Optimization of Fluence Map for CyberKnife Raster Scanning Intensity Modulated Radiotherapy.

Background/aim: Stereotactic body radiotherapy for prostate cancer using CyberKnife with circular cone requires a long treatment time. Raster scanning intensity modulated radiotherapy (RS-IMRT) has a potential of improving treatment efficacy, introducing shorter treatment time, better target dose uniformity, and lower organ at risk (OAR) dose. The purpose of the study was to develop a fluence optimization system for RS-IMRT.

＜Editors' Choice＞ Elective nodal irradiation versus involved field radiotherapy for limited disease small cell lung cancer: a single-institution experience.

Elective nodal irradiation (ENI) and involved field radiotherapy (IFRT) are definitive radiotherapeutic approaches used to treat patients with limited-disease small cell lung cancer (LD-SCLC). However, no solid consensus exists on their optimal target volume. The current study aimed to assess the clinical outcomes of patients with LD-SCLC who received definitive ENI or IFRT.

Development of raster scanning IMRT using a robotic radiosurgery system.

Treatment time with the CyberKnife frameless radiosurgery system is prolonged due to the motion of the robotic arm. We have developed a novel scanning irradiation method to reduce treatment time. We generated treatment plans mimicking eight-field intensity-modulated radiotherapy (IMRT) plans generated for the Novalis radiosurgery system.

Small-field dosimetry of TrueBeam flattened and flattening filter-free beams: A multi-institutional analysis.

Purpose: Detector-dependent interinstitutional variations of the beam data may lead to uncertainties of the delivered dose to patients. Here we evaluated the inter-unit variability of the flattened and flattening filter-free (FFF) beam data of multiple TrueBeam (Varian Medical Systems) linear accelerators focusing on the small-field dosimetry.

Methods: The beam data of 6- and 10-MV photon beams with and without flattening filter measured for modeling of an iPLAN treatment planning system (BrainLAB) were collected from 12 institutions - ten HD120 Multileaf Collimator (MLC) and two Millennium120 MLC.

Inter-institutional variability of small-field-dosimetry beams among HD120 multileaf collimators: a multi-institutional analysis.

Detector selection and technical problems can result in large variations in small-field-dosimetry data among institutions. In this study, we evaluated inter-institutional variability in the small-field-beam data of the Novalis Tx linear accelerator (Varian Medical Systems and BrainLAB) with an HD120 multileaf collimator. Beam data for modeling an iPLAN treatment planning system (BrainLAB) were collected from 19 institutions and median values of percentage depth doses (PDD), diagonal profiles, transversal profiles, and ratios of detector readings (detector output factors; OF ) were calculated.

Long-term Outcomes of Radiotherapy Regimen of 72 Gy in 30 Fractions for Prostate Cancer.

Background/aim: The long-term efficacy and safety of moderately hypofractionated intensity-modulated radiation therapy (MH-IMRT) in prostate cancer remains uncertain. This study aimed to evaluate MH-IMRT regimen of 72 Gy in 30 fractions in patients with prostate cancer.

Patients And Methods: The outcomes of 412 consecutive prostate cancer patients, who received MH-IMRT between May 2007 and December 2012, were retrospectively reviewed.

Early intervention using high-precision radiotherapy preserved visual function for five consecutive patients with optic nerve sheath meningioma.

Background: There has been a paradigm shift in the treatment for optic nerve sheath meningioma (ONSM) from surgery to fractionated stereotactic radiotherapy (FSRT) in other countries. However, FSRT has seldom been performed in Japan. The purpose of this retrospective study is to reconfirm the effectiveness of early intervention with precision radiotherapy for ONSM reported in our previous study.

[Radiofrequency Ablation under Computed Tomography during Arterial Portography for Hypovascular Liver Metastases from Advanced Pancreatic Cancer].

A 70's man had been treated with gemcitabine(GEM)and nab-paclitaxel(nabPTX)combination for advanced pancreatic tail cancer with splenic invasion and liver metastases. However, the primary lesion was not controlled, then intensity-modulat- ed radiation therapy(76.5 Gy/17 Fr)was performed for primary lesion.

Definitive re-irradiation using intensity-modulated radiation therapy in cancers of the head and neck, focusing on rare tumors.

Purpose: To analyze the outcomes following re-irradiation for local recurrence of rare head and neck tumors.

Material And Methods: We retrospectively analyzed 11 patients who had received intensity-modulated radiation therapy (IMRT) for recurrent tumors in the head and neck except for laryngopharynx.

Results: Primary tumor sites included the maxillary sinus, nasal cavity, and external ear canal in six, three, and two patients, respectively.

Effect of primary tumor location and tumor size on the response to radiotherapy for liver metastases from colorectal cancer.

Metastatic liver tumors (MLTs) from colorectal cancer (CRC) are often treated with stereotactic body radiation therapy (SBRT). The present study aimed to examine the predictive factors for response of MLTs to SBRT. A total of 39 MLTs from 24 patients with CRC were retrospectively analyzed.

Feasibility study of a non-invasive eye fixation and monitoring device using a right-angle prism mirror for intensity-modulated radiotherapy for choroidal melanoma.

We aimed to describe the feasibility and efficacy of a novel non-invasive fixation and monitoring (F-M) device for the eyeballs (which uses a right-angle prism mirror as the optic axis guide) in three consecutive patients with choroidal melanoma who were treated with intensity-modulated radiotherapy (IMRT). The device consists of an immobilization shell, a right-angle prism mirror, a high magnification optical zoom video camera, a guide lamp, a digital voice recorder, a personal computer, and a National Television System Committee standard analog video cable. Using the right-angle prism mirror, the antero-posterior axis was determined coincident with the optic axis connecting the centers of the cornea and pupil.

Threshold doses and prediction of visually apparent liver dysfunction after stereotactic body radiation therapy in cirrhotic and normal livers using magnetic resonance imaging.

The purpose of the present study was to investigate the threshold dose for focal liver damage after stereotactic body radiation therapy (SBRT) in cirrhotic and normal livers using magnetic resonance imaging (MRI). A total of 64 patients who underwent SBRT for liver tumors, including 54 cirrhotic patients with hepatocellular carcinoma (HCC) and 10 non-cirrhotic patients with liver metastases, were analyzed. MRI was performed 3-6 months after SBRT, using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced T1-weighted sequences.

Outcomes and toxicity of radiotherapy for refractory bone and soft tissue sarcomas.

Surgical resection is a well-established treatment option for sarcoma. However, anatomical barriers often hamper radical surgical procedures. The treatment of unresectable sarcoma, including local or distant failures following initial treatment, is challenging.

Evaluation of potential internal target volume of liver tumors using cine-MRI.

Purpose: Four-dimensional computed tomography (4DCT) is widely used for evaluating moving tumors, including lung and liver cancers. For patients with unstable respiration, however, the 4DCT may not visualize tumor motion properly. High-speed magnetic resonance imaging (MRI) sequences (cine-MRI) permit direct visualization of respiratory motion of liver tumors without considering radiation dose exposure to patients.

Adaptive replanning intensity-modulated radiotherapy for choroidal metastasis of breast cancer using optical coherence tomography.

Swept source optical coherence tomography (SS-OCT) is a convenient method for precise, early-stage detection of choroidal metastatic lesions, involving assessment of tumor response, and for regular follow-up studies. Using information obtained with SS-OCT, we performed intensity-modulated radiotherapy (IMRT) for a patient with choroidal metastasis from breast cancer with more accuracy than had been previously possible. We made replanning adaptive radiotherapy (ART) three times based on the rapid tumor shrinkage detected by weekly assessments with SS-OCT.

Clinical introduction of Monte Carlo treatment planning for lung stereotactic body radiotherapy.

The purpose of this study was to investigate the impact of Monte Carlo (MC) calculations and optimized dose definitions in stereotactic body radiotherapy (SBRT) for lung cancer patients. We used a retrospective patient review and basic virtual phantom to determine dose prescriptions. Fifty-three patients underwent SBRT.

[Evaluation of new methods for removing moire artifact of radiochromic film].

An optical interference-pattern, a moire artifact, is produced during the film scanning process using a flatbed scanner. Images with moire artifacts include optical density fluctuations thereby leading to inaccuracy of measurement. In this study, we proposed two methods for removing moire artifacts from radiochromic film and compared dose response and profile as well as image resolution and size between our proposed methods versus the conventional process.

Multi-institutional retrospective analysis of the inhomogeneity correction for radiation therapy of lung cancer.

The purpose of this work is to retrospectively analyze the effect of the inhomogeneity correction using clinically treated plan of stage III non-small-cell lung cancer within multiple institutions in Japan. Twenty-five patients among five facilities of radiation therapy were registered for this study. The isocenter dose or D(95) of PTV or other important values were compared with and without an inhomogeneity correction using model-based algorithm.