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Purpose: We aimed to evaluate the magnetic resonance imaging (MRI) appearance changes during stereotactic radiotherapy (SRT) for large sized brain metastases, and analyze the lesions necessitating treatment plan modification., Materials and Methods: A total of 23 patients (27 lesions, >2 cm in tumor diameter) underwent SRT and all lesions were evaluated the appearance changes which had the necessity of the treatment plan modification. The appearance change of tumor during SRT was evaluated using gadolinium-enhanced MRI. The reasons of the modification were classified into tumor reduction, tumor enlargement, displacement, and shape change., Results: Among the 27 lesions, 55.6% required the treatment plan modification. The reasons were tumor reduction in six lesions, tumor enlargement in three lesions, displacement in three lesions, and shape change in three lesions. The planning target volume (PTV) size changed up to 43.0% and the shift of center of PTV was a maximum of 1.7 mm. The pathological status (adenocarcinoma vs others) and timing of steroid administration (prior vs after SRT start) were the predictive factors of tumor changes required the modification., Conclusions: As tumor changes might occur even during short period of SRT, the treatment plan evaluation and modification were important in SRT for large brain metastases.

Background: Previously, the physical dose-enhancement factor (D phys EF) enhancement was introduced. However, the dose enhancement considering the biological effectiveness was not shown., Purpose: The aim of the current study was to evaluate the biological dose-enhancement factor (D bio EF) by the dose rate and to compare the D phys EF and the D bio EF in Lipiodol for liver Stereotactic Body Radiation Therapy (SBRT)., Materials and Methods: Flattening-filter-free (FFF) 6-MV (6MVX) and 10MVX beams were delivered by TrueBeam. A virtual inhomogeneity phantom and a liver SBRT patient-treatment plan were used. The D phys EF and lineal energy distribution ( y ) distribution was calculated from Monte Carlo simulations. Using a microdosimetric-kinetic (MK) model that is estimated based on the linear-quadratic formula for Lipiodol using human liver hepatocellular cells (HepG2), the biological dose and biological dose enhancement factor (D bio EF) were calculated. The dose rate in the simulation was changed from 0.1 to 24 Gy/min., Results: The D bio EF (DR:2Gy/min) and D phys EF with 10MVX FFF beam were 23.2% and 19.1% at maximum and 12.8% and 11.1% on average in the Lipiodol. In the comparison of the D bio EF between 0.1-24 Gy/min, the D bio EF was 21.2% and 11.1% with 0.1 Gy/min for 6MVX and 10 MVX, respectively. The D bio EF was larger than DEF for the 6MVX and 10MVX FFF beams. In clinical cases with the 10MVX FFF beam, the D bio EF and D phys EF in the Lipiodol region can increase the in-tumor dose by approximately 11% and 10%, respectively, without increasing the dose to normal tissue., Conclusions: The lower-energy and higher-dose-rate beams were contributed to the biological dose. The Lipiodol caused the enhancement of the physical dose and biological effectiveness., Advances in Knowledge: The biological dose enhancement (D bio EF) should be considered in the high-density material such as the Lipiodol., (© 2019 Greater Poland Cancer Centre. Published by Elsevier B.V. All rights reserved.)

In a previous study, a phantom study of a contrast agent extraction system with computed tomography (CT) number and raw-data-based electron density (ED) was described. The current study improved this system with monochromatic CT (mCT) number and evaluated an anthropomorphic phantom for delineation of the contrast-enhanced region. Dual-energy CT images were scanned with a tissue-equivalent phantom and an anthropomorphic phantom with an iodinated contrast agent (1-130 mg/mL). The 40, 70, and 130 keV mCT images were reconstructed with 80 and 135 kV CT images. The contrast agent was separated from other materials using the gradient of the mCT number (GmCT) and the threshold mCT numbers. The system was analyzed using in-house software with Python. The evaluation of the accuracy for the contrast agent extraction was performed by measuring the ratio of the volume (ROV). The mCT number of the contrast agent and bone materials, liver, and muscle in the tissue-equivalent phantom was obviously greater than - 78 HU. The deviation of the mCT numbers between bone materials in tissue-equivalent phantom and the contrast agent were larger than 8 HU. The GmCT was within 4.0 in the tissue-equivalent phantom and more than 6.0 in the contrast agent. The ROV was 0.97-1.00 at more than 1 mg/mL contrast agent. Improved the contrast agent extraction system could be used for a patient's CT image. It could extract the iodinated tumor or lesion automatically. The contrast agent extraction system was improved by the mCT number. It is expected to only extract the contrast-enhanced region automatically.

Objectives: The aim of the current study is to evaluate the accuracy and the precision of raw-data-based relative electron density (RED raw ) and the calibration-based RED (RED cal ) at a range of low-RED to high-RED for tissue-equivalent phantom materials by comparing them with reference RED (RED ref ) and to present the difference of RED raw and RED cal for the contrast medium using dual-energy CT (DECT)., Methods: The RED raw images were reconstructed by raw-data-based decomposition using DECT. For evaluation of the accuracy of the RED raw , RED ref was calculated for the tissue-equivalent phantom materials based on their specified density and elemental composition. The RED cal images were calculated using three models: Lung-Bone model, Lung-Ti model and Lung-Ti (SEMAR) model which used single-energy metal artifact reduction (SEMAR). The difference between RED raw and RED cal was calculated., Results: In the titanium rod core, the deviations of RED raw and RED cal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) from RED ref were 0.45%, 50.8%, 15.4% and 15.0%, respectively. The largest differences between RED raw and RED cal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) in the contrast medium phantom were 8.2%, -23.7%, and 28.7%, respectively. However, the differences between RED raw and RED cal values were within 10% at 20 mg/ml. The standard deviation of the RED raw was significantly smaller than the RED cal with three models in the titanium and the materials that had low CT numbers., Conclusion: The RED cal values could be affected by beam hardening artifacts and the RED cal was less accurate than RED raw for high-Z materials as titanium., Advances in Knowledge: The raw-data-based reconstruction method could reduce the beam hardening artifact compared with image-based reconstruction and increase the accuracy for the RED estimation in high-Z materials, such as titanium and iodinated contrast medium.

Purpose: The output of a linear accelerator (linac) is one of the most important quality assurance (QA) factors in radiotherapy. However, there is no quantitative rationale for frequency and tolerance. The purpose of this study is to develop a novel risk analysis of clinical reference dosimetry based on failure modes and effects analysis (FMEA)., Methods: Clinical reference dosimetry data and the daily output data of two linacs (Clinac iX and Clinac 6EX) at Hiroshima University Hospital were analyzed. The analysis involved the number of patients per year for five types of fractionations. Risk priority number (RPN) is defined as the product of occurrence (O), severity (S), and detectability (D) in standard FMEA. In addition, we introduced "severity due to output drifting" (mean output change per day) (S') and the number of patients per year for five types of fractionations (W). We calculated the RPN = O × S × D × S' × W and quantitatively evaluated the risk for clinical reference dosimetry., Results: Fewer fractions and less output calibration frequency resulted in higher RPN. Since clinical reference dosimetry data has a drift effect, which is missing in human processes, it was essential to use S' in addition to standard FMEA. Moreover, the parameter W was important in evaluating interinstitutional QA for clinical reference dosimetry. The relative risk of Clinac 6EX to Clinac iX was different approximately by twofold., Conclusions: We developed a novel index that can quantitatively evaluate risk for clinical reference dosimetry of each facility and machines in common on the basis of FMEA., (Copyright © 2019 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of this study was to perform a comparison between robust optimization and planning target volume (PTV)-based optimization plans using volumetric modulated arc-therapy (VMAT) by evaluating perturbed doses induced by localization offsets for setup uncertainties in larynx cancer radiation therapy., Methods: Ten patients with early-stage (T1-2N0) glottis carcinoma were selected. The clinical target volume (CTV), carotid arteries, and spinal cord were contoured by a radiation oncologist. PTV-based and robust optimization plans were normalized at D 50% to the PTV and D 98% to the CTV, respectively. Both optimization plans were evaluated using perturbed doses by specifying user defined shifted values from the isocenter. CTV dose (D 98% , D 50% , and D 2% ), homogeneity index (HI) and conformity index (CI 95% , CI 80% , and CI 50% ), as well as doses to the carotid arteries and spinal cord were compared between PTV-based and robust optimization plans., Results: The robust optimization plans exhibited superior CTV coverage and a reduced dose to the carotid arteries compared to the PTV-based optimization plans (p < 0.05). HI, CI 95% and the dose to the spinal cord did not significantly differ between the PTV-based and robust optimization plans (p > 0.05). The robust optimization plans showed better CI 80% and CI 50% compared to the PTV-based optimization plans (p < 0.05). Plan perturbed evaluations showed that the robust optimization plan has small variations in the doses to the CTV, carotid arteries, and spinal cord compared to the PTV-based optimization plan., Conclusions: The robust optimization plan may be a suitable treatment method in radiotherapy for larynx cancer patient., (Copyright © 2019 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of this study was to develop an end-to-end postal audit test to examine the coincidence between the imaging isocenter and treatment beam isocenter of the image guided radiotherapy (IGRT) linac system for Japan Clinical Oncology Group (JCOG) trials, as a part of IGRT credentialing of institutions participating in JCOG trials., Methods: We developed an end-to-end postal audit test to verify radiation positional errors associated with IGRT techniques. This test is intended for simulating a clinical IGRT flow and uses a static cubic phantom measuring 15 × 15 × 15 cm 3 and weighing approximately 3.4 kg. The phantom has four gold fiducial markers and a spherical dummy target for setup, with known shift values from the phantom center. Two pairs of Gafchromic RTQA2 films were inserted 5 mm from the phantom's anterior-posterior and right-left surfaces. Radiation positional errors at the isocenter were determined by analyzing the center of the radiation field on the films and the known shift values of the dummy target. The test was performed on 47 IGRT devices at 35 institutions., Results: Radiation positional errors were within acceptance levels (1 mm/1°) for 42 IGRT devices (89.4%) in the first check. Median time to complete IGRT credentialing was 11.5 days. This audit method was applicable for any radiotherapy machine with an IGRT device., Conclusions: A postal audit test to verify radiation positional errors for JCOG trials was successfully developed. In the postal audit, all but one institution passed this credentialing item within two trials., (Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Aim and Background: IGRT based on bone matching may produce a large target positioning error in terms of the reproducibility of expiration breath-holding on SBRT for liver cancer. We evaluated the intrafractional and interfractional errors using the diaphragm position at the end of expiration by utilising Abches and analysed the factor of the interfractional error., Materials and Methods: Intrafractional and interfractional errors were measured using a couple of frontal kV images, planning computed tomography (pCT) and daily cone-beam computed tomography (CBCT). Moreover, max-min diaphragm position within daily CBCT image sets with respect to pCT and the maximum value of diaphragm position difference between CBCT and pCT were calculated., Results: The mean ± SD (standard deviation) of the intra-fraction diaphragm position variation in the frontal kV images was 1.0 ± 0.7 mm in the C-C direction. The inter-fractional diaphragm changes were 0.4 ± 4.6 mm in the C-C direction, 1.4 ± 2.2 mm in the A-P direction, and -0.6 ± 1.8 mm in the L-R direction. There were no significant differences between the maximum value of the max-min diaphragm position within daily CBCT image sets with respect to pCT and the maximum value of diaphragm position difference between CBCT and pCT., Conclusions: Residual intrafractional variability of diaphragm position is minimal, but large interfractional diaphragm changes were observed. There was a small effect in the patient condition difference between pCT and CBCT. The impact of the difference in daily breath-holds on the interfractional diaphragm position was large or the difference in daily breath-holding heavily influenced the interfractional diaphragm change.

Objectives: We examine the contrast agent Lipiodol effect on the relative biological effectiveness (RBE) values for flattening filter free (FFF) and flattening filter (FF) beams of 6 MV-Xray (6 MVX) and 10 MVX., Methods: Lipiodol was placed at 5 cm depth in water. According to the microdosimetric kinetic model, the RBE values for killing the human liver hepatocellular cells were calculated from dose and lineal energy (yd(y)) from Monte Carlo simulations. RBE 200kVX and RBE Co were defined as the ratios of dose using reference radiation (200 kVX, Co-ɤ) to the dose of test radiation (FFF and FF beams for 6 MV and 10 MV) to produce the same biological effects. The dose enhancement RBE (RBE DE ) was defined as the ratios of a dose without Lipiodol to with Lipiodol using to produce the same biological effects. The dose needed to achieve 10% (D 10% ) and 1% cell survival (D 1% ) was evaluated by cell surviving fraction (SF) formula., Results: The deviation of mean y‾ D values with and without Lipiodol were 3.9-4.8% for 6 MVX and 3.5-3.6% for 10 MVX. The RBE 200kVX and RBE Co with Lipiodol were larger than that without Lipiodol. The RBE DE was larger for FFF beam than for FF beam. The deviation of RBE DE for FFF and FF beams of 6 MVX was larger than that of 10 MVX., Conclusion: The presence of Lipiodol seemed to locally increase the absorbed dose and to also cause an enhancement of the relative biological effectiveness., (Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

It is a useful method for the adaptive radiotherapy (ART) to calculate absorbed dose accurately on the image set taken by on-board cone beam computed tomography (CBCT) attached to linac for image-guided radiation therapy (IGRT). For this purpose, a simple and accurate calculation method is necessary. Several papers report that it is possible to calculate easily and accurately by using several methods of researches in the neck and prostate, but the lung density varies greatly depending on patient thorax condition. In this study, we propose a new dose recalculation method, which is a simple procedure and can achieve accurate dose calculation considered different lung densities in each patient. By using this method, it is possible to calculate exclusive of artifacts in CBCT because of overriding the lung density. The dose error between dose recalculation of the CBCT image and treatment plan agreed within±1%. Therefore, this method is expected to be a useful method for accurate dose calculation with CBCT image for ART.

Aim: Lipiodol was used for stereotactic body radiotherapy combining trans arterial chemoembolization. Lipiodol used for tumour seeking in trans arterial chemoembolization remains in stereotactic body radiation therapy. In our previous study, we reported the dose enhancement effect in Lipiodol with 10× flattening-filter-free (FFF). The objective of our study was to evaluate the dose enhancement and energy spectrum of photons and electrons due to the Lipiodol depth with flattened (FF) and FFF beams., Methods: FF and FFF for 6 MV beams from TrueBeam were used in this study. The Lipiodol (3 × 3 × 3 cm 3 ) was located at depths of 1, 3, 5, 10, 20, and 30 cm in water. The dose enhancement factor (DEF) and the energy fluence were obtained by Monte Carlo calculations of the particle and heavy ion transport code system (PHITS)., Results: The DEFs at the centre of Lipiodol with the FF beam were 6.8, 7.3, 7.6, 7.2, 6.1, and 5.7% and those with the FFF beam were 20.6, 22.0, 21.9, 20.0, 12.3, and 12.1% at depths of 1, 3, 5, 10, 20, and 30 cm, respectively, where Lipiodol was located in water. Moreover, spectrum results showed that more low-energy photons and electrons were present at shallow depth where Lipiodol was located in water. The variation in the low-energy spectrum due to the depth of the Lipiodol position was more explicit with the FFF beam than that with the FF beam., Conclusions: The current study revealed variations in the DEF and energy spectrum due to the depth of the Lipiodol position with the FF and FFF beams. Although the FF beam could reduce the effect of energy dependence due to the depth of the Lipiodol position, the dose enhancement was overall small. To cause a large dose enhancement, the FFF beam with the distance of the patient surface to Lipiodol within 10 cm should be used.

It is important for high-precision radiation therapy that tracking accuracy in dynamic tumor tracking (DTT) using the gimbal X-ray head. We evaluated the tracking accuracy under various respiratory patterns differ from a correlation model [four-dimensional model (4D-model)] in real-time using a digital camera. A sheet of paper with luminous line was placed on the programmable respiratory motion table (CIRS Inc.) and operated with the laser projector. The luminous line was defined as a target and the laser was defined as a gimbal. Motion table was operated at a period of 4 s and amplitude of ±10 mm to create 4D-modeling. This movement was defined as the basic operation. To investigate the tracking accuracy, target and gimbal positions were recorded using a digital camera under amplitudes (±5-20 mm) and periods (2-8 s) and analyzed by ImageJ software (NIH). The maximum tracking errors under various period and amplitude were 1.7-0.9 mm and 0.4-1.9 mm, respectively. From the creation of 4D-modeling, it was confirmed that when the period has shortened and the amplitude has increased, tracking accuracy was reduced.

Purpose: In this study, we demonstrate the feasibility of using split-arcs in volumetric modulated arc therapy (VMAT), tailored for expiratory breath-hold in stereotactic body radiation therapy (SBRT) for liver tumors. We compare it with three-dimensional conformal radiation therapy (3D-CRT) and continuous-VMAT, for ten randomly selected hepatocellular carcinoma cases., Methods: Four coplanar and four non-coplanar beams were used for the 3D-CRT plans. A pair of partial arcs, chosen using a back-and-forth rotating motion, were used for the continuous-VMAT plans. Split-VMAT plans were created using the same arc range as the continuous-VMAT plans, but were split into smaller arcs (<90°), to simulate an expiratory breath hold of <15s. The dose distribution, treatment delivery efficiency, and patient specific quality assurance of the split-VMAT, were verified to ensure that the outcomes were equal, or better than, those for 3D-CRT and continuous-VMAT. The prescription was 48Gy/4 fractions, to 95% of the PTV, using 10MV FFF X-ray beams., Results: The mean dose of the liver-GTV was lower in the split-VMAT compared with that of 3D-CRT. Split-VMAT was more conformal compared with 3D-CRT. The total treatment time for split-VMAT was shorter than that of 3D-CRT. Similar dosimetric indices were observed for split-VMAT and continuous-VMAT. All VMAT plans passed the gamma acceptance test., Conclusions: Split-VMAT designed to accommodate an expiratory breath-hold period of 15s is a feasible and efficient use of liver SBRT, because it does not compromise the quality of the plan, when compared with 3D-CRT or continuous-VMAT., (Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Background: An important issue in indirect dynamic tumor tracking with the Vero4DRT system is the accuracy of the model predictions of the internal target position based on surrogate infrared (IR) marker measurement. We investigated the predictive uncertainty of 4D modeling using an external IR marker, focusing on the effect of the target and surrogate amplitudes and periods., Methods: A programmable respiratory motion table was used to simulate breathing induced organ motion. Sinusoidal motion sequences were produced by a dynamic phantom with different amplitudes and periods. To investigate the 4D modeling error, the following amplitudes (peak-to-peak: 10-40 mm) and periods (2-8 s) were considered. The 95th percentile 4D modeling error (4D- E 95% ) between the detected and predicted target position ( μ  + 2SD) was calculated to investigate the 4D modeling error., Results: 4D- E 95% was linearly related to the target motion amplitude with a coefficient of determination R 2  = 0.99 and ranged from 0.21 to 0.88 mm. The 4D modeling error ranged from 1.49 to 0.14 mm and gradually decreased with increasing target motion period., Conclusions: We analyzed the predictive error in 4D modeling and the error due to the amplitude and period of target. 4D modeling error substantially increased with increasing amplitude and decreasing period of the target motion.

The aim of the current planning study is to evaluate the ability of gadoxetate disodium-enhanced magnetic resonance imaging (EOB-MRI)-guided stereotactic body radiation therapy (SBRT) planning by using intensity-modulated radiation therapy (IMRT) techniques in sparing the functional liver tissues during SBRT for hepatocellular carcinoma. In this study, 20 patients with hepatocellular carcinoma were enrolled. Functional liver tissues were defined according to quantitative liver-spleen contrast ratios ≥ 1.5 on a hepatobiliary phase scan. Functional images were fused with the planning computed tomography (CT) images; the following 2 SBRT plans were designed using a "step-and-shoot" static IMRT technique for each patient: (1) an anatomical SBRT plan optimization based on the total liver; and (2) a functional SBRT plan based on the functional liver. The total prescribed dose was 48 gray (Gy) in 4 fractions. Dosimetric parameters, including dose to 95% of the planning target volume (PTV D 95% ), percentages of total and functional liver volumes, which received doses from 5 to 30 Gy (V5 to V30 and fV5 to fV30), and mean doses to total and functional liver (MLD and fMLD, respectively) of the 2 plans were compared. Compared with anatomical plans, functional image-guided SBRT plans reduced MLD (mean: plan A, 5.5 Gy; and plan F, 5.1 Gy; p < 0.0001) and fMLD (mean: plan A, 5.4 Gy; and plan F, 4.9 Gy; p < 0.0001), as well as V5 to V30 and fV5 to fV30. No differences were noted in PTV coverage and nonhepatic organs at risk (OARs) doses. In conclusion, EOB-MRI-guided SBRT planning using the IMRT technique may preserve functional liver tissues in patients with hepatocellular carcinoma (HCC)., (Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)

Purpose: Published organ motion data have been collected from measurements of a limited number of points within the organ, the centroid, or the edge of the organ. These are derived from the spatial characteristics of respiratory induced motion; however, this approach does not consider non-rigid organ deformation. We propose a novel quantitative method for evaluating respiratory induced organ motion using Deformable Image Registration (DIR)., Method: Two phases from a 4-dimensional computed tomography (4D CT) dataset at maximum inspiration and expiration were each taken from five patients. The left and right lungs, esophagus, stomach, spinal cord, and liver were manually contoured in the end-expiration phase. The hybrid deformable registration algorithm of the RayStation treatment planning system (TPS) was used to deform the end-expiration phase to the end-inspiration phase. From this, the deformation vector field (DVF) was calculated. DVFs consist of DVF LR (left-right), DVF AP (anterior-posterior), and DVF SI (superior-inferior) as separate files. We calculated the vector volume histogram (VVH) and L max (maximum absolute vector of the organ) to evaluate every vector for each individual organ. We also measured respiratory organ motion from the position of the organ centroid in two phases., Results: VVH enabled us to find the absolute distance and volume of the organ contributing to motion points on the curve. Organ motion using the centroid method was smaller than L max using VVH. Using the centroid method, it is difficult to evaluate the deformable organ motion., Conclusion: VVH may be a useful technique in evaluating organ volumetric change during respiratory organ motion., (Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Aim: In high-precision radiation therapy, kilovoltage cone-beam computed tomography plays an important role in verifying the position of patient and localization of the target. However, the exposure dose is a problem with kilovoltage cone-beam computed tomography. Flux overlap region increases the patient dose around the center when the scan is performed in a full-scan mode. We assessed the influence of flux overlap region in a full-scan mode to understand the relationship between dose and image quality and investigated methods to achieve a dose reduction., Method: A Catphan phantom was scanned using various flux overlap region patterns in the pelvis on a full-scan mode. We used an intensity-modulated radiation therapy phantom for measuring the central dose. DoseLab was used to perform image analysis and to evaluate the linearity of the computed tomography values, uniformity, high-contrast resolution, and contrast-to-noise ratio., Results: The Hounsfield unit value varied by ±40 Hounsfield unit of the acceptance value for the X1 field size of 3.5 cm. However, there were no differences in high-contrast resolution and contrast-to-noise ratio among different scan patterns. The absorbed dose decreased by 7% at maximum for the case within the tolerance value., Conclusion: Dose reduction is possible by reducing the overlap region after calibration and by performing computed tomography in the appropriate overlap region.

Purpose: Image-guided radiotherapy (IGRT) based on bone matching can produce large target-positioning errors because of expiration breath-hold reproducibility during stereotactic body radiation therapy (SBRT) for liver tumors. Therefore, the feasibility of diaphragm-based 3D image matching between planning computed tomography (CT) and pretreatment cone-beam CT was investigated., Methods: In 59 liver SBRT cases, Lipiodol uptake after transarterial chemoembolization was defined as a tumor marker. Further, the relative isocenter coordinate that was obtained by Lipiodol matching was defined as the reference coordinate. The distance between the relative isocenter coordinate and reference coordinate, which was obtained from diaphragm matching and bone matching techniques, was defined as the target positioning error. Furthermore, the target positioning error between liver matching and Lipiodol matching was evaluated., Results: The positioning errors in all directions by the diaphragm matching were significantly smaller than those obtained by using by the bone matching technique (p < 0.05). Further, the positioning errors in the A-P and C-C directions that were obtained by using liver matching were significantly smaller than those obtained by using bone matching (p < 0.05). The estimated PTV margins calculated by the formula proposed by van Herk for diaphragm matching, liver matching, and bone matching were 5.0 mm, 5.0 mm, and 11.6 mm in the C-C direction; 3.6 mm, 2.4 mm, and 6.9 mm in the A-P direction; and 2.6 mm, 4.1 mm, and 4.6 mm in the L-R direction, respectively., Conclusions: Diaphragm matching-based IGRT may be an alternative image matching technique for determining liver tumor positions in patients., (Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

The feasibility of single isocenter, multi-arc non-coplanar volumetric modulated arc therapy (VMAT) for multiple brain tumors was studied using an Elekta Synergy linear accelerator with an Agility multileaf collimator and a Monaco treatment planning system. Two VMAT radiosurgery plans consisting of a full arc and three half arcs were created with a prescribed dose of 20 Gy in a single fraction. After dose delivery to a phantom, ionization chambers and radiochromic films were used for dose measurement. The first VMAT radiosurgery plan had nine targets inside the phantom, and the doses were measured by the chambers at two different points and by the films on three sagittal and three coronal planes. The differences between the calculated dose and the dose measured by a Farmer ionization chamber and a pinpoint ionization chamber were <1.00% and <2.30%, respectively, and the average pass rates of gamma indices among the six planes under each of 3%/3 mm and 2%/2 mm criteria were 98.6% and 92.6%, respectively. The second VMAT radiosurgery plan was based on a clinical 14 brain metastases. Differences between calculated and film-measured doses were evaluated on two sagittal planes. The average pass rates of the gamma indices on the planes under each of 3%/3 mm and 2%/2 mm criteria were 97.8% and 88.8%, respectively. It was confirmed that single-isocenter, non-coplanar multi-arc VMAT radiosurgery for multiple brain metastases was feasible using Elekta Synergy with Agility and Monaco treatment planning systems. It was further shown that film dosimetry was accurately performed for a dose of up to nearly 25 Gy., (© The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.)

Dose verification using radiochromic films may bring about moiré artifacts during the film scanning process using a flatbed scanner. A method for removing the moiré artifacts was already reported for reflective scanning. Recently, transmissive scanning using EBT2 films has played a major role for dose verification in intensity-modulated radiation therapy. It was found that placing a nonreflecting glass plate on the detector side could eliminate all the moiré artifacts for transmissive scanning.

Radiotherapy has been widely used in breast cancer in many situations. These are breast irradiation of breast conserving therapy,post mastectomy regional irradiation,irradiation for regional lymph nodes recurrence,breast irradiation of inoperable locally advanced cases,palliative irradiation of brain metastasis,bone metastasis and so on. The relationship among radiotherapy,surgery and systemic therapy has to be considered in those situations. In breast conserving therapy, the usefulness of breast irradiation is well established. Otherwise, a local controllability depend on a grade of residual tumor cell has not been understand. The authors conducted the survey of 941 cases of positive surgical margins and found that doses more than 60 Gy has a tendency for better local control in post menopausal cases. To reduce patient's burden,3 weeks short course irradiation (Canadian protocol) or accelerated partial breast irradiation have been introduced in breast irradiation. A subgroup which has no need to irradiate to conserving breast had not been identified. The timing between postoperative chemotherapy and irradiation is another point that has to be considered. To reduce distant metastasis,chemotherapy first has been considered better. As for post mastectomy regional irradiation, improvement of local and systemic control has been widely known these days. A timing of systemic therapy and irradiation is a point has to consider. In inoperable or far advanced T 4 tumors, breast irradiation with concurrent chemotherapy must be considered in stead of surgery. We have to know a big shortage in Japanese cancer treatment situation that we have few radiation oncologists or medical physicists in Japan. We have to educate those specialists to catch up with increasing cancer patients.