• Radiation Oncology Journal
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• v.20 no.1
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• pp.68-72
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• 2002

This study was done to implement intensity-modulated radiation therapy (IMRT) for the treatment of primary prostate cancer and to compare this technique with conventional treatment methods. A 72-year-old male patient with prostate cancer stage T2a was treated with IMRT delivered with dynamic multi-leaf collimation. Treatment was designed using an inverse planning algorithm, which accepts dose and dose-volume constraints for targets and normal structures. The IMRT plan was compared with a three-dimensional (3D) plan using the same 6 fields technique. Lower normal tissue doses and improved target coverage were achieved using IMRT at current dose levels, and facilitate dose escalation to further enhance locoregional control and organ movement during radiotherapy is an important issue of IMRT in prostate cancer.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.85-91
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• 2008

Intensity-modulated radiation therapy (IMRT) is believed to be one of the best radiation treatment techniques. IMRT is able to deliver fatal doses of radiation to the tumor region with minimal exposure of critical organs. It is essential to have a comprehensive quality assurance program to assure precision and accuracy in treatment, due to the character of IMRT. We applied quality assurance technique to the Eclipse treatment planning system and sought to determine its effectiveness in patient treatment planning. An acrylic phantom, film, and an ionization chamber were used in this study.

• Radiation Oncology Journal
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• v.38 no.1
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• pp.11-17
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• 2020

Purpose: Definitive radiotherapy remains a primary treatment option for early stage glottic cancer. Intensity-modulated radiation therapy (IMRT) has emerged as the standard treatment technique for advanced head and neck cancers, whereas three-dimensional conformal radiotherapy (3D-CRT) has remained standard for early glottic cancers. We used the National Cancer Database (NCDB) to identify predictors of IMRT use and effect on outcome in these patients. Materials and Methods: We queried the NCDB from 2004-2015 for squamous cell carcinoma of the glottic larynx staged Tis-T2N0 treated with radiation alone. Logistic regression was used to identify predictors of IMRT. Cox regression was used to identify factors predictive of overall survival. Propensity matching was conducted to account for indication bias. Results: We identified 15,627 patients, of which 11% received IMRT. IMRT use rose from 2% in 2004 to 16% in 2015. Predictors of IMRT include: increased comorbidity, T2 stage, urban location, chemotherapy, treatment at an academic center, and later treatment year. Predictors of improved survival were female gender, higher income, lower stage, no chemotherapy, academic facility, and more remote year. There was no difference in survival between 3D-CRT and IMRT across all stages. Conclusions: The rate of IMRT use for early stage glottic laryngeal cancer has increased over time. There was no difference in outcome in patients receiving IMRT versus 3D-CRT across the cohort.

• Progress in Medical Physics
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• v.18 no.3
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• pp.167-171
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• 2007

In the case of radiotherapy following breast conservation therapy for breast cancer patients, the characteristic of skin dose was investigated in the treatment of intensity modulated radiation therapy (IMRT) for breast cancer patients by comparing and analysing entrance skin dose irradiated during radiotherapy using tangential technique radiotherpy, and IMRT. The calculation dose irradiated to breast skin was compared with TLD measurement dose in treatment planning by performing the two methods of radiotherapy using tangential technique, and IMRT in treatment planning equipment. The skin absorbed dose was measured to pass a nipple by spacing of 1 cm distance from center to edge of body. In the radiotherapy of tangential technique, for the irradiation of 180 cGy to PTV, the calculation dose was ranged from 103.5 cGy to 155.2 cGy, measurement dose was ranged from 107.5 cGy to 156.2 cGy, and skin dose in the center was maximum 1.45 times more irradiated than that in the edge. In the IMRT, for the irradiation of 180 cGy to PTV, the calculation dose was ranged 9.8 cGy at 80.2 cGy, measurement dose was ranged 8.9 cGy at 77.2 cGy, and skin dose in the center was maximum 0.23 times less irradiated than that in the edge. IMRT was more effective for skin radiation risks because radiation dose irradiated to skin in IMRT was much less than that in radiotherapy of tangential field technique.

• Progress in Medical Physics
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• v.13 no.1
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• pp.32-36
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• 2002

For Intensity Modulated Radiation Therapy(IMRT), the spatial resolution of intensity map(IM) is limited by the width of multi-leaf collimator, which would make an effect on the conformity of the target, as well as organs at risk. Several Methods are suggested to increase the spatial resolution, which can be categorized by the hardware-dependent technique and the software-based technique. However the best solution might be to make the width of MLC finer. it has several obstacles in the respects of technical difficulty and cost. This preliminary study is designed to investigate the clinical effectiveness of the virtual-micro IMRT(VMIMRT) technique, one of the software-based technique. A particular intensity map was created, which has 42$\times$54 pixel dimension ,0.5cm pixel size and 15 intensity levels. Using this intensity map, segment fields of IMRT were generated with 1$\times$lcm, 0.5$\times$1cm, 0.5$\times$0.5cm(VMIM) beamlet size, respectively As results, we found that there was no evidence of improvement for VMIMRT, compared with the 0.5$\times$lcm beamlet size which can be delivered by 1cm width MLC. The reason seems to be due to the constraint of VMIMRT. Further study is required to prove the benefit of the VIMRT in clinical case like head and neck cancer, where is expected that higher resolution than 1cm is necessary.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.6-8
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• 2002

Intensity modulated radiotherapy (IMRT) is an advanced but expensive form of 3-dimensional conformal radiation therapy technique. While the initial clinical data appear to be promising for some treatment sites, the cost effectiveness of the treatment modality has yet to be justified by long-term clinical outcome. This presentation reviews the potential efficacy and limitation of IMRT in respect of the practicality, dosimetry, and resource aspects. It tries to explore and draw conclusions on the strategies for using this sophisticated and expensive treatment technique from AFOMP perspective.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6133-6137
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• 2012

Purpose: To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume with intensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC). Methods and Materials: This retrospective study used data from 5 consecutive patients with NPC who were treated with bolus for large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients were treated radically with IMRT according to our institution's protocol. Re-planning with IMRT without bolus for these patients with exactly the same target volumes were done for comparison. Comparison of the plans was done by comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N. Results: The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. The mean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showed an absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had an advantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). The mean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only 23.5 Gy for the plans without bolus. Conclusion: Neck node bolus technique should be strongly considered in the treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry compared t o non-bolus plans with acceptable skin toxicity.

• Radiation Oncology Journal
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• v.36 no.1
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.68-73
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• 2002

In standard teletherapy, a treatment plan is generated with the aid of a treatment planning system, but it is common to perform an independent monitor unit verification calculation (MUVC). In exact analogy, we propose and demonstrate that a simple and accurate MUVC in Intensity Modulated Radiotherapy (IMRT) is possible. We introduce a concept of Modified Clarkson Integration (MCI). In MCI, we exploit the rotational symmetry of scattering to simplify the dose calculation. For dose calculation along a central axis (CAX), we first replace the incident IMRT fluence by an azimuthally averaged fluence. Second, the Clarkson Integration is carried over annular sectors instead of over pie sectors. We wrote a computer code, implementing the MCI technique, in order to perform a MUVC for IMRT purposes. We applied the code to IMRT plans generated by CORVUS. The input to the code consists of CORVUS plan data (e.g., DMLC files, jaw settings, MU for each IMRT field, depth to isocenter for each IMRT field), and the output is dose contribution by individual IMRT field to the isocenter. The code uses measured beam data for Sc, Sp, TPR, (D/Mu)$\_$ref/ and includes effects from MLC transmission, and radiation field offset. On a 266 MHZ desktop computer, the code takes less than 15 sec to calculate a dose. The doses calculated with MCI algorithm agreed within +/- 3% with the doses calculated by CORVUS, which uses a 1cm x 1cm pencil beam in dose calculation. In the present version of MCI, skin contour variations and inhomogeneities were neglected.

• Radiation Oncology Journal
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• v.28 no.1
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• pp.39-49
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• 2010

Purpose: This aim of this study is to analyze the dosimetric difference between intensity-modulated radiation therapy (IMRT) using 3 or 5 beams and MSF in the radiotherapy of the left breast. Materials and Methods: We performed a comparative analysis of two radiotherapy modalities that can achieve improved dose homogeneity. First is the multistatic fields technique that simultaneously uses both major and minor irradiation fields. The other is IMRT, which employs 3 or 5 beams using a fixed multileaf collimator. We designed treatment plans for 16 early left breast cancer patients who had taken breast conservation surgery and radiotherapy, and analyzed them from a dosimetric standpoint. Results: For the mean values of $V_{95}$ and dose homogeneity index, no statistically significant difference was observed among the three therapies. Extreme hot spots receiving over 110% of the prescribed dose were not found in any of the three methods. A Tukey test performed on IMRT showed a significantly larger increase in exposure dose to the ipsilateral lung and heart than multistatic fields technique (MSF) in the low-dose area, but in the high-dose area, MSF showed a slight increase. Conclusion: In order to improve dose homogeneity, the application of MSF, which can be easily planned and applied more widely, is considered an optimal alternative to IMRT for radiotherapy of early left breast cancer.