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Retrospective Analysis of the Relationship between Bone Marrow Dose Volume Parameters and Acute MyelosuppressionObjective:The correlation between dose volume of bone marrow cavity and acute myelosuppression in patients with cervical cancer receiving VMAT radiotherapy was analyzed retrospectively.Methdos:A total of 50 patients with cervical cancer who received simultaneous radiotherapy and chemotherapy in our hospital from 2018.07 to 2019.04 were randomly selected by EXCEL table,including 8 patients with?-?A stage and 42 patients with ?B-? stage,with a median age of 54 years.All patients were treated with cisplatin 40mg/m2 weekly regimen and external radiotherapy with VMAT radiotherapy combined with 192 Ir high dose rate intracavitary brachytherapy.The bone marrow cavities of all patients were delineated and the dose parameters of bone marrow cavities were calculated in the radiotherapy planning system Elekta Monaco.Chi-square test was used to analyze the general data of patients.T-test and logistic regression were used to analyze the correlation between bone marrow dosimetry parameters(V5,V10,V15,V20,V25,V30,V35,V40,V45,V50,Dmean)and the incidence of acute myelosuppression,and the critical value was determined by ROC curve.Results:1.The white blood cell count of 50 patients before radiotherapy was 6.96±2.51*109/L and decreased rapidly to 4.23±2.29*109/L when 2-3 weeks after the beginning of radiotherapy,and there was no significant decrease in the course of follow-up treatment.The platelet decreased from 231.42±77.42*109/L before radiotherapy to less than 140.06±62.67*109/L when 2-3 weeks after the beginning of radiotherapy,and the follow-up was basically stable.Hemoglobin decreased from 115.42±17.65g/L before radiotherapy to 107.66± 15.60g/L when 2-3 weeks after the beginning of radiotherapy,and continued to decrease to 102.82±17.49g/L during follow-up treatment.2.Among the 50 patients,the incidence of grade 2 and above myelosuppression was 76%(38/50),and the incidence of severe myelosuppression(3-4)was 42%(21/50).Univariate analysis showed thatV30,V35,V40 and V45 in patients with myelosuppression of grade 2 and above(53.00±6.84%,41.45±8.09%,29.71±7.95%,18.73±6.33%)were significantly higher than those of patients with myelosuppression below grade 2(46.08±9.43%,33.52±10.10%,20.48±8.01%,11.70±7.22%).P values were 0.008,0.008,0.008 and 0.002.Through multivariate analysis,it was found that there was a significant correlation between bone marrow irradiation dose V40 and grade 2 and above acute myelosuppression(P=0.018,<0.05).The threshold of bone marrow V40 was determined to be 30%by ROC curve and Jordan index.Conclusion:Bone marrow radiation dose V40 is significantly related to grade 2 and above acute myelosuppression in patients with cervical cancer undergoing simultaneous radiotherapy and chemotherapy.Limiting the radiation dose of V40 to less than 30%in the process of radiotherapy is expected to reduce the incidence of acute myelosuppression of grade 2 and above to a certain extent,and its clinical observation results need to be further studied.Part ? VMAT Radiotherapy Planning Strategy of Simultaneous Radiochemotherapy for Bone Marrow-protected in Middle-aged and Elderly Patients with Cervical CancerObjective:The dose volume parameters,target suitability and uniformity of endangered organs and target among pelvic limited plan,bone marrow limited plan and non-pelvic and bone marrow limited plan were compared and analyzed,and the relatively excellent bone marrow limited protection mode was explored.Methdos:Eight patients with cervical cancer who received radical radiotherapy in our hospital from 2019.05 to 2019.08 were selected by random table,with a median age of 60 years(51 to 78 years),1 patient of IIA stage and 7 patients in IIB-IV stage.The pelvis and bone marrow cavity were delineated in the radiotherapy planning system Elekta Monaco,and three groups of VMAT plans were made.one group of plans were not limited to the pelvis and bone marrow cavity,and the other two groups were limited to the pelvis and bone marrow cavity respectively.The other limit parameters of the endangered organs and the prescription dose requirements of the target area of the three groups were consistent.After the completion of the plan,the three groups of plans were normalized according to 95%CTV to receive 5000cGy.Three groups of dosimetric parameters of planned bladder,rectum and bone marrow volume(V5,V10,V15,V20,V25,V30,V45,V50,Dmean);PTV CI and HI;PTV dosimetry parameters(V110,V105);Planned maximum dose(Dmax)were collected.And further use the analysis of variance to analyze and compare the above parameters.Results:Compared with the three groups of plans,the bone marrow dosimetry parameters V25,V30,V35,V40,V45,V50,Dmean(46.99±7.13,34.24±6.28,23.08±4.62,14.50±3.87,7.87±3.21,3.09±2.29,25.40±2.02)in the bone marrow cavity limited group were lower than those in the pelvic limited group(58.20±3.32,49.51±3.75,38.78±3.71,28.04±4.02,9.26±2.95,29.39±1.72).P values were 0.000,0.000,0.000,0.000,0.000,0.000,0.001.It was also lower than that in the unrestricted group(64.20±5.16,53.70±5.96,41.63±6.75,30.03±6.48,18.88±4.87,7.50±3.54,31.59±2.37),P values were 0.001,0·000,0.000,0.000,0.000,0.000,0.000,0.007,0.000.The HI of bone marrow cavity limited group(1.231±0.485)was worse than that of unlimited group(1.164 ±0.024).The PTV V110%in the pelvic limited group was higher than that in the unlimited group(P=0.000,<0.05),and the PTV V105%in the pelvic limited group was higher than that in the unlimited group(P=0.023,<0.05.The PTV V105%in the pelvic limited group was significantly higher than that in the unlimited group(P=0.000,<0.05),and the PTV V105%in the pelvic limited group was higher than that in the unlimited group(P=0.023,<0.05).There was no significant difference in dosimetric parameters of bladder and rectum,CI,and Dmax among the three groups.Conclusion:Using VMAT technology to make a plan,delineating the bone marrow cavity and pelvis with limited protection of bone marrow can reduce the radiation dose of pelvic bone marrow,but does not significantly affect the dose of bladder and rectum and the suitability of the target area.Among them,the dose of bone marrow cavity limit is more lower than that of pelvic limit plan.The PTV HI of bone marrow limited plan was worse than that of unlimited plan,and the pelvic limited plan could improve the V110 and V105 of PTV target.In the VMAT plan design,the limited amount of bone marrow cavity and pelvis can be used to make cervical cancer radiotherapy plan to reduce the bone marrow radiation dose,hopefully to reduce the incidence of severe myelosuppression and improve the quality of life of patients after treatment. |
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