Percutaneous puncture implantation of radioactive particles for the treatment of tumors has the advantages of high precision and conformability, which has attracted more and more attention from the medical profession and has become one of the hot spots for the treatment of malignant tumors in recent years. Since April 2005, our department has been carrying out CT-guided percutaneous puncture 125I particle implantation for the treatment of malignant tumors, and the 32 cases of middle and advanced lung cancer treated are summarized as follows.
1. Materials and methods
1.1 General information
From April 2005 to November 2007, 32 cases of intermediate to advanced lung cancer were treated by CT-guided percutaneous implantation of 125I radioactive particles in our department, of which 22 were male and 10 were female, aged 42-73 years old, with an average age of 56.8 years. There were 14 cases of central type, 18 cases of peripheral type, 21 cases of left lung and 11 cases of right lung. Pathological diagnosis: 12 cases of squamous carcinoma, 13 cases of adenocarcinoma, and 7 cases of small cell undifferentiated carcinoma. the TNM stage was Ⅲ-Ⅳ in all cases.
1.2 Methods
1.2.1 Computerized three-dimensional treatment planning system (TPS) The three-dimensional treatment planning system and quality verification system of radioactive particle therapy (HGGR-2000) were provided by Zhuhai Hejia Medical Equipment Co.
1.2.2 Particle implantation needle and implantation device Zhuhai Hejia Medical Equipment Co. The implantation needle has a diameter of 18G, with a graduated surface, and can be connected to the implantation device. The implanters are fully enclosed radiation-proof continuous-implanters with 30 particles per implant.
1.2.3125I radioactive particles 125I particles (type 6711) with activity of 0.8mCi, sealed structure with titanium coating, size of 4.5mm×0.8mm, half-life T1/2=60.2d, effective inter-tissue action diameter of 1.7cm. particles were sterilized by high pressure dry heat.
1.2.4 Surgical method
CT thin layer scans were performed on all patients 1 week before particle implantation to determine the tumor volume, and the images were transmitted to the TPS planning system to do 125I particle implantation treatment planning. According to the prescribed dose, the deployment source plan was designed. Three-dimensional reconstruction was performed according to the CT data to observe the tumor size, morphology, location, and relationship with the large blood vessels in the pulmonary hilum. 125I particles are ordered according to the number and activity of particles derived from the treatment plan.
The patient was placed in supine or prone position, and the particle needle entry point and the angle and depth of the needle entry were determined according to the CT scan image, and marked on the skin surface. The needle is inserted under CT guidance, and the tissue specimen is first cut with a biopsy gun for pathological biopsy.
The implantation needle is inserted into the target site, and the CT scan is confirmed. Retreat the needle to the edge of the tumor, adjust the angle and then re-enter the needle, enter the target site under CT guidance, and continue to release several particles as before. Adjust the angle 3-5 times in the same way, and select a total of 1 to 3 injection points. After implantation, the CT scan was repeated to observe whether the particle distribution was in accordance with the TPS treatment plan, if not, additional particles were needed, and the occurrence and extent of complications were observed to guide clinical treatment.
Postoperatively, anti-infection and hemostatic treatment were given, and blood pressure, heart rate and other vital signs were observed for 12h.
1.3 Follow up and efficacy determination
CT examinations were done in 1 and 2 months after surgery, and thereafter, CT was followed up and reexamined every 2-3 months to observe the efficacy, side effects and complications. The evaluation of efficacy was based on the treatment standard of solid tumors established by WHO: complete remission (CR): complete disappearance of tumor lesions for more than 4 weeks; partial remission (PR): reduction of the product of the maximum diameter and the maximum vertical transverse diameter of the tumor by more than 50%; micro-effect (MR): reduction of the product of the two by 25% to 50%; no change (NC): reduction of the product of the two by <25%.
2.Results
In this group of 32 cases, a total of 1008 125I radioactive particles were implanted, with an average of 31.5 particles, the largest case used 68 particles, and the smallest used 8 particles. The activity of the particles used was 0.8 mCi. The surgical operation time was 1 to 2.5 h.
In this group, the effective rate was 59.36%, 83.87% and 86.67% at 2, 4 and 6 months follow-up, respectively, as shown in Table 2. 1 case died of cerebral hemorrhage at 4 months postoperatively and 1 case died of systemic metastasis at 5 months postoperatively during the follow-up.
In terms of symptom relief, 100% (32/32) of chest pain was relieved, 75% (18/24) of chest tightness and shortness of breath was relieved, 76.47% (13/17) of hemoptysis was cured, and 100% (11/11) of obstructive pulmonary atelectasis was cured.
Pneumothorax occurred in 5 cases (15.62%, 5/32) after surgery, 4 cases on the day of surgery and 1 case 2 days after surgery. The patient had no discomfort and was not treated. No other serious complications or treatment-related deaths occurred in this group.
Table 1 Pathological diagnosis, site and tumor size of 26 patients (cases)
Gender
Pathological diagnosis
Site of lesion
Tumor diameter(cm)
Squamous carcinoma
Adenocarcinoma
Small cell carcinoma
Central type
Peripheral type
<3
3~5
>5
Male 22
9
7
6
11
11
2
8
12
Female 10
3
6
1
3
7
2
1
7
Total
12
13
7
14
18
4
9
19
Table 2 Comparison of the efficacy of 26 patients at 2, 4 and 6 months after surgery (cases)
Time of CT reexamination
Number of cases
CR
PR
MR
NC
Effective rate(%)
2 months
32
2
17
12
1
59.36
4 months
31
4
22
4
1
83.87
6 Months
30
5
21
2
1
86.67
Note: CR is complete remission, PR is partial remission, MR is minimal effect, NC is no change, and the effective rate is CR+PR
3. Discussion
125I particle implantation belongs to a kind of brachytherapy, which destroys and kills tumors without damaging normal tissues by low energy (27-35 keV) gamma rays continuously emitted by 125I particles implanted into tumors or tumor infiltrating tissues. According to the treatment plan developed by TPS, CT-guided implantation of 125I particles into the human tumor target area is a new oncology technique with the advantages of high conformality, high dose in the target area, and significantly improved dose distribution ratio between local and normal tissues in the target area.
Percutaneous puncture implantation of 125I radioactive particles for lung cancer treatment has the following characteristics.
(i) It can better control local lesions, and the literature reports that the effective rate can reach 90% to 100% [1], and the recent effective rate of 32 cases in this group reached 86.67%, which is satisfactory.
②It can effectively relieve the clinical symptoms of patients and improve their survival quality. In this group, the symptoms of chest tightness, shortness of breath and hemoptysis of patients were effectively controlled, and the treatment efficiency of chest pain and obstructive dyspnea reached 100%.
③The effective diameter of 125I radioactive particles is 1.7cm, and the damage to normal tissues after implantation is extremely mild, and there is basically no systemic toxicity.
④It is minimally invasive interventional treatment with few complications. The patients in this group only had slight pneumothorax or a small amount of blood sputum, which disappeared quickly after active treatment.
To improve the treatment effect and reduce complications, it should be noted that: (1) CT has high spatial and density resolution, which guides the puncture positioning precisely and enables the majority of 125I radioactive particles to be implanted in accordance with the requirements of the treatment plan. Ke Mingyao et al. reported the use of transbronchoscopic implantation of particles and Zhang Zhongsong et al. used intraoperative intertissue implantation of 125I radioactive particles for lung cancer, but compared with other guidance methods, CT guidance not only has precise localization, but also allows postoperative evaluation and can facilitate postoperative follow-up and comparison. Zhang Yi et al. concluded that CT guidance is an important factor in determining the success of surgery.
(2) Select a suitable entry point, minimize the number of times the puncture needle passes through the pleura as well as try not to pass through the interlobular pleura, prohibit the tip of the puncture needle from scraping on the pleural surface, and adequately suppress cough after surgery to reduce the occurrence of pneumothorax.
(3) The lung lesion will move up and down to different degrees with breathing, so the needle can be inserted at the end of inspiration or end of expiration to improve the accuracy of particle implantation.
(4) According to the characteristics of the lung lesion, the feasibility of actual operation should be fully considered when selecting the needle entry point. The author suggests to take one level of needle entry in different directions to implant particles, which can reduce the number of times of crossing the pleura, reduce the incidence of pneumothorax, and also achieve satisfactory particle distribution.
(5) Since central lung cancer is often adherent to blood vessels, it is best to enhance the scan first during treatment to facilitate observation of the relationship between the lesion and blood vessels and avoid damaging the surrounding blood vessels during puncture.
Five cases (15.62% (5/32)) had pneumothorax after surgery, which was a small amount of pneumothorax and disappeared on its own after 5 days without special treatment. 4 cases (12.5%, 4/32) coughed up a small amount of blood sputum after surgery, which might be due to the damage of small blood vessels or tumor vessels during puncture, and disappeared after 3 days with hemostatic drugs. It was because the tumor shrunk after treatment and the particle was displaced through the bronchus, which was not re-displaced after 3 months of observation, and the patient had no discomfort and was not given treatment.
Despite the low energy of gamma radiation released by 125I radioactive particles and the short radiation distance, attention should still be paid to radiation protection during the operation. Patients and family members should be informed about the protection before the operation, such as maintaining a certain distance of contact, especially children and pregnant family members should pay more attention.
In conclusion, CT-guided percutaneous puncture 125I radioactive particle implantation for lung cancer is simple, safe, effective and with few complications, and is worth promoting and applying.