CT-Guided Adaptive Radiotherapy for the Treatment of Technically Challenging Oligometastatic Disease: A Case Report.

There is a growing interest in the application of stereotactic body radiotherapy (SBRT) for the treatment of oligometastatic cancers. This increasing appeal of SBRT has highlighted the need for more sophisticated radiotherapy techniques that allow high doses of radiation to be delivered to multiple sites while limiting the exposure of neighboring healthy tissue. A major obstacle to achieving this aim has been the occurrence of interfraction target variability: the tendency of both the tumor and the surrounding tissue to undergo day-to-day non-synchronous shifts in position.

2D IMRT QA passing rate dependency on coronal plane.

Intensity modulated radiation therapy (IMRT) delivery involves a complex series of beam angles and multileaf collimator (MLC) arrangements, requiring quality assurance to be performed to validate delivery before treatment. The purpose of this work is to investigate the effect of dose gradient on quality assurance (QA) passing rate. Many (n = 40) IMRT plans were delivered and measured using a 2D planar array of ion chambers; additionally, eleven plans were measured at several coronal planes.

Therapeutic effects of radiodynamic therapy (RDT) for lung cancer treatment: a combination of 15MV photons and 5-aminolevulinic acid (5-ALA).

Radiodynamic therapy (RDT) uses high-energy photon beams instead of visible/near-infrared light to treat deep-seated tumors that photodynamic therapy cannot achieve due to the low penetration depth of laser beams. The purpose of this study is to investigate the therapeutic effect of RDT with 15 MV photon beams combined with 5-aminolevulinic acid (5-ALA) using a mouse model.A subcutaneous C57BL/6 mouse model of KP1 small-cell lung cancer cell line was used.

Evaluating suggested stricter gamma criteria for linac-based patient-specific delivery QA in the conventional and SBRT environments.

Purpose: To evaluate AAPM TG-218 recommended tolerances for IMRT QA for conventional and SBRT delivery.

Methods: QA analysis was repeated for 150 IMRT/VMAT patients with varying gamma criteria. True composite delivery was utilized, corrected for detector and output variation.

Monte Carlo Dose Calculation - A QA Method for SRT and SBRT Plans in Treating Multiple and Small Metastatic Lesions.

To provide accurate and fast 3-D dose verification for hypofractionated stereotactic radiotherapy (SRT/SBRT) of small and multi targets calculated with a Varian Eclipse treatment planning system (TPS) delivered on a Varian accelerator. Ten brain and lung hypofractionated SRT/SBRT linac-based and CyberKnife plans were generated by the Eclipse system for delivery on the accelerator with the Millenium-120 leaf multileaf collimator (MLC) and Multiplan for the CyberKnife machine. These clinical SRT/SBRT plans required accurate quality assurance measurements to obtain absolute point dose and 3-D dose distributions due to the low number of fractions and high fraction doses.

Dosimetric evaluation of image-guided radiation therapy for prostate cancer.

The aim of this study was to investigate the dosimetric accuracy of imaged-guided radiation therapy for prostate patients using the in-room computed tomography (CT) target localization technique. A Siemens CT-on-rails system was used for patient setup and target localization for intensity-modulated radiation therapy (IMRT) of prostate cancer. Fifteen previously treated prostate patients were included in this retrospective study.

Pelvic Reirradiation Utilizing Pulsed Low-dose Rate Radiation Therapy.

Pulsed low-dose rate radiation therapy has been shown to reduce normal tissue damage while decreasing DNA damage repair in tumor cells. In a cohort of patients treated with palliative or definitive pelvic reirradiation using pulsed low-dose rate radiation therapy, we observed substantial local control and low rates of toxicity.

Time and frequency to observe fiducial markers in MLC-modulated fields during prostate IMRT/VMAT beam delivery.

Objective: This work investigates the time and frequency to observe fiducial markers in MLC-modulated fields during intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) beam delivery for real-time prostate localization.

Methods: Thirty seven prostate patients treated with IMRT or VMAT were included in this retrospective study. DRR images were generated for all MLC segments/control points using the TPS.

Radiodynamic therapy using 15-MV radiation combined with 5-aminolevulinic acid and carbamide peroxide for prostate cancer in vivo.

Photodynamic therapy has been clinically proven to be effective, but its effect is limited to relatively shallow tumors because of its use of visible light. Radiodynamic therapy (RDT) has therefore been investigated as a means to treat deep-seated tumors. In this study, the treatment effect of a novel form of RDT consisting of radiation combined with 5-aminolevulinic acid (5-ALA) and carbamide peroxide was investigated using a mouse model.

AAPM Task Group 329: Reference dose specification for dose calculations: Dose-to-water or dose-to-muscle?

Linac calibration is done in water, but patients are comprised primarily of soft tissue. Conceptually, and specified in NRG/RTOG trials, dose should be reported as dose-to-muscle to describe the dose to the patient. Historically, the dose-to-water of the linac calibration was often converted to dose-to-muscle for patient calculations through manual application of a 0.

Evaluation of the combined use of two different respiratory monitoring systems for 4D CT simulation and gated treatment.

Purpose: Two different respiratory monitoring systems (Varian's Real-Time Position Management (RPM) System and Siemens' ANZAI belt Respiratory Gating System) are compared in the context of respiratory signals and 4D CT images that are accordingly reconstructed. This study aims to evaluate the feasibility of combined use of RPM and ANZAI systems for 4DCT simulation and gated radiotherapy treatment, respectively.

Methods: The RPM infrared reflecting marker and the ANZAI belt pressure sensor were both placed on the patient's abdomen during 4DCT scans.

When and how to treat an IMRT patient on a second accelerator without replanning?

When a linear accelerator is unavailable for treatment, a clinical decision is imminent regarding whether a patient should be treated on a linear accelerator other than the machine the patient was scheduled on, or whether treatment should be postponed until the original Linac becomes available. This work investigates the feasibility of switching patients to different accelerators for intensity-modulated radiation therapy (IMRT). We have performed Monte Carlo simulations of photon beams from different Linac models and vendors.

Induction chemotherapy followed by concurrent chemoradiation and nimotuzumab for locoregionally advanced nasopharyngeal carcinoma: preliminary results from a phase II clinical trial.

Overexpression of epidermal growth factor receptor can be found in more than 80% of patients with locoregionally advanced nasopharyngeal carcinoma and is associated with shorter survival. In this work, we evaluated the feasibility of adding nimotuzumab to chemoradiation in locoregionally advanced nasopharyngeal carcinoma. Twenty-three patients with clinically staged T3-4 or any node-positive disease were enrolled.

Investigation of the clinical potential of scattering foil free electron beams.

Electron beam therapy has been an important radiation therapy modality for many decades. Studies have been conducted recently for more efficient and advanced delivery of electron beam radiation therapy. X-ray contamination is a common problem that exists with all of the advanced electron beam therapy techniques such as Bolus Electron conformal therapy, segmented electron conformal therapy, and modulated electron arc therapy.

Feasibility of replacing patient specific cutouts with a computer-controlled electron multileaf collimator.

A motorized electron multileaf collimator (eMLC) was developed as an add-on device to the Varian linac for delivery of advanced electron beam therapy. It has previously been shown that electron beams collimated by an eMLC have very similar penumbra to those collimated by applicators and cutouts. Thus, manufacturing patient specific cutouts would no longer be necessary, resulting in the reduction of time taken in the cutout fabrication process.

Radiosensitivity enhancement of human hepatocellular carcinoma cell line SMMC-7721 by sorafenib through the MEK/ERK signal pathway.

Purpose: Sorafenib, an oral multikinase inhibitor, is the first agent that has demonstrated an improved overall survival benefit in advanced hepatocellular carcinoma, setting a new standard for first-line treatment. However, the association between radiosensitivity and sorafenib remains unclear. The purpose of this study was to investigate whether sorafenib could enhance radiosensitivity and the possible mechanisms of sorafenib-mediated radiosensitization in human hepatocellular carcinoma cell line SMMC-7721.

Target repositional accuracy and PTV margin verification using three-dimensional cone-beam computed tomography (CBCT) in stereotactic body radiotherapy (SBRT) of lung cancers.

The purpose of this study was to assess target repositional accuracy with respect to the bony structures using daily CBCT, and to validate the planning target volume (PTV) margin used in the lung SBRT. All patients underwent 4D CT scanning in preparation for lung SBRT. The internal target volume (ITV) was outlined from the reconstructed 4D data using the maximum-intensity projection (MIP) algorithm.

Magnetic resonance-based treatment planning for prostate intensity-modulated radiotherapy: creation of digitally reconstructed radiographs.

Purpose: To develop a technique to create magnetic resonance (MR)-based digitally reconstructed radiographs (DRR) for initial patient setup for routine clinical applications of MR-based treatment planning for prostate intensity-modulated radiotherapy.

Methods And Materials: Twenty prostate cancer patients' computed tomography (CT) and MR images were used for the study. Computed tomography and MR images were fused.

In-room CT techniques for image-guided radiation therapy.

Accurate patient setup and target localization are essential to advanced radiation therapy treatment. Significant improvement has been made recently with the development of image-guided radiation therapy, in which image guidance facilitates short treatment course and high dose per fraction radiotherapy, aiming at improving tumor control and quality of life. Many imaging modalities are being investigated, including x-ray computed tomography (CT), ultrasound imaging, positron emission tomography, magnetic resonant imaging, magnetic resonant spectroscopic imaging, and kV/MV imaging with flat panel detectors.

Dosimetry and preliminary acute toxicity in the first 100 men treated for prostate cancer on a randomized hypofractionation dose escalation trial.

Purpose: The alpha/beta ratio for prostate cancer is postulated to be between 1 and 3, giving rise to the hypothesis that there may be a therapeutic advantage to hypofractionation. The dosimetry and acute toxicity are described in the first 100 men enrolled in a randomized trial.

Patients And Methods: The trial compares 76 Gy in 38 fractions (Arm I) to 70.

MRI-based treatment planning for radiotherapy: dosimetric verification for prostate IMRT.

Purpose: Magnetic resonance (MR) and computed tomography (CT) image fusion with CT-based dose calculation is the gold standard for prostate treatment planning. MR and CT fusion with CT-based dose calculation has become a routine procedure for intensity-modulated radiation therapy (IMRT) treatment planning at Fox Chase Cancer Center. The use of MRI alone for treatment planning (or MRI simulation) will remove any errors associated with image fusion.