Shanghai Proton And Heavy Ion Center Research Articles

End-to-end deep learning radiomics: development and validation of a novel attention-based aggregate convolutional neural network to distinguish breast diffuse large B-cell lymphoma from breast invasive ductal carcinoma.

Apart from invasive pathological examination, there is no effective method to differentiate breast diffuse large B-cell lymphoma (DLBCL) from breast invasive ductal carcinoma (IDC). In this study, we aimed to develop and validate an effective deep learning radiomics model to discriminate between DLBCL and IDC. A total of 324 breast nodules from 236 patients with baseline 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) were retrospectively analyzed. After grouping breast DLBCL and breast IDC patients, external and internal datasets were divided according to the data collected by different centers. Preprocessing was then used to process the original PET/CT images and an attention-based aggregate convolutional neural network (AACNN) model was designed. The AACNN model was trained using patches of CT or PET tumor images and optimized with an improved loss function. The final ensemble predictive model was built using distance weight voting. Finally, the model performance was evaluated and statistically verified. A total of 249 breast nodules from Fudan University Shanghai Cancer Center (FUSCC) and 75 breast nodules from Shanghai Proton and Heavy Ion Center (SPHIC) were selected as internal and external datasets, respectively. On the internal testing, our method yielded an area under the curve (AUC), accuracy (ACC), sensitivity (SEN), specificity (SPE), positive predictive value (PPV), negative predictive value (NPV), and harmonic mean of precision and sensitivity (F1) of 0.886, 83.0%, 80.9%, 85.0%, 84.8%, 81.2%, and 0.828, respectively. Meanwhile on the external testing, the results were 0.788, 71.6%, 61.4%, 84.7%, 84.0%, 62.6%, and 0.709, respectively. Our study outlines a deep learning radiomics method which can automatically, noninvasively, and accurately differentiate breast DLBCL from breast IDC, which will be more in line with the needs and strategies of precision medicine, individualized diagnosis, and treatment.

Preliminary clinical outcomes of head and neck squamous cell carcinoma treated with particle beam radiation therapy.

Further improvement in clinical outcomes is needed for patients with head and neck squamous cell carcinoma (HNSCC), as there is typically a poor prognosis at diagnosis. This study aimed to report the preliminary therapeutic outcomes and side effects in patients with HNSCC receiving particle beam radiotherapy (PBRT), owing to the physical and biological advantages of this approach. We retrospectively analyzed 68 patients with newly diagnosed HNSCC who received PBRT at the Shanghai Proton and Heavy Ion Center (SPHIC) between August 2015 and December 2020. The Kaplan-Meier approach was used to determine overall survival (OS), disease-specific survival (DSS), progression-free survival (PFS), local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), and distant metastasis-free survival (DMFS). Common Terminology Criteria for Adverse Events (CTCAE) 4.03 was also used to grade acute and late toxicities. With a median follow-up time of 24.5 months (range, 3-65), the 3-year OS, DSS, PFS, LRFS, RRFS, and DMFS rates for the entire cohort were 79.0%, 84.7%, 67.9%, 83.5%, 83.3%, and 96.1%, respectively. Univariate and multivariate analyses showed that N category was a significant predictor of OS, PFS, and RRFS. In terms of acute toxicities, two patients demonstrated severe mucositis or dysphagia, and two patients also displayed a late toxicity of significant mucosal necrosis. These findings suggest that PBRT can provide patients with HNSCC with a promising therapeutic benefit and manageable toxicity. Prospective evaluation of clinical outcomes with PBRT for HNSCC is warranted, with an emphasis on clinical effectiveness as well as adverse effects and patient quality of life.

The role of carbon-ion radiotherapy in the treatment of adenoid cystic carcinoma of the nasopharynx

Nasopharyngeal adenoid cystic carcinoma (NACC) is a distinct subgroup of adenoid cystic carcinoma (ACC) with limited surgical access but predilection of regional and distant metastasis. Although radiotherapy is an integral treatment for patients with NACC, photon-based radiotherapy yielded suboptimal local control. Because of its advantages in biology and physics properties, carbon-ion radiotherapy (CIRT) was attempted for the treatment of head and neck ACC; however, the use of CIRT specifically for NACC has not been investigated. Patients with NACC that received CIRT alone or a combination of CIRT and proton beam therapy (PBT) at the Shanghai Proton and Heavy Ion Center (SPHIC) between July 2016 and March 2019 were included in the analysis. Patients with newly diagnosed NACC received combined therapy of CIRT (as boost) and PBT, and those with recurrent disease received CIRT alone. Overall survival (OS), local progression-free survival (LPFS), regional progression-free survival (RPFS), and distant metastasis-free survival (DMFS) were calculated by Kaplan-Meier method. A total of 22 patients were included in this analysis. Among those, 18 patients had newly diagnosed NACC (17 with locally advanced disease), and 4 had recurrent NACC including 2 failed previous irradiation. After a median follow-up of 30.9 months, the 2-year OS rate, PFS rate, LPFS rate, RPFS rate and DMFS rate were 100%, 84.8%, 94.4%, 100%, and 84.8%, respectively. Three patients experienced grade 3 mucositis or xerostomia. No late toxicity of grade ≥3 was observed. CIRT alone or in combination with PBT appeared to be a promising modality for the treatment of NACC and produced satisfactory local disease control and toxicity profile. Distant metastasis remained to be a substantial mode for treatment failure. Further follow-up is necessary to evaluate long-term survivals and late toxicity profile.

Intensity-modulated proton and carbon-ion radiation therapy in the management of major salivary gland carcinomas

Primary major salivary gland carcinomas (SGCs) present with diverse histological types that are known to be largely radioresistant with a high tendency to develop distant metastasis (DM). Photon-based radiotherapy (RT) is limited in terms of its therapeutic effect and toxicities. In view of the physical and biological advantages of intensity-modulated proton and/or carbon-ion radiation therapy, we aimed to evaluate the short-term therapeutic effect and toxicities in patients with major SGCs treated with this form of radiation therapy. Between August 2015 and November 2019, a total of 55 consecutive and non-selected major SGC patients who received particle RT at the Shanghai Proton and Heavy Ion Center (SPHIC) were retrospectively analyzed. The 2-year overall survival (OS), progression-free survival (PFS), local-regional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) rates, as well as prognostic factors were analyzed. Additionally, acute and late toxicities were also analyzed. With a median follow-up time of 24 (range, 6-57) months, the 2-year OS, PFS, LRRFS, and DMFS rates were 91.6%, 78.6%, 94.2%, and 83.9%, respectively. At the time of this analysis, four patients had developed local or regional recurrence, and seven additional patients had developed DM. Three patients had died due to disease progression, and another patient with recurrence experienced a late Grade 5 event (hemorrhage) at 9 months after re-irradiation with carbon ion and subsequently died. Otherwise, none of the patients had grade 3 or higher treatment-induced acute or late adverse effects except one who developed grade 3 acute mucositis. Overall, intensity-modulated proton and/or carbon-ion radiation therapy provided satisfactory therapeutic effectiveness in our major SGCs patients with a low incidence of acute and late toxicities.

Comparison of the efficacy and toxicity of postoperative proton versus carbon ion radiotherapy for head and neck cancers

To compare the efficacy and toxicity of adjuvant proton beam vs. carbon-ion beam radiotherapy for head and neck cancers after radical resection and to explore the value of particle beam radiotherapy (PBRT) in postoperative radiotherapy for head and neck cancers. Data from 38 head and neck cancer patients who received adjuvant PBRT after complete surgical resection at the Shanghai Proton and Heavy Ion Center (SPHIC) between October 2015 and March 2019 were retrospectively analyzed. In total, 18 patients received adjuvant proton beam therapy (54-60 GyE/27-30 fractions) and 20 received adjuvant carbon-ion radiotherapy (CIRT) (54-60 GyE/18-20 fractions). Survival rates were calculated using Kaplan-Meier analysis. Toxicity was evaluated according to the Common Terminology Criteria for Adverse Effects (version 4.03). With a median follow-up time of 21 (range, 3-45) months, the 2-year overall survival (OS), progression-free survival (PFS), local-regional recurrence-free survival (LRRFS) and distant metastasis-free survival (DMFS) rates were 93.3%, 87.4%, 94.1%, and 90.7%, respectively, for the entire cohort. The rates after proton beam therapy vs. CIRT were 94.1% vs. 91.7% (P=0.96), 88.1% vs. 86.2% (P=0.96), 94.4% vs. 93.3% (P=0.97), and 88.1% vs. 92.9% (P=0.57), respectively. Furthermore, 16 of the 18 (88.9%) patients developed acute grade I/II dermatitis (13 grade I; 3 grade II) after proton beam therapy, and only 7 of the 20 (35%) patients developed acute grade I dermatitis after CIRT (P=0.001). The incidence of acute grade I/II mucositis and xerostomia in proton and carbon ion cases were 45% vs. 55% (P=0.75) and 56% vs. 50% (P=0.87) respectively. Adjuvant proton beam therapy and CIRT after radical surgical resection for head and neck cancers provided satisfactory therapeutic effectiveness, but no significant difference was observed between the two radiotherapy technologies. However, adjuvant CIRT was associated with a more favorable acute toxicity profile as compared to proton beam therapy with significantly lower frequency and severity of acute dermatitis observed.

Measurements of linear energy transfer (LET) distributions by CR-39 for a therapeutic carbon ion beam with a new 2D ripple filter

This study aims to measure the linear energy transfer (LET) spectra of therapeutic carbon ion beams with a new 2D 6 mm thick ripple filter (RiFi) by using a CR-39 detector. A water phantom was irradiated by three different single energy carbon beams (86.2 MeV/u, 276.5 MeV/u, and 430.0 MeV/u) at Shanghai Proton and Heavy Ion Center (SPHIC), CR-39 detectors were used to measure the LET spectra with and without the RiFi. The Monte Carlo toolkit Geant4 was employed to perform the simulations. The dose-averaged LET (LETd) was calculated according to the LET spectra. The results showed that the 2D RiFi broadens the Bragg peak width and LETd distribution. The simulation LET spectra of primary carbon ions were in good agreement with the experimental results. The LETd can be well estimated by using the measured LET spectra. This result indicated that the RiFi affects the depth-dose distribution and the shape of LET spectra for mono-energetic carbon beams. The CR-39 detector is suitable for LET spectra measurement. It is hoped that this work could provide a new reference method for the cross-validation of basic data in carbon ion clinical quality assurance and benefit clinical treatment.

TOPAS Monte Carlo simulation for a scanning proton therapy system in SPHIC

PurposeThis study aims to use TOPAS Monte Carlo (MC) code to model the beamline of a scanned proton therapy system in Shanghai Proton and Heavy Ion Center (SPHIC). This tool can be useful for treatment plan quality assurance. Methods and materialsIn-air lateral profiles of single proton spots at five positions along the Z-axis were measured, which can then be used to calculate the angular variance, spatial angular covariance, and spatial variance at the beam exit position. The mean energy and energy spread of the primary incident beam for 15 energies were tuned by comparing with measured relative integrated depth dose at the central axis. Three spread-out Bragg peak plans in homogeneous water cubes and one plan with a half anthropomorphic head phantom were created to verify the accuracy of the model. In addition, the comparison was also performed to RayStation TPS with an MC dose calculation engine for the plans. ResultsThe average difference of spot sizes was 1.3% for all five energies. For all 15 energies, the average range (D90) difference was 0.04 mm, the mean distal-fall-off (DDF) difference was 0.04 mm, and the mean full width at half maximum (FWHM) difference was 0.10 mm. For the three homogeneous cube plans, a maximum difference of 0.2 mm for the D90 was observed, and the absolute differences in the lateral penumbras for each plan all agreed within 1 mm. For the plan on the anthropomorphic half head phantom, the mean dose deviation is less than 1.2% compared to measurements. ConclusionWe successfully developed an MC model for the proton scanning system used in SPHIC, which can be helpful for dose verification of the Treatment Planning System (TPS) and quality assurance in the future.

Two-Year Toxicity and Efficacy of Carbon Ion Radiotherapy in the Treatment of Localized Prostate Cancer: A Single-Centered Study.

BackgroundWe aimed at determining the safety and feasibility of spot-scanning carbon ion radiotherapy (CIRT) for patients with localized prostate cancer.MethodsWe enrolled 118 patients with localized prostate cancer who underwent treatment with spot-scanning CIRT at the Shanghai Proton and Heavy Ion Center (SPHIC) from January 2016 to December 2020. The dose was gradually increased from relative biological effectiveness (RBE)-weighted dose (DRBE) = 59.2–65.6 Gy in 16 fractions. The primary endpoint was the occurrence of acute and late toxicities, while the secondary endpoints were biochemical relapse-free survival (bRFS), distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS).ResultsThe median follow-up time was 30.2 months (4.8–62.7 months). Acute grade 1 and 2 genitourinary (GU) toxicities were 15.3% and 18.6%, while acute grade 1 and 2 gastrointestinal (GI) toxicities were 2.5% and 0%, respectively. Late grade 1 and 2 GU toxicities were 4.2% and 1.7%, respectively. No late GI toxicity was observed. Moreover, there were no cases of severe acute or late toxicity (≥ grade 3). No significant association were observed between the factors and the acute GU toxicities, except for clinical target volume (CTV) (p = 0.031) on multivariate analysis. The 2-year bRFS, DMFS, PCSS, and OS were 100%, 100%, 100%, and 98.8%, respectively.ConclusionThe 2-year outcomes were encouraging, providing additional and useful information on the feasibility and safety of spot-scanning CIRT for treating prostate cancer. Thus, we recommend long-term follow-up and prospective multicentered studies to reinforce the role of CIRT in the management of localized prostate cancer.

Secondary and activated X($$\gamma$$) radiation of SPHIC particle therapy facility

We report the secondary X( $$\gamma$$ ) radiation from the accelerator in a normal operating state and activated X( $$\gamma$$ ) radiation from the accelerator devices when the accelerator stops operating in the cancer treatment facility of the Shanghai Proton and Heavy Ion Center (SPHIC). These radiation measurements show us the structural radiation distribution along the beam lines and devices inside the accelerator room when the beam is on and off and can support the radiation protection design of the accelerator facility used for cancer treatment and help evaluate the accumulated radiation dose in the case of an emergency, such as a personal safety system failure or a radiation accident. The radiation dose rate measured in this facility shows that the facility is safe from the radiation protection point. After shooting the quality assurance (QA) beam, the radiation dose rate in the treatment room was also measured to investigate the radiation dose space distribution and decay time dependence. In addition, the time period before safely entering the treatment room after determining the shooting of the QA beam is recommended to be approximately 5 min.

Carbon Ion Radiation Therapy for Salvage Treatment of Locoregionally Recurrent Nasopharyngeal Carcinoma

Reirradiation for locally recurrent nasopharyngeal carcinoma (LR-NPC) after a definitive radiotherapy is challenging and usually associated with severe adverse-effects. The 2-year overall survival (OS) rates of LR-NPC patients treated with X-ray based intensity-modulated radiation (IMRT) ranged between 45%∼60%, depends on the stage at local recurrence. Carbon-ion radiotherapy (CIRT) offers both physical and biological advantages over IMRT. To report the outcomes of 205 LR-NPC patients treated with intensity-modulated CIRT. Patients with locoregionally recurrent, poorly or un-differentiated NPC (WHO type II or III) who underwent salvage therapy with CIRT at the Shanghai Proton and Heavy Ion Center (SPHIC) between May 2015 and June 2019 were included in this analysis. The CIRT doses were 50 to 69 Gray equivalent (GyE) (2.0-3.0 GyE/daily fraction), delivered via raster scanning technology. The 2-year OS, progression-free survival (PFS), local recurrence free survival (LPFS), regional progression-free survival (RPFS), distant metastasis-free survival (DMFS) as well as acute and late toxicities were analyzed. Prognostic indicators of the outcomes were analyzed for overall survival. Among the 205 patients included, 17 patients, 50 patients, 60 patients, and 78 patients, respectively, had recurrent American Joint Committee on Cancer stage I, stage II, stage III, and stage IVA/B disease. With a median follow-up of 18.4 (range, 2.0-74.6) months, the 2-year OS, PFS, LPFS, RPFS, and DMFS rates were 83.1%, 41.8%, 54.0%, 85.4%, and 94.8%, respectively. Favorable prognostic indicators that reached statistical significance included a longer disease-free interval (p=0.001), small volume of gross tumor (p=0.025), stage I-II (vs. stage III-IVB) disease (p < 0.001), lack of necrosis (p=0.023) and carotid artery encasement (p=0.017) before CIRT. No patient developed acute toxicity of grade ≥3 during CIRT. Late treatment-induced severe (grade 3-4) toxicities included mucosal necrosis (20.5%, including patients presented with mucosal necrosis prior to re-irradiation), xerostomia (0.5%), cranial neuropathy (0.5%), and temporal lobe necrosis (0.98%). Among patients experienced mucosal necrosis, grade 4 and 5 hemorrhage were seen in 3.4% (7 patients) and 5.8% (12 patients) with or without local disease progression. The treatment results of the 205 patients received salvage CIRT suggested that the new radiation technology substantially improved the survival outcomes and toxicities profile for LR-NPC, as compared to re-irradiation with photon-based IMRT. Further investigation that compares the efficacy and safety between CIRT vs. IMRT, preferably in prospective manner and with longer follow-up, are needed to confirm these findings.

Development of an isocentric rotating chair positioner to treat patients of head and neck cancer at upright seated position with multiple nonplanar fields in a fixed carbon-ion beamline.

An isocentric rotating chair for a positioner was developed as a nongantry solution to provide multiple nonplanar radiation fields with a maximum tilt of 20 for treating head and neck cancer patients at an upright seated position in a fixed carbon-ion beamline. The preclinical validation of the chair was present for this study funded by a grant through the Shanghai Proton and Heavy Ion Center (SPHIC) in Shanghai, China. The chair was installed in SPHIC. A concept of parallel kinematic was adopted to build the chair. Three movement subunits of the chair are a Stewart hexapod platform and two modules for three-dimensional translation and 360 rotation. This chair can position patients with a tilt up to 20 over a continuous 360 rotation. Any weak structures within each subunit were investigated by industrial static/dynamic simulations of used materials. After manufactured subunits were assembled in a factory, a series of executed six degree-of-freedom (DoF) displacements were measured by using a laser-based dynamic tracking system (LDTS) for the initial validation. Deviations between measured and required displacements, referred to as displacement deviation, were used to evaluate the displacement accuracy of the chair. After satisfying the initial validation in the factory, the chair was disassembled and installed in our treatment room. The displacement accuracy of the chair was revalidated by using the LDTS. Then, an integration validation of the chair was conducted to position a head phantom by using our image-guided radiotherapy (IGRT) system. Because the positioning accuracy of our IGRT system achieved a clinical tolerance of 1.0mm and 1.0 only for a pitch/roll of <5 , the integration validation was conducted on 36 planned fields with a 5 tilt evenly over 360 rotation. To fulfill the general purpose of positioner, the chair allows the execution of any displacement over a cubic treatment volume with a length of 500mm. Materials selected by simulations met required strengths under all circumstances of the clinical usage. The displacement accuracy of the chair satisfied the tolerance of 0.3mm in-translation and 0.3 in-rotation during the initial validation in the factory. After the chair was installed in our institute, a linear displacement deviation of +/-0.6mm was observed over +/-200mm displacements in horizontal X/Y axes. After correcting the linear deviation, the displacement deviations of the chair for horizontal and vertical X/Y/Z axes were within 0.5mm and 0.5 for its revalidation. During the integration validation, the displacement deviation of the chair was 0.8mm and 0.6 when positioning a head phantom for the 36 fields with a 5 tilt. The chair achieved the required clinical tolerance for the clinical application. The tilt angle was limited to within 5 to treat patients through a specific treatment workflow with a proper daily quality assurance program during a clinical trial, started in May 2019. An integration validation with a 20 tilt will be conducted in the near future to realize the full potential of the isocentric rotating chair.

Automatic phase space generation for Monte Carlo calculations of intensity modulated particle therapy

Monte Carlo (MC) is generally considered as the most accurate dose calculation tool for particle therapy. However, a proper description of the beam particle kinematics is a necessary input for a realistic simulation. Such a description can be stored in phase space (PS) files for different beam energies. A PS file contains kinetic information such as energies, positions and travelling directions for particles traversing a plane perpendicular to the beam direction. The accuracy of PS files plays a critical role in the performance of the MC method for dose calculations. A PS file can be generated with a set of parameters describing analytically the beam kinematics. However, determining such parameters can be tedious and time consuming. Thus, we have developed an algorithm to obtain those parameters automatically and efficiently. In this paper, we presented such an algorithm and compared dose calculations using PS automatically generated for the Shanghai Proton and Heavy Ion Center (SPHIC) with measurements. The gamma-index for comparing calculated depth dose distributions (DDD) with measurements are above 96.0% with criterion 0.6%/0.6 mm. For each single energy, the mean difference percentage between calculated lateral spot sizes at 5 different locations along beam direction and measurements are below 3.5%.

Intensity-Modulated Proton and Carbon-Ion Radiation Therapy in the Management of Head and Neck Sarcomas.

PurposeWe report our experience of intensity‐modulated proton and carbon‐ion radiotherapy (IMPT/IMCT) for head and neck sarcomas (HNS).Methods and MaterialsAn analysis of the ongoing prospective data registry from the Shanghai Proton and Heavy Ion Center (SPHIC) for patients with HNS was conducted. The 12‐ and 24‐month rates of local recurrence‐free, overall, distant metastasis‐free, progression‐free survival (LRFS, OS, DMFS, and PFS), and acute/late toxicities were calculated. The prognostic factors for the effectiveness of the treatment were also analyzed.ResultsBetween 7/2014 and 5/2018, 51 consecutive patients with HNS received definitive doses of IMCT (41 cases), IMPT (two cases), or their combination (eight cases). One patient had R0 resection and another treated on the Chinese Food and Drug Administration registration trial received IMPT only. Twenty‐seven patients were treated according to various dose escalation trials or institutional protocols using IMCT or IMPT + IMCT boost. Twenty‐two patients with locoregional recurrence (10 and four patients failed surgery or surgery followed by radiotherapy, respectively) or radiation‐induced second primary sarcomas (eight patients) received salvage particle radiotherapy. With a median follow‐up time of 15.7 months, four patients with second primary sarcoma died. The 1‐ and 2‐year OS, PFS, LRFS, and DMFS rates for the entire cohort were 92.9% vs 90%, 73.6% vs 57.4%, 88.4% vs 78.9%, and 84.6% vs 76.5%, respectively. Those rates for patients without prior radiotherapy were 100% vs 100%, 82.1% vs 65.8%, 93.6% vs 85.3%, and 88.4% vs 79.5%, respectively. Multivariate analyses revealed that re‐irradiation was an independent prognostic factor for both LRFS and PFS (P = 0.015 and 0.037, respectively). In addition, gross tumor volume (GTV) was an independent prognostic factor for PFS (P = 0.048). One patient experienced Grade 3 acute toxicity (oral mucositis); another experienced Grade 4 acute event (hemorrhage) which required embolization. He lately died from hemorrhage (Grade 5) at 3.4 months after the completion of treatment. No patient experienced radiation‐induced acute/late toxicity of ≥ Grade 2 otherwise.ConclusionWith few observed acute/late toxicities, IMPT/IMCT provided effective short‐term tumor control in our patients with HNS. Further investigations, preferably in a prospective fashion, will be required to confirm the efficacy and toxicities of IMPT/IMCT in this group of patients.

Preliminary exploration of clinical factors affecting acute toxicity and quality of life after carbon ion therapy for prostate cancer

PurposeTo assess toxicity and quality-of-life (QOL) after carbon ion radiotherapy (CIRT) at the Shanghai Proton and Heavy Ion Center (SPHIC) and identify clinical factors that correlate with urinary, bowel and sexual function.MethodsSixty-four patients with localized prostate cancer admitted from July 2015 to January 2018 underwent CIRT. At baseline and 5 time-points after radiotherapy, we assessed patients’ QOL using the 26-item edition of the Expanded Prostate Cancer Index-Composite (EPIC-26) Chinese version. Logistic regression was performed to identify clinical factors associated with acute genitourinary (GU) toxicity and relative QOL.ResultsBy the end of CIRT, urinary irritation/obstruction temporarily declined (− 7.92 ± 1.76, p < .001). For urinary incontinence, bowel and sexual QOL, the scores remained stable at 2-year follow-up. The occurrences of acute Grade 1 and 2 GU toxicity were 20.3 and 10.9%, respectively, and of late Grade 1 and 2 GU toxicity were 3.1 and 1.6%, respectively. No acute or late gastrointestinal (GI) toxicity occurred. Transurethral resection of the prostate (TURP) was a risk factor that predicted a decline in urinary related QOL, and age made a difference to bowel-related QOL. For sexual QOL, castration status was a remarkable risk factor. An international prostate symptom score (IPSS) ≥8 increased the risk of Grade 1–2 acute GU toxicity 5.3-fold.ConclusionPatients with prostate cancer had favorable QOL after CIRT. IPSS ≥8 was a risk factor to acute GU toxicity, and TURP predicted a decline in urinary QOL. Age was related to bowel QOL, and castration status was associated with sexual QOL.Trial registrationCarbon Ion Radiotherapy for the Treatment of Localized Prostate Cancer, NCT02739659. Registered April 15, 2016.

OA18 - Proton and Carbon-ion Radiotherapy for High Grade Glioma: Early Results of the Shanghai Proton and Heavy Ion Center (SPHIC)

OA18 - Proton and Carbon-ion Radiotherapy for High Grade Glioma: Early Results of the Shanghai Proton and Heavy Ion Center (SPHIC)

Carbon Ion Radiotherapy for Patients with Extracranial Chordoma or Chondrosarcoma - Initial Experience from Shanghai Proton and Heavy Ion Center

Purpose: The purpose of this study was to evaluate the outcomes of patients with extracranial chordoma or chondrosarcoma treated by carbon ion radiotherapy (CIRT).Patients and methods: Between May 2015 and April 2018, 21 consecutive patients with chordoma (n=16) or chondrosarcoma (n=5) treated by CIRT at Shanghai Proton and Heavy Ion Center (SPHIC) were enrolled. The local control (LC), progression free survival (PFS), and overall survival (OS) rates were estimated using the Kaplan-Meier method. Association between each of the candidate prognostic factors and the estimated LC, PFS or OS was tested using the log rank test.Results: The median gross tumor volume (GTV) was 512.7 ml (range, 142.6-2893.0 ml). The median prescription dose was 69 gray equivalent (GyE) (range, 57-80 GyE). After a median follow-up of 21.8 months (range, 7.2-39.2 months), the 1-year LC, PFS, and OS were 93.8%, 88.4%, and 100%, respectively, whereas the 2-year LC, PFS, and OS were 85.2%, 80.4%, and 100%, respectively. A univariate analysis revealed that age, metal implant status, treatment status, sex, dose, and GTV were not significant prognostic factors for LC, PFS or OS. No grade 2 or higher early and late toxicities were observed within the follow-up.Conclusion: The results of this retrospective study are encouraging. Patients with extracranial chordoma or chondrosarcoma treated by CIRT in our center achieved a favorable shot-term outcome, without developing severe acute or late adverse events. The long-term results deserve further investigation, even in a prospective randomized trial.

Validation of the fast dose calculator for Shanghai Proton and Heavy Ion Center

The fast dose calculator (FDC), a track-repeating algorithm that was initially developed for proton therapy, has been expanded to include carbon. The purpose of this study was to validate FDC as a dose engine for treatment planning of scanning proton and carbon beams at the Shanghai Proton and Heavy Ion Center (SPHIC). For a complete set of clinical reference beams, the absorbed dose calculated with FDC was compared with that measured. A gamma-index analysis found over 94.6% and 100.0% of the measured points for protons had a gamma-index value smaller than unity for the 1%/1 mm and 1.5%/1.5 mm dose/distance agreement criteria, respectively. For carbon, the passing rates were above 80.6% and 92% with and without ripple filter if the criteria was set to 1%/1 mm. The values increased to 90.0%and 96.0% with the criteria 1.5%/1.5 mm. In conclusion, we found that FDC can serve as an accurate dose calculation engine for the SPHIC.

The predictive role of ADC values in prostate cancer patients treated with carbon-ion radiotherapy: initial clinical experience at Shanghai Proton and Heavy Ion Center (SPHIC).

The aim of our study was to investigate the predictive role of apparent diffusion coefficient (ADC) values in evaluating for therapeutic changes from carbon-ion radiotherapy (CIRT) in prostate cancer patients. Thirty-one patients with prostate cancer treated with CIRT were enrolled in this retrospective study. Diffusion-weighted imaging (DWI) at 3-T was performed before and after CIRT. Before and after treatment, ADC values were measured in the tumors and in the benign tissues of the prostate, and serum prostate-specific antigen (PSA) levels were also assessed. We divided the patients into two groups: PSA response (PSA declines ≥50%) and non-PSA response group (PSA declines <50%). After CIRT treatment, the mean ADC value of the tumors (1.23×10(-3)mm(2)/s) was significantly increased as compared with the pretreatment value (1.07×10(-3)mm(2)/s) (p<0.001), whereas the ADC values of the benign tissues after treatment did not significantly increase compared with the pretreatment values (p=0.235). The mean PSA level was significantly reduced from 2.027ng/mL before treatment to 0.822ng/mL, respectively, after treatment (p=0.0063). The mean of ADC changes in PSA response group before and after CIRT was significantly higher than that in non-PSA response group (∆ADC value: 0.217 vs 0.097×10(-3)mm(2)/s, p=0.0229), and the rate of patients with PSA response was higher in the high ∆ADC group (∆ADC≥0.10) than in the low ∆ADC group (∆ADC<0.10) (72.7 and 33.3%, respectively), but marginally significant (p=0.056). Additionally, the baseline tumor ADC values revealed a negative correlation with changes in PSA levels after treatment (correlation coefficient, ρ=-0.524; p=0.0025). Our preliminary results suggest that ADC vales measurement may be a useful imaging biomarker for prediction and early assessment of therapeutic response of prostate cancer to CIRT.