ABSTRACT
Objective:To establish a local effect model (LEM)-based rectal dose volume histogram (DVH) prediction model in prostate cancer patients treated with carbon ion therapy based on Japanese experience, aiming to provide reference for clinically reducing the incidence of rectal adverse reactions.Methods:The planning CT data of 76 patients with prostate cancer were collected. The microdosimetric kinetic model (MKM) was used for initial planning, and the LEM was selected to recalculate the biological dose based on the same fields to MKM. Then, the geometric features and DVH of the rectum were extracted from the LEM plans. The planning data of 61 cases were used to establish the prediction model with linear regression and the other 15 cases were used for validation.Results:The ratio of the overlapped volume between the rectum and the region of interest (ROI) expended from planning target volume by 1 cm along the left and right directions of the rectum could be proved to be the characteristic parameters for linear regression. The mean goodness-of-fit R2 of predicted and LEM plan-based DVH of 15 cases was 0.964. The results of predicted rectal adverse reactions based on predicted DVH were consistent with those of LEM plan-based DVH. Conclusions:The linear regression method used in this study can establish an accurate prediction model of rectal DVH, which may provide certain reference for reducing the incidence of rectal adverse reactions. Nevertheless, the findings remain to be further verified by clinical trials with larger sample size.
ABSTRACT
Objective:To compare dose distributions between photon versus proton and carbon ion radiotherapy (particle therapy, PT) among patients with gross tumors, and to evaluate the safety and efficacy of PT for thymic malignancies (TM).Methods:From Sept 2015 to Aug 2018, 19 patients with TM who underwent non-palliative PT using pencil beam scanning technique in our hospital and had at least one follow-up were retrospectively analyzed. Diseases staged from Ⅰ-Ⅳ B including 15 Ⅲ-Ⅳ B. All the patients had pathological diagnosis with 10 thymomas, 6 carcinomas and 3 neuroendocrine tumors of the thymus. A set of dosimetric comparisons were conducted in patients with gross tumors at a total dose of 66 GyE, in 33 fractions for photon or proton beams and in 22 fractions for carbon ion beams. Five patients without any local treatment and 7 patients after R2 resection received radical radiotherapy of proton 44.0-48.4 GyE in 20-22 fractions plus carbon ion 21.0-23.1 GyE in 7 fractions, 1 case after complete resection (R0 resection) had proton 45 GyE in 25 fractions, 5 cases after R1 resection had proton 60.0-61.6 GyE in 28-30 fractions and 1 case of recurrence after postoperative radiotherapy had only carbon ion 60 GyE in 20 fractions. Results:The median follow up time was 19.0 (2.4-42.9) months. There were 13 patients with gross tumors, with a median largest diameter of 5.7 (2.7-12.8) cm. The dosimetric study showed that proton and carbon-ion plans significantly reduced the maximum dose to the spinal cord, the mean doses to the organs at risk (OARs) including the lung/heart/esophagus, and the integral dose of the exposed area about 25%-65% compared to photon plans. No other toxicities ≥ grade 3 were observed except one myocardial infarction (grade 4 late toxicity). There was no local failure observed. Metastasis to regional lymph node, lung, pleura, skull base, bone or liver occurred in 4 patients with Ⅲ-Ⅳ B stage disease in 6.1-22.8 months after treatment. The 2-year local control and overall survival rates were 100%, disease free survival and distant metastasis free survival rates were 64.6%. Conclusions:For TMs, PT has significant advantages over photon in terms of sparing OARs, and is safe and effective in patients with TMs after short-time follow-up.
ABSTRACT
Objective@#To investigate the effect of lipiodol as embolization agents in liver, after transcatheter arterial chemoembolization, on dose calculation under the carbon ion treatment plan.@*Methods@#The actual relative linear stopping powers(RLSP)in pure lipiodol, pure gel and lipiodol-gel mixture, together with the correctd RLSPs from their CT images, were compared.In seven typical cases with lipiodol deposition area, carbon ion treatment plan was performed for the original lipiodol images.Successively on the basis of analysis that has made, the RLSP in lipiodol deposition area was corrected to be as in normal liver tissue, for which the carbon ion treatment plan was again performed.A comparison was made of differences in water equivalent depth (WED) and dose distribution on different CT images.@*Results@#The RLSP value corrected according to CT image HU value, lipiodol, and lipiodol-gel mixture may increase by 4.6%-139.0% compared with the measured value. In seven typical cases, deposited lipiodol can cause WED to increase by (0.89±0.41) cm along the field track and RBE by(3.83±1.71)Gy within the 1 cm of distal area of target.@*Conclusions@#In order to improve the accuracy of dose distribution calculation, the HU value and/or RLSP in deposited lipiodol area in liver after transcatheter arterial chemoembolization should being corrected to be as in the normal liver tissue.
ABSTRACT
Objective To establish an accurate simulation model for proton scanning beam using Monte Carlo (MC) code.Methods The MC model of proton scanning beam treatment nozzle was established by using MC code FLUKA combined with the geometric structure of the treatment nozzle in Shanghai Proton and Heavy Ion Center (SPHIC).The MC beam model was established through the simulation of the integrated depth dose distribution (IDD) in water and the lateral profile in air at the isocenter points.The model was used to simulate the depth and lateral dose profile of Spread Out Bragg Peak (SOBP) of proton beam.The calucated result were compared with TPS calculation values.Results For the distal R90,the deviations of simulation and measurement at all energies were less than 0.5 mm.For distal fall off (R80-20),the deviations between simulation and measurement at each energy were within 0.1 mm.The biggest difference between measurement and simulation of the proton beam spot size was within 0.45 mm.The result of simulation and TPS calculation of proton SOBP matched well,with the γ index pass rate being higher than 90％ (Criteria:2 mm,2％).Conclusions The MC code FLUKA can be used to model the nozzle of scanning proton beam,which can meet the clinical requirements and accurately simulate the proton beam transport in material.After construction and verification on the basis of measurement,this model can be used as a dose verification tool to evaluate clinical proton treatment plans,in order to reduce the beam time for dose verification and thus increase the number of patient treatment in proton therapy.
ABSTRACT
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.
ABSTRACT
Objective To measure the CT Hounsfield Unit ( HU) and relative stopping power ( RSP) conversion curve. Methods In this study, the RSPs of 12 different tissue equivalent rods were measured with proton and carbon beam in the Shanghai Proton and Heavy Ion Center ( SPHIC) . The same tissue equivalent materials were scanned with CT scanner to acquire the HU. Results Conversion curve for the transformation of HU into RSP was generated for both proton and carbon ion beam. Differences between RSPs measured using proton and carbon beam were ≤0. 64%except lung material. Conclusions A RSP versus HU conversion curve was generated for both protons and carbon ions.
ABSTRACT
Objective To measure the CT Hounsfield Unit ( HU) and relative stopping power ( RSP) conversion curve. Methods In this study, the RSPs of 12 different tissue equivalent rods were measured with proton and carbon beam in the Shanghai Proton and Heavy Ion Center ( SPHIC) . The same tissue equivalent materials were scanned with CT scanner to acquire the HU. Results Conversion curve for the transformation of HU into RSP was generated for both proton and carbon ion beam. Differences between RSPs measured using proton and carbon beam were ≤0. 64%except lung material. Conclusions A RSP versus HU conversion curve was generated for both protons and carbon ions.
ABSTRACT
Objective To explore the safety and efifciency of oral iron therapy and intravenous iron therapy in anemia patients with maintenance hemodialysis,in order to gain experience for clinical treatment of this disease. Methods 88 cases collected in the ifrst people's hospital of Changshu city from July 2010 to March 2013 were divided into research group(n=44) and control group(n=44) by random number table. Control group was given oral iron therapy, and research group was t given intravenous iron. The differences of hemoglobin (Hb), reticulocyte, serum ferritin content, superoxide dismutase (SOD) and serum malondialdehyde (MDA) before and after treatment between two goups were recorded and compared. Results The differences of Hb, serum ferritin and reticulocyte numerical before treatment between two groups were not signiifcant, but signiifcant four weeks after treatment, with higher level in research group(P<0.05).The difference of oxidative stress status before treatment between two groups was not signiifcant, but after treatment, the MDA level in research group was higher than control group(P<0.05),while SOD level was lower than control group(P<0.05). Conclusion Compared with oral iron therapy, intravenous iron has better results in improving anemia, but easy to induce oxidative stress reaction.
ABSTRACT
Objective To investigate the effect of transverse incision surgery for epicanthoplasty with double eyelid fold reconstruction. Design Retrospective case series. Participants 103 patients with epicanthus. Method Transverse incision was applied for epicanthoplasty in all patients, and incorporated with double eyelid fold reconstruction. Patients were followed up 3-6 months. Main Outcome Measures Size of lacrimal caruncle, length of palpebral fissure, inner canthic diameter and scarring degree. Results Lacrimal caruncle was revealed 3/4 merous in 21 cases, 2/3 merous in 56 cases, 1/2 merous in 8 cases. Extent of palpebral fissure was 30-31mm in 5 cases, 28-29 mm in 69 cases, 26-27 mm in 11 cases. Inner canthic diameter was 32-33mm in 61 cases, 30-31 mm in 23 cases, 29 mm in 1 case. The scarring was little in 56 cases, obviously in 29 cases. Epicanthus relapsed in 2 cases. 16 cases lost follow-up. Conclusion Transverse incision surgery for epicanthoplasty with double eyelid fold reconstruction has less tissue damage and minimal scarring produced at the medial cantha. It is a simple and reliable surgical approach for correction of epicanthus.