AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC ...AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning sys- tem： three using c-IMRT with 5 fields （5F）, 7 fields （7F） and 9 fields （gF）, and two using VMAT with a single arc （1A） and double arcs （2A）. The treatment plans were designed to deliver a dose of 60 Gy to the plan-ning target volume （PTV） with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normal- ized to 95% of the PTV that received 100% of the pre- scribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk （OAR） such as lungs, spinal cord and heart. Monitor units （MU） and normal tissue complication probability （NTCP） of OAR were also reported. RESULTS： Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different Io- cations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions： in cervical and upper thoracic EC, the conformity index （CI） was higher in VMAT （1A 0.78 and 2A 0.8） than in c-IMRT （5F 0.62, 7F 0.66 and 9F 0.73） and homogeneity was slightly better in c-IMRT （7F 1.09 and 9F 1.07） than in VMAT （1A 1,1 and 2A 1.09）, Lung V30 was lower in VMAT （1A 12.52 and 2A 12.29） than in c-IMRT （7F 14.35 and 9F 14.81）. The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT （1A 0.76 and 2A 0.74） was higher than in c-IMRT （5F 0.63 Gy and 7F 0.67 Gy）, and homogeneity was almost similar between VMAT and c-IMRT. V20 （2A 21.49 Gy vs 7F 24.59 Gy and 9F 24.16 Gy） and V30 （2A 9.73 Gy vs 5F 12.61 Gy, 7F 11.5 Gy and 9F 11.37 Gy） of lungs in VMAT were lower than in c-IMRT, but low doses to lungs （V5 and Vl0） were increased. V30 （1A 48.12 Gy vs 5F 59.2 Gy, 7F 58.59 Gy and 9F 57.2 Gy）, V40 and V50 of heart in VMAT was lower than in c-IMRT. MUs in VMAT plans were significantly reduced in comparison with c-IMRT, maximum doses to the spinal cord and mean doses of lungs were similar between the two techniques. NTCP of spinal cord was 0 for all cases. NTCP of lungs and heart in VMAT were lower than in c-IMRT. The advantage of VMAT plan was enhanced by doubling the arc. CONCLUSION： Compared with c-IMRT, VMAT, especial- ly the 2A, slightly improves the OAR dose sparing, such as lungs and heart, and reduces NTCP and MU with a better PTV coverage.展开更多
We reported a special case of a locally advanced squamous cell carcinoma of the left lung. Due to pulmonary tuberculosis, the patient had underwent a complete right-side pulmonary lobectomy 20 years ago. Left lung sup...We reported a special case of a locally advanced squamous cell carcinoma of the left lung. Due to pulmonary tuberculosis, the patient had underwent a complete right-side pulmonary lobectomy 20 years ago. Left lung supports his life, he is unable to carry on an operation treatment, so he accepted radiotherapy. Firstly, we defined gross tumor volume (GTV1) by CT simulation location, three-dimensional conformal radiotherapy (3D-CRT) was used until tumor dose reached 50 Gy/25 f. Secondly, by repeating the planning CT scan, defined GTV2, continued to radiotherapy by 2.5 Gy/f until the dose was 65 Gy/31 f. Using the same method for third CT scan, defined GTV3, continued to radiotherapy by 3 Gy/f until the total dose was 74 Gy/34 f. After radiotherapy, the patient acquired complete response and he had no obvious side-effect of radiotherapy. There has been no recurrence for 5 years now.展开更多
Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of ti...Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT （slMRT） planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy （V5, Vl0, V2o, V30, V50）, and mean lung dose （MLD） were analyzed and compared. Results： For the dose-volume parameters, the diameter and the position of the tumor had a significant effect （P 〈 0.05）. With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion： Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.展开更多
基金Supported by The National Natural Science Foundation of China, No. 30870738
文摘AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning sys- tem： three using c-IMRT with 5 fields （5F）, 7 fields （7F） and 9 fields （gF）, and two using VMAT with a single arc （1A） and double arcs （2A）. The treatment plans were designed to deliver a dose of 60 Gy to the plan-ning target volume （PTV） with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normal- ized to 95% of the PTV that received 100% of the pre- scribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk （OAR） such as lungs, spinal cord and heart. Monitor units （MU） and normal tissue complication probability （NTCP） of OAR were also reported. RESULTS： Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different Io- cations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions： in cervical and upper thoracic EC, the conformity index （CI） was higher in VMAT （1A 0.78 and 2A 0.8） than in c-IMRT （5F 0.62, 7F 0.66 and 9F 0.73） and homogeneity was slightly better in c-IMRT （7F 1.09 and 9F 1.07） than in VMAT （1A 1,1 and 2A 1.09）, Lung V30 was lower in VMAT （1A 12.52 and 2A 12.29） than in c-IMRT （7F 14.35 and 9F 14.81）. The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT （1A 0.76 and 2A 0.74） was higher than in c-IMRT （5F 0.63 Gy and 7F 0.67 Gy）, and homogeneity was almost similar between VMAT and c-IMRT. V20 （2A 21.49 Gy vs 7F 24.59 Gy and 9F 24.16 Gy） and V30 （2A 9.73 Gy vs 5F 12.61 Gy, 7F 11.5 Gy and 9F 11.37 Gy） of lungs in VMAT were lower than in c-IMRT, but low doses to lungs （V5 and Vl0） were increased. V30 （1A 48.12 Gy vs 5F 59.2 Gy, 7F 58.59 Gy and 9F 57.2 Gy）, V40 and V50 of heart in VMAT was lower than in c-IMRT. MUs in VMAT plans were significantly reduced in comparison with c-IMRT, maximum doses to the spinal cord and mean doses of lungs were similar between the two techniques. NTCP of spinal cord was 0 for all cases. NTCP of lungs and heart in VMAT were lower than in c-IMRT. The advantage of VMAT plan was enhanced by doubling the arc. CONCLUSION： Compared with c-IMRT, VMAT, especial- ly the 2A, slightly improves the OAR dose sparing, such as lungs and heart, and reduces NTCP and MU with a better PTV coverage.
文摘We reported a special case of a locally advanced squamous cell carcinoma of the left lung. Due to pulmonary tuberculosis, the patient had underwent a complete right-side pulmonary lobectomy 20 years ago. Left lung supports his life, he is unable to carry on an operation treatment, so he accepted radiotherapy. Firstly, we defined gross tumor volume (GTV1) by CT simulation location, three-dimensional conformal radiotherapy (3D-CRT) was used until tumor dose reached 50 Gy/25 f. Secondly, by repeating the planning CT scan, defined GTV2, continued to radiotherapy by 2.5 Gy/f until the dose was 65 Gy/31 f. Using the same method for third CT scan, defined GTV3, continued to radiotherapy by 3 Gy/f until the total dose was 74 Gy/34 f. After radiotherapy, the patient acquired complete response and he had no obvious side-effect of radiotherapy. There has been no recurrence for 5 years now.
文摘Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT （slMRT） planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy （V5, Vl0, V2o, V30, V50）, and mean lung dose （MLD） were analyzed and compared. Results： For the dose-volume parameters, the diameter and the position of the tumor had a significant effect （P 〈 0.05）. With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion： Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.
