Results of a Geant4 benchmarking study for bio-medical applications, performed with the G4-Med system.

Background: Geant4, a Monte Carlo Simulation Toolkit extensively used in bio-medical physics, is in continuous evolution to include newest research findings to improve its accuracy and to respond to the evolving needs of a very diverse user community. In 2014, the G4-Med benchmarking system was born from the effort of the Geant4 Medical Simulation Benchmarking Group, to benchmark and monitor the evolution of Geant4 for medical physics applications. The G4-Med system was first described in our Medical Physics Special Report published in 2021.

Proton FLASH Irradiation Using a Synchrotron Accelerator: Differences by Irradiation Positions.

Purpose: To establish an ultra-high dose-rate (UHDR) radiation system using a synchrotron proton beam accelerator and to compare the effects by irradiation positions on cultured cells and chick embryos.

Methods And Materials: Protons for UHDR were obtained by applying high-frequency power at much higher levels than usual to extract all protons within approximately 50 ms. Subsequently, monitoring with a Faraday cup was performed immediately after synchrotron extraction and the waveform was adjusted accordingly.

Long-term survival outcomes and quality of life of image-guided proton therapy for operable stage I non-small cell lung cancer: A phase 2 study.

Background And Purpose: This study evaluated long-term efficacy, safety, and changes in quality of life (QOL) of patients after image-guided proton therapy (IGPT) for operable stage I non-small cell lung cancer (NSCLC).

Materials And Methods: This single-institutional prospective phase 2 study enrolled patients with operable histologically confirmed stage IA or IB NSCLC (7th edition of UICC). The prescribed dose was 66 Gy relative biological effectiveness equivalents (GyRBE) in 10 fractions for peripheral lesions, or 72.

Spot scanning proton therapy for unresectable bulky retroperitoneal dedifferentiated liposarcoma: a case report.

The development of effective treatment strategies for unresectable retroperitoneal sarcoma is desirable. Herein, we suggest that definitive proton therapy (PT) could be a promising treatment option, regardless of the large size of the tumor. A 52-year-old man presented with a discomfort of the lower abdomen.

Investigation of ionization chamber perturbation factors using proton beam and Fano cavity test for the Monte Carlo simulation code PHITS.

The reference dose for clinical proton beam therapy is based on ionization chamber dosimetry. However, data on uncertainties in proton dosimetry are lacking, and multifaceted studies are required. Monte Carlo simulations are useful tools for calculating ionization chamber dosimetry in radiation fields and are sensitive to the transport algorithm parameters when particles are transported in a heterogeneous region.

Luminescence imaging of water irradiated by protons under FLASH radiation therapy conditions.

FLASH radiation therapy with ultrahigh dose rates (UHDR) has the potential to reduce damage to normal tissue while maintaining anti-tumor efficacy. However, rapid and precise dose distribution measurements remain difficult for FLASH radiation therapy with proton beams. To solve this problem, we performed luminescence imaging of water following irradiation by a UHDR proton beam captured using a charge-coupled device camera.

A survey of practice patterns for adaptive particle therapy for interfractional changes.

Background And Purpose: Anatomical changes may compromise the planned target coverage and organs-at-risk dose in particle therapy. This study reports on the practice patterns for adaptive particle therapy (APT) to evaluate current clinical practice and wishes and barriers to further implementation.

Materials And Methods: An institutional questionnaire was distributed to PT centres worldwide (7/2020-6/2021) asking which type of APT was used, details of the workflow, and what the wishes and barriers to implementation were.

A survey of practice patterns for real-time intrafractional motion-management in particle therapy.

Background And Purpose: Organ motion compromises accurate particle therapy delivery. This study reports on the practice patterns for real-time intrafractional motion-management in particle therapy to evaluate current clinical practice and wishes and barriers to implementation.

Materials And Methods: An institutional questionnaire was distributed to particle therapy centres worldwide (7/2020-6/2021) asking which type(s) of real-time respiratory motion management (RRMM) methods were used, for which treatment sites, and what were the wishes and barriers to implementation.

Deep learning-based in vivo dose verification from proton-induced secondary-electron-bremsstrahlung images with various count level.

Purpose: Proton-induced secondary-electron-bremsstrahlung (SEB) imaging is a promising method for estimating the ranges of particle beam. However, SEB images do not directly represent dose distributions of particle beams. In addition, the ranges estimated from measured images were deviated because of limited spatial resolutions of the developed x-ray camera as well as statistical noise in the images.

Outcomes of proton therapy for non-small cell lung cancer in patients with interstitial pneumonia.

Background: Interstitial pneumonia (IP) is a disease with a poor prognosis. In addition, IP patients are more likely to develop lung cancer. Since IP patients frequently develop toxicities during cancer treatment, minimally invasive cancer treatment is warranted for such patients to maintain their quality of life.

Patient-Reported Quality of Life Outcomes after Moderately Hypofractionated and Normofractionated Proton Therapy for Localized Prostate Cancer.

We retrospectively evaluated the three-year patient-reported quality of life (QOL) after moderately hypofractionated proton therapy (MHPT) for localized prostate cancer in comparison with that after normofractionated PT (NFPT) using the Expanded Prostate Cancer Index Composite-50. Patients who received MHPT (60-63 Gy (relative biological effectiveness equivalents; RBE)/20-21 fractions) ( = 343) or NFPT (74-78 Gy (RBE)/37-39 fractions) ( = 296) between 2013 and 2016 were analyzed. The minimum clinically important difference (MCID) threshold was defined as one-half of a standard deviation of the baseline value.

Evaluating the usefulness of the direct density reconstruction algorithm for intensity modulated and passively scattered proton therapy: Validation using an anthropomorphic phantom.

Purpose: Accurate calculation of the proton beam range inside a patient is an important topic in proton therapy. In recent times, a computed tomography (CT) image reconstruction algorithm was developed for treatment planning to reduce the impact of the variation of the CT number with changes in imaging conditions. In this study, we investigated the usefulness of this new reconstruction algorithm (DirectDensity™: DD) in proton therapy based on its comparison with filtered back projection (FBP).

Evaluation of radiophotoluminescent glass dosimeter response for therapeutic spot scanning proton beam: suggestion of linear energy transfer-based correction.

A radiophotoluminescent glass dosimeter (RGD) is used for a postal audit of a photon beam because of its various excellent characteristics. However, it has not been used for scanning proton beams because its response characteristics have not been verified. In this study, the response of RGD to scanning protons was investigated to develop a dosimetry protocol using the linear energy transfer (LET)-based correction factor.

Spot Scanning Proton Therapy for Sinonasal Malignant Tumors.

Purpose: Treatment of sinonasal malignant tumors is challenging, and evidence to establish a standard treatment is limited. Our objective was to evaluate the efficacy and safety of spot scanning proton therapy (SSPT) for sinonasal malignant tumors.

Patients And Methods: We retrospectively analyzed patients with sinonasal malignant tumors (T1-4bN0-2M0) who underwent SSPT between May 2014 and September 2019.

Changes in sexual function and serum testosterone levels in patients with prostate cancer after image-guided proton therapy.

Since sexual function and testosterone levels after image-guided proton therapy (IGPT) have not yet been examined in detail, we prospectively evaluated changes before and after IGPT. Among patients treated with IGPT with or without combined androgen blockade (CAB) therapy between February 2013 and September 2014, patients who agreed to participate in the study and were followed up for >3 years after IGPT were evaluated. Serum testosterone levels were regularly measured together with prostate-specific antigen (PSA) levels before and after IGPT.

Biological effects of passive scattering and spot scanning proton beams at the distal end of the spread-out Bragg peak in single cells and multicell spheroids.

Purpose: The present study investigated the biological effects of spot scanning and passive scattering proton therapies at the distal end region of the spread-out Bragg peak (SOBP) using single cell and multicell spheroids.

Materials And Methods: The Geant4 Monte Carlo simulation was used to calculate linear energy transfer (LET) values in passive scattering and spot scanning beams. The biological doses of the two beam options at various points of the distal end region of SOBP were investigated using EMT6 single cells and 0.

Dosimetric response of a glass dosimeter in proton beams: LET-dependence and correction factor.

A radiophotoluminescent glass dosimeter (RGD) is widely used in postal audit system for photon beams in Japan. However, proton dosimetry in RGDs is scarcely used owing to a lack of clarity in their response to beam quality. In this study, we investigated RGD response to beam quality for establishing a suitable linear energy transfer (LET)-corrected dosimetry protocol in a therapeutic proton beam.

Image-Guided Proton Therapy for Elderly Patients with Hepatocellular Carcinoma: High Local Control and Quality of Life Preservation.

This study retrospectively investigated the efficacy and safety of image-guided proton therapy (IGPT) for elderly (≥80 years old) hepatocellular carcinoma (HCC) patients. Proton therapy was performed using respiratory-gated and image-guided techniques. Seventy-one elderly HCC patients were treated using IGPT.

Concurrent Chemo-Proton Therapy Using Adaptive Planning for Unresectable Stage 3 Non-Small Cell Lung Cancer: A Phase 2 Study.

Purpose: This study prospectively evaluated the efficacy and safety of concurrent chemo-proton therapy (CCPT) using adaptive planning for unresectable stage III non-small cell lung cancer (NSCLC).

Methods And Materials: The primary endpoint was overall survival (OS). Secondary endpoints were local control rate (LCR), progression-free survival (PFS), incidence of grade 3 or higher adverse events, and changes in quality of life (QOL).

Combined effects of cisplatin and photon or proton irradiation in cultured cells: radiosensitization, patterns of cell death and cell cycle distribution.

The purpose of the current study was to investigate the biological effects of protons and photons in combination with cisplatin in cultured cells and elucidate the mechanisms responsible for their combined effects. To evaluate the sensitizing effects of cisplatin against X-rays and proton beams in HSG, EMT6 and V79 cells, the combination index, a simple measure for quantifying synergism, was estimated from cell survival curves using software capable of performing the Monte Carlo calculation. Cell death and apoptosis were assessed using live cell fluorescence imaging.

Prediction of dose distribution from luminescence image of water using a deep convolutional neural network for particle therapy.

Purpose: We recently obtained nearly the same depth profiles of luminescence images of water as dose for protons by subtracting the Cerenkov light component emitted by secondary electrons of prompt gamma photons. However, estimating the distribution of Cerenkov light with this correction method is time-consuming, depending on the irradiated energy of protons by Monte Carlo simulation. Therefore, we proposed a method of estimating dose distributions from the measured luminescence images of water using a deep convolutional neural network (DCNN).

Liver phantom design and dosimetric verification in participating institutions for a proton beam therapy in patients with resectable hepatocellular carcinoma: Japan Clinical Oncology Group trial (JCOG1315C).

Background And Purpose: In Japan, the first domestic clinical trial of proton beam therapy for the liver was initiated as the Japan Clinical Oncology Group trial (JCOG1315C: Non-randomized controlled study comparing proton beam therapy and hepatectomy for resectable hepatocellular carcinoma). Purposes of this study were to develop a new dosimetric verification system and to carry out a credentialing for the JCOG1315C clinical trial.

Materials And Methods: Accuracy and differences in doses in proton treatment planning among participating institutions were surveyed and investigated.

Proton therapy for non-squamous cell carcinoma of the head and neck: planning comparison and toxicity.

To investigate optimal treatment planning using proton beams for non-squamous cell carcinoma of the head and neck (NSCHN), the dose distributions of plans involving pencil beam scanning (PBS) with or without a patient-specific aperture system (PSAS), passive-scattering proton therapy (PSPT) and X-ray intensity-modulated radiotherapy (IMRT) were compared. As clinical results, toxicities of PBS with PSAS, including changes in quality of life, were reported. Between April 2014 and August 2016, a total of 30 patients were treated using PBS with PSAS.

Dosimetric verification of IMPT using a commercial heterogeneous phantom.

The purpose of this study was to propose a verification method and results of intensity-modulated proton therapy (IMPT), using a commercially available heterogeneous phantom. We used a simple simulated head and neck and prostate phantom. An ionization chamber and radiochromic film were used for measurements of absolute dose and relative dose distribution.