Discussion on application of mean gamma index to Compass 3D dose verification in target area receiving 50% of prescribed dose / 中华放射医学与防护杂志

Objective:To explore the value of using the mean gamma index (GI) in targer area receiving 50% prescribed dose as reference in VMAT planned dose verification through model-based dose calculation and measurement-based dose reconstruction.Methods:Based on Compass dose verificantion system, the VMAT plans for 70 patients were validated using two method. The mean GI and passing rate in target area receiving 50% of prescribed dose area for each validation plan were obtained to evaluate its application value in dose validation. First, plan information obtained by TPS calculation was input into the Compass system for performing independent dose calculation based on the accelerator data model, and obtain a three-dimensional dose based on the independent model calculation. The planned fluence measured for each patient′s treatment plan on the accelerator was reconstructed through the Compass system to obtain a three-dimensional dose based on measurement reconstruction. The three-dimensional dose obtained by the two method were compared with the three-dimensional dose calculated by TPS.Results:Combined with the gamma criteria of 3%/3 mm in the error setting condition of GI analysis, the mean GI in the area receiving 50% of prescribed dose was evaluated. GI≤0.4 was classified as PASS, 0.4 < GI ≤ 0.6 as being clinically acceptable, and GI > 0.6 as FAIL. The VMAT planned dose verification for 70 patients showed that the model-based independent calculation was in a better agreement with the TPS calculation. The GI values were all < 0.6: GI≤0.4 for 67 patients and 0.4 <GI≤ 0.6 for the other 3 patients, with gamma passing rate larger than 92%. The in- vivo measurement-based reconstructed 3D dose are slightly lesser than the model-based planed result ; theGI values were all < 0.6: GI ≤0.4 for 35 patients and 0.4 < GI ≤ 0.6 for other 35 patients, with gamma pass rate larger than 88%, of which gamma passing rate > 90% for 88 patients and < 90% for other 2, all meeting the requirements of clinical dose verification. The model-based independent dose verification is better than the measurement-based reconstructed dose verificantion, and the difference is statistically significant ( t=15.20, 10.71, P < 0.05). Conclusions:The mean GI in target area receiving 50% of prescribed dose can be used as a reference to judge the operatability of clinical plan in clinical dose verification. The mean GI value, in combination with the comprehensive result of gamma passing rate, is more convincing to evaluate dose verification. A combination of model-based dose verification, despite time-saving and labor-saving, and the measurement-based dose verification could become a reliable dose verification method for clinical application.

Effect of carbon fiber postural fixation plate on radiotherapy dose of cervical cancer / 重庆医学

Objective To study the effect of carbon fiber postural fixation plate on radiotherapy dose of cervical cancer.Methods The carbon fiber postural fixation plate model was created in the RayStation plan-ning system,and the difference of attenuation coefficient between the model plate in the planning system and the real plate in the actual measurement was compared to verify the accuracy of the position fixing plate mod-el.A total of 10 patients with cervical cancer were selected,and the plate-free plan was designed on the CT im-age without the fixed plate model,and the dose was calculated.After the plate-free plan was completed,the plan was transplanted to the CT image with the fixed plate model to obtain the plate plan,and the dose was calculated.The dosimetric differences of target volume(PTV)and organ at risk(OAR)between the plate-free plan and the plate plan were compared.Two ArcCHECK verification phantoms were established in the RayStation planning system,which were the ArcCHECK verification phantom with the postural fixation plate model and the ArcCHECK verification phantom without the postural fixation plate model.The 10 cervical cancer plans were transplanted into two verification phantoms for dose calculation.Under the Xinhua accelera-tor,ArcCHECK was placed on the postural fixation plate to perform the validation plan,and the effect of the postural fixation plate model in the planning system on the gamma passing rate of the verification plan was compared.Results For the accuracy of the position fixation plate model was created in the planning system:the deviation(d)of the attenuation coefficient obtained in the planning system and the actual measurement is less than 0.3％.For the cervical cancer plan:compared with the plate without plan,the dose of PTV and OAR in the plate with plan was significantly lower.The average dose of PTV was about 1％lower,and the degree of OAR was different,ranging within 3％.For cervical cancer plan verification:the gamma pass rate of the plate model verification plan was significantly higher than that of the platefree plan model verification plan,and the pass rates of 3 mm/3％and 2 mm/2％were increased by 0.69％and 1.50％,respectively.Conclusion The carbon fiber postural fixation plate has a certain effect on the radiotherapy dose of cervical cancer patients.In order to ensure the accuracy of the target dose,it is recommended to add the postural fixation plate model in the plan design.

Efficacy and influencing factors of sequential and concurrent chemoradiotherapy in the treatment of advanced non-small cell lung cancer in elderly patients / 中国医师进修杂志

Objective:To explore the efficacy of sequential and concurrent chemoradiotherapy in the treatment of advanced non-small cell lung cancer (NSCLC) in the elderly, and to analyze the influencing factors of prognosis and outcome.Methods:The clinical data of 195 elderly patients with advanced NSCLC admitted to Beijing Shijingshan Hospitaland and Beijing Shijitan Hospital from March 2015 to March 2018 were retrospectively analyzed. They were divided into the concurrent chemoradiotherapy (100 cases) and the sequential chemoradiotherapy (95 cases) according to different chemoradiotherapy regiments. The short-term efficacy, 3-year survival, influencing factors of prognosis and toxic and adverse effects of the two groups were compared.Results:The objective response rate in the concurrent chemoradiotherapy group was significantly higher than that in the sequential chemoradiotherapy group: 61.00%(61/100) vs. 44.21%(42/95), there was statistically difference ( χ2 = 5.51, P<0.05). The 2-year and 3-year survival rate in the concurrent chemoradiotherapy group were 52.00% and 23.00%, which were significantly higher than those in the sequential chemoradiotherapy group: 32.60%, 11.60%, there were statistically differences ( P<0.05). Multivariate analysis results showed that smoking, Karnofsky score<70, TNM stage Ⅲb, short-term efficacy and treatment methods/sequential chemoradiotherapy were independent risk factors ( P<0.05). The incidence of radiation esophagitis, bone marrow suppression and lung function damage in the concurrent chemoradiotherapy group were higher than those in the sequential chemoradiotherapy group: 45.00%(45/100) vs. 27.37% (26/95), 36.00%(36/100) vs. 22.11%(21/95), 48.00%(48/100) vs. 26.32%(25/95), there were statistically differences ( χ2 = 6.54, 4.55, 9.78; P<0.05). Conclusions:Concurrent chemoradiotherapy can improve the short-term efficacy, and improve the 2-year and 3-year survival rates in advanced NSCLC in elderly patients, but the adverse effects are significantly enhanced.

Significance of target volume delineation of tumor bed according to metal clips or seroma in determing tumor bed position during radiotherapy after breast-conserving surgery for breast cancer / 肿瘤研究与临床

Objective:To investigate the differences between the mental clips placed intraoperatively and the tumor bed's target volume delineation of seroma based on CT scanning during radiotherapy for breast cancer patients who received breast-conserving surgery in the persuit of a better solution to determine the tumor bed position.Methods:The clinical data of 13 patients with early breast cancer who received postoperative radiotherapy after breast-conserving surgery at Beijing Shijingshan Hospital and Beijing Shijitan Hospital of Capital Medical University from December 2020 to January 2022 were retrospectively analyzed. They all had surgical clips implanted during the surgery. The following methods were used to delineate the target volume of tumor bed, including gross target volume delineation of tumor bed based on the mental clips (GTVtb-Clip), the tumor bed's gross target volume delineation of seroma based on CT scanning (GTVtb-Seroma), and the combination of both (GTVtb-C+S). The volume, diameter on three coordinate axis, neutral point displacement and conformability of these delineation methods were compared.Results:The volume of GTVtb-Clip, GTVtb-Seroma and GTVtb-C+S was (25±10) cm 3, (38±17) cm 3, (49±20) cm 3, and the differences were statistically significant (all P<0.05). The diameter on X axis was (4.7±1.2) cm, (5.3±1.4) cm, (5.7±1.6) cm, respectively in GTVtb-Clip, GTVtb-Seroma and GTVtb-C+S; the diameter on Y axis was (4.6±1.7) cm, (5.0±1.6) cm, (5.7±1.7) cm, respectively in GTVtb-Clip, GTVtb-Seroma and GTVtb-C+S; the diameter on Z axis was (4.4±1.5) cm, (5.2±1.4) cm, (5.6±1.4) cm in GTVtb-Clip, GTVtb-Seroma and GTVtb-C+S. The differences in the diameter of GTVtb-Clip and GTVtb-C+S on X,Y, Z axis were statistically significant (all P<0.05); the differences in the diameter of GTVtb-Seroma and GTVtb-C+S on X, Z axis were statistically significant (all P<0.05); the difference in the diameter of GTVtb-Clip and GTVtb-Seroma on X axis was statistically significant ( P<0.05) .Neutral point displacement was (5.8±1.6) cm, (5.5±1.9) cm, (6.0±1.7) cm, respectively of GTVtb-Clip, GTVtb-Seroma, GTVtb-C+S, and the difference was not statistically significant ( P>0.05). Conformability of GTVtb-Clip and GTVtb-Seroma, GTVtb-Clip and GTVtb-C+S, GTVtb-Seroma and GTVtb-C+S was 0.412±0.112, 0.525±0.095, 0.774±0.112,respectively, and the differences were statistically significant (all P<0.05). Conclusions:During radiotherapy after breast-conserving surgery for breast cancer, compared with the single method, the combination of GTVtb-Clip and GTVtb-Seroma can better cover the real tumor bed, thus reducing the omission of tumor bed and recurrence rate. CT position should better take place at 4 to 8 weeks for patients receiving radiotherapy after breast-conserving surgery, and target volume of tumor bed will be delineated based on the postoperative changes of both mental clips and seroma.

Study on Plasma Protein Binding Rate of Cajanonic Acid A with Different Species of Plasma by Ultrafiltration Combined with UPLC-MS/MS / 中国药房

OBJECTIVE： To compare plasma protein binding rate of cajanonic acid A with different species of plasma. METHODS：Using UPLC-MS/MS as the detection means. Plasma protein binding rate of low， medium and high concentrations of cajanonic acid A （2.5， 5， 20 μg/mL） with rats， rabbits and human plasma were determined by ultrafiltration method. The chromatographic conditions included that Waters BEH C18 as chromatographic column， WatersVanGuard BEH C18 as guard column， mobile phase consisted of ultrapure water solution containing 0.01％ formic acid （solvent A） and acetonitrile solution of 0.01％ formic acid （solvent B） gradient elution， at the flow rate of 0.15 mL/min， column temperature of 30 ℃， sample size of 2 μL. Mass spectrum condition included that ESI， negative ion mode acquisition， capillary voltage of 1.5 kV， cone voltage of 30 V， ion source temperature of 100 ℃， desolvent gas temperature of 400 ℃， cone gas flow of 50 L/h， desolvent gas flow of 800 L/h， scanning range of m/z 50→1 200. RESULTS： At the concentration of 2.5， 5 and 20 μg/mL， the plasma protein binding rates of cajanonic acid A were （75.63±0.90）％， （98.30±0.03）％ and （99.42±0.01）％ in the rats plasma； （79.61±1.08）％， （98.48±0.10）％ and （99.42±0.03）％ in rabbits plasma （n＝3）； （76.74±1.22）％， （97.99±0.11）％ and （99.37±0.01）％ in human plasma （n＝3）. At the concentration of 2.5 μg/mL， plasma protein binding rates of cajanonic acid A in plasma of rats and human were significantly lower than that in plasma of rabbits （P＜0.05）. CONCLUSIONS： The plasma protein binding rate of 5，20 μg/mL cajanonic acid A with rats， rabbits and human plasma are higher than that of 2.5 μg/mL cajanonic acid A. There is significant difference in plasma protein binding rate of 2.5 μg/mL cajanonic acid A with different species of plasma，and there is no significant difference in plasma protein binding rate of 5， 20 μg/mL cajanonic acid A with different species of plasma.

Dosimetry Study of IMRT and 3D-CRT Radiotherapies for Patients with Upper Esophageal Carcinoma / 中国医学物理学杂志

Objective: To compare the difference of intensity modulated radiation therapy (IMRT),3-D imensional conformal radiation therapy (3DCRT) for patients with upper esophageal carcinoma. Methods: Ten patients with upper esophageal carcinoma were treated by intensity modulated radiation therapy and 3-D imensional conformal radiation therapy at the same TPS, the difference of exposure dose between target area and critical organ was compared by dose volume histogram(DVH) with the plan target volume (PTV) must reach 95% of the prescription dose. Results: There was significant difference in dose of 95% plan target volume (PTV) (P 0.05). Compared with 3D-CRT, IMRT planning has better dose distribution and protection of normal tissue. Conclusions: IMRT was better than 3DCRT, IMRT is the best radiation therapy.