Scanned particle-beam tracking with beam correction based on predictive volumetric imaging: A simulation study.

Background: Tracking irradiation to moving targets in spot-scanning particle therapy, which corrects the spot position and energy in real-time, may decrease treatment time and increase accuracy. However, because of the temporal performance of the system, clinical translation remains challenging. Processing time, including image acquisition, volumetric image synthesis, correction assessment, and system response, is required to control the actual treatment system.

Protoacoustic range verification by direct comparison with beam range measurements using a tissue-equivalent polymer gel.

Background And Purpose: Protoacoustics offers a promising method for in vivo range verification in proton therapy. To experimentally assess the protoacoustic range accuracy, conventional tissue-mimicking phantoms (TMPs) often require Monte Carlo (MC) simulations to estimate the ground truth. However, limited knowledge of material properties and/or insufficient fine-tuning of dose models can introduce range errors in MC simulations.

Preliminary assessment of proton linear energy transfer distribution in patients with MRI-guided proton therapy: a simulation study.

. Magnetic resonance imaging (MRI)-guided proton therapy is under development as an advanced technique that combines proton therapy with real-time MRI imaging, offering improved tumor targeting and better protection of adjacent healthy tissues. However, clinically relevant interactions between magnetic fields and linear energy transfer (LET) remain unexplored.

Feasibility of a normoxic N-vinylpyrrolidone-based polymer gel (VIPET) dosimeter for three-dimensional proton beam measurements.

Background: Gel dosimeters enable three-dimensional dose measurement in x-ray and charged-particle therapies. A normoxic N-vinylpyrrolidone-based polymer gel (VIPET) dosimeter is expected to provide high-precision proton dose measurements. However, reports on the fundamental performance of VIPET gel dosimeters in proton beam measurement are limited, and the accuracy of position and dose measurements still needs to be determined.

Two-stage robotic gastrectomy after bypass surgery for a perforated non-curative endoscopic submucosal dissection scar: a case report.

Unlabelled: Here, we report a case of scar perforation caused by endoscopic dilation while the patient was waiting for additional gastrectomy after non-curative endoscopic submucosal dissection (ESD) for early gastric cancer. Although conservative treatment prevented the progression of generalized peritonitis, one-stage meticulous surgery was contraindicated because of abscess formation around the pylorus, which is the main target of lymphatic dissection. Therefore, we performed a two-stage surgery.

Accuracy verification of protoacoustic measurements in a heterogeneous phantom by an optical hydrophone.

Background: Protoacoustics has emerged as a promising real-time range measurement method for proton therapy. Optical hydrophones (OHs) are considered suitable to detect protoacoustic waves owing to their ultracompact size and high sensitivity. In our previous research, we demonstrated that the time-of-arrival (TOA) measured by an OH showed good agreement with the simulated ground truth in a homogeneous medium.

Investigation of interfractional range variation owing to anatomical changes with beam directions based on water equivalent thickness in proton therapy for pancreatic cancer.

To assess the interfractional anatomical range variations (ARVs) with beam directions and their impact on dose distribution in intensity modulated proton therapy, we analyzed water equivalent thickness (WET) from 10 patients with pancreatic cancer. The distributions of the interfractional WET difference ($\Delta{\mathrm{WET}}^{\theta }$) across 360° were visualized using polar histograms. Interfractional ARVs were evaluated using the mean absolute error and ΔWET pass rate, indicating the percentage of $\Delta \mathrm{WE}{\mathrm{T}}^{\theta }$ < thresholds.

Geometric target margin strategy of proton craniospinal irradiation for pediatric medulloblastoma.

In proton craniospinal irradiation (CSI) for skeletally immature pediatric patients, a treatment plan should be developed to ensure that the dose is uniformly delivered to all vertebrae, considering the effects on bone growth balance. The technical (t) clinical target volume (CTV) is conventionally set by manually expanding the CTV from the entire intracranial space and thecal sac, based on the physician's experience. However, there are differences in contouring methods among physicians.

Application of motion prediction based on a long short-term memory network for imaging dose reduction in real-time tumor-tracking radiation therapy.

Purpose: To demonstrate the possibility of using a lower imaging rate while maintaining acceptable accuracy by applying motion prediction to minimize the imaging dose in real-time image-guided radiation therapy.

Methods: Time-series of three-dimensional internal marker positions obtained from 98 patients in liver stereotactic body radiation therapy were used to train and test the long-short-term memory (LSTM) network. For real-time imaging, the root mean squared error (RMSE) of the prediction on three-dimensional marker position made by LSTM, the residual motion of the target under respiratory-gated irradiation, and irradiation efficiency were evaluated.

Feasibility of initiating robotic surgery during the early stages of gastrointestinal surgery education.

Purpose: Minimally invasive surgery for gastrointestinal cancers is rapidly advancing; therefore, surgical education must be changed. This study aimed to examine the feasibility of early initiation of robotic surgery education for surgical residents.

Methods: The ability of staff physicians and residents to handle robotic surgical instruments was assessed using the da Vinci skills simulator (DVSS).

A Single-Institution Prospective Study To Evaluate the Safety and Efficacy of Real- Time Image-Gated Spot-Scanning Proton Therapy (RGPT) for Prostate Cancer.

Purpose: In real-time image-gated spot-scanning proton therapy (RGPT), the dose distribution is distorted by gold fiducial markers placed in the prostate. Distortion can be suppressed by using small markers and more than 2 fields, but additional fields may increase the dose to organs at risk. Therefore, we conducted a prospective study to evaluate the safety and short-term clinical outcome of RGPT for prostate cancer.

Probability of normal tissue complications for hematologic and gastrointestinal toxicity in postoperative whole pelvic radiotherapy for gynecologic malignancies using intensity-modulated proton therapy with robust optimization.

This retrospective treatment-planning study was conducted to determine whether intensity-modulated proton therapy with robust optimization (ro-IMPT) reduces the risk of acute hematologic toxicity (H-T) and acute and late gastrointestinal toxicity (GI-T) in postoperative whole pelvic radiotherapy for gynecologic malignancies when compared with three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated X-ray (IMXT) and single-field optimization proton beam (SFO-PBT) therapies. All plans were created for 13 gynecologic-malignancy patients. The prescribed dose was 45 GyE in 25 fractions for 95% planning target volume in 3D-CRT, IMXT and SFO-PBT plans and for 99% clinical target volume (CTV) in ro-IMPT plans.

Technical note: Application of an optical hydrophone to ionoacoustic range detection in a tissue-mimicking agar phantom.

Background: Ionoacoustics is a promising approach to reduce the range uncertainty in proton therapy. A miniature-sized optical hydrophone (OH) was used as a measuring device to detect weak ionoacoustic signals with a high signal-to-noise ratio in water. However, further development is necessary to prevent wave distortion because of nearby acoustic impedance discontinuities while detection is conducted on the patient's skin.

Ionoacoustic application of an optical hydrophone to detect proton beam range in water.

Background: Proton range uncertainty has been the main factor limiting the ability of proton therapy to concentrate doses to tumors to their full potential. Ionoacoustic (IA) range verification is an approach to reducing this uncertainty by detecting thermoacoustic waves emitted from an irradiated volume immediately following a pulsed proton beam delivery; however, the signal weakness has been an obstacle to its clinical application. To increase the signal-to-noise ratio (SNR) with the conventional piezoelectric hydrophone (PH), the detector-sensitive volume needs to be large, but it could narrow the range of available beam angles and disturb real-time images obtained during beam delivery.

Technical note: Performance evaluation of volumetric imaging based on motion modeling by principal component analysis.

Purpose: To quantitatively evaluate the achievable performance of volumetric imaging based on lung motion modeling by principal component analysis (PCA).

Methods: In volumetric imaging based on PCA, internal deformation was represented as a linear combination of the eigenvectors derived by PCA of the deformation vector fields evaluated from patient-specific four-dimensional-computed tomography (4DCT) datasets. The volumetric image was synthesized by warping the reference CT image with a deformation vector field which was evaluated using optimal principal component coefficients (PCs).

Hyperfractionated intensity-modulated proton therapy for pharyngeal cancer with variable relative biological effectiveness: A simulation study.

Background: The relative biological effectiveness (RBE) of proton is considered to be dependent on biological parameters and fractional dose. While hyperfractionated photon therapy was effective in the treatment of patients with head and neck cancers, its effect in intensity-modulated proton therapy (IMPT) under the variable RBE has not been investigated in detail.

Purpose: To study the effect of variable RBE on hyperfractionated IMPT for the treatment of pharyngeal cancer.

A Consistent Protocol Reveals a Large Heterogeneity in the Biological Effectiveness of Proton and Carbon-Ion Beams for Various Sarcoma and Normal-Tissue-Derived Cell Lines.

This study investigated variations in the relative biological effectiveness (RBE) values among various sarcoma and normal-tissue-derived cell lines (normal cell line) in proton beam and carbon-ion irradiations. We used a consistent protocol that specified the timing of irradiation after plating cells and detailed the colony formation assay. We examined the cell type dependence of RBE for proton beam and carbon-ion irradiations using four human sarcoma cell lines (MG63 osteosarcoma, HT1080 fibrosarcoma, SW872 liposarcoma, and SW1353 chondrosarcoma) and three normal cell lines (HDF human dermal fibroblast, hTERT-HME1 mammary gland, and NuLi-1 bronchus epithelium).

An initial systematic study of the linear energy transfer distributions of a proton beam under a transverse magnetic field.

Purpose: To evaluate the biological effectiveness of magnetic resonance (MR)-guided proton beam therapy, comprehensively characterizing the dose and dose-averaged linear energy transfer (LET ) distributions under a magnetic field is necessary. Although detailed analysis has characterized curved beam paths and distorted dose distributions, the impact of a magnetic field on LET should also be explored to determine the proton relative biological effectiveness (RBE). Hence, this initial study aims to present a basic analysis of LET distributions in the presence of a magnetic field using Monte Carlo simulation (MCS).

Impact of a spatially dependent dose delivery time structure on the biological effectiveness of scanning proton therapy.

Purpose: In the scanning beam delivery of protons, different portions of the target are irradiated with different linear energy transfer protons with various time intervals and irradiation times. This research aimed to evaluate the spatially dependent biological effectiveness of protracted irradiation in scanning proton therapy.

Methods: One and two parallel opposed fields plans were created in water phantom with the prescribed dose of 2 Gy.

Particle therapy using protons or carbon ions for cancer patients with cardiac implantable electronic devices (CIED): a retrospective multi-institutional study.

Purpose: To evaluate the outcomes of particle therapy in cancer patients with cardiac implantable electronic devices (CIEDs).

Materials And Methods: From April 2001 to March 2013, 19,585 patients were treated with proton beam therapy (PBT) or carbon ion therapy (CIT) at 8 institutions. Of these, 69 patients (0.

A treatment planning study of urethra-sparing intensity-modulated proton therapy for localized prostate cancer.

Background And Purpose: Urethra-sparing radiation therapy for localized prostate cancer can reduce the risk of radiation-induced genitourinary toxicity by intentionally underdosing the periurethral transitional zone. We aimed to compare the clinical impact of a urethra-sparing intensity-modulated proton therapy (US-IMPT) plan with that of conventional clinical plans without urethral dose reduction.

Materials And Methods: This study included 13 patients who had undergone proton beam therapy.