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• Thin copper-plastic composite 3D printing radiotherapy bolus. • Superficial dose enhancement under radiotherapy mask. • Flexible 3D printed radiotherapy bolus. The purpose of this work is to evaluate a commercially available copper-plastic composite material for use as a custom fit 3D printed bolus. Superficial dose under copper-plastic composite bolus was assessed for 0.4 mm, 0.6 mm, and 0.8 mm thicknesses. Superficial dose measurements were performed with an Attix parallel plate ionization chamber and radiochromic film. Additionally, a custom-fit bolus was designed for the temporal-frontal cranial region of an anthropomorphic phantom. A treatment plan with a tangential field arrangement was designed, and radiochromic film was used to measure the dose enhancement to the surface of the phantom from the bolus and compared to the calculated dose. It was shown that 3D printed copper-plastic composite bolus can provide the equivalent dose enhancement of thicker conventional bolus. Due to the limited thickness of the copper-plastic composite the bolus can remain flexible, which can aid in the placement of the bolus and improve patient comfort. [ABSTRACT FROM AUTHOR]

• A novel yttrium-90 Superficial Brachytherapy source has been characterized. • Yttrium-90 is a highly conforming source, ideal for the treatment of superficial lesions. • The Conformal Superficial Brachytherapy applicator uses multiple brachytherapy sources. • The Conformal Superficial Brachytherapy applicator was designed to treat non-melanoma skin cancers. To characterize the dose distribution in water of a novel beta-emitting brachytherapy source for use in a Conformal Superficial Brachytherapy (CSBT) device. Yttrium-90 (90Y) sources were designed for use with a uniquely designed CSBT device. Depth dose and planar dose measurements were performed for bare sources and sources housed within a 3D printed source holder. Monte Carlo simulated dose rate distributions were compared to film-based measurements. Gamma analysis was performed to compare simulated and measured dose rates from seven 90Y sources placed simultaneously using the CSBT device. The film-based maximum measured surface dose rate for a bare source in contact with the surface was 3.35 × 10–7 cGy s−1 Bq−1. When placed in the source holder, the maximum measured dose rate was 1.41 × 10–7 cGy s−1 Bq−1. The Monte Carlo simulated depth dose rates were within 10% or 0.02 cm of the measured dose rates for each depth of measurement. The maximum film surface dose rate measured using a seven-source configuration within the CSBT device was 1.78 × 10−7 cGy s−1 Bq−1. Measured and simulated dose rate distribution of the seven-source configuration were compared by gamma analysis and yielded a passing rate of 94.08%. The gamma criteria were 3% for dose-difference and 0.07056 cm for distance-to-agreement. The estimated measured dose rate uncertainty was 5.34%. 90Y is a unique source that can be optimally designed for a customized CSBT device. The rapid dose falloff provided a high dose gradient, ideal for treatment of superficial lesions. The dose rate uncertainty of the 90Y-based CSBT device was within acceptable brachytherapy standards and warrants further investigation. [ABSTRACT FROM AUTHOR]

• A correspondence model was created to estimate tumor motion in the thorax. • 4DCT images and displacement of the patient's skin on the thoracic area were used. • The patient's skin displacement during radiation therapy is used as model's input. • The application of the model to phantom and five patients are presented. We present a patient-specific model to estimate tumor location in the thorax during radiation therapy using chest surface displacement as the surrogate signal. Two types of data are used for model construction: Four-dimensional computed tomography (4D-CT) images of the patient and the displacement of two points on the patient's skin on the thoracic area. Principal component analysis is used to fit the correspondence model. This model incorporates the recorded surrogate signals during radiation delivery as input and delivers the 3D trajectory of the tumor as output. We evaluated the accuracy of the proposed model on a respiratory phantom and five lung cancer patients. For the respiratory phantom, the location of the center of the sphere during treatment was calculated in three directions: Left-Right (LR), Anterior-Posterior (AP) and, Superior-Inferior (SI). The error of localization was less than 1 mm in the LR and AP directions and less than 2 mm in the SI direction. The location of the tumor center for two of the patients, and the location of the apex of the diaphragm for the other three, was calculated in three directions. For all patients, the localization error in the LR and AP directions was less than 1.1 mm for two fractions and the maximum localization error in the SI direction was 6.4 mm. This work presents a feasibility study of utilizing surface displacement data to locate the tumor in the thorax during radiation treatment. Future work will validate the model on a larger patient population. [ABSTRACT FROM AUTHOR]