| Primary lung cancer is the leading cause of mortality among the oncologic patient population.Surgery remains the main curative selection for patients with early-stage non-small-cell lung cancer(NSCLC).Radiotherapy(RT)and?or chemotherapy are commonly used for patients who are not considered surgical candidates.However,these modalities are not usually curative and are almost always accompanied by various toxic complications.Intraoperative brachytherapy with Computed tomography(CT)-guided percutaneous radioactive iodine-125(125I)seed implantation has been proven to be an effective therapeutic modality and an alternative to external beam radiation therapy(EBRT)for patients with lung cancer.However,the conventional CT guidance exhibits certain disadvantages,such as the lack of real-time visualization,prolonged procedure time and a high incidence of complications.Besides,accurate model-based dose calculations are important for understanding how to safely and effectively adopt new radionuclides and to better inform the current use of 125 I sources in lung brachytherapy.The purpose of the present study was to evaluate the feasibility and efficacy of percutaneous interstitial brachytherapy using 125 I radioactive seeds under computed tomographic(CT)guidance for malignant lung tumors.To analyze the risk factors for pneumothorax and bleeding after CT-guided percutaneous interstitial iodine?125 seeds brachytherapy.TPS(Treatment Planning System)was performed before and after 125 I implantation to investigate dosimetry for permanent implant lung brachytherapy considering a range of source energies and various implant sites in the lung.PART 1: Feasibility and clinical value of CT?guided iodine-125 implantation for lung cancer Objective: The aim was to evaluate the safety,feasibility and efficacy of computed tomography(CT)?guided percutaneous interstitial brachytherapy using radioactive iodine?125(125I)seeds for the treatment of lung cancer.Materials and Methods: Included in this study were 45 male and35 female patients aged 52–85 years(mean 72?year)who were diagnosed with lung cancer.Of the 80 cases of lung cancer,38 were pathologically confirmed as squamous cell carcinoma,29 as adenocarcinoma,2 as small cell lung cancer,and 11 as metastatic lung cancer.Percutaneous interstitial implantation of radioactive 125 I seeds was performed under CT guidance.The treatment planning system was used to reconstruct three ?dimensional images of the tumor to determine the quantity and distribution of 125 I seeds to be implanted.Under CT guidance,125 I seeds were embedded into the tumor,with the matched peripheral dose set at 100–130 Gy.Follow?up CT scan was done in 2?month to explore the treatment efficacy.The pain relief time,life quality(cough and chest tightness)and complications were observed.Results: The procedure was successful in all patients.No major procedure?associated death occurred.The duration of follow?up was 6?month.Complete response(CR)was seen in 38 cases(47.5%),partial response(PR)was seen in 27 cases(33.75%),stable disease(SD)was seen in 10 cases(12.5%),and progressive disease was seen in 5 cases(6.25%),with a local control rate(CR + PR + SD)of 93.75%.The 2?,4? and 6?month overall response rate(CR + PR)was 78%,83% and 81%,respectively.The pain relief rate in 4-month was 82.3%.Conclusion: Implantation of CT?guided 125 I seeds is a safe and effective alternative option for the treatment of lung cancer.PART 2: Risk factor analysis of pneumothorax and pulmonary hemorrhage complicating CT-guided iodine-125 percutaneous interstitial implantation Objective: To evaluate the risk factors for pneumothorax and bleeding after CT-guided percutaneous interstitial brachytherapy using radioactive iodine?125 seeds for the treatment of lung cancer.Materials and Methods: We reviewed 80 CT-guided percutaneous lung interstitial brachytherapy using radioactive iodine?125 seeds procedures.The risk factors for pneumothorax and bleeding were determined by analysis of variables related to patient demographics,lung lesions and puncture procedures.Results: The main complications were hemoptysis(80%;64 of 80 procedures)and pneumothorax(33.8%;27of 80 procedures).The highest bleeding risk correlated with a lesion depth of 1-2cm and >4cm.The highest pneumothorax rate correlated with a lesion size 0.5-2cm and a lesion depth >4cm.Conclusion: Pneumothorax and bleeding is the most common complications after CT-guided percutaneous lung interstitial brachytherapy using radioactive iodine?125 seeds,and the rate of bleeding is higher than pneumothorax.The risk factors for highest bleeding rate are lesion size and lesion depth.The risk factor for highest pneumothorax rate is lesion depth.PART 3: The dosimetric study of CT-guided 125 I seed implantation in the treatment of lung cancerObjective: To research the dosimetry guiding significance and clinical value of TPS(treatment planning system)through preoperative TPS plan,inoperative TPS guidence and postoperative TPS confirmation for the treatment of 125 I seed implantation.Materials and Methods: Eighty patients with non small-cell lung cancer(NSCLC)confirmed by fine?needle aspiration biopsy or bronchoscopic pathology were treated with CT guidance of 125 I seeds implantation.CT iamges were inputted to TPS to reconstruct the three-dimension images of tumor.The preoperative plan was then completed according to TPS,and to calculate the seed numbers,to simulate the placement position and to evaluate the dose distribution.Inoperative process of 125I seed implantation treatment was monitored and guided by TPS real-timely.The matched peripheral dose was 110-130 Gy,and the prescribed dose was 110 Gy.Dosimetric verification by TPS was finished in one week after seed implantation.The difference of D80,D90,D100,V90,V100,V150(the percentage of the planning target volume covered by the 100% prescription dose),MPD(minimum peripheral dose),Dmean(mean absorbed dose),and PTV were compared between pre-implantation and post-implantation.All the patients were assessed with follow?up CT examinations at the 2,4,6months after the surgery to explore the treatment efficacy.Results: No difference was found in D80,D90,V150,MPD,Dmean and PTV between pre-implantation and post-implantation(t=1.82?1.73?1.59?0.80?0.21 ? 1.73,P>0.05),but were difference in D100,V90,V100(t=3.32?3.52?3.29,P<0.05).After 6 months follow-up,the numbers of pataients for complete remission(CR),partial remission(PR),stable disease(SD),and progress disease(PD)were 38,27,10,and 5 respectively.The local control rates(CR +PR+SD)was 93.75%.The overall effective rate(CR+PR)of 2,4,6 months was 78%,83%,81% respectively.Nine patients had fever after operation.In the 4th month after seed implantation,one patient died of multisystem failure and one patient had grade-two skin reaction.Two patients died of distant metastasis after 6 months.Conclusions: Expected dosimetric distribution can be realized according to TPS dosimetric verification during CT guided 125 I Seed implantation.The inoperative plan can avoid high dose or low dose area,to guarantee the conformability of target area dose and protect the surrounding normal tissues.In some patients,low dose in the peripheral region of targets is due to the constraints of bony structures and organs at risk. |
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