' attempts to fabricate 2D KCl:Eu²⁺ storage phosphor films (SPFs) using both a physical vapor deposition (PVD) method and a tape casting method. X-ray diffraction analysis showed that a 10 µm thick PVD sample was composed of highly crystalline KCl.

SU-E-T-286: Verification of Treatment Delivery Monitor Unit (MU) Calculation and Dose Estimation of Bilateral Total Body Irradiation (TBI).

Purpose: TBI treatment delivery MU and patient dose estimation are calculated manually at our institution. This study was to verify the accuracyof MU calculation and dose estimation of bilateral TBI by application of tissue heterogeneity correction.

Methods: Twelve TBI patients were simulated from neck to thigh in bilateral TBI position.

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry.

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KC1:Eu2+), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study.

Methods: Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study.

Theoretical and empirical investigations of KCl : Eu2+ for nearly water-equivalent radiotherapy dosimetry.

Purpose: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl : Eu2+) a promising dosimetry material. The purpose of this study is to model KCl : Eu2+ point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl : Eu2+ storage phosphor films (SPFs).

Methods: KCl : Eu2+ point dosimeters were irradiated using a 6 MV beam at four depths (5-20 cm) for each of five square field sizes (5 x 5-25 x 25 cm2).

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl: Eu2+.

This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.