International Journal of Particle Therapy

Particle therapy (PT) represents a significant advancement in cancer treatment, precisely targeting tumor cells while sparing surrounding healthy tissues thanks to the unique depth-dose profiles of the charged particles. Furthermore, their linear energy transfer and relative biological effectiveness enhance their capability to treat radioresistant tumors, including hypoxic ones. Over the years, extensive research has paved the way for PT's clinical application, and current efforts aim to refine its efficacy and precision, minimizing the toxicities...

PURPOSE: Radiation-induced lymphopenia is a common immune toxicity that adversely impacts treatment outcomes. We report here our approach to translate a deep-learning (DL) model developed to predict severe lymphopenia risk among esophageal cancer into a strategy for incorporating the immune system as an organ-at-risk (iOAR) to mitigate the risk. MATERIALS AND METHODS: We conducted "virtual clinical trials" utilizing retrospective data for 10 intensity-modulated radiation therapy (IMRT) and 10 passively-scattered proton therapy (PSPT) esophageal cancer patients...

PURPOSE: Single vocal cord irradiation (SVCI) is a promising technique to maintain excellent oncologic control and potentially improve upon toxicities for treatment of early-stage glottic squamous cell carcinomas. We sought to investigate whether pencil beam scanning (PBS) proton therapy could improve upon the already favorable dose gradients demonstrated with volumetric modulated arc therapy (VMAT) SVCI. PATIENTS AND METHODS: A 64-year-old gentleman was treated in our department with 6X-flattening filter-free VMAT SVCI to 58...

This case study explores the strategic decision-making and safety considerations in managing a unique scenario where a pacemaker dependent patient, requiring adjuvant radiotherapy for bilateral breast cancer. The conventional pacemaker was located entirely within the treatment target, without the option for transposition because of the bilateral chest treatment, resulting in significant risk of malfunction caused by exposing it to the full prescribed dose. Consequently, the decision was made to replace the conventional pacemaker with a leadless device Micra implanted directly into the heart to mitigate direct device radiation and potential adverse effects of proton therapy on the cardiac device...

PURPOSE: Effective dose to circulating immune cells (EDIC) is associated with survival in lung and esophageal cancer patients. This study aimed to evaluate the benefit of intensity-modulated proton therapy (IMPT) for EDIC reduction compared with volumetric modulated arc therapy (VMAT) in mediastinal Hodgkin lymphoma (mHL) patients. MATERIALS AND METHODS: Ten consecutive mHL patients treated with involved-site IMPT after frontline chemotherapy were included...

PURPOSE: Rectal toxicity after prostate cancer (PCa) radiation therapy (RT) may be greater with protons compared with photon intensity-modulated RT, perhaps due to lateral penumbra and end-of-range uncertainty. Rectal spacers (RSs) have been shown to mitigate RT-associated acute/late rectal toxicity in men treated with photons. The relative benefit of RS in men treated with protons versus photons is unknown. We hypothesize that RS will confer greater bowel toxicity benefits in PCa treated with protons versus photons...

PURPOSE: The aim of this study is to determine the most beneficial radiation treatment technique for pediatric patients with thoracic and abdominal neuroblastoma (NBL), through a dosimetric comparison between photon Volumetric Modulated Arc Therapy and proton Intensity-Modulated Proton Therapy treatment plans. MATERIALS AND METHODS: A retrospective analysis was conducted on a multicentre case series of 19 patients with thoracic and/or abdominal NBL who underwent radiation therapy, following the recommendations of the European protocol for high-risk NBL (HR-NBL2/SIOPEN)...

PURPOSE: Periodic quality assurance CTs (QACTs) are routine in proton beam therapy. In this study, we tested whether the necessity for a QACT could be determined by evaluating the change in beam path length (BPL) on daily cone-beam CT (CBCT). PATIENTS AND METHODS: In this Institutional Review Board-approved study, we retrospectively analyzed 959 CBCT images from 78 patients with sarcomas treated with proton pencil-beam scanning. Plans on 17 QACTs out of a total of 243 were clinically determined to be replanned for various reasons...

PURPOSE: This study aimed to quantify the changes in intratumoral blood flow after carbon-ion radiation therapy (CIRT) for early-stage breast cancer and analyze their clinical significance. PATIENTS AND METHODS: We included 38 patients with early-stage breast cancer who underwent CIRT. Dynamic imaging was performed using a 3T superconducting magnetic resonance scanner to quantify the washin index (idx), which reflects contrast uptake, and washout idx, which reflects the rate of contrast washout from tumor tissue...

PURPOSE: It is known that radiation to dentofacial structures during childhood can lead to developmental disturbances. However, this appears to be a relatively subordinated research subject. For this reason, this review aims to establish the current evidence base on the effect of PBT on dentofacial development in paediatric patients treated for cancer in the head and neck region. MATERIALS AND METHODS: A comprehensive search was undertaken to identify both published and unpublished studies or reports...

PURPOSE: Emerging data have illuminated the impact of effective radiation dose to immune cells (EDIC) on outcomes in patients with locally advanced, unresectable non-small cell lung cancer (NSCLC) treated with intensity-modulated radiotherapy (IMRT). Hypothesizing that intensity-modulated proton therapy (IMPT) may reduce EDIC versus IMRT, we conducted a dosimetric analysis of patients treated at our institution. MATERIALS AND METHODS: Data were retrospectively collected for 12 patients with locally advanced, unresectable NSCLC diagnosed between 2019 and 2021 who had physician-approved IMRT and IMPT plans...

PURPOSE: To report clinical and dosimetric characteristics of 5-fraction stereotactic ablative radiotherapy (SABR) using intensity modulated proton therapy (IMPT) for localized prostate cancer. MATERIALS AND METHODS: All patients receiving IMPT SABR from 2017 to 2021 for localized prostate cancer at our institution were included. Five fractions were delivered every other day to the prostate +/- seminal vesicles [clinical target volume (CTV)] with 3 mm/3% robustness...

PURPOSE: In concurrent chemoradiotherapy for advanced esophageal cancer, a 2-phase method consisting of initial irradiation of a wide elective nodal region and boost irradiation of the primary lesion is commonly employed. Although dose escalation to the primary lesion may be required to achieve higher local control rates, the radiation dose to critical organs must not exceed dose constraints. To achieve an optimum balance of dose prescription and dose reduction to surrounding organs, such as the lungs and heart, we compared hybrid dose distributions and investigated the best combination of the following recent irradiation techniques: volumetric modulation arc therapy (VMAT), proton broad-beam irradiation, and intensity-modulated proton beam therapy (IMPT)...

PURPOSE: To identify the characteristics, indications, and toxicities among patients receiving proton beam therapy (PBT) in the final year of life at an academic medical center. MATERIALS AND METHODS: A retrospective review of patients who received PBT within the final 12 months of life was performed. Electronic medical records were reviewed for patient and treatment details from 2010 to 2019. Patients were followed from the start of PBT until death or last follow-up...

PURPOSE: To evaluate intrafractional motion effects as a function of peak-to-peak motion and period during single-field, single-fraction and single-field, multifraction irradiation of the moving target in spot-scanning proton therapy. MATERIALS AND METHODS: An in-house dynamic phantom was used to simulate peak-to-peak motion of 5, 10, and 20 mm with periods of 2, 4, and 8 seconds. The dose distribution in the moving target was measured using radiochromic films...

PURPOSE: Evidence suggests that proton-beam therapy (PBT) results in less toxicity and postoperative complications compared to photon-based radiotherapy in patients who receive chemoradiotherapy followed by esophagectomy for cancer. Ninety-day mortality (90DM) is an important measure of the postoperative (nononcologic) outcome as proxy of quality-of-care. We hypothesize that PBT could reduce 90DM compared to photon-based radiotherapy. MATERIALS AND METHODS: From a single-center retrospective database patients treated with chemoradiotherapy before esophagectomy for cancer were selected (1998-2022)...

PURPOSE: In breast cancer, improved treatment approaches that reduce injury to lung tissue and early diagnosis and intervention for lung toxicity are increasingly important in survivorship. The aims of this study are to (1) compare lung tissue radiographic changes in women treated with conventional photon radiation therapy and those treated with proton therapy (PT), (2) assess the volume of lung irradiated to 5 Gy (V5) and 20 Gy (V20) by treatment modality, and (3) quantify the effects of V5, V20, time, and smoking history on the severity of tissue radiographic changes...

PURPOSE: To report the current practice pattern of the proton stereotactic body radiation therapy (SBRT) for prostate treatments. MATERIALS AND METHODS: A survey was designed to inquire about the practice of proton SBRT treatment for prostate cancer. The survey was distributed to all 30 proton therapy centers in the United States that participate in the National Clinical Trial Network in February, 2023. The survey focused on usage, patient selection criteria, prescriptions, target contours, dose constraints, treatment plan optimization and evaluation methods, patient-specific QA, and image-guided radiation therapy (IGRT) methods...

PURPOSE: We performed computed tomography (CT)-stopping power ratio (SPR) calibration in a carbon-ion therapy facility and evaluated SPR estimation accuracy. MATERIALS AND METHODS: A polybinary tissue model method was used for the calibration of CT numbers and SPR. As a verification by dose calculation, we created a virtual phantom to which the CT-SPR calibration table was applied. Then, SPR was calculated from the change in the range of the treatment planning beam when changing to 19 different CT numbers, and the accuracy of the treatment planning system (TPS) calculation of SPR values from the CT-SPR calibration table was validated...

PURPOSE: Pediatric acute myeloid leukemia (AML) often involves extramedullary sites, which can be resistant to standard induction chemotherapy. Consolidative radiation therapy can be used in select cases to improve local control rates and help bridge patients to curative stem cell transplants. However, there is no previously published data to support the use of proton radiotherapy (PT) in this setting. We present radiographic findings and pathologic outcomes of the first reported patient with extramedullary ocular AML to be treated with PT...