A frameless method for stereotactic radiotherapy

Jones, Douglas; Christopherson, D.; Washington, John T.; Hafermann, Mark D.; Rieke, J.; Travaglini, John; Vermeulen, Sandra

doi:10.1259/0007-1285-66-792-1142

Cited by 29 publications

(13 citation statements)

References 9 publications

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“…DISCUSSION Frameless methods have been developed for stereotactic radiosurgery, but all require some method of reliably positioning the patient with respect to the radiation source. Jones and his colleagues 7 have used gold markers implanted in the skin and a moulded semi-rigid face mask to help hold the patient in place during treatment. The gold markers have the virtue of being visible on plain radiographs, permitting their identification on beam films.…”

Section: Resultsmentioning

confidence: 99%

Frameless Stereotaxy for Pre-treatment Planning and Post-treatment Evaluation of Radiosurgery

Schwartz

Ramaseshan

O’Brien

et al. 1994

Can. j. neurol. sci.

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In our centre, 111 patients have been treated with linear accelerator stereotactic radiosurgery. Angiographic, CT and MRI images are generated and the target coordinates calculated in 3 dimensions. For CT scanning, cross sections of perpendicular and oblique fiducial markers are seen. For follow-up CT scans done without the frame, a virtual frame is generated by means of a computer program that places fiducial markers on each CT scan cut, as if the patient had been wearing the OBT frame and the scan produced with the gantry parallel to the base of the frame. The position of the oblique marker may be calculated by knowing the thickness and position of each CT cut. Various natural fiducial markers (bony landmarks) are identified by coordinates in the scan with the patient wearing the real frame and in the scan with the virtual frame applied. A transformation matrix is utilized to establish the equivalence between the original CT scan with the real frame applied and subsequent scans without the real frame but with the virtual frame applied. In effect, the virtual frame is re-applied in exactly the same position as the real frame. Lesion measurements may then be duplicated and growth or regression accurately established. The uncertainty in this system of re-application resides in possible patient movement, CT scan slice thickness and inter-observer error in the identification of natural fiducial markers.Resume: Stereotaxic sans cadrage dans la planification avant traitement et revaluation apres traitement de la radiochirurgie. Cent onze patients ont ete traites dans notre centre par radiochirurgie stereotaxique au moyen d'un accelerateur lineaire. Les images angiographiques, tomodensitometriques et centre par resonance magnetique nucleaire sont generees et les coordonnes de la cible sont calcules en trois dimensions. Pour la tomodensitometrie, des coupes des marqueurs fiduciels en perpendiculaire et en oblique sont visualisees. Pour la tomodensitometrie faite sans cadrage au cours du suivi, un cadrage virtuel est genere au moyen d'un programme informatique qui place les marqueurs fiduciels sur chaque coupe, comme si le patient avait prote le cadrage OBT et le scan est produit avec le pont roulant en position parallele a la base du cadrage. La position du marqueur oblique peut etre calculee en connaissant I'epaisseur et la position de chaque coupe. Differents marqueurs fiduciels naturels (points de repere osseux) sont identifies par des coordonnes sur le scan alors que le patient porte le vrai cadrage et sur le scan alors que le cadrage virtuel est applique. Une transformation matricielle est utilisee pour etablir l'equivalence entre le scan original fait avec le cadrage reel et les scans subsequents faits avec le cadrage virtuel, sans le cadrage reel. En fait, le cadrage virtuel est rapplique exactement dans la meme position que le cadrage reel. Les measures des lesions peuvent alors etre reproduites et on peut evaluer exactement la progression ou la regression. L'incertitude de ce systeme est liee a la po...

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Section: Resultsmentioning

confidence: 99%

Frameless Stereotaxy for Pre-treatment Planning and Post-treatment Evaluation of Radiosurgery

Schwartz

Ramaseshan

O’Brien

et al. 1994

Can. j. neurol. sci.

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“…We have been able to conduct treatments that had a similar precision with regard to other stereotactic techniques, but employing conventional immobilisation systems [20,21].…”

Section: Discussionmentioning

confidence: 99%

“…It is advisable to use a minimally invasive procedure for the implantation of markers to avoid patient discomfort [21]. As we explained previously, the implantation process lasts no more than 30 min and it is conducted under local anaesthesia and through a puncture made on the cranium vault for placing 3 seeds, 2 mm in diameter.…”

Section: Discussionmentioning

confidence: 99%

Analysis of fiducial markers used for on-line verification in the external-beam radiotherapy of patients with cranial tumours

et al. 2007

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“…surgery [22]), removable attachments [23] and implanted structures such as gold markers in fractionated prostate radiotherapy and related fields [24,25]. The latter markers are often located by means of additional imaging such as B-mode ultrasound (US) [24] or X-ray [26].…”

Section: Marker-based Methodsmentioning

confidence: 99%

“…The latter markers are often located by means of additional imaging such as B-mode ultrasound (US) [24] or X-ray [26]. Technically, registration based on fiducial markers is performed by minimizing the Euclidean distance between paired point sets coordinates [27,28], thus, resulting in the aforementioned six parameters of rigid body motion.…”

Section: Marker-based Methodsmentioning

confidence: 99%