scholarly journals The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning

2016 ◽  
Vol 125 (Supplement_1) ◽  
pp. 129-138 ◽  
Author(s):  
João Gabriel Ribeiro Gomes ◽  
Alessandra Augusta Gorgulho ◽  
Amanda de Oliveira López ◽  
Crystian Wilian Chagas Saraiva ◽  
Lucas Petri Damiani ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Gamma Knife ◽  
Treatment Time ◽  
Diffusion Tensor ◽  
Pyramidal Tract ◽  
Planning System ◽  
Treatment Planning System ◽  
Motor Complications ◽  
Clinical Series

OBJECTIVEThe role of tractography in Gamma Knife thalamotomy (GK-T) planning is still unclear. Pyramidal tractography might reduce the risk of radiation injury to the pyramidal tract and reduce motor complications.METHODSIn this study, the ventralis intermedius nucleus (VIM) targets of 20 patients were bilaterally defined using Iplannet Stereotaxy Software, according to the anterior commissure–posterior commissure (AC-PC) line and considering the localization of the pyramidal tract. The 40 targets and tractography were transferred as objects to the GammaPlan Treatment Planning System (GP-TPS). New targets were defined, according to the AC-PC line in the functional targets section of the GP-TPS. The target offsets required to maintain the internal capsule (IC) constraint of < 15 Gy were evaluated. In addition, the strategies available in GP-TPS to maintain the minimum conventional VIM target dose at > 100 Gy were determined.RESULTSA difference was observed between the positions of both targets and the doses to the IC. The lateral (x) and the vertical (z) coordinates were adjusted 1.9 mm medially and 1.3 mm cranially, respectively. The targets defined considering the position of the pyramidal tract were more medial and superior, based on the constraint of 15 Gy touching the object representing the IC in the GP-TPS. The best strategy to meet the set constraints was 90° Gamma angle (GA) with automatic shaping of dose distribution; this was followed by 110° GA. The worst GA was 70°. Treatment time was substantially increased by the shaping strategy, approximately doubling delivery time.CONCLUSIONSRoutine use of DTI pyramidal tractography might be important to fine-tune GK-T planning. DTI tractography, as well as anisotropy showing the VIM, promises to improve Gamma Knife functional procedures. They allow for a more objective definition of dose constraints to the IC and targeting. DTI pyramidal tractography introduced into the treatment planning may reduce the incidence of motor complications and improve efficacy. This needs to be validated in a large clinical series.

Dosimetric comparison of fractionated radiosurgery plans using frameless Gamma Knife ICON and CyberKnife systems with linear accelerator–based radiosurgery plans for multiple large brain metastases

2020 ◽  
Vol 132 (5) ◽  
pp. 1473-1479 ◽  
Author(s):  
Eun Young Han ◽  
He Wang ◽  
Dershan Luo ◽  
Jing Li ◽  
Xin Wang
Keyword(s):  
Brain Metastases ◽  
Gamma Knife ◽  
Linear Accelerator ◽  
Treatment Time ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Normal Brain ◽  
Large Brain ◽  
The Mean

OBJECTIVEFor patients with multiple large brain metastases with at least 1 target volume larger than 10 cm3, multifractionated stereotactic radiosurgery (MF-SRS) has commonly been delivered with a linear accelerator (LINAC). Recent advances of Gamma Knife (GK) units with kilovolt cone-beam CT and CyberKnife (CK) units with multileaf collimators also make them attractive choices. The purpose of this study was to compare the dosimetry of MF-SRS plans deliverable on GK, CK, and LINAC and to discuss related clinical issues.METHODSTen patients with 2 or more large brain metastases who had been treated with MF-SRS on LINAC were identified. The median planning target volume was 18.31 cm3 (mean 21.31 cm3, range 3.42–49.97 cm3), and the median prescribed dose was 27.0 Gy (mean 26.7 Gy, range 21–30 Gy), administered in 3 to 5 fractions. Clinical LINAC treatment plans were generated using inverse planning with intensity modulation on a Pinnacle treatment planning system (version 9.10) for the Varian TrueBeam STx system. GK and CK planning were retrospectively performed using Leksell GammaPlan version 10.1 and Accuray Precision version 1.1.0.0 for the CK M6 system. Tumor coverage, Paddick conformity index (CI), gradient index (GI), and normal brain tissue receiving 4, 12, and 20 Gy were used to compare plan quality. Net beam-on time and approximate planning time were also collected for all cases.RESULTSPlans from all 3 modalities satisfied clinical requirements in target coverage and normal tissue sparing. The mean CI was comparable (0.79, 0.78, and 0.76) for the GK, CK, and LINAC plans. The mean GI was 3.1 for both the GK and the CK plans, whereas the mean GI of the LINAC plans was 4.1. The lower GI of the GK and CK plans would have resulted in significantly lower normal brain volumes receiving a medium or high dose. On average, GK and CK plans spared the normal brain volume receiving at least 12 Gy and 20 Gy by approximately 20% in comparison with the LINAC plans. However, the mean beam-on time of GK (∼ 64 minutes assuming a dose rate of 2.5 Gy/minute) plans was significantly longer than that of CK (∼ 31 minutes) or LINAC (∼ 4 minutes) plans.CONCLUSIONSAll 3 modalities are capable of treating multiple large brain lesions with MF-SRS. GK has the most flexible workflow and excellent dosimetry, but could be limited by the treatment time. CK has dosimetry comparable to that of GK with a consistent treatment time of approximately 30 minutes. LINAC has a much shorter treatment time, but residual rotational error could be a concern.

The Role of A Conventional Simulator in Multileaf-Plan Simulation: A Proposal

2001 ◽  
Vol 87 (2) ◽  
pp. 91-94 ◽  
Author(s):  
Carlo Capirci ◽  
Polico Cesare ◽  
Giovanni Mandoliti ◽  
Giovanni Pavanato ◽  
Marcello Gava ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Planning System ◽  
Hard Copy ◽  
Treatment Planning System ◽  
Magnification Factor ◽  
Radiographic Images ◽  
Modern Computer

Modern computer networks provide satisfying levels of data recording and verification between the treatment planning system (TPS) and the accelerators, while the main weakness of the preparation chain remains the simulation. When a conventional simulator is employed, it may adversely affect the three-dimensional treatment planning system (3DPS) process because of the difficulty to document the leaf positions on the simulator location films and on the patient's skin. With a conventional simulator, hard copies of the DRRs of each field and CT scans at isocenter level are needed. In an attempt to transfer more information displayed from a BEV perspective from the 3DPS to simulator radiographs, this study aimed to reduce the quality loss by using a 2D conventional simulator in a 3DPS process. We realized an acetate photocopy of TPS data for each field, from a BEV perspective, containing: DRR, wire frames of the PTV, organs at risk and MLC aperture. The photocopies, with an appropriate magnification factor to obtain a correct projective value (ratio 1:1) at isocenter level, are carefully placed on the radiographic images on the same hard copy which allows us to better understand possible setup errors and obliges us to correct these. The method provides reliable documentation, facilitates treatment verification, and fulfils the criteria for MLC simulation. It is accurate, simple, and very inexpensive.

Monte Carlo calculation of single-beam dose profiles used in a gamma knife treatment planning system

1998 ◽  
Vol 25 (9) ◽  
pp. 1673-1675 ◽  
Author(s):  
Joel Y. C. Cheung ◽  
K. N. Yu ◽  
C. P. Yu ◽  
Robert T. K. Ho
Keyword(s):  
Monte Carlo ◽  
Treatment Planning ◽  
Gamma Knife ◽  
Monte Carlo Calculation ◽  
Planning System ◽  
Treatment Planning System ◽  
Single Beam ◽  
Beam Dose

Linac-stereotactic radiosurgery (LSRS) in the management of trigeminal neuralgia

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 18603-18603
Author(s):  
S. Gurley ◽  
R. Mark ◽  
P. J. Anderson ◽  
T. Neumann ◽  
M. Nair
Keyword(s):  
Trigeminal Neuralgia ◽  
Stereotactic Radiosurgery ◽  
Treatment Planning ◽  
Gamma Knife ◽  
Root Zone ◽  
Planning System ◽  
Response To Treatment ◽  
Treatment Planning System ◽  
Facial Numbness ◽  
Mri Scans

18603 Background: Stereotactic Radiosurgery (SRS) with the Gamma Knife (GK) has been used successfully in the treatment of Trigeminal Neuralgia (TN). Results have been comparable to open surgery. There have been few reports with the use of LSRS in the management of TN. We report our updated results with LSRS in the treatment of TN. Methods: Between 2000 and 2006, 37 patients with medically refractory TN were treated with LSRS. Prior neurosurgical intervention had been performed in 28 patients. Ten patients had one procedure, 10 patients two, and 3 patients three interventions. All patients had typical TN. LSRS was given to the cranial nerve V entry root zone into the brainstem. Targeting was defined by CT and MRI Scans, and CT Cisternogram, utilizing axial, coronal, and sagittal images. Treatment planning was accomplished thru the Radionics Treatment Planning System. The dose was 87 Gy to Dm, in one fraction using the 5 mm collimator and 6 arcs with the 20% Isodose line just touching the brainstem. This dosimetry is similar to Gamma Knife. The dose rate was 400 MU/min. Average Arc length was 130 degrees. Response to treatment was defined as excellent (no pain, off analgesics), good (no pain, with analgesics), and poor (continued pain despite analgesics). Results: With a median follow-up of 40 months (range 6–72 months), 73% (27/37) of patients have reported an excellent or good result after LSRS. One patient has sustained permanent ipsilateral facial numbness. Conclusions: LSRS offers comparable results to Gamma Knife SRS, with respect to both pain relief and complications, in the management of TN. No significant financial relationships to disclose.

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