Radiosurgery of functioning pituitary adenomas: Comparison of different treatment techniques including dynamic and conformal arcs, shaped beams, and IMRT

Grabenbauer, Gerhard G.; Ernst-Stecken, Antje; Schneider, Florian; Lambrecht, Ulrike; Ganslandt, Oliver

doi:10.1016/j.ijrobp.2006.05.076

Cited by 14 publications

(14 citation statements)

References 41 publications

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“…Treatments can be administered by means of circular or multileaf collimator-based forward planning strategies or multileaf collimator-based inverse planning methods, with patients immobilised by frame-based or frameless techniques employing image guidance methodologies [20]. At present, several treatment planning techniques are available for linac-based SRS, but in an individual case the best choice for one or other of these techniques is not always obvious, in spite of several planning studies that have been published [21][22][23][24][25][26].…”

Section: Discussionmentioning

confidence: 99%

Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery

Tanyi¹,

Kato²,

Chen³

et al. 2011

BJR

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Objectives: The impact of two multileaf collimator (MLC) systems for linear accelerator-based intracranial stereotactic radiosurgery (SRS) was assessed. Methods: 68 lesions formed the basis of this study. 2.5 mm leaf width plans served as reference. Comparative plans, with identical planning parameters, were based on a 5 mm leaf width MLC system. Two collimation strategies, with collimation fixed at 0 u or 90 u and optimised per arc or beam, were also assessed. Dose computation was based on the pencil beam algorithm with allowance for tissue heterogeneity. Plan normalisation was such that 100% of the prescription dose covered 95% of the planning target volume. Plan evaluation was based on target coverage and normal tissue avoidance criteria. Results: The median conformity index difference between the MLC systems ranged between 0.8% and 14.2%; the 2.5 mm MLC exhibited better dose conformation. The median reduction of normal tissue exposed to >100%, >50% and >25% of the prescription dose ranged from 13.4% to 29.7%, favouring the 2.5 mm MLC system. Dose fall-off was steeper for the 2.5 mm MLC system with an overall median absolute difference ranging from 0.4 to 1.2 mm. The use of collimation optimisation resulted in a decrease in differences between the MLC systems. The results demonstrated the dosimetric merit of the 2.5 mm leaf width MLC system over the 5 mm leaf width system, albeit small, for the investigated range of intracranial SRS targets. Conclusion:The clinical significance of these results warrants further investigation to determine whether the observed dosimetric advantages translate into outcome improvements.

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Section: Discussionmentioning

confidence: 99%

Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery

Tanyi¹,

Kato²,

Chen³

et al. 2011

BJR

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“…Linac-based stereotactic radiotherapy and radiosurgery as well as gamma knife radiosurgery have emerged as treatment options, and the results achieved by those techniques are encouraging [7,11,24,27,28,35,36]. Whether late side effects (e.g., hypopituitarism) following stereotactic techniques are less frequent than after conventional external-beam radiotherapy has not yet been shown, since most follow-up data are still limited [5,8,14,18,20,23,29].…”

Section: Discussionmentioning

confidence: 99%

Long-Term Follow-up of Patients with Pituitary Macroadenomas after Postoperative Radiation Therapy

et al. 2007

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“…The dose prescription has been commonly defined at the specific percentage isodose surface (IDS) (e.g. 80% or 90%) normalised to 100% at the isocentre in many institutions [5][6][7][8][9][10][11][12]. Because the planning methods and the selection of the prescription IDS have been left to the discretion of each institution, a substantial variability has been observed in the method of dose prescription and/or in the assessment of a ''marginal dose'' [1,[5][6][7][8][9][10][11][12].…”

mentioning

confidence: 99%

Characterisation of dose distribution in linear accelerator-based intracranial stereotactic radiosurgery with the dynamic conformal arc technique: consideration of the optimal method for dose prescription and evaluation

Ohtakara

Hayashi²,

Hoshi³

2012

BJR

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Objectives: The purpose of this study was to characterise dose distribution in linear accelerator-based intracranial stereotactic radiosurgery using the dynamic conformal arc technique, and to validate the pertinence of dose prescription to the specific percentage isodose surface (IDS). Methods: 73 plans for brain metastases were reviewed and replanned with a uniform method for target definition and treatment planning. Results: In all cases except 1 the dose prescription to the 80% IDS satisfied the criteria of the standardised prescription IDS as previously proposed. However, both of the planning target volume (PTV) coverage values for the 80% and 90% IDSs and the PTV D99 and D95 (IDS receiving at least 99% or 95% of the PTV) were inconsistent and significantly increased as a function of the PTV size. The 80% IDS for a PTV of more than 5 cm 3 achieved adequate PTV coverage without a leaf margin. The dose conformity for 80% IDS gradually worsened as the PTV increased, whereas that for the PTV D99 or D95 improved as a function of the PTV size. The addition of a leaf margin attained 100% PTV coverage for 80% IDS, while leading to a poorer dose conformity. Conclusion: The dose prescription to the specific percentage IDS does not necessarily guarantee consistent target coverage, D99 and D95, and desirable dose conformity in proportion to the target volume. The dose prescription and evaluation at the specific target coverage would therefore be preferable as an objective method in order to report the ''marginal dose'' and to clearly compare the planning parameters with those from other modalities.

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Radiosurgery of functioning pituitary adenomas: Comparison of different treatment techniques including dynamic and conformal arcs, shaped beams, and IMRT

Cited by 14 publications

References 41 publications

Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery

Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery

Long-Term Follow-up of Patients with Pituitary Macroadenomas after Postoperative Radiation Therapy

Characterisation of dose distribution in linear accelerator-based intracranial stereotactic radiosurgery with the dynamic conformal arc technique: consideration of the optimal method for dose prescription and evaluation

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