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In this review article, we introduced the importance of "motion management" in advanced particle therapy. Several publications have reported that organ motion causes dose distribution disturbances due to interplay and blurring effects. Furthermore, motion can result in target dose miss and unwanted dose to healthy structures around the target. To avoid these problems, motion should be assessed and monitored prior and during treatment. In this review article, we give an overview about clinically available motion monitoring systems. Based on the acquired motion information an adequate motion mitigation technique should be chosen. This article reviews the clinical status of motion mitigation techniques like rescanning, gating and tracking. A limited number of centers have now started the treatment of targets in the thorax and abdomen using scanned particle beams. Therefore, the establishment of guidelines for motion monitoring and motion mitigation will be essential in the coming years., (© 2017 American Association of Physicists in Medicine.)

We evaluated the CT number accuracy in determining a CT calibration method for treatment planning by use of a 256 multi-slice CT (MSCT) scanner. An electron density phantom, which extends full length in the longitudinal direction, was scanned by the 256 MSCT scanner in a single rotation. We inserted four types of samples (air, 100 % ethanol, 40 wt% aqueous K(2)HPO(4), and water) into the phantom. The regions of interest were set for all image slices, and the average CT number was calculated in the transverse and longitudinal sections. For the transverse image direction, the CT number became lower toward the center of the phantom with almost all samples. The causes of these phenomena might be attributed to the effects of scattered radiation and those of beam hardening due to the high-atomic-number material (40 wt% aqueous K(2)HPO(4)). However, the phenomena were too complicated to allow us to determine their causes only from the present studies. Meanwhile, for increasing the accuracy of the CT number calibration, a single sample should be inserted, and this step should be repeated with different samples. For the longitudinal direction, the CT number for a 40 wt % aqueous K(2)HPO(4) sample increased by 30 HU from the anode to the cathode side due to variations in the X-ray energy caused by the heel effect. The caveat is that the CT number varies in the longitudinal direction when a CT scanner with a wide beam width is used.

Purpose: In moving target irradiation with pencil beam scanning, the interplay effect between the target motion and the scanned beam is a problem because this effect causes over or under dosage in the target volume. To overcome this, we have studied rescanning using a gating technique., Methods: A simulation and experimental study was carried out. In the experiment, we used the fast scanning system developed at the HIMAC to verify the validity of phase controlled rescanning method, in which the time for rescanning irradiation of each slice is matched to the gating duration., Results: Simulation and experimental results showed that controlling the scan speed to match the respiration cycle with rescans can deliver the blurred dose distribution. In the comparison between the static measurements and the moving measurements with the phase controlled rescanning method, the dose difference was less than 2% for pinpoint chambers in the target volume., Conclusions: The simulation and experimental results demonstrated that the phase controlled rescanning method makes it possible to deliver the dose distribution close to the expected one. As an experimental result for 3D irradiation, it was estimated that blurring by the probability density function was not only for a lateral distribution, but also for a distal distribution, even in the lateral rescanning.

Image-guided radiotherapy (IGRT) is in the midst of a strong development and implementation cycle, stimulated by pioneering work performed in Japan. We present a review of the rationale, technology, and methodology of image guidance, as well as an overview of current work in IGRT at the Massachusetts General Hospital. The technology is rapidly evolving, and synergisms between the various acquisition approaches are converging to provide unparalleled information on target and normal tissue location and motion. With these new approaches to patient localization, we expect improved clinical results to be forthcoming.

Although slow-rotation CT scanning (slow-scan CT: SSCT) has been used for radiation therapy planning, based on the rationale that the average duration of the human respiratory cycle is 4 s, a number of physical and quantitative questions require answering before it can be adopted for clinical use. This study was performed to evaluate SSCT physically in comparison with other scan methods, including respiratory-gated CT (RGCT), and to develop procedures to improve treatment accuracy. Evaluation items were geometrical accuracy, volume accuracy, water equivalent length and dose distribution using the 256-detector row CT with three scan methods. Fast-scan CT (FSCT) was defined as obtaining all respiratory phases in cine scan mode at 1.0 s per rotation. FSCT-ave was the averaged FSCT images in all respiratory phases, obtained by reconstructing short time intervals. SSCT has been defined as scanning with slow gantry rotation to capture the whole respiratory cycle in one rotation. RGCT was scanned at the most stable point in the respiratory cycle, which provides the same image as that by FSCT at the most stable point. Results showed that all evaluation items were dependent on motion characteristics. The findings of this study indicate that 3D planning based solely on SSCT under free breathing may result in underdosing of the target volume and increase toxicity to surrounding normal tissues. Of the three methods, RGCT showed the best ability to significantly increase the accuracy of dose distribution, and provided more information to minimize the margins. FSCT-ave is a satisfactory radiotherapy planning alternative if RGCT is not available.

We compared the dose distributions of carbon-ion pencil beam scanning (C-PBS), proton pencil beam scanning (P-PBS) and Volumetric Modulated Arc Therapy (VMAT) for locally recurrent rectal cancer. The C-PBS treatment planning computed tomography (CT) data sets of 10 locally recurrent rectal cancer cases were randomly selected. Three treatment plans were created using identical prescribed doses. The beam angles for C-PBS and P-PBS were identical. Dosimetry, including the dose received by 95% of the planning target volume (PTV) (D95%), dose to the 2 cc receiving the maximum dose (D2cc), organ at risk (OAR) volume receiving > 15Gy (V15) and > 30Gy (V30), was evaluated. Statistical significance was assessed using the Wilcoxon signed-rank test. Mean PTV-D95% values were > 95% of the volume for P-PBS and C-PBS, whereas that for VMAT was 94.3%. However, PTV-D95% values in P-PBS and VMAT were < 95% in five and two cases, respectively, due to the OAR dose reduction. V30 and V15 to the rectum/intestine for C-PBS (V30 = 4.2 ± 3.2 cc, V15 = 13.8 ± 10.6 cc) and P-PBS (V30 = 7.3 ± 5.6 cc, V15 = 21.3 ± 13.5 cc) were significantly lower than those for VMAT (V30 = 17.1 ± 10.6 cc, V15 = 55.2 ± 28.6 cc). Bladder-V30 values with P-PBS/C-PBS (3.9 ± 4.8 Gy(RBE)/3.0 ± 4.0 Gy(RBE)) were significantly lower than those with VMAT (7.9 ± 8.1 Gy). C-PBS provided superior dose conformation and lower OAR doses compared with P-PBS and VMAT. C-PBS may be the best choice for cases in which VMAT and P-PBS cannot satisfy dose constraints. C-PBS could be another choice for cases in which VMAT and P-PBS cannot satisfy dose constraints, thereby avoiding surgical resection. [ABSTRACT FROM AUTHOR]

• We developed a deep neural network (DNN)-based artifact reduction method. • Our developed DNN successfully reduced the artifacts in the respective CT image sections. • Additional information such as multiple phase images or artifact map increased the artifact reduction accuracy. Breathing artifact may affect the quality of four-dimensional computed tomography (4DCT) images. We developed a deep neural network (DNN)-based artifact reduction method. We used 857 thoracoabdominal 4DCT data sets scanned with 320-section CT with no 4DCT artifact within any volume (ground-truth image). The limitations of graphics processing unit (GPU) memory prevent importation of CT volume data into the DNN. To simulate 4DCT artifact, we interposed 4DCT images from other breathing phases at selected couch positions. Two DNNs, DNN1 and DNN2, were trained to maintain the quality of the output image to that of the ground truth by importing a single and 10 CT images, respectively. A third DNN consisting of an artifact classifier and image generator networks was added. The classifier network was based on residual networks and trained to detect CT section interposition-caused artifacts (artifact map). The generator network reduced artifacts by importing the coronal image data and the artifact map. By repeating the 4DCT artifact reduction with coronal images, the geometrical accuracy in the sagittal sections could be improved, especially with DNN3. Diaphragm position was most accurate when DNN3 was applied. DNN2 corrected artifacts by using CT images from other phases, but DNN2 also modified artifact-free regions. Additional information related to the 4DCT artifact, including information from other respiratory phases (DNN2) and/or artifact regions (DNN3), provided substantial improvement over DNN1. Interposition-related artifacts were reduced by use of an artifact positional map (DNN3). [ABSTRACT FROM AUTHOR]

To shorten the treatment procedure and increase the treatment efficiency, we performed planning studies to evaluate the 4D dose (4DD) distributions of different number of irradiation fields with the fixed treatment ports of scanning carbon-ion beam delivery. We enrolled 10 lung cancer patients treated with respiratory-gated scanning carbon-ion therapy. 4-field, 3-field, and 2-field plans were generated with fixed treatment ports by rotating the beam angle with a 20∼40-degree difference. For each field, the range-adapted internal target volume (raITV) was calculated. The prescription dose of 50 Gy (RBE)-weighted dose with 1 fraction was optimized on the reference phase (T50). The 4DD distributions were calculated for each patient, and dose metrics of CTV dose coverage and OARs sparing were evaluated. p < 0.05 was considered to be statistically significant by Wilcoxon signed-rank test. The sufficient CTV-D95 > 97.8% could be achieved for all the three types of treatment plan. The Dmax of skin was increased (= 19.1 ± 5.7 Gy (RBE)) for the 2-field plans as compared to 4-field plans (= 14.2 ± 6.6 Gy (RBE), p = 0.006), which is still acceptable for clinical use (<35 Gy (RBE)). And there were no differences (p > 0.076) of V20 of lung (= 15.5 ± 6.6%, 16.2 ± 7.0%, 15.6 ± 6.3%) and Dmax of spinal cord (= 3.0 ± 2.9, 3.4 ± 3.9, 3.3 ± 4.3 Gy (RBE)) among the three types of plans. Lung treatment plans under the fixed orthogonal beam ports with zero-degree couch pitch angle is feasible for clinical use to further increase the treatment efficiency and throughput. • The 4-field versus 2-field carbon ion treatment plans were compared for the first time. • The range-adapted ITV and fast rescanning protocols were used in the 4D dose distribution calculation. • Both the target dose coverage and OAR sparing were clinical acceptable under 2-field plans. [ABSTRACT FROM AUTHOR]

Purpose: Having implemented amplitude-based respiratory gating for scanned carbon-ion beam therapy, we sought to evaluate its effect on positional accuracy and throughput.Methods and Materials: A total of 10 patients with tumors of the lung and liver participated in the first clinical trials at our center. Treatment planning was conducted with 4-dimensional computed tomography (4DCT) under free-breathing conditions. The planning target volume (PTV) was calculated by adding a 2- to 3-mm setup margin outside the clinical target volume (CTV) within the gating window. The treatment beam was on when the CTV was within the PTV. Tumor position was detected in real time with a markerless tumor tracking system using paired x-ray fluoroscopic imaging units.Results: The patient setup error (mean ± SD) was 1.1 ± 1.2 mm/0.6 ± 0.4°. The mean internal gating accuracy (95% confidence interval [CI]) was 0.5 mm. If external gating had been applied to this treatment, the mean gating accuracy (95% CI) would have been 4.1 mm. The fluoroscopic radiation doses (mean ± SD) were 23.7 ± 21.8 mGy per beam and less than 487.5 mGy total throughout the treatment course. The setup, preparation, and irradiation times (mean ± SD) were 8.9 ± 8.2 min, 9.5 ± 4.6 min, and 4.0 ± 2.4 min, respectively. The treatment room occupation time was 36.7 ± 67.5 min.Conclusions: Internal gating had a much higher accuracy than external gating. By the addition of a setup margin of 2 to 3 mm, internal gating positional error was less than 2.2 mm at 95% CI. [ABSTRACT FROM AUTHOR]

Purpose: To characterize and quantify multiorgan respiration-induced motion in the abdomen in liver and pancreatic cancer patients. Methods and Materials: Four-dimensional computed tomography scans were acquired for 18 patients treated for abdominal tumors. Contours of multiple abdominal organs were drawn by the radiation oncologist at one respiratory phase; these contours were propagated to other respiratory phases by deformable registration. Three-dimensional organ models were generated from the resulting contours at each phase. Motions of the bounding box and center of mass were extracted and analyzed for the clinical target volume and organs at risk. Results: On average, the center of mass motion for liver clinical target volumes was 9.7 mm (SD 5 mm) in the superior–inferior direction, with a range of 3 to 18 mm; for pancreatic tumors, the average was 5 mm (SD 1 mm) m with a range of 3 to 7 mm. Abdominal organs move in unison, but with varying amplitudes. Gating near exhale (T40–T60) reduces the range of motion by a factor of ∼10. Conclusion: We have used deformable registration to calculate the trajectories of abdominal organs in four dimensions, based on center of mass and bounding box motion metrics. Our results are compared with previously reported studies. Possible reasons for differences are discussed. [Copyright &y& Elsevier]

Purpose: In radiotherapy with a scanned carbon-ion beam, its Bragg peak is shifted along the depth direction either by inserting the range shifter plates or by changing the beam-extraction energy of a synchrotron. In the former technique (range shifter scanning: RS), the range shifter plates broaden the beam size and produce secondary fragments through nuclear reactions. In the latter technique (active-energy scanning: ES), it may take several seconds to change the beam energy depending on the synchrotron operation cycle, leading to a long treatment time. The authors propose a hybrid depth scan technique (hybrid scanning: HS), where several beam energies are used in conjunction with the range shifter plates for finer range shift. In this study, HS is evaluated from the viewpoints of dose distribution and treatment time. Methods: Assuming realistic accelerator and beam-delivery systems, the authors performed computer simulations using GEANT4 Monte Carlo code for beam modeling and a treatment planning system to evaluate HS. Three target volumes with the same dimensions of 60 × 60 × 60 mm3 were generated at depths of 45, 85, and 125 mm in water phantom, and uniform clinical dose was planned for these targets. The sizes of lateral dose falloff and the peak to plateau ratio defined as the ratio of the clinical dose averaged over the target to the clinical dose at the entrance as well as the treatment time were compared among the three depth scan techniques. Results: The sizes of lateral dose falloffs at the center of SOBP are 11.4, 8.5, and 5.9 mm for the three targets in RS, while they are 5.7, 4.8, and 4.6 mm in ES and 6.6, 5.7, and 5.0 mm in HS, respectively. The peak to plateau ratios are 1.39, 1.96, and 2.15 in RS, while they are 1.48, 2.04, and 2.19 in ES and 1.47, 2.03, and 2.18 in HS, respectively. The treatment times are 128.7, 128.6, and 128.6 s in ES, while they are 61.2, 54.6, and 47.8 s in RS and 43.2, 44.1, and 44.7 s in HS, respectively. The multiple scattering and the nuclear reaction by range shifter degraded the beam qualities such as lateral dose falloff and peak to plateau ratio, which was especially pronounced for the shallow target in RS. The depth scan timing was limited by accelerator cycle in ES. That increased the treatment time by a few times. Conclusions: This study revealed that HS can provide dose distributions with steeper lateral dose falloffs and higher peak to plateau ratio comparing to RS and comparable to ES. In addition, the treatment time can be considerably reduced in HS compared to ES. [ABSTRACT FROM AUTHOR]

Abstract: The recent broad adoption of 4-D computed tomography (4DCT) scanning in radiotherapy has allowed the accurate determination of the target volume of tumors by minimizing image degradation caused by respiratory motion. Although the radiation exposure of the treatment beam is significantly greater than that of CT scans used for treatment planning, it is important to recognize and optimize the radiation exposure in 4DCT from the radiological protection point of view. Here, radiation exposure in 4DCT was measured with a 16 multidetector CT. Organ doses were measured using thermoluminescence radiation dosimeter chips inserted at respective anatomical sites of an anthropomorphic phantom. Results were compared with those with the helical CT scan mode. The effective dose measured for 4DCT was 24.7 mSv, approximately four times higher than that for helical CT. However, the increase in treatment accuracy afforded by 4DCT means its use in radiotherapy is inevitable. The patient exposure in the 4DCT could be of value by clarifying the advantage of the treatment planning using 4DCT. [Copyright &y& Elsevier]

Purpose: Range variations during respiration affect the penetration of charged particle beams and can result in beam overshoot or undershoot to the target. We have developed analysis tools to quantify the water equivalent pathlength (WEL) variations resulting from respiration (WEL analyzer, Aqualyzer), as well as a data explorer to view WEL variations interactively. Methods and Materials: The metrics to characterize and quantify penetration of a charged particle beam during respiration were calculated semiautomatically. The analysis involved the generation of images that (1) encode the radiologic pathlength across a beam''s eye view image during the respiratory phase, (2) display the variation of the radiologic pathlength relative to a reference respiratory phase, (3) display isopenetration as a function of breathing, and (4) show range fluctuation images for a compensating bolus when applied to four-dimensional computed tomography. Additional quantities relevant to the analysis of charged particle beams in a breathing patient that are calculated include the beam overshoot volume and beam overshoot distance. These quantities are calculated as a function of time, gantry angle, and position. Results: The software was applied to test cases to illustrate its utility in the analysis of range variations of charged particle beams in the treatment of lung tumors. Conclusion: WEL analysis is useful in the rapid assessment of range variations in the treatment of lung tumors and in determining the optimal gantry angle and respiratory gating window. The extension of encoding range fluctuations to a beam''s eye view display is helpful in designing plans that are more robust in the presence of motion. [Copyright &y& Elsevier]

Purpose: Water equivalent path length (WEL) variations due to respiration can change the range of a charged particle beam and result in beam overshoot to critical organs or beam undershoot to tumor. We have studied range fluctuations by analyzing four-dimensional computed tomography data and quantitatively assessing potential beam overshoot. Methods and Materials: The maximal intensity volume is calculated by combining the gross tumor volume contours at each respiratory phase in the four-dimensional computed tomography study. The first target volume calculates the maximal intensity volume for the entire respiratory cycle (internal target volume [ITV]-radiotherapy [RT]), and the second target volume is the maximal intensity volume corresponding to gated RT (gated-RT, ∼30% phase window around exhalation). A compensator at each respiratory phase is calculated. Two “composite” compensators for ITV-RT and gated-RT are then designed by selecting the minimal compensator depth at the respective respiratory phase. These compensators are then applied to the four-dimensional computed tomography data to estimate beam penetration. Analysis metrics include range fluctuation and overshoot volume, both as a function of gantry angle. We compared WEL fluctuations observed in treating the ITV-RT versus gated-RT in 11 lung patients. Results: The WEL fluctuations were <21.8 mm-WEL and 9.5 mm-WEL for ITV-RT and gated-RT, respectively for all patients. Gated-RT reduced the beam overshoot volume by approximately a factor of four compared with ITV-RT. Such range fluctuations can affect the efficacy of treatment and result in an excessive dose to a distal critical organ. Conclusion: Time varying range fluctuation analysis provides information useful for determining appropriate patient-specific treatment parameters in charged particle RT. This analysis can also be useful for optimizing planning and delivery. [Copyright &y& Elsevier]

Purpose: To analyze the water equivalent pathlength (WEL) fluctuations resulting from cardiac motion and display these variations on a beam''s-eye-view image; the analysis provides insight into the accuracy of lung tumor irradiation with heavy charged particle beams. Materials and Methods: Volumetric cine computed tomography (CT) images were obtained on 7 lung cancer patients under free-breathing conditions with a 256-multislice CT scanner. Cardiac phase was determined by selecting systole and diastole. A WEL difference image (ΔWEL) was calculated by subtracting the WEL image at end-systole from that at end-diastole at respiratory exhalation phase. Two calculation regions were defined: Region 1 was limited to the volume defined by planes bounding the heart; Region 2 included the entire body thickness for a given beam''s-eye-view angle. Results: The ΔWEL values observed in Region 1 showed fluctuations at the periphery of the heart that varied from 20.4 (SD, 5.2) mm WEL to −15.6 (3.2) mm WEL. The areas over which these range perturbation values were observed were 36.8 (32.4) mm2 and 6.0 (2.8) mm2 for positive and negative WEL, respectively. The WEL fluctuations in Region 2 increased by approximately 3–4 mm WEL, whereas negative WEL fluctuations changed by approximately −4 to –5 mm WEL, compared with WEL for Region 1; areas over 20 mm WEL changes in Region 2 increased by 9 mm2 for positive ΔWEL and 2 mm2 for negative ΔWEL. Conclusions: Cine CT with a 256-multislice CT scanner captures both volumetric cardiac and respiratory motion with a temporal resolution sufficient to estimate range fluctuations by these motions. This information can be used to assess the range perturbations that charged particle beams may experience in irradiation of lung or esophageal tumors adjacent to the heart. [Copyright &y& Elsevier]

Abstract: Purpose: To enhance the precision of treatment planning for tumors which move under respiration, we developed a respiratory-correlated segment reconstruction method (RS) based on the Feldkamp–Davis–Kress algorithm (FDK) which provides high temporal resolution and a high signal-to-noise ratio. We compared full-scan (FS-FDK) and RS-FDK with regard to dose distribution in heavy ion treatment planning. Materials and methods: Data acquisition for RS-FDK is done using a respiratory sensing system in cine scan mode with a 256-multi-detector row CT (256-MDCT). To evaluate the accuracy of irradiation of moving tumors, dose distributions with each algorithm were compared in heavy ion treatment planning using beam parameters obtained with FS-FDK. Results: Images obtained using RS-FDK did not show motion artifacts and visualized the edges of the liver and pulmonary vessels more clearly than those with FS-FDK. The iso-dose distributions for FS-FDK covered the target volume; in contrast, RS-FDK with the beam parameter of FS-FDK image provided an insufficient dose to the target and a considerable dose to normal tissues around it. Conclusions: The information provided by RS-FDK improves accuracy in the prescription of dose-to-target volume. Further, RS-FDK allows greater precision in the delivery of radiotherapy, including 4D radiation therapy. [Copyright &y& Elsevier]

Abstract: This is an initial demonstration of volumetric cine imaging under free breathing in lung cancer patients using the second model of the 256-detector row CT (256MDCT). Scan range is 128mm in the cranio-caudal direction with a 0.5mm slice thickness and effective temporal resolution of 250ms. Volumetric cine images are satisfactorily obtained for the thin sections which can be used to create cine loops in multiple planes. Thus, the 256MDCT overcomes some of the limitations of current respiratory-gated CT or 4D-CT scan techniques and has the potential for use in 4D-IMRT planning and 4D radiation therapy. [Copyright &y& Elsevier]

Carbon ion radiotherapy provides a concentrated dose distribution to the target and has several advantages over photon radiotherapy. This study aimed to evaluate the optimal beam direction in carbon ion pencil beam scanning and compare dose distributions between the rotating gantry system (RGS) and fixed-beam port system (FBPS). Patients with locally advanced pancreatic cancer were randomly selected. First, dose-volume parameters of 7-beam directions in the prone position were evaluated. Second, a composite plan developed using 4-beam directions in RGS was compared with that developed using FBPS, with a total prescribed dose of 55.2 Gy (relative biological effectiveness, RBE) in 12 fractions. Target coverages in the composite plan did not widely differ. For the first and second segments of the duodenum, the mean dose of D2cc was not significantly changed (23.80 ± 11.90 Gy [RBE] and 25.63 ± 10.41 Gy [RBE] for RGS and FBPS, respectively). However, the dose-volume histogram curve in RGS showed a prominent dose reduction in the low-dose region. No significant differences were observed in the stomach, third and fourth segments of the duodenum, and spinal cord. The mean dose of the total kidney was similar between RGS and FBPS. Compared with that of FBPS, the 4-beam arrangement in the prone position using RGS provides comparable or superior dose distribution in the surrounding normal organ while achieving the same target coverage. In addition, RGS allows for single-patient positioning. RGS is beneficial in delivering radiotherapy doses to the duodenum and allows for single-patient positioning and a simple planning process. [ABSTRACT FROM AUTHOR]

Purpose: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. Methods and Materials: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial–venous phase and arterial–delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. Results: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0–99.1%) of the prescribed dose to 94.7% (range, 88.0–99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. Conclusions: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior–posterior and left–right beams. [Copyright &y& Elsevier]

The National Institute of Radiological Sciences in Japan started clinical studies of carbon-ion radiotherapy (CIRT) in 1994. Due to the high linear energy transfer (LET) of highly charged particles, carbon-ion beams show high relative biological effectiveness in cell killing, especially at the Bragg peak of dose near the beam range, which is controlled to conform to a tumor. Recent technological developments for CIRT include fast pencil-beam scanning, fluoroscopic respiratory motion management, advanced beam modeling for treatment planning, and a superconducting rotating gantry, which have contributed to accuracy, precision, and conformation of dose, operational efficiency, and patient comfort. With technological maturity, CIRT facilities are rapidly increasing in Asia and Europe. Ongoing developments include extension to multiple ion species and facility downsizing to raise the quality and availability of ion-beam therapy in medical care. [ABSTRACT FROM AUTHOR]

Pencil-beam scanning (PBS) proton therapy (PT), particularly intensity modulated PT, represents the latest advanced PT technology for treating cancers, including thoracic malignancies. On the basis of virtual clinical studies, PBS-PT appears to have great potential in its ability to tightly tailor the dose to the target while sparing critical structures, thereby reducing treatment-related toxicities, particularly for tumors in areas with complicated anatomy. However, implementing PBS-PT for moving targets has several additional technical challenges compared with intensity modulated photon radiation therapy or passive scattering PT. Four-dimensional computed tomography-based motion management and robust optimization and evaluation are crucial for minimizing uncertainties associated with beam range and organ motion. Rigorous quality assurance is required to validate dose delivery both before and during the course of treatment. Active motion management (eg, breath hold), beam gating, rescanning, tracking, or adaptive planning may be needed for cases involving significant motion or changes in motion or anatomy over the course of treatment. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate whether external-beam radiotherapy (EBRT) with concurrent continuous 5-fluorouracil (5-FU) infusion affects the length and quality of survival in patients with locally unresectable pancreatic cancer.Methods: Thirty-one patients with histologically proven locally advanced and unresectable pancreatic cancer without distant metastases were evaluated in this prospective randomized trial. Sixteen patients received EBRT (50.4 Gy/28 fractions) with concurrent continuous infusion of 5-FU (200 mg/m2/day), whereas 15 patients received no chemoradiation. The length and quality of survival was analyzed and compared for the two groups.Results: The median survival of 13.2 months and the 1-year survival rate of 53.3% in the chemoradiation group were significantly better than the respective 6.4 months and 0% in the group without chemoradiotherapy (p = 0.0009). The average monthly Karnofsky score, a quality of life indicator, was 77.1 in the chemoradiation group, which was significantly higher than the 65.5 in the group without chemoradiotherapy (p < 0.0001). The number of hospital days per month of survival was significantly less in the chemoradiation than in the no-therapy group (12.3 vs. 19.0 days, p < 0.05). In the chemoradiation group, 5 patients (31%) had a partial response, and 9 (56%) had radiologically stable disease at a median duration of 6.1 months. The patients who had chemoradiation had a lower rate of liver and peritoneal metastases than patients without chemoradiotherapy (31% vs. 64%). Of 10 patients who experienced pain before chemoradiation, 8 (80%) received pain relief that lasted a median of 5.2 months.Conclusions: EBRT with concurrent continuous 5-FU infusion increased the length and quality of survival as compared to no chemoradiotherapy and provided a definite palliative benefit for patients with unresectable pancreatic cancer. [Copyright &y& Elsevier]