Tumor models were simulated in purebred Beagles at the T9-10 levels of the spinal cord and treated with spinal image-guided radiation therapy or conventional radiation therapy with 50 or 70 Gy total radiation. Three m...Tumor models were simulated in purebred Beagles at the T9-10 levels of the spinal cord and treated with spinal image-guided radiation therapy or conventional radiation therapy with 50 or 70 Gy total radiation. Three months after radiation, neuronal injury at the T9-10 levels was observed, including reversible injury induced by spinal image-guided radiation therapy and apoptosis induced by conventional radiation therapy. The number of apoptotic cells and expression of the proapoptotic protein Fas were significantly reduced, but expression of the anti-apoptotic protein heat shock protein 70 was significantly increased after image-guided radiation therapy compared with the conventional method of the same radiation dose. Moreover, the spinal cord cell apoptotic index positively correlated with the ratio of Fas/heat shock protein 70. These findings indicate that 3 months of radiation therapy can induce a late response in the spinal cord to radiation therapy; image-guided radiation therapy is safer and results in less neuronal injury compared with conventional radiation therapy.展开更多
The reproducibility of patient setup is an important issue for head and neck cancers treated with intensity-modulated radiation therapy (IMRT). In this study, an image-guided radiation therapy (IGRT) system has been u...The reproducibility of patient setup is an important issue for head and neck cancers treated with intensity-modulated radiation therapy (IMRT). In this study, an image-guided radiation therapy (IGRT) system has been used to minimize the uncertainty of patient setup while standard thermoplastic masks were used to provide adequate immobilization for the head and neck. However, they do not provide sufficient immobilization of the shoulders, which is an important requirement in comprehensive nodal irradiation. Therefore, we investigated the setup and rotational shifts in head and neck cancer patients undergoing IMRT for which this immobilization device had been used together with an IGRT system. The setup and rotational shifts of patients were analyzed using the ExacTrac X-ray 6D IGRT system. The patients were classified as having head and neck tumors in the upper or lower regions. The upper neck nodes included lymph nodal level II while the lower neck nodes included lymph nodal levels III and IV. Clinical data from 227 treatment sessions of 12 head and neck cancer patients were analyzed. The random translational error in inter-and intra-fraction errors of the anterio-posterior (AP) direction might influence the rotational errors of pitch and roll in the upper region. At the same time, the random translational error in the inter-and intra-fraction errors of the AP direction might influence the rotational error of roll in the lower region. We believe that these random translational errors should be considered during treatment. We found variability in random translational errors for different regions in the anatomy of head and neck cancer patients due to rotational shifts. Depending on the location of the primary lesion or the selected nodal treatment targets, these relative positional variations should be considered when setup and rotational shifts are corrected with IGRT systems before treatment.展开更多
Primary and metastatic liver cancer is an increasingly common and difficult to control disease entity.Radiation offers a non-invasive treatment alternative for these patients who often have few options and a poor prog...Primary and metastatic liver cancer is an increasingly common and difficult to control disease entity.Radiation offers a non-invasive treatment alternative for these patients who often have few options and a poor prognosis.However,the anatomy and aggressiveness of liver cancer poses significant challenges such as accurate localization at simulation and treatment,management of motion and appropriate selection of dose regimen.This article aims to review the options available and provide information for the practical implementation and/or improvement of liver cancer radiation programs within the context of stereotactic body radiotherapy and image-guided radiotherapy guidelines.Specific patient inclusion and exclusion criteria are presented given the significant toxicity found in certain sub-populations treated with radiation.Indeed,certain sub-populations,such as those with tumor thrombosis or those with larger lesions treated with transarterial chemoembolization,have been shown to have significant improvements in outcome with the addition of radiation and merit special consideration.Implementing a liver radiation programrequires three primary challenges to be addressed:(1) immobilization and motion management;(2) localization;and(3) dose regimen and constraint selection.Strategies to deal with motion include simple internal target volume(ITV) expansions,non-gated ITV reduction strategies,breath hold methods,and surrogate marker methods to enable gating or tracking.Localization of the tumor and organs-at-risk are addressed using contrast infusion techniques to take advantage of different normal liver and cancer vascular anatomy,imaging modalities,and margin management.Finally,a dose response has been demonstrated and dose regimens appear to be converging.A more uniform approach to treatment in terms of technique,dose selection and patient selection will allow us to study liver radiation in larger and,hopefully,multicenter randomized studies.展开更多
Stereotactic body radiotherapy(SBRT) is a widely accepted option for the treatment of medically inoperable early-stage non-small cell lung cancer(NSCLC).Herein,we highlight the importance of interfraction image guidan...Stereotactic body radiotherapy(SBRT) is a widely accepted option for the treatment of medically inoperable early-stage non-small cell lung cancer(NSCLC).Herein,we highlight the importance of interfraction image guidance during SBRT.We describe a case of earlystage NSCLC associated with segmental atelectasis that translocated 15 mm anteroinferiorly due to re-expansion of the adjacent segmental atelectasis following the first fraction.The case exemplifies the importance of crosssectional image-guided radiotherapy that shows the intended target,as opposed to aligning based on rigid anatomy alone,especially in cases associated with potentially "volatile" anatomic areas.展开更多
Background: For image-guided radiotherapy(IGRT) of prostate cancer, the current standard is online image guidance which can effectively correct setup errors and inter-fraction rigid organ motion. However, planning mar...Background: For image-guided radiotherapy(IGRT) of prostate cancer, the current standard is online image guidance which can effectively correct setup errors and inter-fraction rigid organ motion. However, planning margins are still necessary for deformation and intra-fraction motion. Objective: This paper aims to investigate an adaptive planning technique incorporating offline dose feedback to manage interfraction motion and residuals from online corrections. Methods:Repeated CT scans from 28 patients were studied. Online IG was simulated by matching center-of-mass of prostate. A seven-beam IMRT plan with zero margins was designed for each patient. Dose distribution at each fraction was evaluated based on actual target and OARs from that fraction. Cumulative dose was calculated using deformable registration and compared to initial plan. If deviation exceeded pre-defined 2% threshold in prostate D99 an adaptive planning technique called dose compensation was invoked, in which cumulative dose was fed back to the planning system and dose deficit was made up through boost radiation in future fractions through IMRT. Results: If 2% under-dose was allowed at the end of course, then 11 patients failed. If the same criteria was assessed at the end of each week(every 5 fractions), then 14 patients failed. The average dose deficit for these 14 patients was4.4%. They improved to 2% after weekly compensation. 10(out of 14) patients passed criterion after weekly dose compensation; 3 failed marginally; 1 failed significantly(10% deficit). A more aggressive compensation frequency(every 3 fractions) could reduce the dose deficit to the acceptable level for this patient. The doses to OARs were not significantly different from online IG only without dose compensation.Conclusion: We demonstrated an offline dose compensation technique in prostate IGRT which can effectively account for residual uncertainties uncorrectable in online IG. Dose compensation allows further margin reduction and critical organs sparing.展开更多
基金supported by the National Natural Science Foundation of China,No.81060182the Natural Science Foundation of Xinjiang Uygur Autonomous Region,No.2012211B34the Key Technology Research and Development and Major Program of Xinjiang Uygur Autonomous Region,No.200833116
文摘Tumor models were simulated in purebred Beagles at the T9-10 levels of the spinal cord and treated with spinal image-guided radiation therapy or conventional radiation therapy with 50 or 70 Gy total radiation. Three months after radiation, neuronal injury at the T9-10 levels was observed, including reversible injury induced by spinal image-guided radiation therapy and apoptosis induced by conventional radiation therapy. The number of apoptotic cells and expression of the proapoptotic protein Fas were significantly reduced, but expression of the anti-apoptotic protein heat shock protein 70 was significantly increased after image-guided radiation therapy compared with the conventional method of the same radiation dose. Moreover, the spinal cord cell apoptotic index positively correlated with the ratio of Fas/heat shock protein 70. These findings indicate that 3 months of radiation therapy can induce a late response in the spinal cord to radiation therapy; image-guided radiation therapy is safer and results in less neuronal injury compared with conventional radiation therapy.
文摘The reproducibility of patient setup is an important issue for head and neck cancers treated with intensity-modulated radiation therapy (IMRT). In this study, an image-guided radiation therapy (IGRT) system has been used to minimize the uncertainty of patient setup while standard thermoplastic masks were used to provide adequate immobilization for the head and neck. However, they do not provide sufficient immobilization of the shoulders, which is an important requirement in comprehensive nodal irradiation. Therefore, we investigated the setup and rotational shifts in head and neck cancer patients undergoing IMRT for which this immobilization device had been used together with an IGRT system. The setup and rotational shifts of patients were analyzed using the ExacTrac X-ray 6D IGRT system. The patients were classified as having head and neck tumors in the upper or lower regions. The upper neck nodes included lymph nodal level II while the lower neck nodes included lymph nodal levels III and IV. Clinical data from 227 treatment sessions of 12 head and neck cancer patients were analyzed. The random translational error in inter-and intra-fraction errors of the anterio-posterior (AP) direction might influence the rotational errors of pitch and roll in the upper region. At the same time, the random translational error in the inter-and intra-fraction errors of the AP direction might influence the rotational error of roll in the lower region. We believe that these random translational errors should be considered during treatment. We found variability in random translational errors for different regions in the anatomy of head and neck cancer patients due to rotational shifts. Depending on the location of the primary lesion or the selected nodal treatment targets, these relative positional variations should be considered when setup and rotational shifts are corrected with IGRT systems before treatment.
文摘Primary and metastatic liver cancer is an increasingly common and difficult to control disease entity.Radiation offers a non-invasive treatment alternative for these patients who often have few options and a poor prognosis.However,the anatomy and aggressiveness of liver cancer poses significant challenges such as accurate localization at simulation and treatment,management of motion and appropriate selection of dose regimen.This article aims to review the options available and provide information for the practical implementation and/or improvement of liver cancer radiation programs within the context of stereotactic body radiotherapy and image-guided radiotherapy guidelines.Specific patient inclusion and exclusion criteria are presented given the significant toxicity found in certain sub-populations treated with radiation.Indeed,certain sub-populations,such as those with tumor thrombosis or those with larger lesions treated with transarterial chemoembolization,have been shown to have significant improvements in outcome with the addition of radiation and merit special consideration.Implementing a liver radiation programrequires three primary challenges to be addressed:(1) immobilization and motion management;(2) localization;and(3) dose regimen and constraint selection.Strategies to deal with motion include simple internal target volume(ITV) expansions,non-gated ITV reduction strategies,breath hold methods,and surrogate marker methods to enable gating or tracking.Localization of the tumor and organs-at-risk are addressed using contrast infusion techniques to take advantage of different normal liver and cancer vascular anatomy,imaging modalities,and margin management.Finally,a dose response has been demonstrated and dose regimens appear to be converging.A more uniform approach to treatment in terms of technique,dose selection and patient selection will allow us to study liver radiation in larger and,hopefully,multicenter randomized studies.
文摘Stereotactic body radiotherapy(SBRT) is a widely accepted option for the treatment of medically inoperable early-stage non-small cell lung cancer(NSCLC).Herein,we highlight the importance of interfraction image guidance during SBRT.We describe a case of earlystage NSCLC associated with segmental atelectasis that translocated 15 mm anteroinferiorly due to re-expansion of the adjacent segmental atelectasis following the first fraction.The case exemplifies the importance of crosssectional image-guided radiotherapy that shows the intended target,as opposed to aligning based on rigid anatomy alone,especially in cases associated with potentially "volatile" anatomic areas.
文摘Background: For image-guided radiotherapy(IGRT) of prostate cancer, the current standard is online image guidance which can effectively correct setup errors and inter-fraction rigid organ motion. However, planning margins are still necessary for deformation and intra-fraction motion. Objective: This paper aims to investigate an adaptive planning technique incorporating offline dose feedback to manage interfraction motion and residuals from online corrections. Methods:Repeated CT scans from 28 patients were studied. Online IG was simulated by matching center-of-mass of prostate. A seven-beam IMRT plan with zero margins was designed for each patient. Dose distribution at each fraction was evaluated based on actual target and OARs from that fraction. Cumulative dose was calculated using deformable registration and compared to initial plan. If deviation exceeded pre-defined 2% threshold in prostate D99 an adaptive planning technique called dose compensation was invoked, in which cumulative dose was fed back to the planning system and dose deficit was made up through boost radiation in future fractions through IMRT. Results: If 2% under-dose was allowed at the end of course, then 11 patients failed. If the same criteria was assessed at the end of each week(every 5 fractions), then 14 patients failed. The average dose deficit for these 14 patients was4.4%. They improved to 2% after weekly compensation. 10(out of 14) patients passed criterion after weekly dose compensation; 3 failed marginally; 1 failed significantly(10% deficit). A more aggressive compensation frequency(every 3 fractions) could reduce the dose deficit to the acceptable level for this patient. The doses to OARs were not significantly different from online IG only without dose compensation.Conclusion: We demonstrated an offline dose compensation technique in prostate IGRT which can effectively account for residual uncertainties uncorrectable in online IG. Dose compensation allows further margin reduction and critical organs sparing.
