Quality control report of tumor radiotherapy in Zhejiang province / 中华放射肿瘤学杂志

Objective To discover the existing problems and provide appropriate suggestions and countermeasures through the quality control inspection.MethodsA comprehensive quality control inspection was conducted for the radiotherapy equipment in 45 hospitals in Zhejiang province.The physical,technical,clinical and radiotherapy process and the parameters related to quality control were evaluated.Results As of December 31,2017,a total of 62 linear accelerators from 45 hospitals have been assessed.In the radiotherapy process,multiple quality control problems were identified in terms of radiotherapy equipment configuration,clinical work quality,radiotherapy technology and personnel qualifications.Besides,unreasonable equipment configuration,shortage of radiotherapy staff,clinical work flow and the quality assurance of physical radiotherapy remained to be resolved.Conclusion Regular quality control of radiotherapy plays a pivotal role in ensuring the accuracy,effectiveness and medical safety of radiotherapy.

Experience and efficacy of SBRT for lung cancer:an analysis of 200 patients / 中华放射肿瘤学杂志

Objective To evaluate the safety and clinical efficacy of stereotactic body radiation therapy (SBRT) for lung cancer.Methods A retrospective analysis was performed on 200 patients with primary non-small cell lung cancer (NSCLC)(118 patients) or solitary pulmonary metastasis (82 patients) who underwent SBRT in Zhejiang Cancer Hospital from January 2012 to September 2015.The 80% isodose line covered 95% of the planning target volume,and the 100% isodose line covered 100% of the internal gross tumor volume.The fractional dose was 4.0-18.0 Gy daily or every other day,and the biologically equivalent dose ranged from 40.0 to 151.2 Gy (median 100 Gy).Results All patients completed treatment.The follow-up rate was 96.0%.The complete response and partial response rates were 14.8%(17/115) and 65.2%(75/115) for the primary tumor group,versus 25%(19/77) and 38%(29/77) for the metastasis group.The incidence rates of grade Ⅱ and Ⅲ acute radiation pneumonitis were 4.7% and 3.1%,respectively.The median follow-up was 14.9 months.The 1-and 2-year local control rates were 95.7% and 84.3% for the primary tumor group,versus 92% and 73% for the metastasis group.The 1-and 2-year overall survival rates were 94.5% and 92.0% for the primary tumor group,versus 85% and 62% for the metastasis group.Conclusions SBRT is a safe and effective treatment for early primary NSCLC and solitary pulmonary metastasis,resulting in high 1-and 2-year local control and overall survival rates and low rate of complications.

Development and research on the voxelized dose program based on AAPM TG-43 for the brachtherapy combined with EBRT / 中华放射肿瘤学杂志

Objective To develop a brachtherapy (BT) dose calculation program based on AAPM TG-43UI formula.With this program we can combine the dose result of external beam radiotherapy (EBRT) and BT together which is calculated by the different treatment planning TPS.Methods BT treatment data, such as source parameter, dwelling position and dwelling time, are retrieved from Nucletron Plato planning system and converted to ADAC planning system coordinate.The BT 3D dose distribution is re-calculated as well.Then the 3D dose distribution is exported to ADAC planning system.In that way, ADAC planning system can display either the EBRT dose or the BT dose and the combined dose can be calculated, displayed and evaluated as well.Results BT dose calculation result of our program which based on AAPM TG-43UI formula is identical with which of Plato (<0.1%).Furthermore, the BT dose can be transfer to the ADAC easily and the dose distributions of combined therapy can be merged in ADAC.Conclusions Our program can be used to combine the dose result of EBRT and BT from different TPS.

An application of template in intensity modulated radiotherapy planning / 中华放射肿瘤学杂志

Objeetive To study the application of template in intensity modulated radiotherapy (IMRT)planning.Methods With Philips Pinnacle3(R) version 7.6c treatment planning system(TPS) platform.a template for left breast cancer's IMRT planning was customized by using the function of scripting.Ten patients received IMRT alone after breast-conserving surgery were selected,two IMRT plans were designed for each patient:individual plan and the plan based on the template.Dose parameters of target,including conformal index(CI)and homogeneity index(HI),dose-volume histogram parameters,including V30,V20 of lung and cardiac,and the planning time were compared respectively.Results Of the two IMRT plans based on the template method and individual method.The average time of design an IMRT plan were 7±0.82 min and 36.5±6.84 min(t=13.55,P=0.000),the PTV average CI were 0.851± 0.015 and 0.845±0.032(t=0.59,P=0.560),the PTV average HI were(13.2±1.3)%and(14.4±1.6)%(t=1.804,P=0.08),the lung average V30 were(8.80±0.53)%and(8.31±0.74)%(t= cardiac average V30 were(9.89±1.14)%and(9.66±1.43)%(t=0.41,P=0.688).Conclusion For the tumor with the same location and stage,the application of template can simplify planning process and reduce working time,which was worthy of expansion.

Dosimetric evaluation of different IMRT treatment plans for non-small cell lung cancer / 中华放射医学与防护杂志

Objective To investigate the optimal treatment planning of intensity modulated radiotherapy (IMRT) for non-small cell lung cancer (NSCLC) .Methods Two types of treatment plans were designed for 11 patients with inoperable NSCLC disease.In the first plan(PTV60 plan) ,60 Gy was prescribed to the planning target volume(PTV) which was created using CTV(GTV +6-8 mm) plus the margin for organ motion and setup uncertainties.In the second plan(PTV70 plan) ,70 Gy was prescribed to the PTV which was created using GTV plus the margin for organ motion and setup uncertainties.The dose-volume histogram,the planning target volume coverage,and other dosimetric parameters of normal structures were compared between the two plans.Results These two plans were not significantly different in the dose heterogeneity,but commpared with the PTV60 plan,the PTV70 plan significantly improved 60 Gy volume with regard to PTV coverage.The values of V_(20) and V_5 of lung were reduced in average by (1.69 ±0.42) % ,and (1.29 ±1.09) % (t ＝ 0.047,0.264,P ＝ 0.002) ,respectively.Conclusions The planning of 70 Gy to the PTV using GTV plus the margin for organ motion and setup uncertainties might be better than that of 60 Gy to the PTV using CTV(GTV +6-8 mm) plus the margin for organ motion and setup uncertainties.

Application of correlation statistical analysis model in IMRT planning optimization / 中华放射肿瘤学杂志

Objective To study the application of correlation statistical analysis model in IMRT planning optimization. Methods A correlation statistical analysis model was established. IMRT plans of 5 prostate cancer patients were randomly chosen from the ADAC Pinacal 7.6 version planning system. The beam parameters, objective functions of the target area and optimization parameters of the primary plan were kept unchanged. The main optimization parameters including EUD parameter a,weight (w) and EUD_(max) of OAR were adjusted in optimization procedure successively. The correlation analysis (CF) and optimization efficiency analysis (OF) were carried out on the results of the optimization. The optimal value of parameters (MORt{}) with the best dose distribution was obtained and substituted in the corresponding primary plan.After optimization, the dose distributions of the two IMRT plans were compared. Results There were signif-icant differences with different optimization methods. The EUD parameter a and weight factor (w) almost had no effect on volume dose of OAR (OF < 0.01), though had obvious effect on the maximum dose and mean dose (OF≈1). The CF analysis showed that the correlation between the PTV ( V_(95)) volume and OAR dose was different when the EUD parameter a and w were applied for optimization. Meanwhile, the difference was proportional to the distance between the target area and OAR. The mean dose of OAR was decreased and the mean dose of PTV was more close to the prescription dose when the optimization parameters of the prima-ry plan were substituted with MOR{a} ,MOR{w} and MORt{EUD_(max)}. Besides, the DVH and isedose dis-tribution of the secondary plan were better. Conclusions The correlation statistical analysis model can be used to accurately determine the scope of optimization parameters in the IMRT planning procedure in prostate cancer, and an IMRT plan which fulfils the clinical requirement can be obtained efficiently.

Optimization of beam orientations in three-dimensional conformal radiotherapy with the genetic algorithm / 中华放射肿瘤学杂志

Objective To develop a beam orientation optimization algorithm for the gantry orientation in three-dimensional conformal radiotherapy(3 DCRT).Methods Patients' data were imported from the Pinnacle v 7.2 treatment planning system.including the DICOMRT and dose distribution files.These imported files were merged using a uniforiB coordinate system.The algorithm determined the optimized beam weight for each beam group and optimized the beam orientation with genetic algorithm.The optimized parameters,including the optimized beam orientations and weights,were exposed back to the Pinnacle v 7.2 to compare with the conventional 3DCRT plan.The optimized algorithm was implemented with our in-house program. The dose distributions, the DVH diagram and the conformity index of two lung cancer patients were compared. Results for the two lung cancer patients,the conformity index of the optimized plan(0.59 and 0.7)was higher than the conwentional 3DCRT plan(0.36 and 0.58).The maximum dose in spinal cord was reduced by 17.8%and 22.4%,the lung V20 reduced by 3.12%and 4.35%,and V30 reduced by 4.47%and 1.49%.For the brain tumor patient. the dose of lens and eyes was also decreased significantly. Conclusion This beam orientation optimization can be used as an assistant planning tool.

Percutaneous CT guided interstial ~(125)Ⅰ seeds implantation for refractory pelvic malignant tumors;efficacy and technique / 介入放射学杂志

Objective To evaluate the efficacy of percutaneous CT guided interstitial 125Ⅰ seeds implantation treatment for refractory pelvic malignant tumors and discuss the procedure of technique.Methods Twenty-three patients with refractory pelvic malignant tumors(25 lesions,diameter 3.5-7.0 cm,mean 4.5 cm) showing failure response to full chemotherapy and/or radical radiotherapy after tumors resection were undergone percutaneous CT guided intratumoral 125Ⅰseed implantation.Treatment plan system(TPS)was used to design the distribution and number of 125Ⅰ seeds according to matched peripheral dose(MPD)1-3 days before the procedure.Of which 6 cases received combined internal iliac arterial infusion chemotherapy before or after the 125Ⅰ seed implantation procedure.Results 9 ～ 75(mean 27)125Ⅰ seeds were implanted into a single tumor at first time including 6 patients with intraarterial chemotherapy for 14 cycles(mean 2.3 cycles),showed relief of clinical pain symptoms in 16 of 23 cases,72 h ～ 4 w after the seeds implantation;with the an effective rate of 69.6%.Follow up for 2-34 months(median,21 months),CT or MRI performed 2 months after the seeds implantation showed no CR,but PR in 18 cases,SD in 4 cases,and PD in 1 case,with overall response rate of 78%(18/23),and no serious complication.In addition,20 cases survived,with the longest one of 34 months and the other 3 died.Conclusions Intratumoral 125Ⅰ seeds implantation under CT guidance for pelvic refractory malignant tumors is safe,minimally invasive,and effective.

Pilot study on radiotherapy quality control and quality assurance in Zhejiang province / 中华放射肿瘤学杂志

Objective To evaluate the methods of carrying out radiotherapy quality control (QC) and quality assurance (QA) in the whole province. Methods From 1995, radiotherapy quality control center of Zhejiang province (the guiding team consists of specialists in radiation oncology of the province) has carried out a QC and QA program including evaluation of administration, departmental infrastructure, equipment, staff and treatment for 28 centers in the whole province. The regulation and scoring system were designed and first informed to every center, with the 28 centers checked and examined by the guiding team from 1999 to 2000. Results Great variations in equipment and staff were observed among participating centers. Equipment condition was not very satisfactory. Most of the treatment protocols were reasonable except that the indication for radiotherapy was not strict enough in some centers. Conclusions It is feasible for the radiotherapy quality control center to check and examine the department of radiation oncology in the whole province. Good QC and QA is invaluable to standardize the treatment protocol and ensure the radiotherapy quality and also helpful to carry out multi center study in the future.

Dosimetry of mono-isocenter irradiation technique in radiotherapy for nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Objective To study the dosimetry of mono isocenter irradiation technique in radiotherapy for nasopharyngeal carcinoma. Methods Conventional and mono isocenter irradiation techniques were used to simulate irradiation of the phantom and nasopharyngeal carcinoma patients with Siemens primus linear accelerator equipped with asymmetric collimators. Dose uniformity?isodose distribution and field overlap were measured at the plane of junction with TLD and film dosimeter on the phantom. The reproducibility of the set up was tested on patients with verification films. Results For an applied dose of 1?Gy, TLD dosimetry showed that the mean dose at the junction of fields were 1.01 ?Gy for the mono isocenter technique as compared to 1.09 1.13?Gy for the conventional technique. An ideal isodose distribution at the junction with mono isocenter technique was found by film dosimetry. The reproducibility of the set up was obviously better for the mono isocenter technique, with less field overlap (1mm) and set up deviation (0.5?mm) than those (6 14?mm and 3?mm) of the conventional technique. Conclusions This investigation of junction dosimetry confirms the potential advantage of the mono isocentric technique. Not only does it lead to superior dosimetry in the plane of junction but also associates with a better reproducibility of the set up.