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Objective To quantify the setup errors for the different anatomical sites of patients who received intensity-modulated radiotherapy (IMRT) with linear accelerator on-board kilovolt fan beam CT(kV-FBCT) as non-isocenter IGRT and megavolt cone beam CT (MV-CBCT) as isocenter IGRT. Methods A retrospective analysis was performedon 70 patients who underwent radiotherapy, kV-FBCT, and/or MV-CBCT scans after each routine setup prior to IMRT. The average displacement (M), systematic error (Σ), and random error (б) at different treatment sites in the left-right, anterior-posterior, and cranial-caudal directions were calculated according to the individual displacements. The formula 2.5Σ+0.7б was used to estimate the PTV margin in respective direction. For each single patient, the root mean square in three directions was used as 3D displacement. Results A total of 1130 displacements were recorded in the 70 patients. The PTV margin was estimated to be 1.9-3.1 mm in head and neck cancer, 2.8-5.1 mm in thoracic cancer, 4.6-5.1 mm in breast cancer, 3.0-5.5 mm in upper abdominal cancer, and 3.5-6.8 mm in pelvic tumor. For the 3D mean displacements, the head and neck, thoracic, breast, upper abdominal, and pelvic cancer were 2.4±1.0, 4.0±1.6, 4.1±2.0, 4.6±2.1, and 4.6±2.1 mm, respectively. The average 3D displacement obtained by kV-FBCT and MV-CBCT were 4.1 and 3.4 mm, respectively (P=0.212). Conclusion The quantitative setup-error data can be obtained using linear accelerator on-board FBCT, and the non-isocenter IGRT induced set-up error cannot be negligible.
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Photobiomodulation therapy (PBMT) is the use of red or near-infrared light to heal, restore, and stimulate physiological processes that repair damage caused by trauma or a disease. PBMT is widely used in sports injuries, arthritis, neuropathic pain, and back and neck pain. In recent years, PBMT is a safe and effective tool for toxic reactions associated with cancer treatment, such as oral mucositis in patients undergoing chemo-radiotherapy for head and neck cancer or stem cell transplantation, radiation-associated dry mouth, taste disorders, radiation dermatitis, post-radiotherapy fibrosis, and lymphedema associated with head and neck cancer and breast cancer. However, the equipment and optimal dosimetric parameters for PBMT have not been fully defined and need to be further explored.
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Objective To design a method for detecting multileaf collimator (MLC) leaf position accuracy in implementing a static intensity-modulated plan and to analyze the impacts of leaf errors on dose of targets and normal organs.Methods Static intensity-modulated planning for twenty lung cancer cases through dose verification was sorted in an ascending order according to the number of segment,and then the first and the last 10 plans were sorted as the simple plan group and the complex plan group,respectively.These plans were transmitted to a Varian 600CD accelerator and implemented by it.Photos were taken with PV aS500 electronic portal imaging device (EPID) and actual position of leafs was determined by gradient algorithm to calculate the pass rate for leaf verification.MLC files were modified according to examination results and the plans were re-calculated while keeping other parameters unchanged.Thus,difference of targets and normal organs dose distribution before and after the appearance of leaf errors were obtained.Results The dose distribution of most organs after leaf errors were increased or decreased,and the maximum dose of spinal cord in the sixth and thirteen cases exceeded the limit of 45 Gy.In the group of simple plan only the changes of maximum dose to the spinal cord were statistically significant(t =-3.08,P ＜ 0.05),while in the group of the complex plan all changes of D95％ of PGTV and PTV,maximum dose of the spinal cord,V20 of lung and V40 of heart were statistically significant(t =-1.89,-1.99,-2.36,-2.55,-1.85,P ＜ 0.05).Conclusions To ensure the safety and effects,it was necessary to detect leaf position,particularly the complex intensity-modulated planning.Electronic portal imaging devices and treatment planning system could detect leaf positions during the implementation of a plan and obtain the actual dose of targets and normal organs.
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Objective:To investigate the role of planning risk volume (PRV) in estimating the radiation dose for various cardiac substructures (CS). Methods:The CS of 23 patients with left-sided breast cancer who underwent postoperative intensity-modulated ra-diotherapy (IMRT) was delineated. PRV was expanded from CS with an additional margin determined by the mean amplitude of cardi-ac motion. Two IMRT plans were designed. The volume, mean dose, maximal dose (D2%), and standard deviation of CS and its PRV were calculated. Results:In comparison to the volume of CS, the PRV of the heart, specifically the left ventricle, increased by 50%to 80%, whereas the PRV of the main coronary arteries and sub-branches increased by 18.7 times to 42.6 times. In the two IMRT plans, the mean dose to the heart, anterior myocardial territory, anterior descending artery, and their corresponding PRVs ranged from 9.4 Gy to 11.4 Gy, 11.0 Gy to 17.5 Gy, and 22.6 Gy to 27.8 Gy, respectively. The D2%to CS and its PRV was 24.5 Gy to 36.2 Gy, 28.2 Gy to 38.8Gy, and 36 Gy to 45 Gy. The mean dose and D2%to the coronary arteries, including both left and right main coronary arteries, right marginal artery, and left circumflex artery, were 8.6 Gy to 14.9 Gy and 12.5 Gy to 23.7 Gy, respectively. The difference of the mean dose and D2%to CS and its corresponding PRVs was 2.5%to 12.5%and 8.0%to 43.1%, respectively. Compared with the stan-dard deviation of the radiation dose to CS, majority of the standard deviation to PRVs increased significantly. Conclusion:The radia-tion dose difference between CS and its corresponding PRVs is<12%.
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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.
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Objective To study the toxicity and efficacy of induction chemotherapy followed by concurrent cisplatin chemotherapy and three dimensional conformal radiotherapy (3DCRT) for inoperable locally advanced non-small cell lung cancer (LA-NSCLC). Methods Totally 76 patients with LA-NSCLC received two cycles induction chemotherapy followed by 3DCRT with a median dose of 68 Gy (64 to 74 Gy).During the 3DCRT, cisplatin (25 mg/m2, weekly) was given intravenously for 6-7 times. Results The CR rate, PR rate and overall response rate of induction chemotherapy were 3% ,42% and 45%. After the concurrent chemoradiation, the corresponding figures were 10%, 62% and 72%. The median survival time (MST) and median progression-free survival (PFS) of all patients were 16.6 months and 10.3 months. The 1-, 2- and 3-year overall survival (OS) and PFS rates were 67% , 35% , 21% and 42% , 15%, 6%. Of patients with stage ⅢA and stage ⅢB disease,the MST were 19.7 months and 15.6 months, the PFS were 10.8 months and 9.4 months. The major treatment-related toxicities included radiation esophagitis, radiation pneumonitis, nausea ( or vomiting) and leukopenia. The major pattern of treatment failure was distant metastasis. Forty-five patients (59%) experienced the local recurrence or/and distant metastasis, including 4 (9%) with in-field failure, 38 (84%) distant metastasis and 3 (7%) malignant pleural effusion. Conclusions Induction chemotherapy followed by concurrent weekly cisplatin and 3DCRT for inoperable locally advanced NSCLC results in encouraging outcomes and acceptable tolerance.