The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma
Abstract Background This planning study compares different radiotherapy techniques for patients with pituitary adenoma, including flatness filter free mode (FFF), concerning plan quality and secondary malignancies for potentially young patients. The flatness filter has been described as main source...
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| Format: | Article |
| Language: | English |
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BMC
2020-02-01
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| Series: | BMC Cancer |
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| Online Access: | https://doi.org/10.1186/s12885-020-6535-y |
| _version_ | 1818456016604364800 |
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| author | Marius Treutwein Felix Steger Rainer Loeschel Oliver Koelbl Barbara Dobler |
| author_facet | Marius Treutwein Felix Steger Rainer Loeschel Oliver Koelbl Barbara Dobler |
| author_sort | Marius Treutwein |
| collection | DOAJ |
| description | Abstract Background This planning study compares different radiotherapy techniques for patients with pituitary adenoma, including flatness filter free mode (FFF), concerning plan quality and secondary malignancies for potentially young patients. The flatness filter has been described as main source of photon scatter. Material and methods Eleven patients with pituitary adenoma were included. An Elekta Synergy™ linac was used in the treatment planning system Oncentra® and for the measurements. 3D plans, IMRT, and VMAT plans and non-coplanar varieties were considered. The plan quality was evaluated regarding homogeneity, conformity, delivery time and dose to the organs at risk. The secondary malignancy risk was calculated from dose volume data and from measured dose to the periphery using different models for carcinoma and sarcoma risk. Results The homogeneity and conformity were nearly unchanged with and without flattening filter, neither was the delivery time found substantively different. VMAT plans were more homogenous, conformal and faster in delivery than IMRT plans. The secondary cancer risk was reduced with FFF both in the treated region and in the periphery. VMAT plans resulted in a higher secondary brain cancer risk than IMRT plans, but the risk for secondary peripheral cancer was reduced. Secondary sarcoma risk plays a minor role. No advantage was found for non-coplanar techniques. The FFF delivery times were not shortened due to additional monitor units needed and technical limitations. The risk for secondary brain cancer seems to depend on the irradiated volume. Secondary sarcoma risk is much smaller than carcinoma risk in accordance to the results of the atomic bomb survivors. The reduction of the peripheral dose and resulting secondary malignancy risk for FFF is statistically significant. However, it is negligible in comparison to the risk in the treated region. Conclusion Treatments with FFF can reduce secondary malignancy risk while retaining similar quality as with flattening filter and should be preferred. VMAT plans show the best plan quality combined with lowest peripheral secondary malignancy risk, but highest level of second brain cancer risk. Taking this into account VMAT FFF seems the most advantageous technique for the treatment of pituitary adenomas with the given equipment. |
| first_indexed | 2024-12-14T22:19:58Z |
| format | Article |
| id | doaj.art-7612796038154b359d0ad67decb1776d |
| institution | Directory Open Access Journal |
| issn | 1471-2407 |
| language | English |
| last_indexed | 2024-12-14T22:19:58Z |
| publishDate | 2020-02-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Cancer |
| spelling | doaj.art-7612796038154b359d0ad67decb1776d2022-12-21T22:45:31ZengBMCBMC Cancer1471-24072020-02-0120111310.1186/s12885-020-6535-yThe influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenomaMarius Treutwein0Felix Steger1Rainer Loeschel2Oliver Koelbl3Barbara Dobler4Department for radiotherapy, Regensburg University Medical CenterDepartment for radiotherapy, Regensburg University Medical CenterFaculty of computer science and mathematics, Ostbayerische Technische HochschuleDepartment for radiotherapy, Regensburg University Medical CenterDepartment for radiotherapy, Regensburg University Medical CenterAbstract Background This planning study compares different radiotherapy techniques for patients with pituitary adenoma, including flatness filter free mode (FFF), concerning plan quality and secondary malignancies for potentially young patients. The flatness filter has been described as main source of photon scatter. Material and methods Eleven patients with pituitary adenoma were included. An Elekta Synergy™ linac was used in the treatment planning system Oncentra® and for the measurements. 3D plans, IMRT, and VMAT plans and non-coplanar varieties were considered. The plan quality was evaluated regarding homogeneity, conformity, delivery time and dose to the organs at risk. The secondary malignancy risk was calculated from dose volume data and from measured dose to the periphery using different models for carcinoma and sarcoma risk. Results The homogeneity and conformity were nearly unchanged with and without flattening filter, neither was the delivery time found substantively different. VMAT plans were more homogenous, conformal and faster in delivery than IMRT plans. The secondary cancer risk was reduced with FFF both in the treated region and in the periphery. VMAT plans resulted in a higher secondary brain cancer risk than IMRT plans, but the risk for secondary peripheral cancer was reduced. Secondary sarcoma risk plays a minor role. No advantage was found for non-coplanar techniques. The FFF delivery times were not shortened due to additional monitor units needed and technical limitations. The risk for secondary brain cancer seems to depend on the irradiated volume. Secondary sarcoma risk is much smaller than carcinoma risk in accordance to the results of the atomic bomb survivors. The reduction of the peripheral dose and resulting secondary malignancy risk for FFF is statistically significant. However, it is negligible in comparison to the risk in the treated region. Conclusion Treatments with FFF can reduce secondary malignancy risk while retaining similar quality as with flattening filter and should be preferred. VMAT plans show the best plan quality combined with lowest peripheral secondary malignancy risk, but highest level of second brain cancer risk. Taking this into account VMAT FFF seems the most advantageous technique for the treatment of pituitary adenomas with the given equipment.https://doi.org/10.1186/s12885-020-6535-yPituitary adenomaTreatment planningSecondary malignoma riskFlattening filter free |
| spellingShingle | Marius Treutwein Felix Steger Rainer Loeschel Oliver Koelbl Barbara Dobler The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma BMC Cancer Pituitary adenoma Treatment planning Secondary malignoma risk Flattening filter free |
| title | The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| title_full | The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| title_fullStr | The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| title_full_unstemmed | The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| title_short | The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| title_sort | influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma |
| topic | Pituitary adenoma Treatment planning Secondary malignoma risk Flattening filter free |
| url | https://doi.org/10.1186/s12885-020-6535-y |
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