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Objective@#To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs.@*Methods@#Totally 7 medical electronic linear accelerators from Varian, Siemens and Elekta were selected. The polystyrene phantom provided by IAEA was conducted with CT scan. After irradiation with 6 MV X-rays, the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.@*Results@#According to the IAEA requirements, the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0%. For PTV, the measured relative deviations for 5 accelerators were in the range of -4.0% to 3.4%, consistent with the IAEA requirements, whereas the values for the other 2 accelerators were in the range of -7.0% to 10.6%, not consistent with the requirements. For OAR, the values for 4 accelerators were in the range of -5.6% to 3.3%, consistent with the IAEA requirements, whereas the values for the other 3 accelerators were in the range of -20.8% to 11.5%, not meeting the requirements. As required by the IAEA, the 2D dose distribution 3 mm/3% pass rate should be higher than 90%. The measured values for 5 accelerators were in the range of 91.8% to 98.5%, consistent with the requirements, whereas the values measured for the other 2 were 45.0% and 77.0% respectively, not meeting the requirements.@*Conclusions@#It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT. This method should be applied to not only quality verification but also hospital internal audit to the extent possible.
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Objective@#To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT.@*Methods@#Eight accelerators of different models were selected in Henan province. The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR. IMRT was performed with phantom exposed to a 6 MV X-rays. The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.@*Results@#According to IAEA requirements, the relative deviations of the TLD-measured and TPS-planned values were within ±7.0% for the prescribed doses to PTV and OAR. The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within -0.3% to 6.9% for 8 accelerators, all consistent with the IAEA requirements. For OAR, the relative deviations of TLD-measured and TPS-planned were within -7.0% to 0.3% for 6 accelerators, consistent with the requirements, whereas those for other 2 accelerators were within -10.8% to -8.4%, not up to the requirements. IAEA required that, for 2D dose distribution, the pass rate of 3 mm/3% be ≥90%. The measured values for 7 accelerators were from 90.2% to 99.9%, consistent with the requirements, whereas that for another one was 70.0%, not meeting the requirement.@*Conclusions@#The method to verify, using radiochromic film and TLD, the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable. It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.
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Objective@#To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose.@*Methods@#Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province. A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU. After the phantom was irradiated with 6 MV X-ray, the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.@*Results@#The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0%. For PTV, the measured-to-planned deviation values for 7 accelerator were within -5.4% to 6.5%, all consistent with the IAEA requirements. For OAR, the values for 5 accelerators were within -2.2% to 6.7%, not consistent the requirements, whereas the values for the other 2 were -8.6% and 8.2% respectively, beyond the required values. The IAEA required that the 2D dose distribution 3 mm/3% pass rate be higher than 90%. The measured values for 7 accelerators were in the range of 90.3%-98.9%, all consistent with the requirements.@*Conclusions@#It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT. It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.
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Objective@#To validate the method for measuring the TPV and OAR doses and 2D dose distribution in IMRT through using TLD and radiochromic film.@*Methods@#Eight medical linear accelerators (Valian, Elekta, Siemens) were selected. The polystyrene phantom provided by IAEA was CT scanned and the image obtained was transferred to TPS for formulation of treatment plan, prescription of PTV and OAR doses and calculation of corresponding monitoring unit (MU), IMRT was performed on the phantom using 6 MV X-ray. Irradiated TLDs and films were measured and evaluated at the Secondary Standard Dosimetry Laboratory at the Radiation Safety Institute of Chinese Center for Disease Control and Prevention.@*Results@#According to IAEA requirement, the relative deviations between TLD-measured and TPS-planned doses were within ±7.0% for the prescribed PTV and OAR doses. As measured result, the PTV values for 8 accelerators were in the range of 0.6% to 5.9%, consistent with the IAEA requirements, whereas the OAT values for 8 accelerators were within -0.6% to 7.0%, consistent the requirements. As IAEA required, the 2D dose distribution passing rate of 3 mm/3% should be higher than 90%. The film-measured and TPS-planned values for 8 accelerators were within 90.2% to 100.0%, consistent with the requirements.@*Conclusions@#TLD and radiochromic film are feasible in validating the PTV and OAR doses and the 2D dose distribution pass rate in IMRT. This method can be widely used in quality audit and internal verification in IMRT in medical institutiions on a large scale.
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Objective@#To develop the methodology for using TLD and radiochromic film to measure the planned target volume (PTV) and organ at risk (OAR) doses and 2D dose distribution in IMRT, in order to provide technical guidance on the dose quality audit in IMRT at home.@*Methods@#China has participated in the research project launched by the international multi-radiotherapy centre (IMRC). IMRT polystyrene phantom provided by IAEA was scanned by CT scanner and then the scanned images were transmitted to TPS to outline prescribed dose to PTV and to OAR. The former was limited to 400 cGy while the latter limited to 200 cGy. IMRT was implemented with the phantom irradiated using 6 MV X-ray. The irradiated TLDs and films were sent to IAEA dosimerty laboratory for measurement and calculation. Jiangsu, Sichuan, Hubei and Henan provinces were selected to engage with this study for their variety of accelerators and highly skilled physicists. The procedures used were the same as in the IMRC and the irradiated TLDs and films were required to send to external audit group for measurement and calculation.@*Results@#According to IAEA requirement, the relative deviations of the TLD-measured and TPS planned doses are within ±7.0% for PTV and OAR. The China′s research results at the IMRC have shown that the relative deviation of TLD-measured and TPS-planned values for the upper and lower PTV were -0.2% and 0.8%, respectively, consistent with the IAEA requirement, and the values for upper and lower OAR were -0.6% and -1.0%, respectively, consistent with the requirement. As the results have shown in four provinces, the relative deviations of the TLD-measured and TPS-planned were within 0 to 10.6% for upper and lower PTV and -0.6% to 20.9% for upper and lower OAR. According to IAEA requirement, the passing rate should be greater than 90% for 3 mm /3% for 2D dose distribution. China′s result at the IMRC is 100%, being excellent. The four provinces′ results have shown that 2D dose distribution pass rate of 3 mm/3% was in the range of 45.0%-100.0%.@*Conclusions@#The uses of TLD in quality audit for PTV and OAR doses and the radiochromic film in 2D dose distribution pass rate in IMRT are characterized by scientific feasibility, strong operability, easy-to-mail and data realibility. They are can be applied to quality assurance and audit in medical institutions in the country to on a large scale.
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Objective To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs.Methods Totally 7 medical electronic linear accelerators from Varian,Siemens and Elekta were selected.The polystyrene phantom provided by IAEA was conducted with CT scan.After irradiation with 6 MV X-rays,the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results According to the IAEA requirements,the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0％.For PTV,the measured relative deviations for 5 accelerators were in the range of-4.0％ to 3.4％,consistent with the IAEA requirements,whereas the values for the other 2 accelerators were in the range of-7.0％ to 10.6％,not consistent with the requirements.For OAR,the values for 4 accelerators were in the range of-5.6％ to 3.3％,consistent with the IAEA requirements,whereas the values for the other 3 accelerators were in the range of-20.8％ to 11.5％,not meeting the requirements.As required by the IAEA,the 2D dose distribution 3 mm/3％ pass rate should be higher than 90％.The measured values for 5 accelerators were in the range of 91.8％ to 98.5％,consistent with the requirements,whereas the values measured for the other 2 were 45.0％ and 77.0％ respectively,not meeting the requirements.Conclusions It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT.This method should be applied to not only quality verification but also hospital internal audit to the extent possible.
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Objective To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT.Methods Eight accelerators of different models were selected in Henan province.The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR.IMRT was performed with phantom exposed to a 6 MV X-rays.The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention.Results According to IAEA requirements,the relative deviations of the TLD-measured and TPS-planned values were within ±7.0％ for the prescribed doses to PTV and OAR.The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within-0.3％ to 6.9％ for 8 accelerators,all consistent with the IAEA requirements.For OAR,the relative deviations of TLD-measured and TPS-planned were within-7.0％ to 0.3％ for 6 accelerators,consistent with the requirements,whereas those for other 2 accelerators were within-10.8％ to-8.4％,not up to the requirements.IAEA required that,for 2D dose distribution,the pass rate of 3 mm/3％ be ≥ 90％.The measured values for 7 accelerators were from 90.2％ to 99.9％,consistent with the requirements,whereas that for another one was 70.0％,not meeting the requirement.Conclusions The method to verify,using radiochromic film and TLD,the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable.It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.
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Objective To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose.Methods Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province.A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU.After the phantom was irradiated with 6 MV X-ray,the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0％.For PTV,the measured-to-planned deviation values for 7 accelerator were within-5.4％ to 6.5％,all consistent with the IAEA requirements.For OAR,the values for 5 accelerators were within-2.2％ to 6.7％,not consistent the requirements,whereas the values for the other 2 were-8.6％ and 8.2％ respectively,beyond the required values.The IAEA required that the 2D dose distribution 3 mm/3％ pass rate be higher than 90％.The measured values for 7 accelerators were in the range of 90.3％-98.9％,all consistent with the requirements.Conclusions It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT.It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.
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Objective To validate the method for measuring the TPV and OAR doses and 2D dose distribution in IMRT through using TLD and radiochromic film.Methods Eight medical linear accelerators (Valian,Elekta,Siemens) were selected.The polystyrene phantom provided by IAEA was CT scanned and the image obtained was transferred to TPS for formulation of treatment plan,prescription of PTV and OAR doses and calculation of corresponding monitoring unit (MU),IMRT was performed on the phantom using 6 MV X-ray.Irradiated TLDs and films were measured and evaluated at the Secondary Standard Dosimetry Laboratory at the Radiation Safety Institute of Chinese Center for Disease Control and Prevention.Results According to IAEA requirement,the relative deviations between TLD-measured and TPS-planned doses were within ±7.0％ for the prescribed PTV and OAR doses.As measured result,the PTV values for 8 accelerators were in the range of 0.6％ to 5.9％,consistent with the IAEA requirements,whereas the OAT values for 8 accelerators were within-0.6％ to 7.0％,consistent the requirements.As IAEA required,the 2D dose distribution passing rate of 3 mm/3％ should be higher than 90％.The filmmeasured and TPS-planned values for 8 accelerators were within 90.2％ to 100.0％,consistent with the requirements.Conclusions TLD and radiochromic film are feasible in validating the PTV and OAR doses and the 2D dose distribution pass rate in IMRT.This method can be widely used in quality audit and internal verification in IMRT in medical institutiions on a large scale.
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Objective To develop the methodology for using TLD and radiochromic film to measure the planned target volume (PTV) and organ at risk (OAR) doses and 2D dose distribution in IMRT,in order to provide technical guidance on the dose quality audit in IMRT at home.Methods China has participated in the research project launched by the international multi-radiotherapy centre (IMRC).IMRT polystyrene phantom provided by IAEA was scanned by CT scanner and then the scanned images were transmitted to TPS to outline prescribed dose to PTV and to OAR.The former was limited to 400 cGy while the latter limited to 200 cGy.IMRT was implemented with the phantom irradiated using 6 MV X-ray.The irradiated TLDs and films were sent to IAEA dosimerty laboratory for measurement and calculation.Jiangsu,Sichuan,Hubei and Henan provinces were selected to engage with this study for their variety of accelerators and highly skilled physicists.The procedures used were the same as in the IMRC and the irradiated TLDs and films were required to send to external audit group for measurement and calculation.Results According to IAEA requirement,the relative deviations of the TLD-measured and TPS planned doses are within ±7.0％ for PTV and OAR.The China's research results at the IMRC have shown that the relative deviation of TLD-measured and TPS-planned values for the upper and lower PTV were-0.2％ and 0.8％,respectively,consistent with the IAEA requirement,and the values for upper and lower OAR were -0.6％ and-1.0％,respectively,consistent with the requirement.As the results have shown in four provinces,the relative deviations of the TLD-measured and TPS-planned were within 0 to 10.6％ for upper and lower PTV and-0.6％ to 20.9％ for upper and lower OAR.According to IAEA requirement,the passing rate should be greater than 90％ for 3 mm /3％ for 2D dose distribution.China's result at the IMRC is 100％,being excellent.The four provinces' results have shown that 2D dose distribution pass rate of 3 mm/3％ was in the range of 45.0％-100.0％.Conclusions The uses of TLD in quality audit for PTV and OAR doses and the radiochromic film in 2D dose distribution pass rate in IMRT are characterized by scientific feasibility,strong operability,easy-to-mail and data realibility.They are can be applied to quality assurance and audit in medical institutions in the country to on a large scale.
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Purpose: To assess the potential advantage of intensity-modulated radiotherapy (IMRT) over 3D-conformal radiotherapy (3D-CRT) planning in postoperative adjuvant radiotherapy for patients with gastric carcinoma. Methods and materials: In a retrospective study, for plan comparison, dose distribution was recalculated in 15 patients treated with 3D-CRT on the contoured structures of same CT images using an IMRT technique. 3D-conformal plans with three fields and four-fields were compared with seven-field dynamic IMRT plans. The different plans were compared by analyzing the dose coverage of planning target volume using TV95, Dmean, uniformity index, conformity index and homogeneity index parameters. To assess critical organ sparing, Dmean, Dmax, dose to one-third and two-third volumes of the OARs and percentage of volumes receiving more than their tolerance doses were compared. Results: The average dose coverage values of PTV with 3F-CRT and 4F-CRT plans were comparable, where as IMRT plans achieved better target coverage(p<0.001) with higher conformity index value of 0.81±0.07 compared to both the 3D-CRT plans. The doses to the liver and bowel reduced significantly (p<0.001) with IMRT plans compared to other 3D-CRT plans. For all OARs the percentage of volumes receiving more than their tolerance doses were reduced with the IMRT plans. Conclusion: This study showed that a better target coverage and significant dose reduction to OARs could be achieved with the IMRT plans. The IMRT can be preferred with caution for organ motion. The authors are currently studying organ motion in the upper abdomen to use IMRT for patient treatment.