Geometric evaluation and quantifying dosimetric impact of diverse deformable image registration algorithms on abdomen images with biomechanically modeled deformations.

Purpose: Deformable image registration (DIR) has been increasingly used in radiation therapy (RT). The accuracy of DIR algorithms and how it impacts on the RT plan dosimetrically were examined in our study for abdominal sites using biomechanically modeled deformations.

Methods: Five pancreatic cancer patients were enrolled in this study.

Automated planning of stereotactic spine re-irradiation using cumulative dose limits.

Background And Purpose: The lack of dedicated tools in commercial planning systems currently restricts efficient review and planning for re-irradiation. The aim of this study was to develop an automated re-irradiation planning framework based on cumulative doses.

Materials And Methods: We performed a retrospective study of 14 patients who received spine SBRT re-irradiation near a previously irradiated treatment site.

Creating patient-specific digital phantoms with a longitudinal atlas for evaluating deformable CT-CBCT registration in adaptive lung radiotherapy.

Background: Quality assurance of deformable image registration (DIR) is challenging because the ground truth is often unavailable. In addition, current approaches that rely on artificial transformations do not adequately resemble clinical scenarios encountered in adaptive radiotherapy.

Purpose: We developed an atlas-based method to create a variety of patient-specific serial digital phantoms with CBCT-like image quality to assess the DIR performance for longitudinal CBCT imaging data in adaptive lung radiotherapy.

Comparative study of SRS end-to-end QA processes of a diode array device and an anthropomorphic phantom loaded with GafChromic XD film.

Purpose: End-to-end testing (E2E) is a necessary process for assessing the readiness of the stereotactic radiosurgery (SRS) program and annual QA of an SRS system according to the AAPM MPPG 9a. This study investigates the differences between using a new SRS MapCHECK (SRSMC) system and an anthropomorphic phantom film-based system in a large network with different SRS delivery techniques.

Methods And Materials: Three SRS capable Linacs (Varian Medical Systems, Palo Alto, CA) at three different regional sites were chosen to represent a hospital network, a Trilogy with an M120 multi-leaf collimator (MLC), a TrueBeam with an M120 MLC, and a TrueBeam Stx with an HD120 MLC.

Implementation and validation of an in-house geometry optimization software for SRS VMAT planning of multiple cranial metastases.

Purpose: The implementation and evaluation of an in-house developed geometry optimization (GO) software are described. The GO script provides optimal lesion clustering, isocenter placement, and collimator angle of each arc for cranial multi-lesion stereotactic radiosurgery (SRS) volumetric modulated arc therapy (VMAT) planning.

Materials And Methods: An Eclipse-plugin program was developed to facilitate automatic plan geometry generation for multiple metastases SRS VMAT plans.

A dosimetry study of post-mastectomy radiation therapy with AeroForm tissue expander.

Purpose: To evaluate the dosimetric effects of the AeroForm (AirXanpders®, Palo Alto, CA) tissue expander in-situ for breast cancer patients receiving post-mastectomy radiation therapy.

Methods And Materials: A film phantom (P1) was constructed by placing the metallic canister of the AeroForm on a solid water phantom with EBT3 films at five depths ranging from 2.6 mm to 66.

Quantification of accumulated dose and associated anatomical changes of esophagus using weekly Magnetic Resonance Imaging acquired during radiotherapy of locally advanced lung cancer.

Background And Purpose: Minimizing acute esophagitis (AE) in locally advanced non-small cell lung cancer (LA-NSCLC) is critical given the proximity between the esophagus and the tumor. In this pilot study, we developed a clinical platform for quantification of accumulated doses and volumetric changes of esophagus via weekly Magnetic Resonance Imaging (MRI) for adaptive radiotherapy (RT).

Material And Methods: Eleven patients treated via intensity-modulated RT to 60-70 Gy in 2-3 Gy-fractions with concurrent chemotherapy underwent weekly MRIs.

A VMAT planning technique for locally advanced breast cancer patients with expander or implant reconstructions requiring comprehensive postmastectomy radiation therapy.

Locally advanced breast cancer patients with expander or implant reconstructions who require comprehensive postmastectomy radiotherapy (PMRT) can pose unique treatment planning challenges. Traditional 3D conformal radiation techniques often result in large dose inhomogeneity throughout the treatment volumes, inadequate target coverage, or excessive normal tissue doses. We have developed a volumetric modulated arc therapy (VMAT) planning technique without entering through the ipsilateral arm that produced adequate target volume coverage, excellent homogeneity throughout the target volume, and acceptable doses to the normal structures.

Institutional experience with SRS VMAT planning for multiple cranial metastases.

Background And Purpose: This study summarizes the cranial stereotactic radiosurgery (SRS) volumetric modulated arc therapy (VMAT) procedure at our institution.

Materials And Methods: Volumetric modulated arc therapy plans were generated for 40 patients with 188 lesions (range 2-8, median 5) in Eclipse and treated on a TrueBeam STx. Limitations of the custom beam model outside the central 2.

Heart Dosimetry is Correlated With Risk of Radiation Pneumonitis After Lung-Sparing Hemithoracic Pleural Intensity Modulated Radiation Therapy for Malignant Pleural Mesothelioma.

Purpose: To determine clinically helpful dose-volume and clinical metrics correlating with symptomatic radiation pneumonitis (RP) in malignant pleural mesothelioma (MPM) patients with 2 lungs treated with hemithoracic intensity modulated pleural radiation therapy (IMPRINT).

Methods And Materials: Treatment plans and resulting normal organ dose-volume histograms of 103 consecutive MPM patients treated with IMPRINT (February 2005 to January 2015) to the highest dose ≤50.4 Gy satisfying departmental normal tissue constraints were uniformly recalculated.

Geometric dose prediction model for hemithoracic intensity-modulated radiation therapy in mesothelioma patients with two intact lungs.

The presence of two intact lungs makes it challenging to reach a tumoricidal dose with hemithoracic pleural intensity-modulated radiation therapy (IMRT) in patients with malignant pleural mesothelioma (MPM) who underwent pleurectomy/decortications or have unresectable disease. We developed an anatomy-based model to predict attainable prescription dose before starting optimization. Fifty-six clinically delivered IMRT plans were analyzed regarding correlation of prescription dose and individual and total lung volumes, planning target volume (PTV), ipsilateral normal lung volume and ratios: contralateral/ipsilateral lung (CIVR); contralateral lung/PTV (CPVR); ipsilateral lung /PTV (IPVR); ipsilateral normal lung /total lung (INTLVR); ipsilateral normal lung/PTV (INLPVR).

A study on the dose distributions in various materials from an Ir-192 HDR brachytherapy source.

Dose distributions of (192)Ir HDR brachytherapy in phantoms simulating water, bone, lung tissue, water-lung and bone-lung interfaces using the Monte Carlo codes EGS4, FLUKA and MCNP4C are reported. Experiments were designed to gather point dose measurements to verify the Monte Carlo results using Gafchromic film, radiophotoluminescent glass dosimeter, solid water, bone, and lung phantom. The results for radial dose functions and anisotropy functions in solid water phantom were consistent with previously reported data (Williamson and Li).

Motion monitoring for cranial frameless stereotactic radiosurgery using video-based three-dimensional optical surface imaging.

Purpose: To establish a new clinical procedure in frameless stereotactic radiosurgery (SRS) for patient setup verification at treatment couch angles as well as for head-motion monitoring during treatment using video-based optical surface imaging (OSI).

Methods: A video-based three-dimensional (3D) OSI system with three ceiling-mounted camera pods was employed to verify setup at treatment couch angles as well as to monitor head motion during treatment. A noninvasive head immobilization device was utilized, which includes an alpha head mold and a dental mouthpiece with vacuum suction; both were locked to the treatment couch.