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PurposeTo assess the setup errors in radiation therapy for thoracic tumors patients of different somatotypes, and to seek an individualized mathematical basis for defining the planning target volume (PTV).MethodsSixty patients with thoracic tumors were divided into four somatotypes according to their body mass index (BMI), and their body positions were setup by two groups of technicians independently. CT simulations were performed and the reconstructed radiography was digitally generated as reference images for location verification and error measurement. By setting positioning error ranges, the within‐range positioning correction rate was compared among groups.ResultsPosition setups for patients in the emaciated group, moderate group, and overweight group were relatively stable (with minor setup error differences between the two groups of technicians). In emaciated group, moderate group, overweight group, and obese group, setup errors in the right–left direction (R‐L) were 2.2 ± 1.3 mm, 2.2 ± 1.6 mm, 3.9 ± 3.1 mm, and 8.8 ± 3.5 mm, respectively; whereas the setup errors in the four groups in the superior–inferior(S‐I) direction were 2.4 ± 1.8 mm, 2.1 ± 1.9 mm, 3.2 ± 2.6 mm, and 5.4 ± 3.5 mm, and in the anterior–posterior (A‐P) direction were 2.2 ± 1.7 mm, 1.9 ± 1.9 mm, 3.2 ± 2.9 mm, and 6.2 ± 4.2 mm, respectively. Moreover, in the moderate group, the positioning correction rate in the three directions (R‐L, S‐I, and A‐P) was 20%, 9%, 8% within the error range of 5–10 mm, and 3%, 0%, 1% with a more than 10 mm error range. However, in overweight group and obese group, the positioning correction rate in these three directions (also with a more than 10 mm error range) was 23%, 27%, 19% and 21%, 16%, 23%, respectively.ConclusionsIn radiation therapy for patients with thoracic tumors, the definition of PTV should be individualized. Meanwhile, with the increase in BMI, positioning correction rate has a tendency to rise too.

Background: Lung cancer is a leading cause of morbidity and mortality worldwide. Radiotherapy for lung cancer is beneficial in both the radical and palliative settings, and technologic advances in recent years now afford an opportunity for this treatment to be more targeted than ever before. Although the delivery of more accurate forms of radiotherapy has minimized the risks of side-effects, how to utilize this treatment to optimize outcomes remains questionable. This study aimed to evaluate the accuracy of cone beam computed tomography (CBCT) image registration used in image-guided radiotherapy, providing reasonable guidance for clinic application of CBCT in lung cancer. Methods: A total of 53 patients with lung carcinoma including 34 central and 19 peripheral lesions were collected in this study. Varian-IX linear accelerator on-board imaging (OBI) system was used to acquire CBCT scans in threedimensional (3D) conformal radiotherapy before delivery. Different regions (whole lung/target/vertebrae/ipsilateral structure) were manually registered, and the position deviation and the registration time were analyzed. Results: It was suggested that 34 cases belonged to central type and 19 cases belonged to peripheral type. The volume of left lung and right lung was 1242.98 ± 452.46 cc, 1689.69 ± 574.31 cc, respectively. Tumor size was 6.65 ± 3.87 cm in diameter, and 129.67 ± 136.48 cc in volume. The percentage of left lung and right lung was 6.17 ± 1.24%, 4.74 ± 0.38%, respectively. The position deviation value and absolute value of image registration methods of X, Y and Z axis were not significant (P > 0.05). However, registration time (s) between whole lung registration group, tumor registration group, vertebral body registration group, affected lung registration group, and artificial registration group, was 3.651 ± 0.867 s, 1.144 ± 0.129 s, 1.226 ± 0.126 s, 2.081 ± 0.427 s, 179.491 ± 71.975 s, respectively. The differences were significant (P < 0.05). The registration differences between small tumor group and large tumor group were not statistically significant (P > 0.05). Conclusion: The automatic image matching of OBI is accuracy and high reliability in recognition of offset error. Registering body or ipsilateral structure is recommended to be used in CBCT for lung cancer.

Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths worldwide. And radical synchronized chemoradiotherapy has become an important treatment measures for this disease. It is necessary to define the therapeutic target zone based on computer tomography(CT)-images for precise radiotherapy. Therefore, we retrospectively analyzed the regularity of lymph node metastasis in lower cervical section of thoracic esophageal cancer based on CT-images and discussed the range of radiotherapy in supraclavicular zone. The lower cervical lymphatic drainage area was divided into cervical tracheoesophageal groove (CTG), medial supraclavicular zone (MSC zone) and lateral supraclavicular zone (LSC zone) based on CT-images. We found that the rate of lymph node metastasis to medial CTG and MSC zone was relatively high. And rate of lymph node metastasis to the above two zones from middle thoracic section was on an increasing trend with the progress of T stage. Patients at stage T3 and T4 with lymph node metastasis in tracheoesophageal groove in middle thoracic section showed a higher rate of lymph node metastasis in MSC zone. These results demonstrated that the CTG and MSC zone should be clinically included in the supraclavicular target zone for radical radiotherapy, and the T-stage and tumor location should be considered simultaneously.

Concurrent chemoradiotherapy is one of the main treatments for rectal cancer. Bone marrow suppression is one of the critical factors that affect the progress of radiotherapy. We aimed to explore the association of incidence of acute bone marrow suppression with dose-volume parameters of pelvic bone marrow among rectal cancer patients with concurrent chemoradiotherapy. We retrospectively analyzed 50 rectal cancer patients for multivariate logistic regression analyses. Three subdomains of pelvic bone marrow (PBM), bilateral ilium (IBM), lower pelvis (LPBM), and lumbosacral spine (LSBM) were assigned. The radiation dose-volume parameters from the three subdomains and the whole pelvis were evaluated. Compared to Grade 0-1 leukopenia patients, ≥Grade 2 leukopenia patients exhibited significantly higher levels of IBM V20, V25, V35, mean dose (Dmean), LPBM V20, V25, V30, LSBM V15, PBM V15, V20, and PTV. The PBM V20 of ≥Grade 2 neutropenia patients was significantly higher than that of Grade 0-1 neutropenia patients. Multivariate analysis have demonstrated that IBM V20 and LSBM V15 were the independent factors affecting ≥ Grade 2 leukopenia. There is a correlation between low dose-volume parameters with acute bone marrow suppression. IBM V20, LSBM V15 and PBM V20 can be employed as the predictors of acute bone marrow suppression.

Background To compare the accuracy, advantages and disadvantages of automatic registration methods at different anatomical-sites for thoracic image-guided radiation therapy (IGRT). Methods The Varian-IX IGRT system was used to perform a manual registration of the images collected on the first fraction of 60 patients with lung cancer (42 cases central location and 18 cases of peripheral). The registered images were used as reference images. Offline registration was performed for computed tomography-CBCT images using four methods: whole image registration, ipsilateral registration, soft tissue tumor registration, and vertebral body registration. Time taken to complete and deviation value were analyzed between the different methods. Results There were significant differences in absolute deviation value of all the three directions ( P < 0.001) and the time consumption ( P < 0.001) between 4 methods. The Z direction had significant differences in deviation value of 4 methods (0.023 ± 0.128 mm, − 0.030 ± 0.175 mm, − 0.010 ± 0.238 mm, − 0.075 ± 0.137 mm, P = 0.011). The difference was significant in the X direction of the ipsilateral registration method between central and peripheral lung cancer (0.033 ± 0.053 mm vs. 0.067 ± 0.067 mm, P = 0.045). Conclusions The whole lung or affected side registration methods could be recommended to be used in the automatic registration function of the Varian-IX’s On-Board Imaging (OBI) system.

Purpose: To compare the dosimetric impact of coplanar intensity modulated radiation therapy (IMRT) and non-coplanar IMRT for the esophageal carcinoma. Methods: There are forty-five esophageal carcinoma patients, fifteen of whom were cervical and upper thoracic (Group 1) and thirty were middle and lower thoracic (Group 2). Gross tumor volume (GTV), clinical target volume (CTV), and organs at risk (OAR) were contoured by the chief physician in the CMS-XiO treatment planning system. For each patient, one coplanar plan and two non-coplanar plans have been created using the same physical objective function. A detailed dose-volume histogram (DVH) comparison among three plans was then carried out in a tabulated format. Results: 1) In Group 1 patients with PTV volume less than 100cc, the mean dose and dose gradient of non-coplanar plan were much better than those in coplanar plan. 2) In Group 2 patients, the conformity index (CI) for coplanar and two non-coplanar plans were 0.69 ± 0.13, 0.41 ± 0.13, and 0.68 ± 0.15, respectively. The V5, V10, V20, and the mean dose to the lung were lower in the non-coplanar plans compared to ones in coplanar plan. However, the non-coplanar plans resulted in an increase in a dose to the heart, but the dose was still within heart toxicity tolerance. Conclusion: For Group 1 patients, the non-coplanar IMRT plan had less dose gradient and better mean dose than the coplanar IMRT plan. For Group 2 patients, the non-coplanar IMRT could the decrease dose to the lung tissue, thus lowering the probability of radiation pneumonia to esophageal cancer patients. The drawback of non-coplanar IMRT is that, even within toxicity tolerance, it could deliver a higher dose to the heart and spinal cord compared to the coplanar plan. Therefore, for patients with cardiology and neurology concern, non-coplanar IMRT should be used with caution.

Background: Our aim was to analyze the effects of set-up errors on dose distribution in radiotherapy treatment for lung cancer by using kilovoltage cone-beam CT (CBCT). Materials and Methods: In this study, we used a Varian IX linear accelerator system to perform CBCT scans of 30 lung cancer patients before radiotherapy. Subsequently, the image was matched with the planned CT, and the left and right (LR), top and bottom (SI), and front and back (AP) directions were set incorrectly. And in the CMS planning system, the center of the plan has been moved to the center of the actual scan. Finally, the dose distribution before the bed-moving is simulated. We want to explore the impact of the planned target volume setting error (PTV), the total tumor volume (GTV), and radiation of normal tissues. Results: The set-up errors of the LR, SI and AP directions were (-0.20±2.84), (-1.09±5.40), and (-2.61±2.08) mm, respectively. The 5mm error accounted for 97.8%, 73% and 92.6% in the three directions. Statistically significant differences were found in the distribution of 95%PTV dose, the average dose of PTV, 95% GTV dose and the average dose of GTV without bed-moving, compared with the original plan. Conclusions: In clinical lung cancer radiotherapy, the commonly used setting error is usually less than 5mm, most of which are along the AP direction. In this study, we found that the setting error is related to the patient's inherent characteristics and can significantly change the radiation treatment dose in the target area.