TiGRT Treatment Planning System Research Articles

Three-dimensional IMRT QA of Monte Carlo and full scatter convolution algorithms based on 3D film dosimetry

This study aimed to evaluate the dose distribution of the Monte Carlo (MC) code and TiGRT treatment planning system (TPS) compared to experimental measurements. A thirteen-field Intensity-Modulated Radiation Therapy (IMRT) plan was created according to the RTOG H-0022 protocol. A film stack at distances of 3 mm and 1 mm was inserted into the phantom and irradiated. The dose distribution by this IMRT plan was also simulated using EGSnrc. The 3D dose distributions obtained from the TPS and MC calculations were compared against the film measurements (gold standard) using gamma index with conventional (3%-3 mm) and strict (2%-2 mm) criteria. The local gamma passing rate (GPR) for TiGRT-film and MC-film with the conventional criteria at the resolution of 3 mm was 89.36% and 97.94% respectively, and with a resolution of 1 mm, the agreement rate increased to 91.83% and 99.23%, respectively. With the strict criteria at the resolution of 1 mm, the percentage of agreements for TiGRT and MC was about 72.55% and 95.27%, respectively. From the research point of view, the 3D film dosimetry can be used as a valuable dosimetry tool for evaluating the 3D dose distribution in dose computing systems.

Comparison and Evaluation of Different Treatment Plans with IFRT Field and 6 and 18 MV Energies in Hodgkin's Lymphoma Involvement Neck and Mediastinum.

Radiotherapy with large mantle field is an effective technique in increasing the risk of secondary cancers among HL (Hodgkin Lymphoma) patients; therefore, it is essential to choose an effective treatment field including the least medical conditions in radiotherapy. The present study aimed to plan separate fields for neck and mediastinum using various energies, to compare dose distribution with MLC and to block field formation. In this study, 3D conformal treatments, Siemens Oncor accelerator equipped with multi-leaf collimator (MLC) were performed to create anterior-posterior fields. CT-scan data of 18 female patients with neck and mediastinal involvement was imported in TIGRT treatment planning system, and then treatment plans were introduced. Using treatment plan 1, photon 6 MV in neck weighting 1 from interior, 0.5 from posterior, photon 18MV in mediastinum weighting 1 from interior and 0.5 from posterior, it was shown that regarding the common treatment plan used with photon 6 MV, mean dose delivered to breast, lung, esophagus and larynx reduced 6, 7, 41 and 10 percent, respectively and uniformity index improved by 10 percent. Using block compared to MLC in all treatment plans offered improved average dose in all organs under study. To protect breast and lung while using MLC and block in the first treatment plan seemed to be more appropriate; however, using blocks in comparison to MLC increased delivered mean dose in all organs under study. Using separate fields with Pb blocks, though, showed smaller increase.

Assessment of accuracy of out-of-field dose calculations by TiGRT treatment planning system in radiotherapy.

The objective was to quantify the accuracy of dose calculation for out-of-field regions by the commercially available TiGRT version 1.2 (LinaTech, Sunnyvale, CA, USA) treatment planning system (TPS) for a clinical treatment delivered on a Siemens Primus with the single energy of 6 MV. Two tangential open fields were planned by TiGRT TPS to irradiate the left breast of a RANDO phantom. Dose values to out-of-field points were calculated by TiGRT TPS. A RANDO phantom was then irradiated, and dose values at set points were measured using thermoluminescent detectors-100 (TLDs-100) which were located within the phantom. Finally, the TLD-measured dose was compared to the TPS-calculated dose and the accuracy of TPS calculations at different distances from the field edge was quantified. The measurements showed that TiGRT TPS generally underestimated the dose of out-of-field points and this underestimation worsened for regions relatively close to the treatment field edge. The mean underestimation of out-of-field doses was 39%. Nevertheless, the accuracy of dose calculation by this TPS for most in-field regions was within tolerance. This study highlights the limitations of TiGRT TPSs in calculating of the out-of-field dose. It should be noted that out-of-field data for this TPS should only be applied with a certain understanding of the accuracy of calculated dose outside the treatment field. Therefore, using the TPS-calculated dose could lead to an underestimation of secondary cancer risk as well as a weak clinical decision for patients with implantable cardiac pacemakers or pregnant patients.

Radiobiological Evaluation of Three Common Clinical Radiotherapy Techniques Including Combined Photon-Electron, Tangential Beams and Electron Therapy in Left-Sided Mastectomy Patients.

Background:The aim of this study was radiobiological evaluation of different radiotherapy (RT) techniques, namely, combined photon-electron, two tangential photon beams, and electron therapy which are commonly used for treatment of mastectomy patients.Materials and Methods:The mentioned techniques were planned on the computed tomography (CT) images of a chest phantom, using TiGRT treatment planning system (TPS). The TPS dose calculations were verified using Thermo Luminescence dosimeters (TLD) measurements. Dose-volume histogram (DVH) of the plans was generated in the TPS, and also tumor control probability (TCP) and normal tissue complication probability (NTCP) values were calculated using DVH data for each technique. For TCP and NTCP modeling, Poisson Linear-Quadatric (PLQ) and Lyman-Kutcher-Burman (LKB) models were used, respectively.Results:The TCPs for the chest wall, internal mammary nodes, supraclavicular nodes, and axilla for the combined photon-electron was 90%, 90%, 90%, and 65%, respectively, which was higher compared to tangential beams (up to 11%, 11%, 5%, and 5%, respectively) and the electron therapy (up to 11%, 11%, 33%, and 23%, respectively) Whereas the NTCPs of the tangential beams for ipsilateral and contralateral lungs, heart, and chest wall–lung interface was 4%, 1%, 3%, and 5.6%, respectively. These NTCP values were considerably lower than electron therapy (up to 42%, 66%, and 40% and 30%, respectively) and combined photon-electron (up to 55%, 75%, 50%, and 20%, respectively) methods.Conclusion:Tangential beam is suggested for treating mastectomy patients, due to sufficient value of TCP, and also lower NTCP compared to the other techniques such as electron therapy and combined photon-electron.

Radiobiological Model-Based Comparison of Three-Dimensional Conformal and Intensity-Modulated Radiation Therapy Plans for Nasopharyngeal Carcinoma

Introduction: Radiobiological modeling of radiotherapy plans are used for treatment plan comparisons. The current study aimed to compare the three-dimensional conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) plans for nasopharyngeal cancer using radiobiological modeling. Materials and Methods: This study was conducted on 10 patients with nasopharyngeal carcinoma, who were planned for 3DCRT and IMRT treatments by using the TiGRT treatment planning system. The planning target volume (PTV) doses of 70 and 72 Gy were administered for the 3DCRT and IMRT plans, respectively. The BIOLPLAN software and the Niemierko’s equivalent uniform dose (EUD) model were utilized for the estimation of tumor control probability (TCP) and normal tissue complication probability (NTCP). The NTCPs of the spinal cord, brain stem, parotid glands, middle ears, temporomandibular joints (TMJ), mandible, and thyroid were calculated by using two radiobiological models. Results: According to the results, the mean TCPs for 3DCRT and IMRT plans were 89.92%±8.92 and 94.9%±3.86, respectively, showing no statistically significant difference (P=0.08). The NTCPs of the parotid glands, thyroid gland, spinal cord, TMJ, and mandible were considerably lower in the IMRT plans, compared to those in the 3DCRT plans. On the other hand, the calculated NTCPs for the middle ears and brain stem increased for the IMRT plans, which were not statistically significant. On average, the NTCPs of the critical organs were lower based on the EUD model than the Lyman-Kutcher-Burman model. Conclusion: From the radiobiological point of view, the IMRT plans were significantly advantageous over the 3DCRT plans with some small variations in each patient. On average, the two radiobiological models generated different NTCPs depending on the studied organs. Consequently, more studies are needed for the optimization of radiobiological models for the prediction of the treatment outcomes in radiation therapy.

Comparison and Evaluation of Different Treatment Plans with IFRT Field and 6 and 18 MV Energies in Hodgkin’s Lymphoma Involvement Neck and Mediastinum

Background: Radiotherapy with large mantle field is an effective technique in increasing the risk of secondary cancers among HL (Hodgkin Lymphoma) patients; therefore, it is essential to choose an effective treatment field including the least medical conditions in radiotherapy.Objective: The present study aimed to plan separate fields for neck and mediastinum using various energies, to compare dose distribution with MLC and to block field formation.Materials and Methods: In this study, 3D conformal treatments, Siemens Oncor accelerator equipped with multi-leaf collimator (MLC) were performed to create anterior-posterior fields. CT-scan data of 18 female patients with neck and mediastinal involvement was imported in TIGRT treatment planning system, and then treatment plans were introduced.Results and Conclusion: Using treatment plan 1, photon 6 MV in neck weighting 1 from interior, 0.5 from posterior, photon 18MV in mediastinum weighting 1 from interior and 0.5 from posterior, it was shown that regarding the common treatment plan used with photon 6 MV, mean dose delivered to breast, lung, esophagus and larynx reduced 6, 7, 41 and 10 percent, respectively and uniformity index improved by 10 percent. Using block compared to MLC in all treatment plans offered improved average dose in all organs under study. To protect breast and lung while using MLC and block in the first treatment plan seemed to be more appropriate; however, using blocks in comparison to MLC increased delivered mean dose in all organs under study. Using separate fields with Pb blocks, though, showed smaller increase.

Evaluation of dose calculations accuracy of a commercial treatment planning system for the head and neck region in radiotherapy.

The objective was to quantify dose calculation accuracy of TiGRT TPS for head and neck region in radiotherapy. In radiotherapy of head and neck cancers, treatment planning is difficult, due to the complex shape of target volumes and also to spare critical and normal structures. These organs are often very near to the target volumes and have low tolerance to radiation. In this regard, dose calculation accuracy of treatment planning system (TPS) must be high enough. Thermoluminescent dosimeter-100 (TLD-100) chips were used within RANDO phantom for dose measurement. TiGRT TPS was also applied for dose calculation. Finally, difference between measured doses (Dmeas) and calculated doses (Dcalc) was obtained to quantify the dose calculation accuracy of the TPS at head and neck region. For in-field regions, in some points, the TiGRT TPS overestimated the dose compared to the measurements and for other points underestimated the dose. For outside field regions, the TiGRT TPS underestimated the dose compared to the measurements. For most points, the difference values between Dcalc and Dmeas for the in-field and outside field regions were less than 5% and 40%, respectively. Due to the sensitive structures to radiation in the head and neck region, the dose calculation accuracy of TPSs should be sufficient. According to the results of this study, it is concluded that the accuracy of dose calculation of TiGRT TPS is enough for in-field and out of field regions.

The feasibility research of checking treatment plan by using Linatech treatment planning system

Objective To assess the feasibility of secondary by LinaTech TiGRT treatment planning systems. Methods Choosing the Linatech TiGRT treatment planning system, researched and developed by Linatech company, as the third-party check tools. First, using Linatech TPS for recomputing treatment plans for geometrical phantoms designed in TG-119 and patients.after computation, compared the point dose with the measured data of phantoms (Using chameber No.2571 to measure point dose) and original plans. Using PTW verisoft with a criteria of 3% dose difference and 5 mm distance to agreement to assess the dose distribution on center level. After then, you can assess the accuracy of treatment plans. Results Tiny volume changes were found in ROI, especially in small size phantoms orcuspidal regions. For comparing measured data with recomputed plans and original plans, the dose data were found basically identical in TG-119 phantoms. And for patients, the differences between recomputed plans and AAA original plans or AXB original plans were smaller in breast cancer, but they were even bigger innasopharynx cancer, all patient cases showed a gamma passing rate more than 90%.The gamma passing rate of AAA original plans and AXB original plans were 95.6% and 97.53% for breast cancer, and 94.67% and 96.83% for nasopharynx cancer. Conclusions The method of utilizing the LinaTech TiGRT treatment planning system as a third-party check tools to assess the accuracy of plans is feasible, and the validation process is convenient, but some functions still need to improve and the scope of differences still need more patient cases to determine. Key words: Treatment planning system; Intensity-modulated radiotherapy; Quality assure

Assessment of the accuracy of dose calculation in the build-up region of the tangential field of the breast for a radiotherapy treatment planning system.

Aim of the studyOur objective was to quantify the accuracy of dose calculation in the build-up region of the tangential field of the breast for a TiGRT treatment planning system (TPS).Material and methodsThermoluminescent dosimeter (TLD) chips were arranged in a RANDO phantom for the dose measurement. TiGRT TPS was also used for the dose calculation. Finally, confidence limit values were obtained to quantify the accuracy of the dose calculation of the TPS at the build-up region.ResultsIn the open field, for gantry angles of 15°, 30°, and 60°, the confidence limit values were 17.68, 19.97, and 34.62 at a depth of 5 mm, and 24.01, 19.07, and 15.74 at a depth of 15 mm, respectively. In the wedge field, for gantry angles of 15°, 30°, and 60°, the confidence limit values were 21.64, 26.80, and 34.87 at a depth of 5 mm, and 27.92, 22.04, and 20.03 at a depth of 15 mm, respectively. Additionally, the findings showed that at a depth of 5 mm, the confidence limit values increased with increasing gantry angle while at a depth of 15 mm, the confidence limit values decreased with increasing gantry angle.ConclusionsOverall, TiGRT TPS overestimated doses compared to TLD measurements, and the confidence limit values were greater for the wedge field than for the open fields. Our findings suggest that the assessment of dose distributions in large-dose gradient regions (i.e. build-up region) should not entirely rely on TPS calculations.

Assessment of Dose Calculation Accuracy of TiGRT Treatment Planning System for Physical Wedged fields in Radiotherapy

Introduction Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy. Materials and Methods A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calculation accuracy of TPS in these regions. Results The confidence limit values for the central axis, build-up, off-axis, and out-of-field regions were 1.01, 8.62, 1.79, and 55.24, respectively. Furthermore, the results showed that TiGRT TPS underestimated the dose of build-up and out-of-field regions for most points. Conclusion According to the results of the present study, it can be concluded that the dose calculation accuracy of TiGRT TPS for physical wedged fields in the central axis, build-up, and off-axis regions is adequate, while it is insufficient for out-of-field regions.

In vivo skin dose measurement in breast conformal radiotherapy.

Aim of the studyAccurate skin dose assessment is necessary during breast radiotherapy to assure that the skin dose is below the tolerance level and is sufficient to prevent tumour recurrence. The aim of the current study is to measure the skin dose and to evaluate the geometrical/anatomical parameters that affect it.Material and methodsForty patients were simulated by TIGRT treatment planning system and treated with two tangential fields of 6 MV photon beam. Wedge filters were used to homogenise dose distribution for 11 patients. Skin dose was measured by thermoluminescent dosimeters (TLD-100) and the effects of beam incident angle, thickness of irradiated region, and beam entry separation on the skin dose were analysed.ResultsAverage skin dose in treatment course of 50 Gy to the clinical target volume (CTV) was 36.65 Gy. The corresponding dose values for patients who were treated with and without wedge filter were 35.65 and 37.20 Gy, respectively. It was determined that the beam angle affected the average skin dose while the thickness of the irradiated region and the beam entry separation did not affect dose. Since the skin dose measured in this study was lower than the amount required to prevent tumour recurrence, application of bolus material in part of the treatment course is suggested for post-mastectomy advanced breast radiotherapy. It is more important when wedge filters are applied to homogenize dose distribution.

Dose calculations accuracy of TiGRT treatment planning system for small IMRT beamlets in heterogeneous lung phantom

Background : Accurate dose calculaons in small beamlets and lung material have been a great challenge for most of treatment planning systems (TPS). In the current study, the dose calculaon accuracy of TiGRT TPS was evaluated for small beamlets in water and lung phantom by comparison to Monte Carlo (MC) calculaons. Materials and Methods : The head of Siemens Oncorimpression linac was simulated for 6 and 18 MV photon beams using MCNPX MC Code. The model was validated using measured percentage depth dose and beam profiles. Then, the validated model used for dose calculaons for small beamlets in water as well as lung phantoms. For treatment planning purposes, the lung phantom was scanned and imported into the TPS, and then the percentage depth dose values were obtained from plans for small fields of 1×1, 2×2, 3×3 and 4×4 cm 2 in water and lung phantom. Results: For small fields in water phantom, there was a good agreement between TPS and MC for 2×2 to 4×4 cm