SU-FF-T-70: An Independent Verification of Dosimetry for the Leksell Gamma Knife® Treatment Planning System

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.

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Independent verification of monitor unit calculation for radiation treatment planning system

Chinese Journal of Cancer ◽

10.5732/cjc.009.10463 ◽

2010 ◽

Vol 29 (2) ◽

pp. 217-222 ◽

Cited By ~ 5

Author(s):

Li Chen ◽

Li-Xin Chen ◽

Shao-Min Huang ◽

Wen-Zhao Sun ◽

Hong-Qiang Sun ◽

...

Keyword(s):

Treatment Planning ◽

Radiation Treatment ◽

Planning System ◽

Treatment Planning System ◽

Monitor Unit ◽

Radiation Treatment Planning ◽

Independent Verification ◽

Radiation Treatment Planning System

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Independent verification of treatment planning system calculations

Nukleonika ◽

10.2478/nuka-2021-0006 ◽

2021 ◽

Vol 66 (2) ◽

pp. 47-53

Author(s):

Edyta Dąbrowska-Szewczyk ◽

Anna Zawadzka ◽

Beata Brzozowska ◽

Agnieszka Walewska ◽

Paweł Kukołowicz

Keyword(s):

Treatment Planning ◽

Three Dimensional ◽

Conformal Radiotherapy ◽

Target Volume ◽

Planning System ◽

Treatment Planning System ◽

Rank Test ◽

Average Dose ◽

Independent Verification ◽

The Mean

Abstract Purpose According to the available international recommendations, at least one independent verification of the calculations of number of monitor unit (MU) is required for every patient treated by teleradiotherapy. The aim of this study was to estimate the differences of dose distributions calculated with two treatment planning systems: Eclipse (Varian) and Oncentra MasterPlan (Elekta). Materials and methods The analysis was performed for 280 three-dimensional conformal radiotherapy treatment (3D-CRT) plans with photon beams from Varian accelerators: CL 600C/D X6 MV (109 plans), CL 2300C/D X6 MV (43 plans), and CL 2300C/D X15 MV (128 plans). The mean doses in the planning target volume (PTV) and doses at the isocenter point obtained with Eclipse and Oncentra MasterPlan (OMP) were compared with Wilcoxon matched-pairs signed rank test. Additionally, the treatment planning system (TPS) calculations were compared with dosimetric measurements performed in the inhomogeneous phantom. Results Data were analysed for 6 MV plans and for 15 MV plans separately, independently of the treatment machine. The dose values calculated in Eclipse were significantly (p <0.001) higher compared to calculations of OMP system. The average difference of the mean dose to PTV was (1.4 ± 1.0)% for X6 MV and (2.5 ± 0.6)% for X15 MV. Average dose disparities at the isocenter point were (1.3 ± 1.9)% and (2.1 ± 1.0)% for X6 MV and X15 MV beams, respectively. The largest differences were observed in lungs, air cavities, and bone structures. Moreover the variation in dosimetric measurements was less as compared to Eclipse calculations. Conclusions OMP calculations were introduced as the independent MU verification tool with the first action level range equal to 3.5%.

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

Journal of Clinical Oncology ◽

10.1200/jco.2006.24.18_suppl.18603 ◽

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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