Cardiac volume reduction during radiotherapy in patients with esophageal carcinoma.

The present study investigated the factors contributing to cardiac volume reduction (CVR) during radiotherapy (RT) in patients with esophageal carcinoma (EC). This retrospective study included patients with EC treated at National Hospital Organization Shikoku Cancer Center (Matsuyama, Japan). Cardiac delineation was based on initial and off-cord boost (spinal cord-sparing approach) planning computed tomography images. The relationship between CVR and other relevant parameters was analyzed. A total of 58 patients with EC were investigated between January 2016 and January 2022. Univariate and multiple regression analyses revealed a statistically significant association between CVR during RT and the change ratio of the inferior vena cava (IVC) volume and body mass index (BMI) loss. In multivariate analysis of CVR of >10%, only the change in IVC volume exhibited a significant association. Conversely, CVR during RT displayed no association with heart dose-volume parameters, laboratory data, or changes in blood pressure and pulse rate. Among the 12 cases with CVR of >10%, the median movement of the left anterior descending coronary artery region (LADR) was 1.35 cm (range, 0.0-2.7 cm). In conclusion, CVR during RT was most strongly associated with changes in IVC volume, suggesting dehydration as the primary cause, rather than radiation-induced heart damage. LADR movement due to a CVR of >10% may lead to LADR radiation overdose.

Dosimetric predictors and Lyman normal tissue complication probability model of hematological toxicity in cervical cancer patients with treated with pelvic irradiation.

PURPOSE: To identify dosimetric parameters associated with acute hematological toxicity (HT) and identify the corresponding normal tissue complication probability (NTCP) model in cervical cancer patients receiving helical tomotherapy (Tomo) or fixed-field intensity-modulated radiation therapy (ff-IMRT) in combination with chemotherapy, that is, concurrent chemoradiotherapy (CCRT) using the Lyman-Kutcher-Burman normal tissue complication probability (LKB-NTCP) model. METHODS: Data were collected from 232 cervical cancer patients who received Tomo or ff-IMRT from 2015 to 2018. The pelvic bone marrow (PBM) (including the ilium, pubes, ischia, acetabula, proximal femora, and lumbosacral spine) was contoured from the superior boundary (usually the lumbar 5 vertebra) of the planning target volume (PTV) to the proximal end of the femoral head (the lower edge of the ischial tubercle). The parameters of the LKB model predicting ≥grade 2 hematological toxicity (Radiation Therapy Oncology Group [RTOG] grading criteria) (TD50 (1), m, and n) were determined using maximum likelihood analyses. Univariate and multivariate logistic regression analyses were used to identify correlations between dose-volume parameters and the clinical factors of HT. RESULTS: In total, 212 (91.37%) patients experienced ≥grade 2 hematological toxicity. The fitted normal tissue complication probability model parameters were TD50 (1) = 38.90 Gy (95%CI, [36.94, 40.96]), m = 0.13 (95%CI [0.12, 0.16]), and n = 0.04 (95%CI [0.02, 0.05]). Per the univariate analysis, the NTCP (the use of LKB-NTCP with the set of model parameters found, p = 0.023), maximal PBM dose (p = 0.01), mean PBM dose (p = 0.021), radiation dose (p = 0.001), and V16-53 (p < 0. 05) were associated with ≥grade 2 HT. The NTCP (the use of LKB-NTCP with the set of model parameters found, p = 0.023; AUC = 0.87), V16, V17, and V18 ≥ 79.65%, 75.68%, and 72.65%, respectively (p < 0.01, AUC = 0.66∼0.68), V35 and V36 ≥ 30.35% and 28.56%, respectively (p < 0.05; AUC = 0.71), and V47 ≥ 13.43% (p = 0.045; AUC = 0.80) were significant predictors of ≥grade 2 hematological toxicity from the multivariate logistic regression analysis. CONCLUSIONS: The volume of the PBM of patients treated with concurrent chemoradiotherapy and subjected to both low-dose (V16-18 ) and high-dose (V35,36 and V47 ) irradiation was associated with hematological toxicity, depending on the fractional volumes receiving the variable degree of dosage. The NTCP were stronger predictors of toxicity than V16-18 , V35, 36 , and V47 . Hence, avoiding radiation hot spots on the PBM could reduce the incidence of severe HT.

Dose-volume parameters and local tumor control in cervical cancer treated with central-shielding external-beam radiotherapy and CT-based image-guided brachytherapy.

Definitive radiotherapy for cervical cancer consists of external-beam radiotherapy (EBRT) and brachytherapy. In EBRT, a central shield (CS) reduces the dose to the rectum and bladder. The combination of whole-pelvic (WP)- and CS-EBRT and brachytherapy is the standard radiotherapy protocol in Japan. Despite clinical studies, including multi-institutional clinical trials, showing that the Japanese treatment protocol yields favorable treatment outcomes with low rates of late radiation toxicities, dose-volume parameters for the Japanese treatment protocol remain to be established. We conducted a retrospective dose-volume analysis of 103 patients with uterine cervical cancer treated with the Japanese protocol using computed tomography-based adaptive brachytherapy. The 2-year overall survival and 2-year local control rates according to FIGO stage were 100% and 100% for Stage I, 92% and 94% for Stage II, and 85% and 87% for Stage III-IV, respectively. Late adverse effects in the rectum and bladder were acceptable. Receiver operating characteristic analysis discriminated recurrence within the high-risk clinical target volume (HR-CTV) (n = 5) from no local recurrence (n = 96), with the optimal response obtained at a dose of 36.0 GyEQD2 for HR-CTV D90 and 28.0 GyEQD2 for HR-CTV D98. These values were used as cut-offs in Fisher exact tests to show that high HR-CTV D90 and HR-CTV D98 doses for brachytherapy sessions were significantly associated with tumor control within the HR-CTV. These data suggest a contribution of brachytherapy to local tumor control in WP- and CS-EBRT and brachytherapy combination treatment, warranting validation in multi-institutional prospective studies.

Comparison of relative and absolute rectal dose-volume parameters and clinical correlation with acute and late radiation proctitis in prostate cancer patients.

PURPOSE: To compare relative and absolute dose-volume parameters (DV) of the rectum and their clinical correlation with acute and late radiation proctitis (RP) after radiotherapy (RT) for prostate cancer (PCa). PATIENTS AND METHODS: 366 patients received RT for PCa. In total, 49.2% received definitive RT, 20.2% received postoperative RT and 30.6% received salvage RT for biochemical recurrence. In 77.9% of patients, RT was delivered to the prostate or prostate bed, and additional whole pelvic RT was performed in 22.1%. 33.9% received 3D-RT, and 66.1% received IMRT. The median follow-up was 59.5 months (18.0-84.0 months). The relative (in %) and absolute (in ccm) rectal doses from 20-75 Gy including the receiver operating characteristics curves (rAUC) from 30-65 Gy (in % and ccm) and several other clinical parameters were analyzed in univariate and multivariate analyses. We performed the statistical analyses separately for the entire cohort (n = 366), patients with (n = 81) and without (n = 285) pelvic RT, comparing RP vs. RP ≥ grade I. RESULTS: With the exception of the V50Gyccm (p = 0.02) in the univariate analyses for acute RP in the entire patient cohort, no absolute DV parameter (in ccm) was statistically significant associated with either acute or late RP. In the multivariate analyses, 3D-RT (p < 0.008) and rAUCV30-50 Gy% (p = 0.006) were significant parameters for acute RP for the entire cohort, and the V50Gy% (p = 0.01) was the significant parameter for patients with pelvic RT. The rAUCV40-50 Gy% (p = 0.004) was significant for RT to the prostate/prostate bed. Regarding the statistical analysis for late RP, the rAUCV30-65 Gy% (p = 0.001) was significant for the entire cohort, and rAUCV30-50 Gy% (p = 0.001) was significant for RT of the prostate/prostate bed. No parameter was significant in patients with pelvic RT. CONCLUSION: Absolute DV parameters in ccm are not required for RT in PCa patients.

Effect of tumor shape and location on lung volume-dose parameters of intensity-modulated radiation therapy for non-small cell lung cancer / 中华放射肿瘤学杂志

Objective@#To evaluate the effect of tumor shape and location on pulmonary dose-volume parameters by intensity-modulated radiation therapy (IMRT) in patients with non-small cell lung cancer (NSCLC), aiming to provide a reference basis for establishing limits of the pulmonary dose-volume parameters during IMRT.@*Methods@#Clinical data of 208 NSCLC patients undergoing radical IMRT from June 2009 to June 2016 were retrospectively analyzed. According to the tumor shape and location, 208 cases were divided into the vertical bar group (n=127) and the horizontal bar group (n=81), the superior lung group (n=103) and the inferior lung group (n=105). Regression model curve was used to evaluate the effect of tumor shape and location upon the common pulmonary dose-volume parameters(V5, V20, MLD, AVS5 and AVS20).@*Results@#In all groups, the fitting curves of V5, V20 and MLD were manifested in the quadratic equation pattern, and AVS5 and AVS20 in the logarithmic equation manner. In the vertical bar group, the V5(P=0.015), V20(P=0.047) and MLD (P=0.012) were significantly higher, whereas the AVS5(P=0.044) was significantly lower compared with those in the horizontal bar group. No statistical significance was observed in AVS20 between two groups (P=0.490). The tumor location exerted significant effect upon V5 alone (P=0.009).@*Conclusions@#When the tumors presents in the vertical bar shape, the limits of the common lung dose-volume parameters are likely to exceed those of tumors in the vertical bar shape. Lung tumors located in the inferior lobe exerts a more significant effect upon the low-dose region volume compared with the tumors in the superior lobe.

Analysis of the evaluation errors of dose-volume parameters for left ventricular myocardium in esophageal cancer radiotherapy / 中华放射肿瘤学杂志

Objective To evaluate the dynamic variation of the dose-volume parameters of the left ventricular myocardium following heart beat in radiotherapy for esophageal cancer. Methods The left ventricular myocardium of 22 patients was contoured on 20 phases (0％-95％) of electrocardiography (ECG) gated heart 4DCT images. The radiotherapy plan was designed on the simulation CT images,and then the dose distribution of radiotherapy plan was imported into MIM Maestro system and 4D dose-volume histogram (DVH) was reconstructed. The variations of position,volume and dice similarity coefficient (DSC) of the left ventricular myocardium were analyzed. The changing ranges of Dmean ,V10,V20 ,V30 and V40 of the left ventricular myocardium during different phases were statistically compared. Results ( 1 ) The biggest displacement of the left ventricular myocardium was in Y axes. The maximum variation rate of volume and DSC of the left ventricular myocardium were (24.23±11. 35)％ and (184.33±128. 61)％ in different phases with statistical significance (both P<0. 05).(2) The maximum variation rate of Dmean of the left ventricular myocardium was (87.05± 38. 34)％ in different phases with the highest rate of 163. 52％ with statistical significance (P<0. 05).(3) The maximum variation values of V10,V20,V30 and V40 of the left ventricular myocardium were (13.64±4. 33)％,(12.84±4. 55)％,(11.62±4. 85)％ and (3.63±2. 56)％ with statistical significance (all P<0. 05). Conclusions The impact of heart beat on the dose-volume parameters of the left ventricular myocardium should be considered during esophageal cancer radiotherapy. Traditional static 3DCT-based assessment of the dose-volume parameters of the left ventricular myocardium can yield relatively large errors, which is probably reduces the prediction efficiency of the dose-volume parameters for radiation-induced heart injury.

Effect of various methods determining lung volume and fraction dose on the lung dose-volume parameters / 中华放射肿瘤学杂志

Objective To study the effect of various methods determining lung volume and fraction dose on the lung dose-volume parameters for lung cancer patients. Methods Twenty patients with lung cancer were rantdomly enrolled into our study and the plan of three dimensional eonformal radiation therapy(3DCRT)was designed by Varian Eclipse TPS.The lung volumes and the dose-volume parameters were measured under CT value of-300- -980, -400- -980 and -500- -980.Under CT value of -400- -980,total lung volumes were confirmed.The dose-volume parameters of V30,V20,V10 and mean lung dose(MLD)were reevaluated after GTV,CTV and PTV were subtracted from the total lung volumes and when the fraction dose was elevated from 2.0 Gy to 10.0 Gy. Results When the CT value ranged from-300--980 to-500--980,the median reduction of the total lung volumes(-9.10%)was significantly higher than that of V30,V20,V10 and MLD(-3.18%,-1.13%,0.82%and-0.79%,respectively).When the total lung volume was fixed at CT value of-400--980,the alterations of V30,V20,V10 and MLD became more apparent as the increase of the subtracted lung volume,among which the alteration of V30 was most significant while V10 the least.Among five cases with a fixed total dose of 60 Gy and PTV less than 140 cm3,the V30,V20,V10 and MLD were increased to a similar extent(about 40%)when the fraction dose was increased from 2.0 Gy to 10.0 Gy.MLD was increased(36%)when the fraction dose was above 6.0 Gy. Conclusions When CT value ranges from-300- -980 to-500- -980,the total lung volume is influenced most.The alteration of V30,being statistically significant,might have some significance but is not enough to determine the plan of radiotherapy clinically.The alteration of V20、V10 and MLD is not statistically significant.When the overlapped target volume is subtracted from the total lung volumes,the alteration of V30 is the most sign:tifhcant while V10 the least.The fraction dose,being the most consuming factor(＞10%)when comparing with the CT valHe and targeted volume,can significantly influence the dose-volume parameter.