Objective To evaluate the procedures for patient-specific quality assurance ( QA ) measurements using modulated spot scanning beam for proton and carbon ion treatment. Methods Records of 1734 beam measurements were analyzed by using a passing criteria, namely, dose difference between the measured and calculated doses≤3% or distance-to-agreement ( DTA) between them≤3 mm, and meanwhile mean dose deviation in all chambers ≤3% and at least 22 of 24 chamber array having passed this criteria. The results of measurement were categoried by water phantom, treatment room, measurement depth in chamber array, etc. Results Stratification of result showed some correlation between measurement parameters and passing rates. The total passing rates were 97. 7% and 91. 9% for proton and carbon ion beams, respectively. The passing rates were high at all measurement depths for proton beam, but decreased for carbon ion beam with increased depth. Chambers were mostly stable, leading to no significant difference in passing rate between different water phantoms and between different treatment rooms. Conclusions A good agreement was shown between the doses measured by water phantoms with those by the treatment planning system ( TPS) . When the chamber position was deeper than 150 mm in carbon ion measurements, a lower passing rate was observed. This could be caused by uncertainty of ion chamber array setup ( lateral and in depth) in highly modulated beams or by incorrect modelling of scattering by the TPS. These deviations need the further investigation.

Objective: To verify the safety and efficacy of IONTRIS particle therapy system (IONTRIS) in clinical implementation. Methods: Between 6.2014 and 8.2014, a total of 35 patients were enrolled into this trial: 31 males and 4 females with a median age of 69 yrs (range 39-80). Ten patients had locally recurrent head and neck tumors after surgery, 4 cases with thoracic malignancies, 1 case with hepatocellular carcinoma, 1 case with retroperitoneal sarcoma, and 19 cases with non-metastatic prostate carcinomas. Phantom dose verification was mandatory for each field before the start of radiation. Results: Twenty-two patients received carbon ion and 13 had proton irradiation. With a median follow-up time of 1 year, all patients were alive. Among the 16 patients with head and neck, thoracic, and abdominal/pelvic tumors, 2, 1, 12, and 1 cases developed complete response, partial response, stable disease, or disease progression, respectively. Progression-free survival rate was 93.8% (15/16). Among the 19 patients with prostate cancer, biological-recurrence free survival was 100%. Particle therapy was well tolerated in all 35 patients. Twenty-five patients (71.4%) experienced 33 grade 1 acute adverse effects, which subsided at 1 year follow-up. Six (17.1%) patients developed grade 1 late adverse effects. No significant change in ECOG or body weight was observed. Conclusions IONTRIS is safe and effective for clinical use. However, long term follow-up is needed to observe the late toxicity and long term result.