Intensity-modulated radiation therapy (IMRT) has been considered the most successful development in radiation oncology since the introduction of computed tomography into treatment planning that enabled three-dimensional conformal radiotherapy in 1980s. More than three decades have passed since the concept of inverse planning was first introduced in 1982, and IMRT has become the most important and common modality in radiation therapy. This review will present developments in inverse IMRT treatment planning and IMRT delivery using multileaf collimators, along with the associated key concepts. Other relevant issues and future perspectives are also presented.
Radiation Oncology ; Radiotherapy, Conformal

We published in May 10, 2022 a retrospective cohort study comparing the post-radiotherapy (post-RT) hemoglobin levels between patients with breast cancer who underwent intensity-modulated radiotherapy (IMRT) and those who underwent three-dimensional conformal radiotherapy (3D-CRT) in the Radiation Oncology Section of the Department of Radiological and Imaging Sciences of Southern Philippines Medical Center (ROS DORIS-SPMC) from October 2018 to March 2019. It came to our knowledge that the IMRT planning that was done on the patients included in our study was different from the IMRT planning that is currently being done since late 2020. Prior to late 2020, ROS DORIS-SPMC had been implementing forward-planned IMRT, wherein the weight of the multileaf collimator (MLC) segment was preselected at fixed values. In late 2020, ROS DORIS-SPMC started implementing inverse-planned IMRT, wherein the appropriate weights of the MLC segments are determined by an inverse optimization algorithm that creates a more uniform dose distribution throughout the target. Inverse-planned IMRT improves the dose homogeneity within the entire 3D-breast volume, while forward-planned IMRT mainly improves the dose distribution on the inframammary fold.1 Compared to 3D-CRT, however, forward-planned IMRT improves target homogeneity, albeit to a lesser degree than the homogeneity produced by the inverse technique.2 In the original article, we also stated that, for both IMRT and 3D-CRT, each dose fraction is given weekly within a span of 7 to 8 months. We recently confirmed that, among patients with breast cancer, each dose fraction of IMRT or 3D-CRT is given daily within a span of 33 days—28 days for conventional dose and 5 days for boost dose. In this corrigendum, we specify that the IMRT protocol used among the patients in our study was forward-planned IMRT, with all dose fractions given daily for 33 consecutive workdays, excluding weekends and holidays. We also describe here the original statements that we changed or removed because they have become irrelevant in light of the corrections. The table below shows the list of corrections.
Radiotherapy, Intensity-Modulated ; Radiotherapy, Conformal

PURPOSE: To develop a patients' setup verification tool (PSVT) to verify the alignment of the machine and the target isocenters, and the reproducibility of patients' setup for three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT). The utilization of this system is evaluated through phantom and patient case studies. MATERIALS AND METHODS: We developed and clinically tested a new method for patients' setup verification, using digitally reconstructed radiography (DRR), simulation, portal and digital images. The PSVT system was networked to a Pentium PC for the transmission of the acquired images to the PC for analysis. To verify the alignment of the machine and target isocenters, orthogonal pairs of simulation images were used as verification images. Errors in the isocenter alignment were measured by comparing the verification images with DRR of CT images. Orthogonal films were taken of all the patients once a week. These verification films were compared with the DRR were used for the treatment setup. By performing this procedure every treatment, using humanoid phantom and patient cases, the errors of localization can be analyzed, with adjustments made from the translation. The reproducibility of the patients' setup was verified using portal and digital images. RESULTS: The PSVT system was developed to verify the alignment of the machine and the target isocenters, and the reproducibility of the patients' setup for 3DCRT and IMRT. The results show that the localization errors are 0.8+/-0.2 mm (AP) and 1.0+/-0.3 mm (Lateral) in the cases relating to the brain and 1.1+/-0.5 mm (AP) and 1.0+/-0.6 mm (Lateral) in the cases relating to the pelvis. The reproducibility of the patients' setup was verified by visualization, using real-time image acquisition, leading to the practical utilization of our software. CONCLUSION: A PSVT system was developed for the verification of the alignment between machine and the target isocenters, and the reproducibility of the patients' setup in 3DCRT and IMRT. With adjustment of the completed GUI-based algorithm, and a good quality DRR image, our software may be used for clinical applications.
Brain ; Humans ; Pelvis ; Radiography ; Radiotherapy ; Radiotherapy, Conformal

PURPOSE: The Conformal Radiation Therapy has been widely used under favour of development of computer technologies. The delivery of a large number of static radiation fields are being necessary for the conformal irradiation. In this paper, we investigate dosimetric characteristics on penumbra regions of a multileaf collimator(MLC), and compare to those of lead alloy block for he optimal use of the system in 3-D conformal radiotherapy. MATERIALS AND METHODS: The measurement of penumbra by MLC or lead alloy block was performed with 6 or 10 MV X-rays. The film was positioned at a dmax depth and 10 cm depth, and its optical density was determined using a scanning videodensitometer. The effective penumbra, the distance from 80% to 20% isodose lines and 90 to 10 were analyzed as a function of the angle between the direction of leaf motion and the edge defined by leaves. RESULTS: Increasing MLC angle (0-75degree) was observed with increasing the penumbra widths and the scalloping effect. There was no definite differences of penumbra width from 80% to 20% isodose lines, while being the small increase of penumbra width of lead alloy block are agree reasonably with those of MLC within 4.8mm. CONCLUSION: The comparative qualitative study of the penumbra between MLC and lead alloy block demonstrate the clinical acceptability and suitability of the multileaf collimator for 3-D conformal radiotherapy.
Alloys* ; Film Dosimetry ; Pectinidae ; Radiotherapy, Conformal

PURPOSE: The Conformal Radiation Therapy has been widely used under favour of development of computer technologies. The delivery of a large number of static radiation fields are being necessary for the conformal irradiation. In this paper, we investigate dosimetric characteristics on penumbra regions of a multileaf collimator(MLC), and compare to those of lead alloy block for he optimal use of the system in 3-D conformal radiotherapy. MATERIALS AND METHODS: The measurement of penumbra by MLC or lead alloy block was performed with 6 or 10 MV X-rays. The film was positioned at a dmax depth and 10 cm depth, and its optical density was determined using a scanning videodensitometer. The effective penumbra, the distance from 80% to 20% isodose lines and 90 to 10 were analyzed as a function of the angle between the direction of leaf motion and the edge defined by leaves. RESULTS: Increasing MLC angle (0-75degree) was observed with increasing the penumbra widths and the scalloping effect. There was no definite differences of penumbra width from 80% to 20% isodose lines, while being the small increase of penumbra width of lead alloy block are agree reasonably with those of MLC within 4.8mm. CONCLUSION: The comparative qualitative study of the penumbra between MLC and lead alloy block demonstrate the clinical acceptability and suitability of the multileaf collimator for 3-D conformal radiotherapy.
Alloys* ; Film Dosimetry ; Pectinidae ; Radiotherapy, Conformal

PURPOSE: Three dimensional conformal radiotherapy planning is being used widely for the treatment of patients with brain tumor. However, it takes much time to develop an optimal treatment plan, therefore, it is difficult to apply this technique to all patients. To increase the efficiency of this technique, we need to develop standard radiotherapy plans for each site of the brain. Therefore we developed several 3 dimensional conformal radiotherapy plans (3D plans) for tumors at each site of brain, compared them with each other, and with 2 dimensional radiotherapy plans. Finally model plans for each site of the brain were decided. MATERIALS AND METHODS: Imaginary tumors, with sizes commonly observed in the clinic, were designed for each site of the brain and drawn on CT images. The planning target volumes (PTVs) were as follows; temporal tumor-5.7x8.2x7.6 cm, suprasellar tumor-3x4x4.1 cm, thalamic tumor-3.1x5.9x3.7 cm, frontoparietal tumor-5.5x7x5.5 cm, and occipitoparietal tumor-5x5.5x5 cm. Plans using parallel opposed 2 portals and/or 3 portals including fronto-vertex and 2 lateral fields were developed manually as the conventional 2D plans, and 3D noncoplanar conformal plans were developed using beam's eye view and the automatic block drawing tool. Total tumor dose was 54 Gy for a suprasellar tumor, 59.4 Gy and 72 Gy for the other tumors. All dose plans (including 2D plans) were calculated using 3D plan software. Developed plans were compared with each other using dose-volume histograms (DVH), normal tissue complication probabilities (NTCP) and variable dose statistic values (minimum, maximum and mean dose, D5, V83, V85 and V95). Finally a best radiotherapy plan for each site of brain was selected. RESULTS: 1) Temporal tumor; NTCPs and DVHs of the normal tissue of all 3D plans were superior to 2D plans and this trend was more definite when total dose was escalated to 72 Gy (NTCPs of normal brain 2D plans : 27%, 8% 3D plans : 1%, 1%). Various dose statistic values did not show any consistent trend. A 3D plan using 3 noncoplanar portals was selected as a model radiotherapy plan. 2) Suprasellar tumor; NTCPs of all 3D plans and 2D plans did not show significant difference because the total dose of this tumor was only 54 Gy. DVHs of normal brain and brainstem were significantly different for different plans. D5, V85, V95 and mean values showed some consistent trend that was compatible with DVH. All 3D plans were superior to 2D plans even when 3 portals (fronto-vertex and 2 lateral fields) were used for 2D plans. A 3D plan using 7 portals was worse than plans using fewer portals. A 3D plan using 5 noncoplanar portals was selected as a model plan. 3) Thalamic tumor; NTCPs of all 3D plans were lower than the 2D plans when the total dose was elevated to 72 Gy. DVHs of normal tissues showed similar results. V83, V85, V95 showed some consistent differences between plans but not between 3D plans. 3D plans using 5 noncoplanar portals were selected as a model plan. 4) Parietal (fronto- and occipito-) tumors; all NTCPs of the normal brain in 3D plans were lower than in 2D plans. DVH also showed the same results. V83, V85, V95 showed consistent trends with NTCP and DVH. 3D plans using 5 portals for frontoparietal tumor and 6 portals for occipitoparietal tumor were selected as model plans. CONCLUSION: NTCP and DVH showed reasonable differences between plans and were thought to be useful for comparing plans. All 3D plans were superior to 2D plans. Best 3D plans were selected for tumors in each site of brain using NTCP, DVH and finally by the planner's decision.
Brain Neoplasms* ; Brain Stem ; Brain* ; Humans ; Rabeprazole ; Radiotherapy ; Radiotherapy, Conformal*

We present a case of unresectable cancer of the base of tongue treated with hypofractionated 3D conformal radiotherapy and concomitant chemotherapy. Based on the excellent tumour response in this radiotherapy regimen and international experience in short course treatments we shortly reviewed, we propose that this therapeutic approach could be considered in a curative setting for patients unsuitable for the a standard long course radiochemotherapy schedule.
Appointments and Schedules ; Chemoradiotherapy* ; Drug Therapy ; Humans ; Radiotherapy ; Radiotherapy, Conformal ; Tongue*

BACKGROUND: This study aimed to assess the recent changes of radiation therapy (RT) modalities in Korea. In particular, we focused on intensity-modulated radiation therapy (IMRT) utilization as the main index, presenting the application status of advanced RT. METHODS: We collected information from the Korean Health and Insurance Review and Assessment Service data based on the National Health Insurance Service claims and reimbursements records by using treatment codes from 2010 to 2016. We classified locating region of each institution as capital vs. non-capital areas and metropolitan vs. non-metropolitan areas to assess the regional difference in IMRT utilization in Korea. RESULTS: IMRT use has been steadily increased in Korea, with an annual increase estimate (AIE) of 37.9% from 2011 to 2016 (P < 0.001) resulting in IMRT being the second most common RT modality following three-dimensional conformal radiotherapy. In general, an increasing trend of IMRT utilization was observed, regardless of the region. The rate of AIE in the capital areas or metropolitan areas was higher than that in non-capital areas or non-metropolitan areas (40.7% vs. 31.9%; P < 0.001 and 39.7% vs. 29.4%; P < 0.001, respectively). DISCUSSION: The result of our survey showed that IMRT has become one of the most common RT modalities. IMRT is becoming popular in both metropolitan and non-metropolitan areas, while metropolitan area has faster AIE possibly due to concentration of medical resources and movement of advanced patients.
Humans ; Insurance ; Korea ; National Health Programs ; Radiotherapy ; Radiotherapy, Conformal

In this paper, two new concepts of DR (Dose Repulsion) and DG (Dose Gravitation) are presented with their calculation formulas. For the problem of selecting beam arcs in x-knife radiotherapy Planning system, a mathematics model of constrained optimization has been built. Furthermore, we have produced a feasible project of automatic selecting optimized beam arcs plan using SA (Simulated Annealing) arithmetic based on the distribution of the fields of DR and DG in the reduced phase space.
Algorithms ; Brain Neoplasms ; radiotherapy ; Models, Theoretical ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Conformal ; methods

KylinRay-IMRT is the advanced radiotherapy treatment planning module of accurate radiotherapy system (KylinRay) aiming to provide accurate and efficient plan design platform. In this paper the system design, main functions and key technologies of KylinRay-IMRT were introduced. KylinRay-IMRT supports three dimensional conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and many other types of treatment plan design with function modules including patient data management, image registration and fusion, image contouring, image three dimensional reconstruction and visualization, three dimensional conformal radiotherapy planning, intensity modulated radiotherapy planning, plan evaluation and comparison, and report print. KylinRay-IMRT has been tested by the national standard YY/T 0889-2013, the results showed that the performance of KylinRay-IMRT can fully meet the standard requirements.
Humans ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Conformal ; Radiotherapy, Intensity-Modulated ; Tomography, X-Ray Computed