scholarly journals Intensity modulated radiotherapy using Monte Carlo for routine postmastectomy radiotherapy

2012 ◽  
Vol 18 (2) ◽  
pp. 49-58
Author(s):  
Hiba Baha Eldin Sayed Omer
Keyword(s):  
Monte Carlo ◽  
Treatment Planning ◽  
Intensity Modulated Radiotherapy ◽  
Response To Therapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Planning Systems ◽  
Dose Volume Histograms ◽  
Intensity Modulated ◽  
Treatment Planning Systems

Radiotherapy given after mastectomy (PMRT) will reduce the risk of local recurrence by about two-thirds. Clinical and dosimetric trials were carried out using various techniques to optimize the treatments by maximizing the dose to the tumour and minimizing it to the healthy tissues at proximity. Different conventional techniques which have been studied suffer from important dose inhomogeneities due to the complex anatomy of the chest, which reduces the benefits from such treatments. Moreover, due to the heterogeneity of breast cancer, the response to therapy and a systematic approach to treatment cannot be derived and treatment regimens must be determined on a patient-by-patient basis. This is only possible if accurate and fast treatment planning systems are available. Intensity Modulated Radiotherapy (IMRT) allows delivering higher doses to the target volume and limits the doses to the surrounding tissues. The objective of this study is to test the feasibility of applying a Monte Carlo-based treatment planning system, Hyperion accurately in routine Intensity Modulated Radiotherapy (IMRT) postmastectomy. In order to use a treatment planning system for routine work it should prove to provide optimized dose delivery in a suitable time. Treatment planning for IMRT application to PMRT was performed using Hyperion. Constraints were set to deliver the prescribed dose to the target and minimize the dose to the organs at risk. Dose Volume Histograms (DVH) were used to evaluate the set up plans. Time taken to optimize the plan was measured. The target coverage was within the accepted values. Approximately 90% of the breast and 80% of the PTV received 45 Gy or above. The volume of the lung that received 40Gy was less than 10% and the volume that received 20Gy (V20) was less than 25%. The volume of the heart receiving 30 Gy (V30) or above was negligible. This indicates low NTCP of these organs. The time taken for optimization, showed it possible to apply Monte Carlo-based treatment-planning systems for patient-to-patient PMRT.

scholarly journals Dose distribution verification for GZP6 sources: A comparison of Monte Carlo, radiochromic film, and GZP6 treatment planning system

2012 ◽  
Vol 20 (1-2) ◽  
pp. 3-7 ◽  
Author(s):  
Bahreyni Toossi ◽  
Mahdi Ghorbani ◽  
Asghar Mowlavi ◽  
Abdolreza Hashemian ◽  
Soleimani Meigooni
Keyword(s):  
Monte Carlo ◽  
Treatment Planning ◽  
Radiochromic Film ◽  
Planning System ◽  
Treatment Planning System ◽  
Quality Assurance Program ◽  
Monte Carlo Code ◽  
Dose Calculations ◽  
Planning Systems ◽  
Dose Distributions

Background: Treatment planning systems (TPSs) are used for dose calculations in dose delivery by after loading brachytherapy machines. Such planning systems usually use simplified algorithms in their dose calculations. Verification of dose distributions produced by TPS is of clinical importance and is part of a quality assurance program. In this study, the dose distributions generated by GZP6 TPS for two GZP6 sources were verified. Methods: The evaluation was based on the inter comparisons between the isodose curves obtained through Monte Carlo simulations, radiochromic film measurements, and GZP6 treatment planning system. MCNPX Monte Carlo code was used to simulate the sources. Dose measurements were performed in a perspex phantom using Gafchromic? EBT radiochromic films. Comparisons between the results obtained from MC, RCF, and TPS were performed by gamma function calculations with 5% dose/2 mm distance criterion. Results: Based on gamma calculations our results showed that there was good agreement between the dose distributions obtained by the three aforementioned methods in both transverse and longitudinal planes for the GZP6 source No.2. However, for source No. 5, the agreement was good in the transverse plane but it was low in the longitudinal plane. Conclusion: The results showed that dose distributions certified by the GZP6 TPS for the GZP6 source No. 2 were validated. However, for source No. 5 some discrepancies were observed. Accurate knowledge of the activity of each active pellet in the source No. 5 can clarify the cause of the discrepancies.

scholarly journals Implementation of compensator-based intensity modulated radiotherapy with a conventional telecobalt machine using missing tissue approach

2018 ◽  
Vol 24 (4) ◽  
pp. 171-179
Author(s):  
Samuel N. A. Tagoe ◽  
Samuel Y. Mensah ◽  
John J. Fletcher
Keyword(s):  
Treatment Planning ◽  
Specific Treatment ◽  
Intensity Modulated Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Dose Distributions ◽  
Intensity Modulated ◽  
Limit Value ◽  
Tissue Equivalent ◽  
Tissue Equivalent Phantom

Abstract Objectives: The present study aimed to generate intensity-modulated beams with compensators for a conventional telecobalt machine, based on dose distributions generated with a treatment planning system (TPS) performing forward planning, and cannot directly simulate a compensator. Materials and Methods: The following materials were selected for compensator construction: Brass, Copper and Perspex (PMMA). Boluses with varying thicknesses across the surface of a tissue-equivalent phantom were used to achieve beam intensity modulations during treatment planning with the TPS. Beam data measured for specific treatment parameters in a full scatter water phantom with a 0.125 cc cylindrical ionization chamber, with a particular compensator material in the path of beams from the telecobalt machine, and that without the compensator but the heights of water above the detector adjusted to get the same detector readings as before, were used to develop and propose a semi-empirical equation for converting a bolus thickness to compensator material thickness, such that any point within the phantom would receive the planned dose. Once the dimensions of a compensator had been determined, the compensator was constructed using the cubic pile method. The treatment plans generated with the TPS were replicated on the telecobalt machine with a bolus within each beam represented with its corresponding compensator mounted on the accessory holder of the telecobalt machine. Results: Dose distributions measured in the tissue-equivalent phantom with calibrated Gafchromic EBT2 films for compensators constructed based on the proposed approach, were comparable to those of the TPS with deviation less than or equal to ± 3% (mean of 2.29 ± 0.61%) of the measured doses, with resultant confidence limit value of 3.21. Conclusion: The use of the proposed approach for clinical application is recommended, and could facilitate the generation of intensity-modulated beams with limited resources using the missing tissue approach rendering encouraging results.

scholarly journals Comparison of Intensity Modulated Radiotherapy Treatment Plans Between 1.5T MR-Linac and Conventional Linac

2021 ◽  
Vol 20 ◽  
pp. 153303382098587
Author(s):  
Shouliang Ding ◽  
Yongbao Li ◽  
Hongdong Liu ◽  
Rui Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Intensity Modulated Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Current Clinical Practice ◽  
Multiple Tumor ◽  
Dose Volume Histograms ◽  
Intensity Modulated ◽  
Delivery Technique ◽  
Step And Shoot

In this study, we assess the dosimetric qualities and usability of planning for 1.5 T MR-Linac based intensity modulated radiotherapy (MRL-IMRT) for various clinical sites in comparison with IMRT plans using a conventional linac. In total of 30 patients with disease sites in the brain, esophagus, lung, rectum and vertebra were re-planned retrospectively for simulated MRL-IMRT using the Elekta Unity dedicated treatment planning system (TPS) Monaco (v5.40.01). Currently, the step-and-shoot (ss) is the only delivery technique for IMRT available on Unity. All patients were treated on an Elekta Versa HDTM with IMRT using the dynamic multileaf collimator (dMLC) technique, and the plans were designed using Monaco v5.11. For comparison, the same dMLC-IMRT plan was recalculated with the same machine and TPS but only changing the technique to step-and-shoot. The dosimetric qualities of the MRL-IMRT plans, to be evaluated by the Dose Volume Histograms (DVH) metrics, Homogeneity Index and Conformality Index, were compared with the clinical plans. The planning usability was measured by the optimization time and the number of Monitor Units (MUs). Comparing MRL-IMRT with conventional linac based plans, all created plans were clinically equivalent to current clinical practice. However, MRL-IMRT plans had higher dose to skin and larger low dose region of normal tissues. Furthermore, MRL-IMRT plans had significantly reduced optimization time by comparing conventional linac based plans. The number of MUs of MRL-IMRT was increased by 23% compared with ss-IMRT, and no difference from dMLC-IMRT. In conclusion, clinically acceptable plans can be achieved with 1.5 T MR-Linac system for multiple tumor sites. Given the differences in machine characteristics, some minor differences in plan quality were found between MR-Linac plans and current clinical practice and this should be considered in clinical practice.

Quality assurance of intensity-modulated radiotherapy treatment planning: a dosimetric comparison

2018 ◽  
Vol 17 (4) ◽  
pp. 396-402 ◽  
Author(s):  
Saima Altaf ◽  
Khalid Iqbal ◽  
Muhammad Akram ◽  
Saeed A. Buzdar
Keyword(s):  
Quality Assurance ◽  
Radiation Therapy ◽  
Treatment Planning ◽  
Intensity Modulated Radiotherapy ◽  
Intensity Modulated Radiation Therapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Imaging Device ◽  
Intensity Modulated ◽  
Passing Rates

AbstractAimThe purpose of this study was to analyse the comparison of intensity-modulated radiation therapy quality assurance (IMRT QA) using Gafchromic® EBT3 film, Electronic portal imaging device (EPID) and MapCHECK®2.BackgroundPretreatment authentication is the main apprehension in advanced radiation therapy treatment plans such as IMRT.Materials and methodsA total of 20 patients were planned on Eclipse treatment planning system using 6 and 15 MV separately.ResultsGamma index of EBT3 film results shows the following average passing rates: 97% for 6 MV and 96·6% for 15 MV using criteria of ±5% of 3 mm, ±3% of 3 mm and ±3% of 2 mm for brain. However, by using ±5% of 3 mm and ±3% of 3 mm criteria, the average passing rates were 95·4% on 6 MV and 95·2% on 15 MV for prostate. For EPID, the results show the average passing rates as 97·8% for 6 MV and 97·2% for 15 MV in for brain. In cases in which ±5% of 3 mm and ±3% of 3 mm were used, the average passing rates were 96·6% for 6 MVand 96·1% for 15 MV for prostate. MapCHECK®2 results show average passing rates of 96·4% for 6 and 96·2% for 15 MV, respectively, for brain using criteria of ±5% of 3 mm, ±3% of 3 mm and ±3% of 2 mm, whereas for ±5% of 3 mm and ±3% of 3 mm the average rates are 95·2% for 6 and 94·7% for 15 MV in prostate.ConclusionsThe EPID results are better than the other methods, and hence EPID can be used effectively for IMRT pretreatment verifications.

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