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Sample records for intensity-modulated arc therapy

  1. Intensity-modulated arc therapy: principles, technologies and clinical implementation

    NASA Astrophysics Data System (ADS)

    Yu, Cedric X.; Tang, Grace

    2011-03-01

    Intensity-modulated arc therapy (IMAT) was proposed by Yu (1995 Phys. Med. Biol. 40 1435-49) as an alternative to tomotherapy. Over more than a decade, much progress has been made. The advantages and limitations of the IMAT technique have also been better understood. In recent years, single-arc forms of IMAT have emerged and become commercially adopted. The leading example is the volumetric-modulated arc therapy (VMAT), a single-arc form of IMAT that delivers apertures of varying weights with a single-arc rotation that uses dose-rate variation of the treatment machine. With commercial implementation of VMAT, wide clinical adoption has quickly taken root. However, there remains a lack of general understanding for the planning of such arc treatments, as well as what delivery limitations and compromises are made. Commercial promotion and competition add further confusion for the end users. It is therefore necessary to provide a summary of this technology and some guidelines on its clinical implementation. The purpose of this review is to provide a summary of the works from the radiotherapy community that led to wide clinical adoption, and point out the issues that still remain, providing some perspective on its further developments. Because there has been vast experience in IMRT using multiple intensity-modulated fields, comparisons between IMAT and IMRT are also made in the review within the areas of planning, delivery and quality assurance.

  2. Clinical implementation of intensity-modulated arc therapy.

    PubMed

    Shepard, David M; Cao, Daliang

    2011-01-01

    Intensity-modulated arc therapy (IMAT) is a rotational approach to radiation therapy delivered on a conventional linear accelerator using a conventional multileaf collimator. There are 2 key advantages of IMAT. First, the rotational nature of the delivery provides great flexibility in shaping each dose distribution. As a result, IMAT can provide dosimetric advantages relative to fixed-field intensity-modulated radiation therapy (IMRT). The second advantage is the highly efficient nature of the delivery. For centers with an active IMRT program, the clinical implementation of IMAT should be relatively straightforward. For clinical implementation of IMAT, it is important to fully characterize the accuracy of the dose model used, and the performance of the quality assurance equipment.

  3. Arc binary intensity modulated radiation therapy (AB IMRT)

    NASA Astrophysics Data System (ADS)

    Yang, Jun

    The state of the art Intensity Modulate Radiation Therapy (IMRT) has been one of the most significant breakthroughs in the cancer treatment in the past 30 years. There are two types of IMRT systems. The first system is the binary-based tomotherapy, represented by the Peacock (Nomos Corp) and Tomo unit (TomoTherapy Inc.), adopting specific binary collimator leafs to deliver intensity modulated radiation fields in a serial or helical fashion. The other uses the conventional dynamic multileaf collimator (MLC) to deliver intensity modulated fields through a number of gantry positions. The proposed Arc Binary IMRT attempts to deliver Tomo-like IMRT with conventional dynamic MLC and combines the advantages of the two types of IMRT techniques: (1) maximizing the number of pencil beams for better dose optimization, (2) enabling conventional linear accelerator with dynamic MLC to deliver Tomo-like IMRT. In order to deliver IMRT with conventional dynamic MLC in a binary fashion, the slice-by-slice treatment with limited slice thickness has been proposed in the thesis to accommodate the limited MLC traveling speed. Instead of moving the patient to subsequent treatment slices, the proposed method offsets MLC to carry out the whole treatment, slice by slice sequentially, thus avoid patient position error. By denoting one arc pencil beam set as a gene, genetic algorithm (GA) is used as the searching engine for the dose optimization process. The selection of GA parameters is a crucial step and has been studied in depth so that the optimization process will converge with reasonable speed. Several hypothetical and clinical cases have been tested with the proposed IMRT method. The comparison of the dose distribution with other commercially available IMRT systems demonstrates the clear advantage of the new method. The proposed Arc Binary Intensity Modulated Radiation Therapy is not only theoretically sound but practically feasible. The implementation of this method would expand the

  4. Segmentation and leaf sequencing for intensity modulated arc therapy

    SciTech Connect

    Gladwish, Adam; Oliver, Mike; Craig, Jeff; Chen, Jeff; Bauman, Glenn; Fisher, Barbara; Wong, Eugene

    2007-05-15

    A common method in generating intensity modulated radiation therapy (IMRT) plans consists of a three step process: an optimized fluence intensity map (IM) for each beam is generated via inverse planning, this IM is then segmented into discrete levels, and finally, the segmented map is translated into a set of MLC apertures via a leaf sequencing algorithm. To date, limited work has been done on this approach as it pertains to intensity modulated arc therapy (IMAT), specifically in regards to the latter two steps. There are two determining factors that separate IMAT segmentation and leaf sequencing from their IMRT equivalents: (1) the intrinsic 3D nature of the intensity maps (standard 2D maps plus the angular component), and (2) that the dynamic multileaf collimator (MLC) constraints be met using a minimum number of arcs. In this work, we illustrate a technique to create an IMAT plan that replicates Tomotherapy deliveries by applying IMAT specific segmentation and leaf-sequencing algorithms to Tomotherapy output sinograms. We propose and compare two alternative segmentation techniques, a clustering method, and a bottom-up segmentation method (BUS). We also introduce a novel IMAT leaf-sequencing algorithm that explicitly takes leaf movement constraints into consideration. These algorithms were tested with 51 angular projections of the output leaf-open sinograms generated on the Hi-ART II treatment planning system (Tomotherapy Inc.). We present two geometric phantoms and 2 clinical scenarios as sample test cases. In each case 12 IMAT plans were created, ranging from 2 to 7 intensity levels. Half were generated using the BUS segmentation and half with the clustering method. We report on the number of arcs produced as well as differences between Tomotherapy output sinograms and segmented IMAT intensity maps. For each case one plan for each segmentation method is chosen for full Monte Carlo dose calculation (NumeriX LLC) and dose volume histograms (DVH) are calculated

  5. Monte Carlo dose verification for intensity-modulated arc therapy

    NASA Astrophysics Data System (ADS)

    Li, X. Allen; Ma, Lijun; Naqvi, Shahid; Shih, Rompin; Yu, Cedric

    2001-09-01

    Intensity-modulated arc therapy (IMAT), a technique which combines beam rotation and dynamic multileaf collimation, has been implemented in our clinic. Dosimetric errors can be created by the inability of the planning system to accurately account for the effects of tissue inhomogeneities and physical characteristics of the multileaf collimator (MLC). The objective of this study is to explore the use of Monte Carlo (MC) simulation for IMAT dose verification. The BEAM/DOSXYZ Monte Carlo system was implemented to perform dose verification for the IMAT treatment. The implementation includes the simulation of the linac head/MLC (Elekta SL20), the conversion of patient CT images and beam arrangement for 3D dose calculation, the calculation of gantry rotation and leaf motion by a series of static beams and the development of software to automate the entire MC process. The MC calculations were verified by measurements for conventional beam settings. The agreement was within 2%. The IMAT dose distributions generated by a commercial forward planning system (RenderPlan, Elekta) were compared with those calculated by the MC package. For the cases studied, discrepancies of over 10% were found between the MC and the RenderPlan dose calculations. These discrepancies were due in part to the inaccurate dose calculation of the RenderPlan system. The computation time for the IMAT MC calculation was in the range of 20-80 min on 15 Pentium-III computers. The MC method was also useful in verifying the beam apertures used in the IMAT treatments.

  6. Volumetric intensity-modulated arc therapy vs conventional intensity-modulated radiation therapy in nasopharyngeal carcinoma: a dosimetric study

    PubMed Central

    White, Peter; Chan, Kit Chi; Cheng, Ka Wai; Chan, Ka Yiu; Chau, Ming Chun

    2013-01-01

    Dosimetric comparisons between RapidArc (RA) and conventional Intensity-Modulated Radiation Therapy (IMRT) techniques for nasopharyngeal carcinoma (NPC) were performed to address differences in dose coverage of the target, sparing of organs-at-risk (OARs), delivery of monitor units (MUs) and time, to assess whether the RA technique was more beneficial for treatment of NPC. Eight NPC patients (Stages I–IV), who had completed RA treatment, were selected for this study. Computed tomography data sets were re-planned using 7-fields fixed beam IMRT. Quantitative measurements of dose-endpoint values on the dose-volume histograms were carried out for evaluation of: (i) dose homogeneity (D5% – D95%); (ii) degree of conformity (CI95%); (iii) tumor control probability (TCP); (iv) doses to OARs; (v) normal tissue complication probability (NTCP); (vi) treatment time; and (vii) MUs. RA plans achieved better dose conformity and TCP in planning target volumes (PTVs). Target dose homogeneity was not as high as for IMRT plans. Doses to tempero-mandibular joints, clavicles, parotid glands and posterior neck, and their NTCPs were significantly lower in RA plans (P < 0.05). Mean doses to the brainstem and spinal cord were slightly lower in IMRT plans. RA plans allowed for a mean reduction in MUs by 78% (P = 0.006), and a four-fold reduction in treatment delivery times, relative to IMRT plans. RA plans showed superior, or comparable, target coverage and dose conformity in PTVs, but at the expense of inferior dose homogeneity. RA plans also achieved significant improvements in dose reduction to OARs and healthy tissue sparing. A significant reduction in treatment delivery time for RA treatment technique was also noted. PMID:23188186

  7. Volumetric Arc Intensity-Modulated Therapy for Spine Body Radiotherapy: Comparison With Static Intensity-Modulated Treatment

    SciTech Connect

    Wu, Q. Jackie; Yoo, Sua; Kirkpatrick, John P.; Thongphiew, Danthai; Yin Fangfang

    2009-12-01

    Purpose: This clinical study evaluates the feasibility of using volumetric arc-modulated treatment (VMAT) for spine stereotactic body radiotherapy (SBRT) to achieve highly conformal dose distributions that spare adjacent organs at risk (OAR) with reduced treatment time. Methods and Materials: Ten spine SBRT patients were studied retrospectively. The intensity-modulated radiotherapy (IMRT) and VMAT plans were generated using either one or two arcs. Planning target volume (PTV) dose coverage, OAR dose sparing, and normal tissue integral dose were measured and compared. Differences in treatment delivery were also analyzed. Results: The PTV DVHs were comparable between VMAT and IMRT plans in the shoulder (D{sub 99%}-D{sub 90%}), slope (D{sub 90%}-D{sub 10%}), and tail (D{sub 10%}-D{sub 1%}) regions. Only VMAT{sub 2arc} had a better conformity index than IMRT (1.09 vs. 1.15, p = 0.007). For cord sparing, IMRT was the best, and VMAT{sub 1arc} was the worst. Use of IMRT achieved greater than 10% more D{sub 1%} sparing for six of 10 cases and 7% to 15% more D{sub 10%} sparing over the VAMT{sub 1arc}. The differences between IMRT and VAMT{sub 2arc} were smaller and statistically nonsignificant at all dose levels. The differences were also small and statistically nonsignificant for other OAR sparing. The mean monitor units (MUs) were 8711, 7730, and 6317 for IMRT, VMAT{sub 1arc}, and VMAT{sub 2arc} plans, respectively, with a 26% reduction from IMRT to VMAT{sub 2arc}. The mean treatment time was 15.86, 8.56, and 7.88 min for IMRT, VMAT{sub 1arc,} and VMAT{sub 2arc}. The difference in integral dose was statistically nonsignificant. Conclusions: Although VMAT provided comparable PTV coverage for spine SBRT, 1arc showed significantly worse spinal cord sparing compared with IMRT, whereas 2arc was comparable to IMRT. Treatment efficiency is substantially improved with the VMAT.

  8. Impact of machines on plan quality: volumetric modulated arc therapy and intensity modulated radiation therapy.

    PubMed

    Clemente, S; Cozzolino, M; Oliviero, C; Fiorentino, A; Chiumento, C; Fusco, V

    2014-02-01

    To evaluate the impact of different machines on plan quality using both intensity modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques. Eight patients with squamous cell carcinoma of the oropharynx were selected at random. Plans were computed for IMRT and VMAT Smart Arc, using Pinnacle TPS for an Elekta (IMRT-E, VMAT-E) and Varian linac (IMRT-V, VMAT-V). A three-dose level prescription was used to deliver 70, 63 and 58.1 Gy to regions of macroscopic, microscopic high- and low-risk disease, respectively. All doses were given in 35 fractions. Comparisons were performed on dose-volume histogram data, monitor units (MU), and delivery time. VMAT-E plans resulted slightly MU efficient (-24 % p < 0.05) compared to VMAT-V while IMRT-V shortened delivery time (-19 % p < 0.05) compared to IMRT-E. All the delivery techniques resulted in equivalent target coverage in terms of D(98) % and D(2) %. For VMAT technique, a significant improvement of 7 % in homogeneity index (HI) for PTV58.1 was observed for Varian machine. A slight improvement in OARs sparing was observed with Elekta machine both for IMRT and VMAT techniques. Similar plan quality was observed for Elekta and Varian linacs, significant differences were observed in delivery efficiency, as MU number and delivery times, in favor of Elekta and Varian, respectively.

  9. A modular approach to intensity-modulated arc therapy optimization with noncoplanar trajectories

    NASA Astrophysics Data System (ADS)

    Papp, Dávid; Bortfeld, Thomas; Unkelbach, Jan

    2015-07-01

    Utilizing noncoplanar beam angles in volumetric modulated arc therapy (VMAT) has the potential to combine the benefits of arc therapy, such as short treatment times, with the benefits of noncoplanar intensity modulated radiotherapy (IMRT) plans, such as improved organ sparing. Recently, vendors introduced treatment machines that allow for simultaneous couch and gantry motion during beam delivery to make noncoplanar VMAT treatments possible. Our aim is to provide a reliable optimization method for noncoplanar isocentric arc therapy plan optimization. The proposed solution is modular in the sense that it can incorporate different existing beam angle selection and coplanar arc therapy optimization methods. Treatment planning is performed in three steps. First, a number of promising noncoplanar beam directions are selected using an iterative beam selection heuristic; these beams serve as anchor points of the arc therapy trajectory. In the second step, continuous gantry/couch angle trajectories are optimized using a simple combinatorial optimization model to define a beam trajectory that efficiently visits each of the anchor points. Treatment time is controlled by limiting the time the beam needs to trace the prescribed trajectory. In the third and final step, an optimal arc therapy plan is found along the prescribed beam trajectory. In principle any existing arc therapy optimization method could be incorporated into this step; for this work we use a sliding window VMAT algorithm. The approach is demonstrated using two particularly challenging cases. The first one is a lung SBRT patient whose planning goals could not be satisfied with fewer than nine noncoplanar IMRT fields when the patient was treated in the clinic. The second one is a brain tumor patient, where the target volume overlaps with the optic nerves and the chiasm and it is directly adjacent to the brainstem. Both cases illustrate that the large number of angles utilized by isocentric noncoplanar VMAT plans

  10. Hypofractionated Intensity-Modulated Arc Therapy for Lymph Node Metastasized Prostate Cancer

    SciTech Connect

    Fonteyne, Valerie; De Gersem, Werner; De Neve, Wilfried; Jacobs, Filip; Lumen, Nicolaas; Vandecasteele, Katrien; Villeirs, Geert; De Meerleer, Gert

    2009-11-15

    Purpose: To determine the planning results and acute toxicity after hypofractionated intensity-modulated arc radiotherapy and androgen deprivation for lymph node metastasized (Stage N1) prostate cancer. Methods and Materials: A total of 31 patients with Stage T1-T4N1M0 prostate cancer were treated with intensity-modulated arc radiotherapy and 3 years of androgen deprivation as primary treatment. The clinical target volume (CTV{sub p}) was the prostate and seminal vesicles. Elective lymph node areas ({sub e}) were delineated and expanded by 2 mm to create the CTV{sub e}. The planning target volumes (PTV{sub p} and PTV{sub e}) were created using a three-dimensional expansion of the CTV{sub p} and CTV{sub e}, respectively, of 7 mm. A median dose of 69.3 Gy and 50 Gy was prescribed to the PTV{sub p} and PTV{sub e} respectively, to be delivered in 25 fractions. Upper and lower gastrointestinal toxicity was scored using the Radiation Therapy Oncology Group toxicity and radiotherapy-induced lower intestinal toxicity scoring system. Genitourinary toxicity was scored using a combined Radiation Therapy Oncology Group, LENT-SOMA (late effects normal tissue-subjective, objective, management, analytic), and Common Toxicity Criteria toxicity scoring system. Results: The median follow-up time was 3 months. The mean prescription dose to the CTV{sub p} and PTV{sub p} was 70.4 Gy and 68.6 Gy, respectively. The minimal dose to the CTV{sub e} and PTV{sub e} was 49.0 Gy and 47.0 Gy, respectively. No acute Grade 2 or greater gastrointestinal toxicity occurred. Fourteen patients developed acute Grade 2 lower gastrointestinal toxicity. Acute Grade 3 and 2 genitourinary toxicity developed in 2 and 14 patients, respectively. Conclusion: The results of our study have shown that hypofractionated intensity-modulated arc radiotherapy as primary therapy for N1 prostate cancer is feasible with low toxicity.

  11. Fast intensity-modulated arc therapy based on 2-step beam segmentation

    SciTech Connect

    Bratengeier, Klaus; Gainey, Mark; Sauer, Otto A.; Richter, Anne; Flentje, Michael

    2011-01-15

    Purpose: Single or few arc intensity-modulated arc therapy (IMAT) is intended to be a time saving irradiation method, potentially replacing classical intensity-modulated radiotherapy (IMRT). The aim of this work was to evaluate the quality of different IMAT methods with the potential of fast delivery, which also has the possibility of adapting to the daily shape of the target volume. Methods: A planning study was performed. Novel double and triple IMAT techniques based on the geometrical analysis of the target organ at risk geometry (2-step IMAT) were evaluated. They were compared to step and shoot IMRT reference plans generated using direct machine parameter optimization (DMPO). Volumetric arc (VMAT) plans from commercial preclinical software (SMARTARC) were used as an additional benchmark to classify the quality of the novel techniques. Four cases with concave planning target volumes (PTV) with one dominating organ at risk (OAR), viz., the PTV/OAR combination of the ESTRO Quasimodo phantom, breast/lung, spine metastasis/spinal cord, and prostate/rectum, were used for the study. The composite objective value (COV) and other parameters representing the plan quality were studied. Results: The novel 2-step IMAT techniques with geometry based segment definition were as good as or better than DMPO and were superior to the SMARTARC VMAT techniques. For the spine metastasis, the quality measured by the COV differed only by 3%, whereas the COV of the 2-step IMAT for the other three cases decreased by a factor of 1.4-2.4 with respect to the reference plans. Conclusions: Rotational techniques based on geometrical analysis of the optimization problem (2-step IMAT) provide similar or better plan quality than DMPO or the research version of SMARTARC VMAT variants. The results justify pursuing the goal of fast IMAT adaptation based on 2-step IMAT techniques.

  12. Dosimetric comparison of volumetric modulated arc therapy and intensity-modulated radiation therapy for pancreatic malignancies

    SciTech Connect

    Ali, Arif N.; Dhabaan, Anees H.; Jarrio, Christie S.; Siddiqi, Arsalan K.; Landry, Jerome C.

    2012-10-01

    Volumetric-modulated arc therapy (VMAT) has been previously evaluated for several tumor sites and has been shown to provide significant dosimetric and delivery benefits when compared with intensity-modulated radiation therapy (IMRT). To date, there have been no published full reports on the benefits of VMAT use in pancreatic patients compared with IMRT. Ten patients with pancreatic malignancies treated with either IMRT or VMAT were retrospectively identified. Both a double-arc VMAT and a 7-field IMRT plan were generated for each of the 10 patients using the same defined tumor volumes, organs at risk (OAR) volumes, dose, fractionation, and optimization constraints. The planning tumor volume (PTV) maximum dose (55.8 Gy vs. 54.4 Gy), PTV mean dose (53.9 Gy vs. 52.1 Gy), and conformality index (1.11 vs. 0.99) were statistically similar between the IMRT and VMAT plans, respectively. The VMAT plans had a statistically significant reduction in monitor units compared with the IMRT plans (1109 vs. 498, p < 0.001). In addition, the doses to the liver, small bowel, and spinal cord were comparable between the IMRT and VMAT plans. However, the VMAT plans demonstrated a statistically significant reduction in the mean left kidney V{sub 25} (9.4 Gy vs. 2.3 Gy, p = 0.018), mean right kidney V{sub 15} (53.4 Gy vs. 45.9 Gy, p = 0.035), V{sub 20} (32.2 Gy vs. 25.5 Gy, p = 0.016), and V{sub 25} (21.7 Gy vs. 14.9 Gy, p = 0.001). VMAT was investigated in patients with pancreatic malignancies and compared with the current standard of IMRT. VMAT was found to have similar or improved dosimetric parameters for all endpoints considered. Specifically, VMAT provided reduced monitor units and improved bilateral kidney normal tissue dose. The clinical relevance of these benefits in the context of pancreatic cancer patients, however, is currently unclear and requires further investigation.

  13. Intensity-modulated arc therapy to improve radiation dose delivery in the treatment of abdominal neuroblastoma.

    PubMed

    Gains, Jennifer E; Stacey, Christopher; Rosenberg, Ivan; Mandeville, Henry C; Chang, Yen-Ch'ing; D'Souza, Derek; Moroz, Veronica; Wheatley, Keith; Gaze, Mark N

    2013-03-01

    The standard European radiotherapy technique for children with neuroblastoma is a conventional parallel opposed pair. This frequently results in compromise on planning target volume coverage to stay within normal tissue tolerances. This study investigates the use of an intensity-modulated arc therapy (IMAT) technique to improve dose distribution and allow better protocol compliance. Among 20 previously treated patients, ten had received the full prescribed dose with conventional planning (protocol compliant) and ten had a compromise on planning target volume coverage (protocol noncompliant). All patients were replanned with IMAT. Dosimetric parameters of the conventional radiotherapy and IMAT were compared. The dose received by 98% of the planning target volume, homogeneity and conformity indices were all improved with IMAT (p < 0.001). IMAT would have enabled delivery of the full protocol dose in eight out of ten protocol-noncompliant patients. IMAT may improve outcomes through improved protocol compliance and better dose distributions.

  14. Intensity modulated proton therapy

    PubMed Central

    Grassberger, C

    2015-01-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed “pencil beams” of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak—the characteristic peak of dose at the end of range—combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radiotherapy or volumetric modulated arc therapy) with dose modulation along the beam axis as well as lateral, in-field, dose modulation. The clinical practice of IMPT further improves the healthy tissue vs target dose differential in comparison with X-rays and thus allows increased target dose with dose reduction elsewhere. In addition, heavy-charged-particle beams allow for the modulation of biological effects, which is of active interest in combination with dose “painting” within a target. The clinical utilization of IMPT is actively pursued but technical, physical and clinical questions remain. Technical questions pertain to control processes for manipulating pencil beams from the creation of the proton beam to delivery within the patient within the accuracy requirement. Physical questions pertain to the interplay between the proton penetration and variations between planned and actual patient anatomical representation and the intrinsic uncertainty in tissue stopping powers (the measure of energy loss per unit distance). Clinical questions remain concerning the impact and management of the technical and physical questions within the context of the daily treatment delivery, the clinical benefit of IMPT and the biological response differential compared with X-rays against which clinical benefit will be judged. It is expected that IMPT will replace other modes of proton field delivery. Proton radiotherapy, since its first practice 50 years ago, always required the

  15. Leaf-sequencing for intensity-modulated arc therapy using graph algorithms

    SciTech Connect

    Luan Shuang; Wang Chao; Cao Daliang; Chen, Danny Z.; Shepard, David M.; Yu, Cedric X.

    2008-01-15

    Intensity-modulated arc therapy (IMAT) is a rotational IMRT technique. It uses a set of overlapping or nonoverlapping arcs to create a prescribed dose distribution. Despite its numerous advantages, IMAT has not gained widespread clinical applications. This is mainly due to the lack of an effective IMAT leaf-sequencing algorithm that can convert the optimized intensity patterns for all beam directions into IMAT treatment arcs. To address this problem, we have developed an IMAT leaf-sequencing algorithm and software using graph algorithms in computer science. The input to our leaf-sequencing software includes (1) a set of (continuous) intensity patterns optimized by a treatment planning system at a sequence of equally spaced beam angles (typically 10 deg. apart), (2) a maximum leaf motion constraint, and (3) the number of desired arcs, k. The output is a set of treatment arcs that best approximates the set of optimized intensity patterns at all beam angles with guaranteed smooth delivery without violating the maximum leaf motion constraint. The new algorithm consists of the following key steps. First, the optimized intensity patterns are segmented into intensity profiles that are aligned with individual MLC leaf pairs. Then each intensity profile is segmented into k MLC leaf openings using a k-link shortest path algorithm. The leaf openings for all beam angles are subsequently connected together to form 1D IMAT arcs under the maximum leaf motion constraint using a shortest path algorithm. Finally, the 1D IMAT arcs are combined to form IMAT treatment arcs of MLC apertures. The performance of the implemented leaf-sequencing software has been tested for four treatment sites (prostate, breast, head and neck, and lung). In all cases, our leaf-sequencing algorithm produces efficient and highly conformal IMAT plans that rival their counterpart, the tomotherapy plans, and significantly improve the IMRT plans. Algorithm execution times ranging from a few seconds to 2 min are

  16. Kilovoltage Intrafraction Monitoring for Prostate Intensity Modulated Arc Therapy: First Clinical Results

    SciTech Connect

    Ng, Jin Aun; Booth, Jeremy T.; Poulsen, Per R.; Fledelius, Walther; Worm, Esben Schjodt; Eade, Thomas; Hegi, Fiona; Kneebone, Andrew; Kuncic, Zdenka; Keall, Paul J.

    2012-12-01

    Purpose: Most linear accelerators purchased today are equipped with a gantry-mounted kilovoltage X-ray imager which is typically used for patient imaging prior to therapy. A novel application of the X-ray system is kilovoltage intrafraction monitoring (KIM), in which the 3-dimensional (3D) tumor position is determined during treatment. In this paper, we report on the first use of KIM in a prospective clinical study of prostate cancer patients undergoing intensity modulated arc therapy (IMAT). Methods and Materials: Ten prostate cancer patients with implanted fiducial markers undergoing conventionally fractionated IMAT (RapidArc) were enrolled in an ethics-approved study of KIM. KIM involves acquiring kV images as the gantry rotates around the patient during treatment. Post-treatment, markers in these images were segmented to obtain 2D positions. From the 2D positions, a maximum likelihood estimation of a probability density function was used to obtain 3D prostate trajectories. The trajectories were analyzed to determine the motion type and the percentage of time the prostate was displaced {>=}3, 5, 7, and 10 mm. Independent verification of KIM positional accuracy was performed using kV/MV triangulation. Results: KIM was performed for 268 fractions. Various prostate trajectories were observed (ie, continuous target drift, transient excursion, stable target position, persistent excursion, high-frequency excursions, and erratic behavior). For all patients, 3D displacements of {>=}3, 5, 7, and 10 mm were observed 5.6%, 2.2%, 0.7% and 0.4% of the time, respectively. The average systematic accuracy of KIM was measured at 0.46 mm. Conclusions: KIM for prostate IMAT was successfully implemented clinically for the first time. Key advantages of this method are (1) submillimeter accuracy, (2) widespread applicability, and (3) a low barrier to clinical implementation. A disadvantage is that KIM delivers additional imaging dose to the patient.

  17. Feasibility of a unified approach to intensity-modulated radiation therapy and volume-modulated arc therapy optimization and delivery

    SciTech Connect

    Hoover, Douglas A. Chen, Jeff Z.; MacFarlane, Michael; Wong, Eugene; Battista, Jerry J.

    2015-02-15

    Purpose: To study the feasibility of unified intensity-modulated arc therapy (UIMAT) which combines intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) optimization and delivery to produce superior radiation treatment plans, both in terms of dose distribution and efficiency of beam delivery when compared with either VMAT or IMRT alone. Methods: An inverse planning algorithm for UIMAT was prototyped within the PINNACLE treatment planning system (Philips Healthcare). The IMRT and VMAT deliveries are unified within the same arc, with IMRT being delivered at specific gantry angles within the arc. Optimized gantry angles for the IMRT and VMAT phases are assigned automatically by the inverse optimization algorithm. Optimization of the IMRT and VMAT phases is done simultaneously using a direct aperture optimization algorithm. Five treatment plans each for prostate, head and neck, and lung were generated using a unified optimization technique and compared with clinical IMRT or VMAT plans. Delivery verification was performed with an ArcCheck phantom (Sun Nuclear) on a Varian TrueBeam linear accelerator (Varian Medical Systems). Results: In this prototype implementation, the UIMAT plans offered the same target dose coverage while reducing mean doses to organs at risk by 8.4% for head-and-neck cases, 5.7% for lung cases, and 3.5% for prostate cases, compared with the VMAT or IMRT plans. In addition, UIMAT can be delivered with similar efficiency as VMAT. Conclusions: In this proof-of-concept work, a novel radiation therapy optimization and delivery technique that interlaces VMAT or IMRT delivery within the same arc has been demonstrated. Initial results show that unified VMAT/IMRT has the potential to be superior to either standard IMRT or VMAT.

  18. Helical Tomotherapy Versus Single-Arc Intensity-Modulated Arc Therapy: A Collaborative Dosimetric Comparison Between Two Institutions

    SciTech Connect

    Rong Yi; Tang, Grace; Welsh, James S.; Mohiuddin, Majid M.; Paliwal, Bhudatt; Yu, Cedric X.

    2011-09-01

    Purpose: Both helical tomotherapy (HT) and single-arc intensity-modulated arc therapy (IMAT) deliver radiation using rotational beams with multileaf collimators. We report a dual-institution study comparing dosimetric aspects of these two modalities. Methods and Materials: Eight patients each were selected from the University of Maryland (UMM) and the University of Wisconsin Cancer Center Riverview (UWR), for a total of 16 cases. Four cancer sites including brain, head and neck (HN), lung, and prostate were selected. Single-arc IMAT plans were generated at UMM using Varian RapidArc (RA), and HT plans were generated at UWR using Hi-Art II TomoTherapy. All 16 cases were planned based on the identical anatomic contours, prescriptions, and planning objectives. All plans were swapped for analysis at the same time after final approval. Dose indices for targets and critical organs were compared based on dose-volume histograms, the beam-on time, monitor units, and estimated leakage dose. After the disclosure of comparison results, replanning was done for both techniques to minimize diversity in optimization focus from different operators. Results: For the 16 cases compared, the average beam-on time was 1.4 minutes for RA and 4.8 minutes for HT plans. HT provided better target dose homogeneity (7.6% for RA and 4.2% for HT) with a lower maximum dose (110% for RA and 105% for HT). Dose conformation numbers were comparable, with RA being superior to HT (0.67 vs. 0.60). The doses to normal tissues using these two techniques were comparable, with HT showing lower doses for more critical structures. After planning comparison results were exchanged, both techniques demonstrated improvements in dose distributions or treatment delivery times. Conclusions: Both techniques created highly conformal plans that met or exceeded the planning goals. The delivery time and total monitor units were lower in RA than in HT plans, whereas HT provided higher target dose uniformity.

  19. Electromagnetic-Guided DMLC Tracking Enables Motion Management for Intensity Modulated Arc Therapy

    PubMed Central

    Keall, Paul J.; Sawant, Amit; Cho, Byungchul; Ruan, Dan; Wu, Junqing; Poulsen, Per; Petersen, Jay; Newell, Laurence J.; Cattell, Herbert; Korreman, Stine

    2010-01-01

    Purpose Intensity modulated arc therapy (IMAT) is attractive due to high dose conformality and efficient delivery. However, managing intrafraction motion is challenging for IMAT. The purpose of this research was to develop and investigate electromagnetic-guided DMLC tracking as an enabling technology to treat moving targets during IMAT. Materials/Methods A real-time 3D DMLC-based target tracking system was developed and integrated with a linac. The DMLC tracking software inputs a real-time electromagnetically measured target position and the IMAT plan and dynamically creates new leaf positions directed at the moving target. Low and high modulation IMAT plans were created for lung and prostate cancer cases. The IMAT plans were delivered to a 3-axis motion platform programmed with measured patient motion. Dosimetric measurements were acquired by placing an ion chamber array on the moving platform. Measurements were acquired with tracking, without tracking (current clinical practice), and with the phantom in a static position (reference). Analysis of dose distribution differences from the static reference used a γ-test. Results On average, 1.6% of dose points for the lung plans and 1.2% of points for the prostate plans failed the 3mm/3% γ-test with tracking; without tracking 34% and 14% (respectively) of points failed the γ-test. The delivery time was the same with and without tracking. Conclusions For the first time electromagnetic-guided DMLC target tracking with IMAT has been investigated. Dose distributions to moving targets with DMLC tracking were significantly superior to those without tracking. There was no loss of treatment efficiency with DMLC tracking. PMID:20615630

  20. Electromagnetic-Guided Dynamic Multileaf Collimator Tracking Enables Motion Management for Intensity-Modulated Arc Therapy

    SciTech Connect

    Keall, Paul J.; Sawant, Amit; Cho, Byungchul; Ruan, Dan; Wu Junqing; Poulsen, Per; Petersen, Jay; Newell, Laurence J.; Cattell, Herbert; Korreman, Stine

    2011-01-01

    Purpose: Intensity-modulated arc therapy (IMAT) is attractive because of high-dose conformality and efficient delivery. However, managing intrafraction motion is challenging for IMAT. The purpose of this research was to develop and investigate electromagnetically guided dynamic multileaf collimator (DMLC) tracking as an enabling technology to treat moving targets during IMAT. Methods and Materials: A real-time three-dimensional DMLC-based target tracking system was developed and integrated with a linear accelerator. The DMLC tracking software inputs a real-time electromagnetically measured target position and the IMAT plan, and dynamically creates new leaf positions directed at the moving target. Low- and high-modulation IMAT plans were created for lung and prostate cancer cases. The IMAT plans were delivered to a three-axis motion platform programmed with measured patient motion. Dosimetric measurements were acquired by placing an ion chamber array on the moving platform. Measurements were acquired with tracking, without tracking (current clinical practice), and with the phantom in a static position (reference). Analysis of dose distribution differences from the static reference used a {gamma}-test. Results: On average, 1.6% of dose points for the lung plans and 1.2% of points for the prostate plans failed the 3-mm/3% {gamma}-test with tracking; without tracking, 34% and 14% (respectively) of points failed the {gamma}-test. The delivery time was the same with and without tracking. Conclusions: Electromagnetic-guided DMLC target tracking with IMAT has been investigated for the first time. Dose distributions to moving targets with DMLC tracking were significantly superior to those without tracking. There was no loss of treatment efficiency with DMLC tracking.

  1. Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study

    SciTech Connect

    Lee, Katrina Lenards, Nishele; Holson, Janice

    2016-04-01

    The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient's neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to the hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient's data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain.

  2. Postoperative Intensity-Modulated Arc Therapy for Cervical and Endometrial Cancer: A Prospective Report on Toxicity

    SciTech Connect

    Vandecasteele, Katrien; Tummers, Philippe; Makar, Amin; Eijkeren, Marc van; Delrue, Louke; Denys, Hannelore; Lambert, Bieke; Beerens, Anne-Sophie; Van den Broecke, Rudy; Lambein, Kathleen; Fonteyne, Valerie; De Meerleer, Gert

    2012-10-01

    Purpose: To report on toxicity after postoperative intensity-modulated arc therapy (IMAT) for cervical (CC) and endometrial cancer (EC). Methods and Materials: Twenty-four CC and 41 EC patients were treated with postoperative IMAT. If indicated, para-aortic lymph node irradiation (preventive or when affected, PALN) and/or concomitant cisplatin (40 mg/m Superscript-Two , weekly) was administered. The prescribed dose for IMAT was 45 Gy (CC, 25 fractions) and 46 Gy (EC, 23 fractions), followed by a brachytherapeutic boost if possible. Radiation-related toxicity was assessed prospectively. The effect of concomitant cisplatin and PALN irradiation was evaluated. Results: Regarding acute toxicity (n = 65), Grade 3 and 2 acute gastrointestinal toxicity was observed in zero and 63% of patients (79% CC, 54% EC), respectively. Grade 3 and 2 acute genitourinary toxicity was observed in 1% and 18% of patients, respectively. Grade 2 (21%) and 3 (12%) hematologic toxicity (n = 41) occurred only in CC patients. Seventeen percent of CC patients and 2% of EC patients experienced Grade 2 fatigue and skin toxicity, respectively. Adding cisplatin led to an increase in Grade >2 nausea (57% vs. 9%; p = 0.01), Grade 2 nocturia (24% vs. 4%; p = 0.03), Grade {>=}2 hematologic toxicity (38% vs. nil, p = 0.003), Grade {>=}2 leukopenia (33% vs. nil, p = 0.009), and a strong trend toward more fatigue (14% vs. 2%; p = 0.05). Para-aortic lymph node irradiation led to an increase of Grade 2 nocturia (31% vs. 4%, p = 0.008) and a strong trend toward more Grade >2 nausea (44% vs. 18%; p = 0.052). Regarding late toxicity (n = 45), no Grade 3 or 4 late toxicity occurred. Grade 2 gastrointestinal toxicity, genitourinary toxicity, and fatigue occurred in 4%, 9%, and 1% of patients. Neither concomitant cisplatin nor PALN irradiation increased late toxicity rates. Conclusions: Postoperative IMAT for EC or CC is associated with low acute and late toxicity. Concomitant chemotherapy and PALN irradiation

  3. Intensity-Modulated Radiation Therapy (IMRT)

    MedlinePlus

    ... Resources Professions Site Index A-Z Intensity-Modulated Radiation Therapy (IMRT) Intensity-modulated radiotherapy (IMRT) uses linear ... and after this procedure? What is Intensity-Modulated Radiation Therapy and how is it used? Intensity-modulated ...

  4. The GLAaS algorithm for portal dosimetry and quality assurance of RapidArc, an intensity modulated rotational therapy

    PubMed Central

    Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Fogliata, Antonella; Korreman, Stine; Bocanek, Jiri; Cozzi, Luca

    2008-01-01

    Background To expand and test the dosimetric procedure, known as GLAaS, for amorphous silicon detectors to the RapidArc intensity modulated arc delivery with Varian infrastructures and to test the RapidArc dosimetric reliability between calculation and delivery. Methods The GLAaS algorithm was applied and tested on a set of RapidArc fields at both low (6 MV) and high (18 MV) beam energies with a PV-aS1000 detector. Pilot tests for short arcs were performed on a 6 MV beam associated to a PV-aS500. RapidArc is a novel planning and delivery method in the category of intensity modulated arc therapies aiming to deliver highly modulated plans with variable MLC shapes, dose rate and gantry speed during rotation. Tests were repeated for entire (360 degrees) gantry rotations on composite dose plans and for short partial arcs (of ~6 or 12 degrees) to assess GLAaS and RapidArc mutual relationships on global and fine delivery scales. The gamma index concept of Low and the Modulation Index concept of Webb were applied to compare quantitatively TPS dose matrices and dose converted PV images. Results The Gamma Agreement Index computed for a Distance to Agreement of 3 mm and a Dose Difference (ΔD) of 3% was, as mean ± 1 SD, 96.7 ± 1.2% at 6 MV and 94.9 ± 1.3% at 18 MV, over the field area. These findings deteriorated slightly is ΔD was reduced to 2% (93.4 ± 3.2% and 90.1 ± 3.1%, respectively) and improved with ΔD = 4% (98.3 ± 0.8% and 97.3 ± 0.9%, respectively). For all tests a grid of 1 mm and the AAA photon dose calculation algorithm were applied. The spatial resolution of the PV-aS1000 is 0.392 mm/pxl. The Modulation Index for calculations resulted 17.0 ± 3.2 at 6 MV and 15.3 ± 2.7 at 18 MV while the corresponding data for measurements were: 18.5 ± 3.7 and 17.5 ± 3.7. Partial arcs findings were (for ΔD = 3%): GAI = 96.7 ± 0.9% for 6° rotations and 98.0 ± 1.1% for 12° rotations. Conclusion The GLAaS method can be considered as a valid Quality Assurance tool

  5. Single arc volumetric modulated arc therapy for complex brain gliomas: is there an advantage as compared to intensity modulated radiotherapy or by adding a partial arc?

    PubMed

    Davidson, M T M; Masucci, G L; Follwell, M; Blake, S J; Xu, W; Moseley, D J; Sanghera, P; Wong, C S; Perry, J; Tsao, M; Sahgal, A

    2012-06-01

    The objective of this study was to determine if volumetric modulated arc therapy (VMAT) offers advantages over intensity modulated radiotherapy (IMRT) for complex brain gliomas and evaluate the role of an additional partial arc. Twelve patients with glioma involving critical organs at risk (OAR) were selected [six low grade brainstem glioma (BG) and six glioblastoma (GB) cases]. BGs were prescribed 54 Gy/30 fractions (frx), and GB treated to 50 Gy/30 frx to a lower dose PTV (PTV50) with a simultaneous integrated boost delivering a total dose of 60 Gy/30 frx to a higher dose PTV (PTV60). VMAT was planned with a single arc (VMAT1) and with an additional coplanar partial arc spanning 90° (VMAT2). We observed VMATI improving the PTV equivalent uniform dose (EUD) for BG cases (p=0.027), improving the V95 for the PTV50 in GB cases (p=0.026) and resulting in more conformal GB plans (p=0.008) as compare to IMRT. However, for the GB PTV60, IMRT achieved favorable V95 over VMAT1 and VMAT2 (0.0046 and 0.008, respectively). The GB total integral dose (ID) was significantly lower with VMAT1 and VMAT2 (p=0.049 and p=0.006, respectively). Both VMAT1 and VMAT2 reduced the ID, however, only at the 5 Gy threshold for BG cases (p=0.011 and 0.005, respectively). VMAT achieved a lower spinal cord maximum dose and EUD for BG cases and higher optic nerve doses, otherwise no significant differences were observed. VMAT1 yielded the fastest treatment times and least MU. We conclude that VMAT offers faster treatment delivery for complex brain tumors while maintaining similar dosimetric qualities to IMRT. Selective dosimetric advantages in terms of spinal cord sparing and lowering the ID are observed favoring the use of an additional coplanar partial arc.

  6. Efficiency gains for spinal radiosurgery using multicriteria optimization intensity modulated radiation therapy guided volumetric modulated arc therapy planning.

    PubMed

    Chen, Huixiao; Winey, Brian A; Daartz, Juliane; Oh, Kevin S; Shin, John H; Gierga, David P

    2015-01-01

    To evaluate plan quality and delivery efficiency gains of volumetric modulated arc therapy (VMAT) versus a multicriteria optimization-based intensity modulated radiation therapy (MCO-IMRT) for stereotactic radiosurgery of spinal metastases. MCO-IMRT plans (RayStation V2.5; RaySearch Laboratories, Stockholm, Sweden) of 10 spinal radiosurgery cases using 7-9 beams were developed for clinical delivery, and patients were replanned using VMAT with partial arcs. The prescribed dose was 18 Gy, and target coverage was maximized such that the maximum dose to the planning organ-at-risk volume (PRV) of the spinal cord was 10 or 12 Gy. Dose-volume histogram (DVH) constraints from the clinically acceptable MCO-IMRT plans were utilized for VMAT optimization. Plan quality and delivery efficiency with and without collimator rotation for MCO-IMRT and VMAT were compared and analyzed based upon DVH, planning target volume coverage, homogeneity index, conformity number, cord PRV sparing, total monitor units (MU), and delivery time. The VMAT plans were capable of matching most DVH constraints from the MCO-IMRT plans. The ranges of MU were 4808-7193 for MCO-IMRT without collimator rotation, 3509-5907 for MCO-IMRT with collimator rotation, 4444-7309 for VMAT without collimator rotation, and 3277-5643 for VMAT with collimator of 90 degrees. The MU for the VMAT plans were similar to their corresponding MCO-IMRT plans, depending upon the complexity of the target and PRV geometries, but had a larger range. The delivery times of the MCO-IMRT and VMAT plans, both with collimator rotation, were 18.3 ± 2.5 minutes and 14.2 ± 2.0 minutes, respectively (P < .05). The MCO-IMRT and VMAT can create clinically acceptable plans for spinal radiosurgery. The MU for MCO-IMRT and VMAT can be reduced significantly by utilizing a collimator rotation following the orientation of the spinal cord. Plan quality for VMAT is similar to MCO-IMRT, with similar MU for both modalities. Delivery times can be reduced

  7. Experimental validation of a commercial 3D dose verification system for intensity-modulated arc therapies

    NASA Astrophysics Data System (ADS)

    Boggula, Ramesh; Lorenz, Friedlieb; Mueller, Lutz; Birkner, Mattias; Wertz, Hansjoerg; Stieler, Florian; Steil, Volker; Lohr, Frank; Wenz, Frederik

    2010-10-01

    We validate the dosimetric performance of COMPASS®, a novel 3D quality assurance system for verification of volumetric-modulated arc therapy (VMAT) treatment plans that can correlate the delivered dose to the patient's anatomy, taking into account the tissue inhomogeneity. The accuracy of treatment delivery was assessed by the COMPASS® for 12 VMAT plans, and the resulting assessments were evaluated using an ionization chamber and film measurements. Dose-volume relationships were evaluated by the COMPASS® for three additional treatment plans and these were used to verify the accuracy of treatment planning dose calculations. The results matched well between COMPASS® and measurements for the ionization chamber (<=3%) and film (73-99% for gamma(3%/3 mm) < 1 and 98-100% for gamma(5%/5 mm) < 1) for the phantom plans. Differences in dose-volume statistics for the average dose to the PTV were within 2.5% for three treatment plans. For the structures located in the low-dose region, a maximum difference of <9% was observed. In its current implementation, the system could measure the delivered dose with sufficient accuracy and could project the 3D dose distribution directly on the patient's anatomy. Slight deviations were found for large open fields. These could be minimized by improving the COMPASS® in-built beam model.

  8. Comparative analysis of volumetric-modulated arc therapy and intensity-modulated radiotherapy for base of tongue cancer

    PubMed Central

    Nithya, L.; Raj, N. Arunai Nambi; Kumar, Arulraj; Rathinamuthu, Sasikumar; Pandey, Manish Bhushan

    2014-01-01

    The aim of this study was to compare the various dosimetric parameters of dynamic multileaf collimator (MLC) intensity modulated radiation therapy (IMRT) plans with volumetric modulated arc therapy (VMAT) plans for base of tongue cases. All plans were done in Monaco planning system for Elekta synergy linear accelerator with 80 MLC. IMRT plans were planned with nine stationary beams, and VMAT plans were done for 360° arc with single arc or dual arc. The dose to the planning target volumes (PTV) for 70, 63, and 56 Gy was compared. The dose to 95, 98, and 50% volume of PTV were analyzed. The homogeneity index (HI) and the conformity index (CI) of the PTV70 were also analyzed. IMRT and VMAT plan showed similar dose coverage, HI, and CI. Maximum dose and dose to 1-cc volume of spinal cord, planning risk volume (PRV) cord, and brain stem were compared. IMRT plan and VMAT plan showed similar results except for the 1 cc of PRV cord that received slightly higher dose in VMAT plan. Mean dose and dose to 50% volume of right and left parotid glands were analyzed. VMAT plan gave better sparing of parotid glands than IMRT. In normal tissue dose analyses VMAT was better than IMRT. The number of monitor units (MU) required for delivering the good quality of the plan and the time required to deliver the plan for IMRT and VMAT were compared. The number of MUs for VMAT was higher than that of IMRT plans. However, the delivery time was reduced by a factor of two for VMAT compared with IMRT. VMAT plans yielded good quality of the plan compared with IMRT, resulting in reduced treatment time and improved efficiency for base of tongue cases. PMID:24872611

  9. SU-E-T-62: Cardiac Toxicity in Dynamic Conformal Arc Therapy, Intensity-Modulated Radiation Therapy and Volumetric Modulated Arc Therapy of Lung Cancers

    SciTech Connect

    Ming, X; Zhang, Y; Feng, Y; Zhou, L; Deng, J

    2014-06-01

    Purpose: The cardiac toxicity for lung cancer patients, each treated with dynamic conformal arc therapy (DAT), intensity-modulated radiation therapy (IMRT), or volumetric modulated arc therapy (VMAT) is investigated. Methods: 120 lung patients were selected for this study: 25 treated with DAT, 50 with IMRT and 45 with VMAT. For comparison, all plans were generated in the same treatment planning system, normalized such that the 100% isodose lines encompassed 95% of planning target volume. The plan quality was evaluated in terms of homogeneity index (HI) and 95% conformity index (%95 CI) for target dose coverage and mean dose, maximum dose, V{sub 30} Gy as well as V{sub 5} Gy for cardiac toxicity analysis. Results: When all the plans were analyzed, the VMAT plans offered the best target coverage with 95% CI = 0.992 and HI = 1.23. The DAT plans provided the best heart sparing with mean heart dose = 2.3Gy and maximum dose = 11.6Gy, as compared to 5.7 Gy and 31.1 Gy by IMRT as well as 4.6 Gy and 30.9 Gy by VMAT. The mean V30Gy and V5Gy of the heart in the DAT plans were up to 11.7% lower in comparison to the IMRT and VMAT plans. When the tumor volume was considered, the VMAT plans spared up to 70.9% more doses to the heart when the equivalent diameter of the tumor was larger than 4cm. Yet the maximum dose to the heart was reduced the most in the DAT plans with up to 139.8% less than that of the other two plans. Conclusion: Overall, the VMAT plans achieved the best target coverage among the three treatment modalities, and would spare the heart the most for the larger tumors. The DAT plans appeared advantageous in delivering the least maximum dose to the heart as compared to the IMRT and VMAT plans.

  10. Flattening Filter-Free Beams in Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy for Sinonasal Cancer.

    PubMed

    Lu, Jia-Yang; Zheng, Jing; Zhang, Wu-Zhe; Huang, Bao-Tian

    2016-01-01

    To evaluate the dosimetric impacts of flattening filter-free (FFF) beams in intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for sinonasal cancer. For fourteen cases, IMRT and VMAT planning was performed using 6-MV photon beams with both conventional flattened and FFF modes. The four types of plans were compared in terms of target dose homogeneity and conformity, organ-at-risk (OAR) sparing, number of monitor units (MUs) per fraction, treatment time and pure beam-on time. FFF beams led to comparable target dose homogeneity, conformity, increased number of MUs and lower doses to the spinal cord, brainstem and normal tissue, compared with flattened beams in both IMRT and VMAT. FFF beams in IMRT resulted in improvements by up to 5.4% for sparing of the contralateral optic structures, with shortened treatment time by 9.5%. However, FFF beams provided comparable overall OAR sparing and treatment time in VMAT. With FFF mode, VMAT yielded inferior homogeneity and superior conformity compared with IMRT, with comparable overall OAR sparing and significantly shorter treatment time. Using FFF beams in IMRT and VMAT is feasible for the treatment of sinonasal cancer. Our results suggest that the delivery mode of FFF beams may play an encouraging role with better sparing of contralateral optic OARs and treatment efficiency in IMRT, but yield comparable results in VMAT.

  11. Flattening Filter-Free Beams in Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy for Sinonasal Cancer

    PubMed Central

    Huang, Bao-Tian

    2016-01-01

    Purpose To evaluate the dosimetric impacts of flattening filter-free (FFF) beams in intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for sinonasal cancer. Methods For fourteen cases, IMRT and VMAT planning was performed using 6-MV photon beams with both conventional flattened and FFF modes. The four types of plans were compared in terms of target dose homogeneity and conformity, organ-at-risk (OAR) sparing, number of monitor units (MUs) per fraction, treatment time and pure beam-on time. Results FFF beams led to comparable target dose homogeneity, conformity, increased number of MUs and lower doses to the spinal cord, brainstem and normal tissue, compared with flattened beams in both IMRT and VMAT. FFF beams in IMRT resulted in improvements by up to 5.4% for sparing of the contralateral optic structures, with shortened treatment time by 9.5%. However, FFF beams provided comparable overall OAR sparing and treatment time in VMAT. With FFF mode, VMAT yielded inferior homogeneity and superior conformity compared with IMRT, with comparable overall OAR sparing and significantly shorter treatment time. Conclusions Using FFF beams in IMRT and VMAT is feasible for the treatment of sinonasal cancer. Our results suggest that the delivery mode of FFF beams may play an encouraging role with better sparing of contralateral optic OARs and treatment efficiency in IMRT, but yield comparable results in VMAT. PMID:26734731

  12. Dose verification of intensity-modulated arc therapy using an ERGO++ treatment planning system and Elekta internal multileaf collimators for prostate cancer treatment.

    PubMed

    Yoda, K; Nakagawa, K; Shiraishi, K; Okano, Y; Ohtomo, K; Pellegrini, R G

    2009-04-01

    Dose verification of intensity-modulated arc therapy using an ERGO++ treatment planning system and Elekta internal multileaf collimators is described. Prostate intensity-modulated arc therapy was planned using the arc modulation optimization algorithm inverse planning module of ERGO++. After transferring the plan to Elekta Synergy's controller (Elekta Ltd, Crawley, UK), the isocentre dose was measured and compared with a calculated dose using a pinpoint chamber and a water phantom in a cylindrical acrylic enclosure. Subsequently, an EDR2 film was placed inside a multilayer plastic phantom, and total dose distributions were measured in three axial planes as well as in the coronal and sagittal planes to compare the actual dose with the calculated dose. The dose discrepancy at the isocentre was 1.7%. The calculated gamma indices were less than 1 over 90% of the three axial planes, as well as in the coronal and sagittal planes, having a dose greater than 50% of the maximum target dose.

  13. SU-E-T-422: Fast Analytical Beamlet Optimization for Volumetric Intensity-Modulated Arc Therapy

    SciTech Connect

    Chan, Kenny S K; Lee, Louis K Y; Xing, L; Chan, Anthony T C

    2015-06-15

    Purpose: To implement a fast optimization algorithm on CPU/GPU heterogeneous computing platform and to obtain an optimal fluence for a given target dose distribution from the pre-calculated beamlets in an analytical approach. Methods: The 2D target dose distribution was modeled as an n-dimensional vector and estimated by a linear combination of independent basis vectors. The basis set was composed of the pre-calculated beamlet dose distributions at every 6 degrees of gantry angle and the cost function was set as the magnitude square of the vector difference between the target and the estimated dose distribution. The optimal weighting of the basis, which corresponds to the optimal fluence, was obtained analytically by the least square method. Those basis vectors with a positive weighting were selected for entering into the next level of optimization. Totally, 7 levels of optimization were implemented in the study.Ten head-and-neck and ten prostate carcinoma cases were selected for the study and mapped to a round water phantom with a diameter of 20cm. The Matlab computation was performed in a heterogeneous programming environment with Intel i7 CPU and NVIDIA Geforce 840M GPU. Results: In all selected cases, the estimated dose distribution was in a good agreement with the given target dose distribution and their correlation coefficients were found to be in the range of 0.9992 to 0.9997. Their root-mean-square error was monotonically decreasing and converging after 7 cycles of optimization. The computation took only about 10 seconds and the optimal fluence maps at each gantry angle throughout an arc were quickly obtained. Conclusion: An analytical approach is derived for finding the optimal fluence for a given target dose distribution and a fast optimization algorithm implemented on the CPU/GPU heterogeneous computing environment greatly reduces the optimization time.

  14. Volumetric modulated Arc therapy and conventional intensity-modulated radiotherapy for simultaneous maximal intraprostatic boost: a planning comparison study.

    PubMed

    Shaffer, R; Morris, W J; Moiseenko, V; Welsh, M; Crumley, C; Nakano, S; Schmuland, M; Pickles, T; Otto, K

    2009-06-01

    Volumetric modulated arc therapy (VMAT) is a novel extension of intensity-modulated radiotherapy (IMRT) where an optimised three-dimensional dose distribution may be delivered in a single gantry rotation. This optimisation algorithm is the predecessor to Varian's RapidArc. The aim of this study was to compare the ability of conventional static nine-field IMRT (cIMRT) and VMAT to boost as much of the clinical target volume (CTV) as possible to 88.8Gy without exceeding organ at risk (OAR) dose-volume constraints. Optimal cIMRT and VMAT radiotherapy plans were produced for 10 patients with localised prostate cancer using common planning objectives: (1) Treat >or=98% of the planning target volume (PTV) to >or=95% of the prescription dose (74Gy in 37 fractions); (2) keep OAR doses within predefined limits; (3) treat as much of prostate CTV (minus urethra) as possible to >or=120% of prescription dose (=88.8Gy); (4) keep within maximum dose limits in and out of target volumes; (5) conformality index (volume of 95% isodose/volume of PTV)or=120% of the prescription dose (P=0.002). All dose constraints were kept within predefined limits. VMAT and cIMRT required an average of 949 and 1819 monitor units and 3.7 and 9.6min, respectively, to deliver a single radiation fraction. VMAT is able to boost more of the CTV to >or=120% than cIMRT without contravening OAR dose constraints, and uses 48% fewer monitor units. Treatment times were 61% less than with cIMRT.

  15. Volumetric-Modulated Arc Therapy for Stereotactic Body Radiotherapy of Lung Tumors: A Comparison With Intensity-Modulated Radiotherapy Techniques

    SciTech Connect

    Holt, Andrea; Vliet-Vroegindeweij, Corine van; Mans, Anton; Belderbos, Jose S.; Damen, Eugene M.F.

    2011-12-01

    Purpose: To demonstrate the potential of volumetric-modulated arc therapy (VMAT) compared with intensity-modulated radiotherapy (IMRT) techniques with a limited number of segments for stereotactic body radiotherapy (SBRT) for early-stage lung cancer. Methods and Materials: For a random selection of 27 patients eligible for SBRT, coplanar and noncoplanar IMRT and coplanar VMAT (using SmartArc) treatment plans were generated in Pinnacle{sup 3} and compared. In addition, film measurements were performed using an anthropomorphic phantom to evaluate the skin dose for the different treatment techniques. Results: Using VMAT, the delivery times could be reduced to an average of 6.6 min compared with 23.7 min with noncoplanar IMRT. The mean dose to the healthy lung was 4.1 Gy for VMAT and noncoplanar IMRT and 4.2 Gy for coplanar IMRT. The volume of healthy lung receiving >5 Gy and >20 Gy was 18.0% and 5.4% for VMAT, 18.5% and 5.0% for noncoplanar IMRT, and 19.4% and 5.7% for coplanar IMRT, respectively. The dose conformity at 100% and 50% of the prescribed dose of 54 Gy was 1.13 and 5.17 for VMAT, 1.11 and 4.80 for noncoplanar IMRT and 1.12 and 5.31 for coplanar IMRT, respectively. The measured skin doses were comparable for VMAT and noncoplanar IMRT and slightly greater for coplanar IMRT. Conclusions: Coplanar VMAT for SBRT for early-stage lung cancer achieved plan quality and skin dose levels comparable to those using noncoplanar IMRT and slightly better than those with coplanar IMRT. In addition, the delivery time could be reduced by {<=}70% with VMAT.

  16. Whole abdomen radiation therapy in ovarian cancers: a comparison between fixed beam and volumetric arc based intensity modulation

    PubMed Central

    2010-01-01

    Purpose A study was performed to assess dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) for Whole Abdomen Radiotherapy (WAR) after ovarian cancer. Methods and Materials Plans for IMRT and RA were optimised for 5 patients prescribing 25 Gy to the whole abdomen (PTV_WAR) and 45 Gy to the pelvis and pelvic nodes (PTV_Pelvis) with Simultaneous Integrated Boost (SIB) technique. Plans were investigated for 6 MV (RA6, IMRT6) and 15 MV (RA15, IMRT15) photons. Objectives were: for both PTVs V90% > 95%, for PTV_Pelvis: Dmax < 105%; for organs at risk, maximal sparing was required. The MU and delivery time measured treatment efficiency. Pre-treatment Quality assurance was scored with Gamma Agreement Index (GAI) with 3% and 3 mm thresholds. Results IMRT and RapidArc resulted comparable for target coverage. For PTV_WAR, V90% was 99.8 ± 0.2% and 93.4 ± 7.3% for IMRT6 and IMRT15, and 98.4 ± 1.7 and 98.6 ± 0.9% for RA6 and RA15. Target coverage resulted improved for PTV_Pelvis. Dose homogeneity resulted slightly improved by RA (Uniformity was defined as U5-95% = D5%-D95%/Dmean). U5-95% for PTV_WAR was 0.34 ± 0.05 and 0.32 ± 0.06 (IMRT6 and IMRT15), 0.30 ± 0.03 and 0.26 ± 0.04 (RA6 and RA15); for PTV_Pelvis, it resulted equal to 0.1 for all techniques. For organs at risk, small differences were observed between the techniques. MU resulted 3130 ± 221 (IMRT6), 2841 ± 318 (IMRT15), 538 ± 29 (RA6), 635 ± 139 (RA15); the average measured treatment time was 18.0 ± 0.8 and 17.4 ± 2.2 minutes (IMRT6 and IMRT15) and 4.8 ± 0.2 (RA6 and RA15). GAIIMRT6 = 97.3 ± 2.6%, GAIIMRT15 = 94.4 ± 2.1%, GAIRA6 = 98.7 ± 1.0% and GAIRA15 = 95.7 ± 3.7%. Conclusion RapidArc showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT. PMID:21078145

  17. Whole abdomen radiation therapy in ovarian cancers: a comparison between fixed beam and volumetric arc based intensity modulation.

    PubMed

    Mahantshetty, Umesh; Jamema, Swamidas; Engineer, Reena; Deshpande, Deepak; Sarin, Rajiv; Fogliata, Antonella; Nicolini, Giorgia; Clivio, Alessandro; Vanetti, Eugenio; Shrivastava, Shyamkishore; Cozzi, Luca

    2010-11-15

    A study was performed to assess dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) for Whole Abdomen Radiotherapy (WAR) after ovarian cancer. Plans for IMRT and RA were optimised for 5 patients prescribing 25 Gy to the whole abdomen (PTV_WAR) and 45 Gy to the pelvis and pelvic nodes (PTV_Pelvis) with Simultaneous Integrated Boost (SIB) technique. Plans were investigated for 6 MV (RA6, IMRT6) and 15 MV (RA15, IMRT15) photons. Objectives were: for both PTVs V90% > 95%, for PTV_Pelvis: Dmax < 105%; for organs at risk, maximal sparing was required. The MU and delivery time measured treatment efficiency. Pre-treatment Quality assurance was scored with Gamma Agreement Index (GAI) with 3% and 3 mm thresholds. IMRT and RapidArc resulted comparable for target coverage. For PTV_WAR, V90% was 99.8 ± 0.2% and 93.4 ± 7.3% for IMRT6 and IMRT15, and 98.4 ± 1.7 and 98.6 ± 0.9% for RA6 and RA15. Target coverage resulted improved for PTV_Pelvis. Dose homogeneity resulted slightly improved by RA (Uniformity was defined as U5-95% = D5%-D95%/Dmean). U5-95% for PTV_WAR was 0.34 ± 0.05 and 0.32 ± 0.06 (IMRT6 and IMRT15), 0.30 ± 0.03 and 0.26 ± 0.04 (RA6 and RA15); for PTV_Pelvis, it resulted equal to 0.1 for all techniques. For organs at risk, small differences were observed between the techniques. MU resulted 3130 ± 221 (IMRT6), 2841 ± 318 (IMRT15), 538 ± 29 (RA6), 635 ± 139 (RA15); the average measured treatment time was 18.0 ± 0.8 and 17.4 ± 2.2 minutes (IMRT6 and IMRT15) and 4.8 ± 0.2 (RA6 and RA15). GAIIMRT6 = 97.3 ± 2.6%, GAIIMRT15 = 94.4 ± 2.1%, GAIRA6 = 98.7 ± 1.0% and GAIRA15 = 95.7 ± 3.7%. RapidArc showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT.

  18. Stereotactic body radiation therapy for abdominal targets using volumetric intensity modulated arc therapy with RapidArc: feasibility and clinical preliminary results.

    PubMed

    Scorsetti, Marta; Bignardi, Mario; Alongi, Filippo; Fogliata, Antonella; Mancosu, Pietro; Navarria, Piera; Castiglioni, Simona; Pentimalli, Sara; Tozzi, Angelo; Cozzi, Luca

    2011-05-01

    To report early clinical experience in stereotactic body radiation therapy (SBRT) delivered using volumetric intensity modulated arc therapy with RapidArc (RA) in patients with primary or metastatic tumours at abdominal sites. Thirty-seven consecutive patients were treated using RA. Of these, 16 had primary or metastatic liver tumours, nine had pancreatic cancer and 12 a nodal metastasis in the retro-peritoneum. Dose prescription varied from 45 to 75 Gy to the Clinical Target Volume in 3 to 6 fractions. The median follow-up was 12 months (6-22). Early local control and toxicity were investigated and reported. Planning objectives on target volumes and organs at risk were met in most cases. Delivery time ranged from 2.8 ± 0.3 to 9.2 ± 2.4 minutes and pre-treatment plan verification resulted in a Gamma Agreement Index from 95.3 ± 3.8 to 98.3 ± 1.7%. At the time of analysis, local control (freedom from progression) at six months, was assessable in 24 of 37 patients and was achieved in 19 patients with a crude rate of 79.2%. Seven patients experienced treatment-related toxicity. Three patients experienced a mild and transient G1 enteritis and two showed a transient G1 liver damage. Two had late toxicity: one developed chronic enteritis causing G1 diarrhoea and G1 abdominal pain and one suffered at three months a G3 gastric bleeding. No patients experienced G4 acute toxicity. SBRT for abdominal targets delivered by means of RA resulted to be feasible with good early clinical results in terms of local control rate and acute toxicity profile. RA allowed to achieve required target coverage as well as to keep within normal tissue dose/volume constraints.

  19. Dosimetric comparison of hybrid volumetric-modulated arc therapy, volumetric-modulated arc therapy, and intensity-modulated radiation therapy for left-sided early breast cancer

    SciTech Connect

    Lin, Jia-Fu; Yeh, Dah-Cherng; Yeh, Hui-Ling; Chang, Chen-Fa; Lin, Jin-Ching

    2015-10-01

    To compare the dosimetric performance of 3 different treatment techniques: hybrid volumetric-modulated arc therapy (hybrid-VMAT), pure-VMAT, and fixed-field intensity-modulated radiation therapy (F-IMRT) for whole-breast irradiation of left-sided early breast cancer. The hybrid-VMAT treatment technique and 2 other treatment techniques—pure-VMAT and F-IMRT—were compared retrospectively in 10 patients with left-sided early breast cancer. The treatment plans of these patients were replanned using the same contours based on the original computed tomography (CT) data sets. Dosimetric parameters were calculated to evaluate plan quality. Total monitor units (MUs) and delivery time were also recorded and evaluated. The hybrid-VMAT plan generated the best results in dose coverage of the target and the dose uniformity inside the target (p < 0.0001 for conformal index [CI]; p = 0.0002 for homogeneity index [HI] of planning target volume [PTV]{sub 50.4} {sub Gy} and p < 0.0001 for HI of PTV{sub 62} {sub Gy}). Volumes of ipsilateral lung irradiated to doses of 20 Gy (V{sub 20} {sub Gy}) and 5 Gy (V{sub 5} {sub Gy}) by the hybrid-VMAT plan were significantly less than those of the F-IMRT and the pure-VMAT plans. The volume of ipsilateral lung irradiated to a dose of 5 Gy was significantly less using the hybrid-VMAT plan than that using the F-IMRT or the pure-VMAT plan. The total mean MUs for the hybrid-VMAT plan were significantly less than those for the F-IMRT or the pure-VMAT plan. The mean machine delivery time was 3.23 ± 0.29 minutes for the hybrid-VMAT plans, which is longer than that for the pure-VMAT plans but shorter than that for the F-IMRT plans. The hybrid-VMAT plan is feasible for whole-breast irradiation of left-sided early breast cancer.

  20. Dosimetric comparison of hybrid volumetric-modulated arc therapy, volumetric-modulated arc therapy, and intensity-modulated radiation therapy for left-sided early breast cancer.

    PubMed

    Lin, Jia-Fu; Yeh, Dah-Cherng; Yeh, Hui-Ling; Chang, Chen-Fa; Lin, Jin-Ching

    2015-01-01

    To compare the dosimetric performance of 3 different treatment techniques: hybrid volumetric-modulated arc therapy (hybrid-VMAT), pure-VMAT, and fixed-field intensity-modulated radiation therapy (F-IMRT) for whole-breast irradiation of left-sided early breast cancer. The hybrid-VMAT treatment technique and 2 other treatment techniques—pure-VMAT and F-IMRT—were compared retrospectively in 10 patients with left-sided early breast cancer. The treatment plans of these patients were replanned using the same contours based on the original computed tomography (CT) data sets. Dosimetric parameters were calculated to evaluate plan quality. Total monitor units (MUs) and delivery time were also recorded and evaluated. The hybrid-VMAT plan generated the best results in dose coverage of the target and the dose uniformity inside the target (p < 0.0001 for conformal index [CI]; p = 0.0002 for homogeneity index [HI] of planning target volume [PTV](50.4 Gy) and p < 0.0001 for HI of PTV(62 Gy)). Volumes of ipsilateral lung irradiated to doses of 20 Gy (V(20 Gy)) and 5 Gy (V(5 Gy)) by the hybrid-VMAT plan were significantly less than those of the F-IMRT and the pure-VMAT plans. The volume of ipsilateral lung irradiated to a dose of 5 Gy was significantly less using the hybrid-VMAT plan than that using the F-IMRT or the pure-VMAT plan. The total mean MUs for the hybrid-VMAT plan were significantly less than those for the F-IMRT or the pure-VMAT plan. The mean machine delivery time was 3.23 ± 0.29 minutes for the hybrid-VMAT plans, which is longer than that for the pure-VMAT plans but shorter than that for the F-IMRT plans. The hybrid-VMAT plan is feasible for whole-breast irradiation of left-sided early breast cancer. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  1. Intensity-modulated radiation therapy.

    PubMed

    Goffman, Thomas E; Glatstein, Eli

    2002-07-01

    Intensity-modulated radiation therapy (IMRT) is an increasingly popular technical means of tightly focusing the radiation dose around a cancer. As with stereotactic radiotherapy, IMRT uses multiple fields and angles to converge on the target. The potential for total dose escalation and for escalation of daily fraction size to the gross cancer is exciting. The excitement, however, has greatly overshadowed a range of radiobiological and clinical concerns.

  2. Dosimetric and radiobiological comparison of Forward Tangent Intensity Modulated Radiation Therapy (FT-IMRT) and Volumetric Modulated Arc Therapy (VMAT) for early stage whole breast cancer

    NASA Astrophysics Data System (ADS)

    Moshiri Sedeh, Nader

    Intensity Modulated Radiation Therapy (IMRT) is a well-known type of external beam radiation therapy. The advancement in technology has had an inevitable influence in radiation oncology as well that has led to a newer and faster dose delivery technique called Volumetric Modulated Arc Therapy (VMAT). Since the presence of the VMAT modality in clinics in the late 2000, there have been many studies in order to compare the results of the VMAT modality with the current popular modality IMRT for various tumor sites in the body such as brain, prostate, head and neck, cervix and anal carcinoma. This is the first study to compare VMAT with IMRT for breast cancer. The results show that the RapidArc technique in Eclipse version 11 does not improve all aspects of the treatment plans for the breast cases automatically and easily, but it needs to be manipulated by extra techniques to create acceptable plans thus further research is needed.

  3. SmartArc-based volumetric modulated arc therapy for endometrial cancer: a dosimetric comparison with helical tomotherapy and intensity-modulated radiation therapy

    PubMed Central

    2013-01-01

    Background The purpose of the present study was to investigate the feasibility of using volumetric modulated arc therapy with SmartArc (VMAT-S) to achieve radiation delivery efficiency higher than that of intensity-modulated radiotherapy (IMRT) and helical tomotherapy (HT) when treating endometrial cancer, while maintaining plan quality. Methods Nine patients with endometrial cancer were retrospectively studied. Three plans per patient were generated for VMAT-S, IMRT and HT. The dose distributions for the planning target volume (PTV), organs at risk (OARs) and normal tissue were compared. The monitor units (MUs) and treatment delivery time were also evaluated. Results The average homogeneity index was 1.06, 1.10 and 1.07 for the VMAT-S, IMRT and HT plans, respectively. The V40 for the rectum, bladder and pelvis bone decreased by 9.0%, 3.0% and 3.0%, respectively, in the VMAT-S plan relative to the IMRT plan. The target coverage and sparing of OARs were comparable between the VMAT-S and HT plans. The average MU was 823, 1105 and 8403 for VMAT-S, IMRT and HT, respectively; the average delivery time was 2.6, 8.6 and 9.5 minutes, respectively. Conclusions For endometrial cancer, the VMAT-S plan provided comparable quality with significantly shorter delivery time and fewer MUs than with the IMRT and HT plans. In addition, more homogeneous PTV coverage and superior sparing of OARs in the medium to high dose region were observed in the VMAT-S relative to the IMRT plan. PMID:24175929

  4. SU-E-J-70: Evaluation of Multiple Isocentric Intensity Modulated and Volumetric Modulated Arc Therapy Techniques Using Portal Dosimetry

    SciTech Connect

    Muralidhar, K Raja; Pangam, S; Kolla, J; Ponaganti, S; Ali, M; Vuba, S; Mariyappan, P; Babaiah, M; Komanduri, K

    2015-06-15

    Purpose: To develop a method for verification of dose distribution in a patient during treatment using multiple isocentric Intensity modulated and volumetric modulated arc therapy techniques with portal dosimetry. Methods: Varian True Beam accelerator, equipped with an aS1000 megavoltage electronic portal imaging device (EPID) has an integrated image mode for portal dosimetry (PD). The source-to-imager distance was taken at 150 cm to avoid collision to the table. Fourteen fractions were analyzed for this study. During shift in a single plan from one isocenter to another isocenter, EPID also shifted longitudinally for each field by taking the extent of divergence of beam into the consideration for EPID distance of 150cm. Patients were given treatment everyday with EPID placed in proper position for each field. Several parameters were obtained by comparing the dose distribution between fractions to fraction. The impact of the intra-fraction and inter-fraction of the patient in combination with isocenter shift of the beams were observed. Results: During treatment, measurements were performed by EPID and were evaluated by the gamma method. Analysis was done between fractions for multiple isocenter treatments. The pass rates of the gamma analysis with a criterion of 3% and 3 mm for the 14 fractions were over 97.8% with good consistency. Whereas maximum gamma exceeded the criteria in few fractions (in<1 cc vol). Average gamma was observed in the criteria of 0.5%. Maximum dose difference and average dose differences were less than 0.22 CU and 0.01 CU for maximum tolerance of 1.0 CU and 0.2 CU respectively. Conclusion: EPID with extended distance is ideal method to verify the multiple isocentric dose distribution in patient during treatment, especially cold and hot spots in junction dose. Verification of shifts as well as the dose differences between each fraction due to inter-fraction and intra-fraction of the patient can be derived.

  5. SU-E-T-449: Hippocampal Sparing Radiotherapy Using Intensity Modulated Radiotherapy and Volumetric Modulated Arc Therapy

    SciTech Connect

    Moon, S; Kim, D; Chung, W; Yoon, M

    2015-06-15

    Purpose: The hippocampus sparing during the cranial irradiation has become interesting because it may mitigate radiation-induced neurocognitive toxicity. Herein we report our preliminary study for sparing the hippocampus with and without tilling condition for patient with brain metastases. Methods: Ten patients previously treated with whole brain were reviewed. Five patients tilted the head to around 30 degrees and others were treated without tilting. Treatment plans of linear accelerator (Linac)-based volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) were generated for prescription dose of 30 Gy in 15 fractions. Hippocampal avoidance regions were created with 5-mm volumetric expansion around the hippocampus. Whole brain, hippocampus and hippocampal avoidance volume were 1372cm3, 6cm3 and 30cm3 and hippocampal avoidance volume was 2.2% of the whole brain planned target volume in average. Organs at risk (OARs) are hippocampus, eyes, lens, and cochleae. Coverage index (CVI), conformity index (CI), homogeneity index (HI) and mean dose to OARs were used to compare dose characteristic of tilted and non-tilted cases. Results: In IMRT, when CI, CVI and HI of whole brain were 0.88, 0.09 and 0.98 in both tilted and non-tilted cases, absorbed dose of hippocampal avoidance volume in tilted cases were 10% lower than non-tilted cases. Doses in other OARs such as eyes, lens, and cochleae were also decreased about 20% when tilting the head. When CI, HI and CVI in VMAT were 0.9, 0.08 and 0.99, the dose-decreased ratio of OARs in both with and without tilting cases were almost the same with IMRT. But absolute dose of hippocampal avoidance volume in VMAT was 30% lower than IMRT. Conclusion: This study confirms that dose to hippocampus decreases if patients tilt the head. When treating the whole brain with head tilted, patients can acquire the same successful treatment Result and also preserve their valuable memory.

  6. Comparison of intensity-modulated radiotherapy and forward-planning dynamic arc therapy techniques for prostate cancer.

    PubMed

    Metwaly, Mohamed; Awaad, Awaad Mousa; El-Sayed, El-Sayed Mahmoud; Sallam, Abdel Sattar Mohamed

    2008-10-24

    We compare an inverse-planning intensity-modulated radiotherapy (IMRT) technique with three previously published forward-planning dynamic arc therapy techniques and a newly implemented technique for treatment of prostate only. The three previously published dynamic arc techniques are dynamic arc therapy (DAT), two-axis dynamic arc therapy (2A-DAT), and modified dynamic arc therapy (M-DAT). The newly implemented technique is the bilateral wedged dynamic arc (BW-DAT). In all dynamic arcs, the multileaf collimator is moving during rotation to fit the prostate, except that, in 2A-DAT, it is fitting two separate symmetrical rhombi including the prostate. The rectum is shielded during rotation only in the cases of M-DAT and BW-DAT. The results obtained indicate that the BW-DAT, M-DAT, and DAT techniques provide the intended dose coverage of the prescribed dose to the planning target volume (PTV)--that is, 95% of the PTV is covered by 100% of the dose. The maximum dose to a 3-cm margin of healthy tissue that surrounds the PTV is lower by 2.5% in the case of IMRT than in both BW-DAT and M-DAT, but it is lower by 5.0% than that in both DAT and 2A-DAT. The maximum dose to the rest of the healthy tissue in the case of BW-DAT is 33.2 Gy +/- 2.2 Gy. This dose covers percentage healthy body volumes of 8% +/- 3.2% with IMRT, 4% +/- 1.5% with DAT, and 6% +/- 1.2% with both 2A-DAT and M-DAT. Also, this dose is much lower than the accepted maximum dose (52 Gy) to the femoral heads and necks according to Report 62 from the International Commission on Radiation Units and Measurements. Accordingly, it would be possible to neglect delineation of the femoral heads and necks as organs at risk in cases of BW-DAT. Doses to 15%, 25%, 35%, and 50% (D15%, D25%, D35%, and D50%) of the rectum volume in the case of BW-DAT were 43.5 Gy +/- 8.6 Gy, 24.2 Gy +/- 8.7 Gy, 13.2 Gy +/- 4.2 Gy, and 5.7 Gy +/- 2.1 Gy respectively. The D15% of rectum in the case of IMRT was lower than that in BW-DAT, M

  7. Comparative dosimetry of volumetric modulated arc therapy and limited-angle static intensity-modulated radiation therapy for early-stage larynx cancer

    SciTech Connect

    Riegel, Adam C.; Antone, Jeffrey; Schwartz, David L.

    2013-04-01

    To compare relative carotid and normal tissue sparing using volumetric-modulated arc therapy (VMAT) or intensity-modulated radiation therapy (IMRT) for early-stage larynx cancer. Seven treatment plans were retrospectively created on 2 commercial treatment planning systems for 11 consecutive patients with T1-2N0 larynx cancer. Conventional plans consisted of opposed-wedged fields. IMRT planning used an anterior 3-field beam arrangement. Two VMAT plans were created, a full 360° arc and an anterior 180° arc. Given planning target volume (PTV) coverage of 95% total volume at 95% of 6300 cGy and maximum spinal cord dose below 2500 cGy, mean carotid artery dose was pushed as low as possible for each plan. Deliverability was assessed by comparing measured and planned planar dose with the gamma (γ) index. Full-arc planning provided the most effective carotid sparing but yielded the highest mean normal tissue dose (where normal tissue was defined as all soft tissue minus PTV). Static IMRT produced next-best carotid sparing with lower normal tissue dose. The anterior half-arc produced the highest carotid artery dose, in some cases comparable with conventional opposed fields. On the whole, carotid sparing was inversely related to normal tissue dose sparing. Mean γ indexes were much less than 1, consistent with accurate delivery of planned treatment. Full-arc VMAT yields greater carotid sparing than half-arc VMAT. Limited-angle IMRT remains a reasonable alternative to full-arc VMAT, given its ability to mediate the competing demands of carotid and normal tissue dose constraints. The respective clinical significance of carotid and normal tissue sparing will require prospective evaluation.

  8. The impact of leaf width and plan complexity on DMLC tracking of prostate intensity modulated arc therapy

    PubMed Central

    Pommer, Tobias; Falk, Marianne; Poulsen, Per Rugaard; Keall, Paul J.; O’Brien, Ricky T.; Munck af Rosenschöld, Per

    2013-01-01

    Purpose: Intensity modulated arc therapy (IMAT) is commonly used to treat prostate cancer. The purpose of this study was to evaluate the impact of leaf width and plan complexity on dynamic multileaf collimator (DMLC) tracking for prostate motion management during IMAT treatments. Methods: Prostate IMAT plans were delivered with either a high-definition MLC (HDMLC) or a Millennium MLC (M-MLC) (0.25 and 0.50 cm central leaf width, respectively), with and without DMLC tracking, to a dosimetric phantom that reproduced four prostate motion traces. The plan complexity was varied by applying leaf position constraints during plan optimization. A subset of the M-MLC plans was converted for delivery with the HDMLC, isolating the effect of the different leaf widths. The gamma index was used for evaluation. Tracking errors caused by target localization, leaf fitting, and leaf adjustment were analyzed. Results: The gamma pass rate was significantly improved with DMLC tracking compared to no tracking (p < 0.001). With DMLC tracking, the average gamma index pass rate was 98.6% (range 94.8%–100%) with the HDMLC and 98.1% (range 95.4%–99.7%) with the M-MLC, using 3%, 3 mm criteria and the planned dose as reference. The corresponding pass rates without tracking were 87.6% (range 76.2%–94.7%) and 91.1% (range 81.4%–97.6%), respectively. Decreased plan complexity improved the pass rate when static target measurements were used as reference, but not with the planned dose as reference. The main cause of tracking errors was leaf fitting errors, which were decreased by 42% by halving the leaf width. Conclusions: DMLC tracking successfully compensated for the prostate motion. The finer leaf width of the HDMLC improved the tracking accuracy compared to the M-MLC. The tracking improvement with limited plan complexity was small and not discernible when using the planned dose as reference. PMID:24320425

  9. Sci—Fri AM: Mountain — 05: Unified Optimization and Delivery of Intensity-modulated Radiation Therapy and Volume-modulated Arc Therapy

    SciTech Connect

    Chen, J; Hoover, D; MacFarlane, M; Wong, E

    2014-08-15

    Purpose: To study the feasibility of a unified intensity-modulated arc therapy (UIMAT) that combines IMRT and VMAT optimization and delivery in order to produce efficient and superior radiation treatment plans. Methods: Inverse planning for UIMAT was prototyped on the Pinnacle treatment planning system (Philips Medical Systems). UIMAT integrates IMRT and VMAT delivery in the same arc where IMRT was delivered with gantry speed close to zero. Optimal gantry angles for the IMRT phases were selected automatically by the inverse optimization algorithm. Optimization of the VMAT phases and IMRT phases were done simultaneously using Pinnacle's direct machine parameter optimization algorithm. Five treatment plans each for prostate, head and neck, and lung were generated using our unified technique and compared with clinical VMAT or IMRT plans. Delivery verification was performed on an ArcCheck phantom (Sun Nuclear) and delivered in clinical mode on a Varian TrueBeam linear accelerator. Results: In this prototype implementation, compared to the VMAT or IMRT plans, with the plans normalized to the same dose coverage to the planning target volumes, the UIMAT plans produced improved OAR sparing for head and neck cases, while for lung and prostate cases, the dosimetric improvements for OARs were not as significant. In this proof-of-concept work, we demonstrated that a novel radiation therapy delivery technique combining VMAT and IMRT delivery in the same arc is feasible. Initial results showed UIMAT has the potential to be superior to either standard IMRT or VMAT.

  10. Effects of full-neck volumetric-modulated arc therapy vs split-field intensity-modulated head and neck radiation therapy on low neck targets and structures

    PubMed Central

    Anamalayil, Shibu J; Teo, Boon-Keng K; Lin, Alexander; Lustig, Robert A

    2016-01-01

    Objective: While split-field intensity-modulated radiation therapy (SF-IMRT) decreases dose to low neck (LAN) structures such as the glottic larynx compared with full-neck intensity-modulated radiation therapy (IMRT), it is unknown whether SF-IMRT affords superior dose avoidance to organs than whole neck-field volumetric-modulated arc therapy (WF-VMAT). Methods: 10 patients treated definitively with radiation for oropharyngeal, oral cavity or nasopharyngeal carcinoma were compared. Only patients ideally suited for SF-IMRT plans were included. The glottic larynx, supraglottic larynx, arytenoids, pharyngeal constrictors, oesophagus, brachial plexus and target volume coverage in the LAN were compared between WF-VMAT and SF-IMRT. Results: Volumetric-modulated arc therapy (VMAT) yielded statistically significant decreases in maximum dose to the arytenoids and mean dose to the oesophagus. There was no difference in dose to the glottic larynx, supraglottic larynx, pharyngeal constrictors and brachial plexus. WF-VMAT led to improved coverage to 50/2 Gy fraction equivalent in LAN compared with SF-IMRT using an anteroposterior (AP) LAN field but no difference to the 60/2 Gy fraction equivalent between SF-IMRT and WF-VMAT using AP/posterior–anterior LAN boost. Conclusion: WF-VMAT affords equivalent glottic and supraglottic larynx dose and lower dose to the arytenoids and oesophagus. WF-VMAT better covers most LAN target structures. Given these findings as well as concerns with matchline cold spots or hotspots with SF-IMRT, patients requiring comprehensive elective nodal irradiation should typically be treated with WF-VMAT. Advances in Knowledge: SF-IMRT for larynx sparing has better dosimetric results to normal structures than whole-neck IMRT, but with increased matchline recurrence risk. We show dosimetric equivalence or superiority of WF-VMAT compared with SF-IMRT. PMID:27043353

  11. Pelvic Lymph Node Irradiation Including Pararectal Sentinel Nodes for Prostate Cancer Patients: Treatment Optimization Comparing Intensity Modulated X-rays, Volumetric Modulated Arc Therapy, and Intensity Modulated Proton Therapy.

    PubMed

    Vees, Hansjörg; Dipasquale, Giovanna; Nouet, Philippe; Zilli, Thomas; Cozzi, Luca; Miralbell, Raymond

    2015-04-01

    We aimed to assess the dosimetric impact of advanced delivery radiotherapy techniques using either intensity modulated x-ray beams (IMXT), volumetric modulated arc therapy (VMAT), or intensity modulated proton therapy (IMPT), for high-risk prostate cancer patients with sentinel nodes in the pararectal region. Twenty high-risk prostate cancer patients were included in a prospective trial evaluating sentinel nodes on pelvic SPECT acquisition. To be eligible for the dosimetric study, patients had to present with pararectal sentinel nodes usually not included in the clinical target volume encompassing the pelvic lymph nodes. Radiotherapy-plans including the prostate, the seminal vesicles, and the pelvic lymph nodes with the pararectal sentinel nodes were optimized for 6 eligible patients. IMXT and IMPT were delivered with 7 and 3 beams respectively and VMAT with 2 arcs. Results were assessed with Dose-Volume Histograms and predictive normal tissue complication probabilities (NTCPs) models between the three competing treatment modalities aiming to deliver a total dose of 50.4 Gy in 1.8 Gy daily fractions. Target coverage was optimized with IMPT when compared to IMXT and VMAT. Coverage of the sentinel node was slightly better with IMXT (D98% 5 57.3 ± 5.1 Gy) when compared with VMAT (D98% 5 56.2 ± 4.1 Gy). The irradiation of rectal, bladder, small bowel, and femoral heads volumes was significantly reduced with IMPT when compared to IMXT and VMAT. NTCPs rates for rectal and bladder ≥ grade-3 late toxicity were better with IMPT (0.4 ± 0.0% and 0.0 ± 0.0%) compared with IMXT (4.6 ± 3.3% and 1.4 ± 1.1%), and VMAT (4.5 ± 4.0% and 1.6 ± 1.6%), respectively. Acceptable dose-volume distributions and low rectal and urinary NTCPs were estimated to geometrically complex pelvic volumes such as the ones proposed in this study using IMXT, VMAT and IMPT. IMPT succeeded, however, to propose the best physical and biological treatment plans compared to both X-ray derived plans.

  12. A dosimetric comparative study: Volumetric modulated arc therapy vs intensity-modulated radiation therapy in the treatment of nasal cavity carcinomas

    SciTech Connect

    Nguyen, Kham; Cummings, David; Lanza, Vincent C.; Morris, Kathleen; Wang, Congjun; Sutton, Jordan; Garcia, John

    2013-10-01

    The purpose of this study was to evaluate the differences between volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) in the treatment of nasal cavity carcinomas. The treatment of 10 patients, who had completed IMRT treatment for resected tumors of the nasal cavity, was replanned with the Philips Pinnacle{sup 3} Version 9 treatment-planning system. The IMRT plans used a 9-beam technique whereas the VMAT (known as SmartArc) plans used a 3-arc technique. Both types of plans were optimized using Philips Pinnacle{sup 3} Direct Machine Parameter Optimization algorithm. IMRT and VMAT plans' quality was compared by evaluating the maximum, minimum, and mean doses to the target volumes and organs at risk, monitor units (MUs), and the treatment delivery time. Our results indicate that VMAT is capable of greatly reducing treatment delivery time and MUs compared with IMRT. The reduction of treatment delivery time and MUs can decrease the effects of intrafractional uncertainties that can occur because of patient movement during treatment delivery. VMAT's plans further reduce doses to critical structures that are in close proximity to the target volume.

  13. IMAT-SIM: A new method for the clinical dosimetry of intensity-modulated arc therapy (IMAT)

    SciTech Connect

    Iori, Mauro; Cagni, Elisabetta; Nahum, Alan E.; Borasi, Giovanni

    2007-07-15

    Dynamic-gantry multi-leaf collimator (MLC)-based, intensity-modulated radiotherapy (IMAT) has been proposed as an alternative to tomotherapy. In contrast to fixed-gantry, MLC-based intensity-modulated radiotherapy (IMRT), where commercial treatment planning systems (TPS) or dosimetric analysis software currently provide many automatic tools enabling two-dimensional (2D) detectors (matrix or electronic portal imaging devices) to be used as measurement systems, for the planning and delivery of IMAT these tools are generally not available. A new dosimetric method is proposed to overcome some of these limitations. By converting the MLC files of IMAT beams from arc to fixed gantry-angle modality, while keeping the leaf trajectories equal, IMAT plans can be both simulated in the TPS and executed as fixed-gantry, sliding-window DMLC treatments. In support of this idea, measurements of six IMAT plans, in their double form of original arcs and converted fixed-gantry DMLC beams (IMAT-SIM), have been compared among themselves and with their corresponding IMAT-SIM TPS calculations. Radiographic films and a 2D matrix ionization chamber detector rigidly attached to the accelerator gantry and set into a cubic plastic phantom have been used for these measurements. Finally, the TPS calculation-algorithm implementations of both conformal dynamic MLC arc (CD-ARC) modalities, used for clinical IMAT calculations, and DMLC modalities (IMAT-SIM), proposed as references for validating IMAT plan dose-distributions, have been compared. The comparisons between IMAT and IMAT-SIM delivered beams have shown very good agreement with similar shapes of the measured dose profiles which can achieve a mean deviation ({+-}2{sigma}) of (0.35{+-}0.16) mm and (0.37{+-}0.14)%, with maximum deviations of 1.5 mm and 3%. Matching the IMAT measurements with their corresponding IMAT-SIM data calculated by the TPS, these deviations remain in the range of (1.01{+-}0.28) mm and (-1.76{+-}0.42)%, with maximums of

  14. Whole Abdominopelvic Radiotherapy Using Intensity-Modulated Arc Therapy in the Palliative Treatment of Chemotherapy-Resistant Ovarian Cancer With Bulky Peritoneal Disease: A Single-Institution Experience

    SciTech Connect

    De Meerleer, Gert; Vandecasteele, Katrien; Ost, Piet; Delrue, Louke; Denys, Hannelore; Makar, Amin; Speleers, Bruno; Van Belle, Simon; Van den Broecke, Rudy; Fonteyne, Valerie; De Neve, Wilfried

    2011-03-01

    Purpose: To retrospectively review our experience with whole abdominopelvic radiotherapy (WAPRT) using intensity-modulated arc therapy in the palliative treatment of chemotherapy-resistant ovarian cancer with bulky peritoneal disease. Methods and Materials: Between April 2002 and April 2008, 13 patients were treated with WAPRT using intensity-modulated arc therapy. We prescribed a dose of 33 Gy to be delivered in 22 fractions of 1.5 Gy to the abdomen and pelvis. All patients had International Federation of Gynecology and Obstetrics Stage III or IV ovarian cancer at the initial diagnosis. At referral, the median age was 61 years, and the patients had been heavily pretreated with surgery and chemotherapy. All patients had symptoms from their disease, including gastrointestinal obstruction or subobstruction in 6, minor gastrointestinal symptoms in 2, pain in 4, ascites in 1, and vaginal bleeding in 2. A complete symptom or biochemical response required complete resolution of the patient's symptoms or cancer antigen-125 level. A partial response required {>=}50% resolution of these parameters. The actuarial survival was calculated from the start of radiotherapy. Results: The median overall survival was 21 weeks, with a 6-month overall survival rate of 45%. The 9 patients who completed treatment obtained a complete symptom response, except for ascites (partial response). The median and mean response duration (all symptoms grouped) was 24 and 37 weeks, respectively. Of the 6 patients presenting with obstruction or subobstruction, 4 obtained a complete symptom response (median duration, 16 weeks). Conclusion: WAPRT delivered using intensity-modulated arc therapy offers important palliation in the case of peritoneal metastatic ovarian cancer. WAPRT resolved intestinal obstruction for a substantial period.

  15. Dosimetric Evaluation of Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy, and Helical Tomotherapy for Hippocampal-Avoidance Whole Brain Radiotherapy

    PubMed Central

    Rong, Yi; Evans, Josh; Xu-Welliver, Meng; Pickett, Cadron; Jia, Guang; Chen, Quan; Zuo, Li

    2015-01-01

    Background Whole brain radiotherapy (WBRT) is a vital tool in radiation oncology and beyond, but it can result in adverse health effects such as neurocognitive decline. Hippocampal Avoidance WBRT (HA-WBRT) is a strategy that aims to mitigate the neuro-cognitive side effects of whole brain radiotherapy treatment by sparing the hippocampi while delivering the prescribed dose to the rest of the brain. Several competing modalities capable of delivering HA-WBRT, include: Philips Pinnacle step-and-shoot intensity modulated radiotherapy (IMRT), Varian RapidArc volumetric modulated arc therapy (RapidArc), and helical TomoTherapy (TomoTherapy). Methods In this study we compared these methods using 10 patient datasets. Anonymized planning CT (computerized tomography) scans and contour data based on fused MRI images were collected. Three independent planners generated treatment plans for the patients using three modalities, respectively. All treatment plans met the RTOG 0933 criteria for HA-WBRT treatment. Results In dosimetric comparisons between the three modalities, TomoTherapy has a significantly superior homogeneity index of 0.15 ± 0.03 compared to the other two modalities (0.28 ± .04, p < .005 for IMRT and 0.22 ± 0.03, p < .005 for RapidArc). RapidArc has the fastest average delivery time of 2.5 min compared to the other modalities (15 min for IMRT and 18 min for TomoTherapy). Conclusion TomoTherapy is considered to be the preferred modality for HA-WBRT due to its superior dose distribution. When TomoTherapy is not available or treatment time is a concern, RapidArc can provide sufficient dose distribution meeting RTOG criteria and efficient treatment delivery. PMID:25894615

  16. Evaluation of Uncertainty-Based Stopping Criteria for Monte Carlo Calculations of Intensity-Modulated Radiotherapy and Arc Therapy Patient Dose Distributions

    SciTech Connect

    Vanderstraeten, Barbara Olteanu, Ana Maria Luiza; Reynaert, Nick; Leal, Antonio; Neve, Wilfried de; Thierens, Hubert

    2007-10-01

    Purpose: To formulate uncertainty-based stopping criteria for Monte Carlo (MC) calculations of intensity-modulated radiotherapy and intensity-modulated arc therapy patient dose distributions and evaluate their influence on MC simulation times and dose characteristics. Methods and Materials: For each structure of interest, stopping criteria were formulated as follows: {sigma}{sub rel} {<=}{sigma}{sub rel,tol} or D{sigma}{sub rel} {<=}D{sub lim}{sigma}{sub rel,tol} within {>=}95% of the voxels, where {sigma}{sub rel} represents the relative statistical uncertainty on the estimated dose, D. The tolerated uncertainty ({sigma}{sub rel,tol}) was 2%. The dose limit (D{sub lim}) equaled the planning target volume (PTV) prescription dose or a dose value related to the organ at risk (OAR) planning constraints. An intensity-modulated radiotherapy-lung, intensity-modulated radiotherapy-ethmoid sinus, and intensity-modulated arc therapy-rectum patient case were studied. The PTV-stopping criteria-based calculations were compared with the PTV+OAR-stopping criteria-based calculations. Results: The MC dose distributions complied with the PTV-stopping criteria after 14% (lung), 21% (ethmoid), and 12% (rectum) of the simulation times of a 100 million histories reference calculation, and increased to 29%, 44%, and 51%, respectively, by the addition of the OAR-stopping criteria. Dose-volume histograms corresponding to the PTV-stopping criteria, PTV+OAR-stopping criteria, and reference dose calculations were indiscernible. The median local dose differences between the PTV-stopping criteria and the reference calculations amounted to 1.4% (lung), 2.1% (ethmoid), and 2.5% (rectum). Conclusions: For the patient cases studied, the MC calculations using PTV-stopping criteria only allowed accurate treatment plan evaluation. The proposed stopping criteria provided a flexible tool to assist MC patient dose calculations. The structures of interest and appropriate values of {sigma}{sub rel

  17. Stereotactic body radiation therapy planning with duodenal sparing using volumetric-modulated arc therapy vs intensity-modulated radiation therapy in locally advanced pancreatic cancer: A dosimetric analysis

    SciTech Connect

    Kumar, Rachit; Wild, Aaron T.; Ziegler, Mark A.; Hooker, Ted K.; Dah, Samson D.; Tran, Phuoc T.; Kang, Jun; Smith, Koren; Zeng, Jing; Pawlik, Timothy M.; Tryggestad, Erik; Ford, Eric; Herman, Joseph M.

    2013-10-01

    Stereotactic body radiation therapy (SBRT) achieves excellent local control for locally advanced pancreatic cancer (LAPC), but may increase late duodenal toxicity. Volumetric-modulated arc therapy (VMAT) delivers intensity-modulated radiation therapy (IMRT) with a rotating gantry rather than multiple fixed beams. This study dosimetrically evaluates the feasibility of implementing duodenal constraints for SBRT using VMAT vs IMRT. Non–duodenal sparing (NS) and duodenal-sparing (DS) VMAT and IMRT plans delivering 25 Gy in 1 fraction were generated for 15 patients with LAPC. DS plans were constrained to duodenal D{sub max} of<30 Gy at any point. VMAT used 1 360° coplanar arc with 4° spacing between control points, whereas IMRT used 9 coplanar beams with fixed gantry positions at 40° angles. Dosimetric parameters for target volumes and organs at risk were compared for DS planning vs NS planning and VMAT vs IMRT using paired-sample Wilcoxon signed rank tests. Both DS VMAT and DS IMRT achieved significantly reduced duodenal D{sub mean}, D{sub max}, D{sub 1cc}, D{sub 4%}, and V{sub 20} {sub Gy} compared with NS plans (all p≤0.002). DS constraints compromised target coverage for IMRT as demonstrated by reduced V{sub 95%} (p = 0.01) and D{sub mean} (p = 0.02), but not for VMAT. DS constraints resulted in increased dose to right kidney, spinal cord, stomach, and liver for VMAT. Direct comparison of DS VMAT and DS IMRT revealed that VMAT was superior in sparing the left kidney (p<0.001) and the spinal cord (p<0.001), whereas IMRT was superior in sparing the stomach (p = 0.05) and the liver (p = 0.003). DS VMAT required 21% fewer monitor units (p<0.001) and delivered treatment 2.4 minutes faster (p<0.001) than DS IMRT. Implementing DS constraints during SBRT planning for LAPC can significantly reduce duodenal point or volumetric dose parameters for both VMAT and IMRT. The primary consequence of implementing DS constraints for VMAT is increased dose to other organs at

  18. Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation—A comparison with traditional techniques

    SciTech Connect

    Studenski, Matthew T.; Shen, Xinglei; Yu, Yan; Xiao, Ying; Shi, Wenyin; Biswas, Tithi; Werner-Wasik, Maria; Harrison, Amy S.

    2013-04-01

    Craniospinal irradiation (CSI) poses a challenging planning process because of the complex target volume. Traditional 3D conformal CSI does not spare any critical organs, resulting in toxicity in patients. Here the dosimetric advantages of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are compared with classic conformal planning in adults for both cranial and spine fields to develop a clinically feasible technique that is both effective and efficient. Ten adult patients treated with CSI were retrospectively identified. For the cranial fields, 5-field IMRT and dual 356° VMAT arcs were compared with opposed lateral 3D conformal radiotherapy (3D-CRT) fields. For the spine fields, traditional posterior-anterior (PA) PA fields were compared with isocentric 5-field IMRT plans and single 200° VMAT arcs. Two adult patients have been treated using this IMRT technique to date and extensive quality assurance, especially for the junction regions, was performed. For the cranial fields, the IMRT technique had the highest planned target volume (PTV) maximum and was the least efficient, whereas the VMAT technique provided the greatest parotid sparing with better efficiency. 3D-CRT provided the most efficient delivery but with the highest parotid dose. For the spine fields, VMAT provided the best PTV coverage but had the highest mean dose to all organs at risk (OAR). 3D-CRT had the highest PTV and OAR maximum doses but was the most efficient. IMRT provides the greatest OAR sparing but the longest delivery time. For those patients with unresectable disease that can benefit from a higher, definitive dose, 3D-CRT–opposed laterals are the most clinically feasible technique for cranial fields and for spine fields. Although inefficient, the IMRT technique is the most clinically feasible because of the increased mean OAR dose with the VMAT technique. Quality assurance of the beams, especially the junction regions, is essential.

  19. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer

    SciTech Connect

    Martin, Jeffrey M.; Handorf, Elizabeth A.; Price, Robert A.; Cherian, George; Buyyounouski, Mark K.; Chen, David Y.; Kutikov, Alexander; Johnson, Matthew E.; Ma, Chung-Ming Charlie; Horwitz, Eric M.

    2015-10-01

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.

  20. Multi-institutional comparison of volumetric modulated arc therapy vs. intensity-modulated radiation therapy for head-and-neck cancer: a planning study

    PubMed Central

    2013-01-01

    Background Compared to static beam Intensity-Modulated Radiation Therapy (IMRT), the main advantage of Volumetric Modulated Arc Therapy (VMAT) is a shortened delivery time, which leads to improved patient comfort and possibly smaller intra-fraction movements. This study aims at a treatment planner-independent comparison of radiotherapy treatment planning of IMRT and VMAT for head-and-neck cancer performed by several institutes and based on the same CT- and contouring data. Methods Five institutes generated IMRT and VMAT plans for five oropharyngeal cancer patients using either Pinnacle3 or Oncentra Masterplan to be delivered on Elekta linear accelerators. Results Comparison of VMAT and IMRT plans within the same patient and institute showed significantly better sparing for almost all OARs with VMAT. The average mean dose to the parotid glands and oral cavity was reduced from 27.2 Gy and 39.4 Gy for IMRT to 25.0 Gy and 36.7 Gy for VMAT, respectively. The dose conformity at 95% of the prescribed dose for PTVboost and PTVtotal was 1.45 and 1.62 for IMRT and 1.37 and 1.50 for VMAT, respectively. The average effective delivery time was reduced from 13:15 min for IMRT to 5:54 min for VMAT. Conclusions Independently of institution-specific optimization strategies, the quality of the VMAT plans including double arcs was superior to step-and-shoot IMRT plans including 5–9 beam ports, while the effective treatment delivery time was shortened by ~50% with VMAT. PMID:23369221

  1. Plan quality and delivery time comparisons between volumetric modulated arc therapy and intensity modulated radiation therapy for scalp angiosarcoma: A planning study.

    PubMed

    Kai, Yudai; Toya, Ryo; Saito, Tetsuo; Kuraoka, Akiko; Shimohigashi, Yoshinobu; Nakaguchi, Yuji; Maruyama, Masato; Murakami, Ryuji; Yamashita, Yasuyuki; Oya, Natsuo

    2017-07-29

    Due to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery. Herein, we investigated whether volumetric modulated arc therapy (VMAT) is superior to intensity modulated radiation therapy (IMRT) in terms of the plan quality and delivery time. Three different coplanar treatment plans were created for four patients, comprising a two-arc VMAT plan as well as 5-field and 9-field IMRT plans with 6 MV beams. The X-ray Voxel Monte Carlo algorithm was employed for dose calculation. A radiation therapy dose of 60 Gy was prescribed to the planning target volume (PTV) in 30 fractions. The homogeneity indexes (HIs) and conformity indexes (CIs) of the PTV, organs at risk (OARs) doses and delivery times were calculated and compared. For the VMAT, 5-field and 9-field IMRT plans, the mean HIs were 0.14, 0.16 and 0.15; CIs100% were 0.63, 0.61 and 0.64; CIs98% were 0.72, 0.66 and 0.70 and CIs95% were 0.74, 0.67 and 0.71 respectively. All mean dose parameters of the VMAT and 9-field IMRT plans for the brain were equal to or lower than those of the 5-field IMRT plan. For the 5-field IMRT plan, the dose constraints for the left lens were not satisfied in two patients. The mean delivery times were 3.3, 11.1 and 14.7 min for the VMAT, 5-field and 9-field IMRT plans respectively. The VMAT plan quality is comparable to that of 9-field IMRT, with a reduced delivery time. Therefore, VMAT represents a valuable, sophisticated irradiation technique for treating scalp angiosarcoma. © 2017 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.

  2. Dosimetric effects of weight loss or gain during volumetric modulated arc therapy and intensity-modulated radiation therapy for prostate cancer

    SciTech Connect

    Pair, Matthew L.; Du, Weiliang; Rojas, Hector D.; Kanke, James E.; McGuire, Sean E.; Lee, Andrew K.; Kuban, Deborah A.; Kudchadker, Rajat J.

    2013-10-01

    Weight loss or gain during the course of radiation therapy for prostate cancer can alter the planned dose to the target volumes and critical organs. Typically, source-to-surface distance (SSD) measurements are documented by therapists on a weekly basis to ensure that patients' exterior surface and isocenter-to-skin surface distances remain stable. The radiation oncology team then determines whether the patient has undergone a physical change sufficient to require a new treatment plan. The effect of weight change (SSD increase or decrease) on intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) dosimetry is not well known, and it is unclear when rescanning or replanning is needed. The purpose of this study was to determine the effects of weight change (SSD increase or decrease) on IMRT or VMAT dose delivery in patients with prostate cancer and to determine the SSD change threshold for replanning. Whether IMRT or VMAT provides better dose stability under weight change conditions was also determined. We generated clinical IMRT and VMAT prostate and seminal vesicle treatment plans for varying SSDs for 10 randomly selected patients with prostate cancer. The differences due to SSD change were quantified by a specific dose change for a specified volume of interest. The target mean dose, decreased or increased by 2.9% per 1-cm SSD decrease or increase in IMRT and by 3.6% in VMAT. If the SSD deviation is more than 1 cm, the radiation oncology team should determine whether to continue treatment without modifications, to adjust monitor units, or to resimulate and replan.

  3. Analysis of dose distribution in organs at risk in patients with prostate cancer treated with the intensity-modulated radiation therapy and arc technique.

    PubMed

    Biegała, Michał; Hydzik, Adam

    2016-01-01

    This study describes a comparative analysis of treatment plans in 48 patients with prostate cancer treated with ionizing radiation. Each patient was subjected to the intensity-modulated radiation therapy (IMRT) and arc technique. In each treatment plan, the organs at risk were assessed: the urinary bladder, rectum and heads of the femur, as well as the volume of normal tissue. The following features were compared: treatment time, conformity indices for the planning target volume, mean doses and standard deviation in organs at risk, and organ volumes for each particular dose. The treatment period in the arc technique is 13.7% shorter than in the IMRT technique. Comparing the results of the IMRT and arc techniques (arc vs. IMRT), the mean values were 29.21 ± 12.91 Gy versus 28.36 ± 13.79 Gy for the bladder, 20.36 ± 3.16 Gy versus 18.17 ± 5.11 Gy for the right femoral head, and 18.98 ± 3.28 Gy versus 16.67 ± 5.15 Gy for the left femoral head. For the rectum, lower values were obtained after application of the arc technique, not the IMRT technique: 35.84 ± 12.28 Gy versus 35.90 ± 13.05 Gy. The results indicate that the applied therapy has a statistically significant influence on the volume for a particular dose with regard to the urinary bladder. It is advisable to apply the IMRT technique to patients who need the femur heads and urinary bladder protected by exposing them to low irradiation doses.

  4. Dosimetric comparison between step-shoot intensity-modulated radiotherapy and volumetric-modulated arc therapy for upper thoracic and cervical esophageal carcinoma

    SciTech Connect

    Gao, Min; Li, Qilin; Ning, Zhonghua; Gu, Wendong; Huang, Jin; Mu, Jinming; Pei, Honglei

    2016-07-01

    To compare and analyze the dosimetric characteristics of volumetric modulated arc therapy (VMAT) vs step-shoot intensity-modulated radiation therapy (sIMRT) for upper thoracic and cervical esophageal carcinoma. Single-arc VMAT (VMAT1), dual-arc VMAT (VMAT2), and 7-field sIMRT plans were designed for 30 patients with upper thoracic or cervical esophageal carcinoma. Planning target volume (PTV) was prescribed to 50.4 Gy in 28 fractions, and PTV1 was prescribed to 60 Gy in 28 fractions. The parameters evaluated included dose homogeneity and conformality, dose to organs at risk (OARs), and delivery efficiency. (1) In comparison to sIMRT, VMAT provided a systematic improvement in PTV1 coverage. The homogeneity index of VMAT1 was better than that of VMAT2. There were no significant differences among sIMRT, VMAT1, and VMAT2 in PTV coverage. (2) VMAT1 and VMAT2 reduced the maximum dose of spinal cord as compared with sIMRT (p < 0.05). The rest dose-volume characteristics of OARs were similar. (3) Monitor units of VMAT2 and VMAT1 were more than sIMRT. However, the treatment time of VMAT1, VMAT2, and sIMRT was (2.0 ± 0.2), (2.8 ± 0.3), and (9.8 ± 0.8) minutes, respectively. VMAT1 was the fastest, and the difference was statistically significant. In the treatment of upper thoracic and cervical esophageal carcinoma by the AXESSE linac, compared with 7-field sIMRT, VMAT showed better PTV1 coverage and superior spinal cord sparing. Single-arc VMAT had similar target volume coverage and the sparing of OAR to dual-arc VMAT, with shortest treatment time and highest treatment efficiency in the 3 kinds of plans.

  5. A comparison of treatment plan quality between Tri-Co-60 intensity modulated radiation therapy and volumetric modulated arc therapy for cervical cancer.

    PubMed

    Park, Jong Min; Park, So-Yeon; Kim, Jung-In; Kang, Hyun-Cheol; Choi, Chang Heon

    2017-08-01

    To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for cervical cancer. A total of 20 patients who received postoperative radiotherapy for cervical cancer were selected. For each patient, a tri-Co-60 IMRT plan for which the target volume was the planning target volume (PTV) generated by adding 1mm isotropic margins from the clinical target volume (CTV) and a VMAT plan for which the target volume was the PTV generated by adding 7mm and 10mm margins from the CTV were generated. The tri-Co-60 IMRT plans were generated with the ViewRay™ system while the VMAT plans were generated with 15-MV photon beams from a linear accelerator (prescription dose=50.4Gy in 28 fractions). The average volumes of the PTVs and CTVs were 704.9cc±87.8cc and 271.6cc±51.6cc, respectively. No noticeable differences in the dose-volumetric parameters for the target volumes were observed between the tri-Co-60 IMRT and VMAT plans. The values of V40Gy for the small bowel and rectal wall, V45Gy of the bladder, and V35Gy of the femoral heads for the VMAT plans were 14.6%±7.8%, 54.4%±4.2%, 30.0%±4.7%, and 8.9%±3.3%, respectively. Those of the tri-Co-60 IMRT plans were 2.8%±2.1%, 23.0%±8.9%, 17.1%±6.1%, and 0.3%±0.4%, respectively. Owing to the target margin reduction capability, the tri-Co-60 IMRT plans were more favorable than the VMAT plans for cervical cancer. Copyright © 2017. Published by Elsevier Ltd.

  6. Which T Category of Nasopharyngeal Carcinoma May Benefit Most from Volumetric Modulated Arc Therapy Compared with Step and Shoot Intensity Modulated Radiation Therapy

    PubMed Central

    Yin, Wen-Jing; Tang, Ling-Long; Yu, Xiao-Li; Chen, Mo; Qi, Zhen-Yu; Liu, Meng-Zhong; Ma, Jun

    2013-01-01

    Background To compare volumetric modulated arc therapy (VMAT) with conventional step and shoot intensity modulated radiation therapy (s-IMRT) in nasopharyngeal carcinoma (NPC) patients, and identify which T category patient gains the maximum benefit from VMAT. Methods Fifty-two patients that randomly selected from 205 patients received VMAT at a single center were retrospectively replanned with s-IMRT. For a fair comparison, the planning target volume (PTV) coverage of the 2 plans was normalized to the same level. A standard planning constraint set was used; the constraints for the organs at risk (OARs) were individually adapted. The calculated doses to the PTV and OARs were compared for s-IMRT and VMAT plans generated using the Monaco treatment planning system. Results VMAT and s-IMRT plans had similar PTV coverage and OAR sparing within all T categories. However, in stratified analysis, VMAT plans lead to better or similar sparing of the OARs in early T category patients; and lead to poorer sparing of the OARs in advanced T category patients (P<0.05). VMAT shows significant advantages for low dose burden (P<0.05) compared with s-IMRT. The delivery time per fraction for VMAT (424±64 s) was shorter than s-IMRT (778 ± 126 s, p<0.01). Conclusions VMAT provides similar dose coverage of the PTVs and similar/better normal tissue sparing in early T category NPC, and poorer OARs sparing in advanced T category NPC. And VMAT shows significant advantages for low dose burden and delivery time. PMID:24086503

  7. Dosimetric Impact of Using the Acuros XB Algorithm for Intensity Modulated Radiation Therapy and RapidArc Planning in Nasopharyngeal Carcinomas

    SciTech Connect

    Kan, Monica W.K.; Leung, Lucullus H.T.; Yu, Peter K.N.

    2013-01-01

    Purpose: To assess the dosimetric implications for the intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy with RapidArc (RA) of nasopharyngeal carcinomas (NPC) due to the use of the Acuros XB (AXB) algorithm versus the anisotropic analytical algorithm (AAA). Methods and Materials: Nine-field sliding window IMRT and triple-arc RA plans produced for 12 patients with NPC using AAA were recalculated using AXB. The dose distributions to multiple planning target volumes (PTVs) with different prescribed doses and critical organs were compared. The PTVs were separated into components in bone, air, and tissue. The change of doses by AXB due to air and bone, and the variation of the amount of dose changes with number of fields was also studied using simple geometric phantoms. Results: Using AXB instead of AAA, the averaged mean dose to PTV{sub 70} (70 Gy was prescribed to PTV{sub 70}) was found to be 0.9% and 1.2% lower for IMRT and RA, respectively. It was approximately 1% lower in tissue, 2% lower in bone, and 1% higher in air. The averaged minimum dose to PTV{sub 70} in bone was approximately 4% lower for both IMRT and RA, whereas it was approximately 1.5% lower for PTV{sub 70} in tissue. The decrease in target doses estimated by AXB was mostly contributed from the presence of bone, less from tissue, and none from air. A similar trend was observed for PTV{sub 60} (60 Gy was prescribed to PTV{sub 60}). The doses to most serial organs were found to be 1% to 3% lower and to other organs 4% to 10% lower for both techniques. Conclusions: The use of the AXB algorithm is highly recommended for IMRT and RapidArc planning for NPC cases.

  8. Quality of treatment plans and accuracy of in vivo portal dosimetry in hybrid intensity-modulated radiation therapy and volumetric modulated arc therapy for prostate cancer.

    PubMed

    Bedford, James L; Smyth, Gregory; Hanson, Ian M; Tree, Alison C; Dearnaley, David P; Hansen, Vibeke N

    2016-08-01

    Delivering selected parts of volumetric modulated arc therapy (VMAT) plans using step-and-shoot intensity modulated radiotherapy (IMRT) beams has the potential to increase plan quality by allowing specific aperture positioning. This study investigates the quality of treatment plans and the accuracy of in vivo portal dosimetry in such a hybrid approach for the case of prostate radiotherapy. Conformal and limited-modulation VMAT plans were produced, together with five hybrid IMRT/VMAT plans, in which 0%, 25%, 50%, 75% or 100% of the segments were sequenced for IMRT, while the remainder were sequenced for VMAT. Integrated portal images were predicted for the plans. The plans were then delivered as a single hybrid beam using an Elekta Synergy accelerator with Agility head to a water-equivalent phantom and treatment time, isocentric dose and portal images were measured. Increasing the IMRT percentage improves dose uniformity to the planning target volume (p<0.01 for 50% IMRT or more), substantially reduces the volume of rectum irradiated to 65Gy (p=0.02 for 25% IMRT) and increases the monitor units (p<0.001). Delivery time also increases substantially. All plans show accurate delivery of dose and reliable prediction of portal images. Hybrid IMRT/VMAT can be efficiently planned and delivered as a single beam sequence. Beyond 25% IMRT, the delivery time becomes unacceptably long, with increased risk of intrafraction motion, but 25% IMRT is an attractive compromise. Integrated portal images can be used to perform in vivo dosimetry for this technique. Copyright © 2016 The Royal Marsden NHS Foundation Trust. Published by Elsevier Ireland Ltd.. All rights reserved.

  9. SU-E-T-166: Evaluation of Integral Dose in Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy for Head and Neck Cancer Patient

    SciTech Connect

    Al-Basheer, A; Hunag, J; Kaminski, J; Dasher, B; Howington, J; Stewart, J; Martin, D; Kong, F; Jin, J

    2014-06-01

    Purpose: Volumetric Modulated Arc Therapy (VMAT) usually achieves higher conformity of radiation doses to targets and less delivery time than Intensity Modulated Radiation Therapy (IMRT). We hypothesized that VMAT will increase integral dose (ID) to patients which will decrease the count of white blood count (WBC) lymphocytes, and consequently has a subsequent impact on the immune system. The purpose of this study is to evaluate the ID to patients undergoing IMRT and VMAT for Head and Neck cancers and its impact on the immune system. Methods: As a pilot study, 30 head and neck patients who received 9-fields IMRT or 3-arcs Radip-Arcbased VMAT were included in this study. Ten of these patients who received the VMAT plans were re-planned using IMRT with the same objectives. ID was calculated for all cases. All patients also had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. Results: For the 10 re-planned patients, the mean ID was 13.3 Gy/voxel (range 10.2–17.5 Gy/voxel) for the 9-fields IMRT plans, and was 15.9 Gy/voxel (range 12.4-20.9 Gy/voxel) for the 3-Arc VMAT plan (p=0.01). The integral dose was significant correlated with reducing WBC count during RT even when controlling for concurrent chemotherapy (R square =0.56, p=0.008). Conclusion: Although VMAT can deliver higher radiation dose conformality to targets, this benefit is achieved generally at the cost of greater integral doses to normal tissue outside the planning target volume (PTV). Lower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. This study is ongoing in our Institution to exam the impact of integral doses and WBC on overall survival.

  10. Automated Volumetric Modulated Arc Therapy Treatment Planning for Stage III Lung Cancer: How Does It Compare With Intensity-Modulated Radio Therapy?

    SciTech Connect

    Quan, Enzhuo M.; Chang, Joe Y.; Liao Zhongxing; Xia Tingyi; Yuan Zhiyong; Liu Hui; Li, Xiaoqiang; Wages, Cody A.; Mohan, Radhe; Zhang Xiaodong

    2012-09-01

    Purpose: To compare the quality of volumetric modulated arc therapy (VMAT) or intensity-modulated radiation therapy (IMRT) plans generated by an automated inverse planning system with that of dosimetrist-generated IMRT treatment plans for patients with stage III lung cancer. Methods and Materials: Two groups of 8 patients with stage III lung cancer were randomly selected. For group 1, the dosimetrists spent their best effort in designing IMRT plans to compete with the automated inverse planning system (mdaccAutoPlan); for group 2, the dosimetrists were not in competition and spent their regular effort. Five experienced radiation oncologists independently blind-reviewed and ranked the three plans for each patient: a rank of 1 was the best and 3 was the worst. Dosimetric measures were also performed to quantitatively evaluate the three types of plans. Results: Blind rankings from different oncologists were generally consistent. For group 1, the auto-VMAT, auto-IMRT, and manual IMRT plans received average ranks of 1.6, 2.13, and 2.18, respectively. The auto-VMAT plans in group 1 had 10% higher planning tumor volume (PTV) conformality and 24% lower esophagus V70 (the volume receiving 70 Gy or more) than the manual IMRT plans; they also resulted in more than 20% higher complication-free tumor control probability (P+) than either type of IMRT plans. The auto- and manual IMRT plans in this group yielded generally comparable dosimetric measures. For group 2, the auto-VMAT, auto-IMRT, and manual IMRT plans received average ranks of 1.55, 1.75, and 2.75, respectively. Compared to the manual IMRT plans in this group, the auto-VMAT plans and auto-IMRT plans showed, respectively, 17% and 14% higher PTV dose conformality, 8% and 17% lower mean lung dose, 17% and 26% lower mean heart dose, and 36% and 23% higher P+. Conclusions: mdaccAutoPlan is capable of generating high-quality VMAT and IMRT treatment plans for stage III lung cancer. Manual IMRT plans could achieve quality

  11. SU-E-T-618: Plan Robustness Study of Volumetric-Modulated Arc Therapy Vs. Intensity-Modulated Radiation Therapy for Head and Neck Cancer

    SciTech Connect

    Liu, W; Patel, S; Shen, J; Harrington, D; Stoker, J; Ding, X; Hu, Y; Wong, W; Halyard, M; Schild, S; Ezzell, G; Bues, M

    2015-06-15

    Purpose: Lack of plan robustness may contribute to local failure in volumetric-modulated arc therapy (VMAT) to treat head and neck (H&N) cancer. Thus we compared plan robustness of VMAT with intensity-modulated radiation therapy (IMRT). Methods: VMAT and IMRT plans were created for 9 H&N cancer patients. For each plan, six new perturbed dose distributions were computed — one each for ± 3mm setup deviations along the S-I, A-P and L-R directions. We used three robustness quantification tools: (1) worst-case analysis (WCA); (2) dose-volume histograms (DVHs) band (DVHB); and (3) root-mean-square-dose deviation (RMSD) volume histogram (DDVH). DDVH represents the relative volume (y) on the vertical axis and the RMSD (x) on the horizontal axis. Similar to DVH, this means that y% of the volume of the indicated structure has the RMSD at least x Gy[RBE].The width from the first two methods at different target DVH indices (such as D95 and D5) and the area under the DDVH curves (AUC) for the target were used to indicate plan robustness. In these robustness quantification tools, the smaller the value, the more robust the plan is. Plan robustness evaluation metrics were compared using Wilcoxon test. Results: DVHB showed the width at D95 from IMRT to be larger than from VMAT (unit Gy) [1.59 vs 1.18 (p=0.49)], while the width at D5 from IMRT was found to be slightly larger than from VMAT [0.59 vs 0.54 (p=0.84)]. WCA showed similar results [D95: 3.28 vs 3.00 (p=0.56); D5: 1.68 vs 1.95 (p=0.23)]. DDVH showed the AUC from IMRT to be slightly smaller than from VMAT [1.13 vs 1.15 (p=0.43)]. Conclusion: VMAT plan robustness is comparable to IMRT plan robustness. The plan robustness conclusions from WCA and DVHB are DVH parameter dependent. On the other hand DDVH captures the overall effect of uncertainties on the dose to a volume of interest. NIH/NCI K25CA168984; Eagles Cancer Research Career Development; The Lawrence W. and Marilyn W. Matteson Fund for Cancer Research Mayo ASU Seed

  12. A practical method of modeling a treatment couch using cone-beam computed tomography for intensity-modulated radiation therapy and RapidArc treatment delivery

    SciTech Connect

    Aldosary, Ghada; Nobah, Ahmad; Al-Zorkani, Faisal; Devic, Slobodan; Moftah, Belal

    2015-01-01

    The effect of a treatment couch on dose perturbation is not always fully considered in intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). In the course of inverse planning radiotherapy techniques, beam parameter optimization may change in the absence of the couch, causing errors in the calculated dose distributions. Although modern treatment planning systems (TPS) include data for the treatment couch components, they are not manufactured identically. Thus, variations in their Hounsfield unit (HU) values may exist. Moreover, a radiotherapy facility may wish to have a third-party custom tabletop installed that is not included by the TPS vendor. This study demonstrates a practical and simple method of acquiring reliable computed tomography (CT) data for the treatment couch and shows how the absorbed dose calculated with the modeled treatment couch can differ from that with the default treatment couch found in the TPS. We also experimentally verified that neglecting to incorporate the treatment couch completely in the treatment planning process might result in dose differences of up to 9.5% and 7.3% for 4-MV and 10-MV photon beams, respectively. Furthermore, 20 RapidArc and IMRT cases were used to quantify the change in calculated dose distributions caused by using either the default or modeled couch. From 2-dimensional (2D) ionization chamber array measurements, we observed large dose distribution differences between the measurements and calculations when the couch was omitted that varied according to the planning technique and anatomic site. Thus, incorporating the treatment couch in the dose calculation phase of treatment planning significantly decreases dose calculation errors.

  13. Neutron Measurements for Intensity Modulated Radiation Therapy

    SciTech Connect

    Ipe, Nisy E.

    2000-04-21

    The beam-on time for intensity modulated radiation therapy (IMRT) is increased significantly compared with conventional radiotherapy treatments. Further, the presence of beam modulation devices may potentially affect neutron production. Therefore, neutron measurements were performed for 15 MV photon beams on a Varian Clinac accelerator to determine the impact of IMRT on neutron dose equivalent to the patient.

  14. Intensity modulated arc therapy implementation in a three phase adaptive (18)F-FDG-PET voxel intensity-based planning strategy for head-and-neck cancer.

    PubMed

    Berwouts, Dieter; Olteanu, Luiza Ana Maria; Speleers, Bruno; Duprez, Frédéric; Madani, Indira; Vercauteren, Tom; De Neve, Wilfried; De Gersem, Werner

    2016-04-02

    This study investigates the implementation of a new intensity modulated arc therapy (IMAT) class solution in comparison to a 6-static beam step-and-shoot intensity modulated radiotherapy (s-IMRT) for three-phase adaptive (18)F-FDG-PET-voxel-based dose-painting-by-numbers (DPBN) for head-and-neck cancer. We developed (18)F-FDG-PET-voxel intensity-based IMAT employing multiple arcs and compared it to clinically used s-IMRT DPBN. Three IMAT plans using (18)F-FDG-PET/CT acquired before treatment (phase I), after 8 fractions (phase II) and CT acquired after 18 fractions (phase III) were generated for each of 10 patients treated with 3 s-IMRT plans based on the same image sets. Based on deformable image registration (ABAS, version 0.41, Elekta CMS Software, Maryland Heights, MO), doses of the 3 plans were summed on the pretreatment CT using validated in-house developed software. Dosimetric indices in targets and organs-at-risk (OARs), biologic conformity of treatment plans set at ≤5 %, treatment quality and efficiency were compared between IMAT and s-IMRT for the whole group and for individual patients. Doses to most organs-at-risk (OARs) were significantly better in IMAT plans, while target levels were similar for both types of plans. On average, IMAT ipsilateral and contralateral parotid mean doses were 14.0 % (p = 0.001) and 12.7 % (p < 0.001) lower, respectively. Pharyngeal constrictors D50% levels were similar or reduced with up to 54.9 % for IMAT compared to s-IMRT for individual patient cases. IMAT significantly improved biologic conformity by 2.1 % for treatment phases I and II. 3D phantom measurements reported an agreement of ≥95 % for 3 % and 3 mm criteria for both treatment modalities. IMAT delivery time was significantly shortened on average by 41.1 %. IMAT implementation significantly improved the biologic conformity as compared to s-IMRT in adaptive dose-escalated DPBN treatments. The better OAR sparing and faster delivery highly improved the treatment

  15. Dosimetric and efficiency comparison of high-dose radiotherapy for esophageal cancer: volumetric modulated arc therapy versus fixed-field intensity-modulated radiotherapy.

    PubMed

    Lin, C-Y; Huang, W-Y; Jen, Y-M; Chen, C-M; Su, Y-F; Chao, H-L; Lin, C-S

    2014-08-01

    The aim of this study was to compare high-dose volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (ff-IMRT) plans for the treatment of patients with middle-thoracic esophageal cancer. Eight patients with cT2-3N0M0 middle-thoracic esophageal cancer were enrolled. The treatment planning system was the version 9 of the Pinnacle(3) with SmartArc (Philips Healthcare, Fitchburg, WI, USA). VMAT and ff-IMRT treatment plans were generated for each case, and both techniques were used to deliver 50 Gy to the planning target volume (PTV(50)) and then provided a 16-Gy boost (PTV(66)). The VMAT plans provided superior PTV(66) coverage compared with the ff-IMRT plans (P = 0.034), whereas the ff-IMRT plans provided more appropriate dose homogeneity to the PTV(50) (P = 0.017). In the lung, the V(5) and V(10) were lower for the ff-IMRT plans than for the VMAT plans, whereas the V(20) was lower for the VMAT plans. The delivery time was significantly shorter for the VMAT plans than for the ff-IMRT plans (P = 0.012). In addition, the VMAT plans delivered fewer monitor units. The VMAT technique required a shorter planning time than the ff-IMRT technique (3.8 ± 0.8 hours vs. 5.4 ± 0.6 hours, P = 0.011). The major advantages of VMAT plans are higher efficiency and an approximately 50% reduction in delivery time compared with the ff-IMRT plans, with comparable plan quality. Further clinical investigations to evaluate the use of high-dose VMAT for the treatment of esophageal cancer are warranted. © 2013 Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

  16. Which technique for radiation is most beneficial for patients with locally advanced cervical cancer? Intensity modulated proton therapy versus intensity modulated photon treatment, helical tomotherapy and volumetric arc therapy for primary radiation - an intraindividual comparison.

    PubMed

    Marnitz, Simone; Wlodarczyk, Waldemar; Neumann, Oliver; Koehler, Christhardt; Weihrauch, Mirko; Budach, Volker; Cozzi, Luca

    2015-04-17

    To compare highly sophisticated intensity-modulated radiotherapy (IMRT) delivered by either helical tomotherapy (HT), RapidArc (RA), IMRT with protons (IMPT) in patients with locally advanced cervical cancer. Twenty cervical cancer patients were irradiated using either conventional IMRT, VMAT or HT; ten received pelvic (PEL) and ten extended field irradiation (EFRT). The dose to the planning-target volume A (PTV_A: cervix, uterus, pelvic ± para-aortic lymph nodes) was 1.8/50.4 Gy. The SIB dose for the parametrium (PTV_B), was 2.12/59.36 Gy. MRI-guided brachytherapy was administered with 5 fractions up to 25 Gy. For EBRT, the lower target constraints were 95% of the prescribed dose in 95% of the target volume. The irradiated small bowel (SB) volumes were kept as low as possible. For every patient, target parameters as well as doses to the organs at risk (SB, bladder, rectum) were evaluated intra-individually for IMRT, HT, VMAT and IMPT. All techniques provided excellent target volume coverage, homogeneity, conformity. With IMPT, there was a significant reduction of the mean dose (Dmean) of the SB from 30.2 ± 4.0 Gy (IMRT); 27.6 ± 5.6 Gy (HT); 34.1 ± 7.0 (RA) to 18.6 ± 5.9 Gy (IMPT) for pelvic radiation and 26.3 ± 3.2 Gy (IMRT); 24.0 ± 4.1 (HT); 25.3 ± 3.7 (RA) to 13.8 ± 2.8 Gy (IMPT) for patients with EFRT, which corresponds to a reduction of 38-52% for the Dmean (SB). Futhermore, the low dose bath (V10Gy) to the small bowel was reduced by 50% with IMPT in comparison to all photon techniques. Furthermore, Dmean to the bladder and rectum was decresed by 7-9 Gy with IMPT in patents with pelvic radiation and EFRT. All modern techniques (were proved to be dosimetrically adequate regarding coverage, conformity and homogeneity of the target. Protons offered the best sparing of small bowel and rectum and therefore could contribute to a significant reduction of acute and late toxicity in cervical cancer treatment.

  17. Implementation of Constant Dose Rate and Constant Angular Spacing Intensity-modulated Arc Therapy for Cervical Cancer by Using a Conventional Linear Accelerator

    PubMed Central

    Zhang, Ruo-Hui; Fan, Xiao-Mei; Bai, Wen-Wen; Cao, Yan-Kun

    2016-01-01

    Background: Volumetric-modulated arc therapy (VMAT) can only be implemented on the new generation linacs such as the Varian Trilogy® and Elekta Synergy®. This prevents most existing linacs from delivering VMAT. The purpose of this study was to investigate the feasibility of using a conventional linear accelerator delivering constant dose rate and constant angular spacing intensity-modulated arc therapy (CDR-CAS-IMAT) for treating cervical cancer. Methods: Twenty patients with cervical cancer previously treated with intensity-modulated radiation therapy (IMRT) using Varian Clinical 23EX were retreated using CDR-CAS-IMAT. The planning target volume (PTV) was set as 50.4 Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), target volume conformity index (CI), the dose to organs at risk, radiation delivery time, and monitor units (MUs) were also compared. The paired t-test was used to analyze the two data sets. All statistical analyses were performed using SPSS 19.0 software. Results: Compared to the IMRT group, the CDR-CAS-IMAT group showed better PTV CI (0.85 ± 0.03 vs. 0.81 ± 0.03, P = 0.001), clinical target volume CI (0.46 ± 0.05 vs. 0.43 ± 0.05, P = 0.001), HI (0.09±0.02 vs. 0.11 ± 0.02, P = 0.005) and D95 (5196.33 ± 28.24 cGy vs. 5162.63 ± 31.12 cGy, P = 0.000), and cord D2 (3743.8 ± 118.7 cGy vs. 3806.2 ± 98.7 cGy, P = 0.017) and rectum V40 (41.9 ± 6.1% vs. 44.2 ± 4.8%, P = 0.026). Treatment time (422.7 ± 46.7 s vs. 84.6 ± 7.8 s, P = 0.000) and the total plan Mus (927.4 ± 79.1 vs. 787.5 ± 78.5, P = 0.000) decreased by a factor of 0.8 and 0.15, respectively. The IMRT group plans were superior to the CDR-CAS-IMAT group plans considering decreasing bladder V50 (17.4 ± 4.5% vs. 16.6 ± 4.2%, P = 0.049), bowel V30 (39.6 ± 6.5% vs. 36.6 ± 7.5%, P = 0.008), and low-dose irradiation volume; there were no significant differences in other statistical indexes. Conclusions

  18. Treatment Plan Technique and Quality for Single-Isocenter Stereotactic Ablative Radiotherapy of Multiple Lung Lesions with Volumetric-Modulated Arc Therapy or Intensity-Modulated Radiosurgery.

    PubMed

    Quan, Kimmen; Xu, Karen M; Lalonde, Ron; Horne, Zachary D; Bernard, Mark E; McCoy, Chuck; Clump, David A; Burton, Steven A; Heron, Dwight E

    2015-01-01

    The aim of this study is to provide a practical approach to the planning technique and evaluation of plan quality for the multi-lesion, single-isocenter stereotactic ablative radiotherapy (SABR) of the lung. Eleven patients with two or more lung lesions underwent single-isocenter volumetric-modulated arc therapy (VMAT) radiosurgery or IMRS. All plans were normalized to the target maximum dose. For each plan, all targets were treated to the same dose. Plan conformity and dose gradient were maximized with dose-control tuning structures surrounding targets. For comparison, multi-isocenter plans were retrospectively created for four patients. Conformity index (CI), homogeneity index (HI), gradient index (GI), and gradient distance (GD) were calculated for each plan. V5, V10, and V20 of the lung and organs at risk (OARs) were collected. Treatment time and total monitor units (MUs) were also recorded. One patient had four lesions and the remainder had two lesions. Six patients received VMAT and five patients received intensity-modulated radiosurgery (IMRS). For those treated with VMAT, two patients received 3-arc VMAT and four received 2-arc VMAT. For those treated with IMRS, two patients were treated with 10 and 11 beams, respectively, and the rest received 12 beams. Prescription doses ranged from 30 to 54 Gy in three to five fractions. The median prescribed isodose line was 84% (range: 80-86%). The median maximum dose was 57.1 Gy (range: 35.7-65.1 Gy). The mean combined PTV was 49.57 cm(3) (range: 14.90-87.38 cm(3)). For single-isocenter plans, the median CI was 1.15 (range: 0.97-1.53). The median HI was 1.19 (range: 1.16-1.28). The median GI was 4.60 (range: 4.16-7.37). The median maximum radiation dose (Dmax) to total lung was 55.6 Gy (range: 35.7-62.0 Gy). The median mean radiation dose to the lung (Dmean) was 4.2 Gy (range: 1.1-9.3 Gy). The median lung V5 was 18.7% (range: 3.8-41.3%). There was no significant difference in CI, HI, GI, GD, V5, V10

  19. Simultaneous integrated boost radiotherapy for bilateral breast: a treatment planning and dosimetric comparison for volumetric modulated arc and fixed field intensity modulated therapy

    PubMed Central

    Nicolini, Giorgia; Clivio, Alessandro; Fogliata, Antonella; Vanetti, Eugenio; Cozzi, Luca

    2009-01-01

    Purpose A study was performed comparing dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) on patients with bilateral breast carcinoma. Materials and methods Plans for IMRT and RA, were optimised for 10 patients prescribing 50 Gy to the breast (PTVII, 2.0 Gy/fraction) and 60 Gy to the tumour bed (PTVI, 2.4 Gy/fraction). Objectives were: for PTVs V90%>95%, Dmax<107%; Mean lung dose MLD<15 Gy, V20 Gy<22%; heart involvement was to be minimised. The MU and delivery time measured treatment efficiency. Pre-treatment dosimetry was performed using EPID and a 2D-array based methods. Results For PTVII minus PTVI, V90% was 97.8 ± 3.4% for RA and 94.0 ± 3.5% for IMRT (findings are reported as mean ± 1 standard deviation); D5%-D95% (homogeneity) was 7.3 ± 1.4 Gy (RA) and 11.0 ± 1.1 Gy (IMRT). Conformity index (V95%/VPTVII) was 1.10 ± 0.06 (RA) and 1.14 ± 0.09 (IMRT). MLD was <9.5 Gy for all cases on each lung, V20 Gy was 9.7 ± 1.3% (RA) and 12.8 ± 2.5% (IMRT) on left lung, similar for right lung. Mean dose to heart was 6.0 ± 2.7 Gy (RA) and 7.4 ± 2.5 Gy (IMRT). MU resulted in 796 ± 121 (RA) and 1398 ± 301 (IMRT); the average measured treatment time was 3.0 ± 0.1 minutes (RA) and 11.5 ± 2.0 (IMRT). From pre-treatment dosimetry, % of field area with γ <1 resulted 98.8 ± 1.3% and 99.1 ± 1.5% for RA and IMRT respectively with EPID and 99.1 ± 1.8% and 99.5 ± 1.3% with 2D-array (ΔD = 3% and DTA = 3 mm). Conclusion RapidArc showed dosimetric improvements with respect to IMRT, delivery parameters confirmed its logistical advantages, pre-treatment dosimetry proved its reliability. PMID:19630947

  20. Dosimetric and radiobiological characterizations of prostate intensity-modulated radiotherapy and volumetric-modulated arc therapy: A single-institution review of ninety cases

    PubMed Central

    Khan, Muhammad Isa; Jiang, Runqing; Kiciak, Alexander; ur Rehman, Jalil; Afzal, Muhammad; Chow, James C. L.

    2016-01-01

    This study reviewed prostate volumetric-modulated arc therapy (VMAT) plans with intensity-modulated radiotherapy (IMRT) plans after prostate IMRT technique was replaced by VMAT in an institution. Characterizations of dosimetry and radiobiological variation in prostate were determined based on treatment plans of 40 prostate IMRT patients (planning target volume = 77.8–335 cm3) and 50 VMAT patients (planning target volume = 120–351 cm3) treated before and after 2013, respectively. Both IMRT and VMAT plans used the same dose-volume criteria in the inverse planning optimization. Dose-volume histogram, mean doses of target and normal tissues (rectum, bladder and femoral heads), dose-volume points (D99% of planning target volume; D30%, D50%, V30 Gy and V35 Gy of rectum and bladder; D5%, V14 Gy, V22 Gy of femoral heads), conformity index (CI), homogeneity index (HI), gradient index (GI), prostate tumor control probability (TCP), and rectal normal tissue complication probability (NTCP) based on the Lyman-Burman-Kutcher algorithm were calculated for each IMRT and VMAT plan. From our results, VMAT plan was found better due to its higher (1.05%) CI, lower (0.83%) HI and (0.75%) GI than IMRT. Comparing doses in normal tissues between IMRT and VMAT, it was found that IMRT mostly delivered higher doses of about 1.05% to the normal tissues than VMAT. Prostate TCP and rectal NTCP were found increased (1%) for VMAT than IMRT. It is seen that VMAT technique can decrease the dose-volume evaluation criteria for the normal tissues. Based on our dosimetric and radiobiological results in treatment plans, it is concluded that our VMAT implementation could produce comparable or slightly better target coverage and normal tissue sparing with a faster treatment time in prostate radiotherapy. PMID:27651562

  1. Treatment of left sided breast cancer for a patient with funnel chest: volumetric-modulated arc therapy vs. 3D-CRT and intensity-modulated radiotherapy.

    PubMed

    Haertl, Petra M; Pohl, Fabian; Weidner, Karin; Groeger, Christian; Koelbl, Oliver; Dobler, Barbara

    2013-01-01

    This case study presents a rare case of left-sided breast cancer in a patient with funnel chest, which is a technical challenge for radiation therapy planning. To identify the best treatment technique for this case, 3 techniques were compared: conventional tangential fields (3D conformal radiotherapy [3D-CRT]), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). The plans were created for a SynergyS® (Elekta, Ltd, Crawley, UK) linear accelerator with a BeamModulator™ head and 6-MV photons. The planning system was Oncentra Masterplan® v3.3 SP1 (Nucletron BV, Veenendal, Netherlands). Calculations were performed with collapsed cone algorithm. Dose prescription was 50.4 Gy to the average of the planning target volume (PTV). PTV coverage and homogeneity was comparable for all techniques. VMAT allowed reducing dose to the ipsilateral organs at risk (OAR) and the contralateral breast compared with IMRT and 3D-CRT: The volume of the left lung receiving 20 Gy was 19.3% for VMAT, 26.1% for IMRT, and 32.4% for 3D-CRT. In the heart, a D(15%) of 9.7 Gy could be achieved with VMAT compared with 14 Gy for IMRT and 46 Gy for 3D-CRT. In the contralateral breast, D(15%) was 6.4 Gy for VMAT, 8.8 Gy for IMRT, and 10.2 Gy for 3D-CRT. In the contralateral lung, however, the lowest dose was achieved with 3D-CRT with D(10%) of 1.7 Gy for 3D-CRT, and 6.7 Gy for both IMRT and VMAT. The lowest number of monitor units (MU) per 1.8-Gy fraction was required by 3D-CRT (192 MU) followed by VMAT (518 MU) and IMRT (727 MU). Treatment time was similar for 3D-CRT (3 min) and VMAT (4 min) but substantially increased for IMRT (13 min). VMAT is considered the best treatment option for the presented case of a patient with funnel chest. It allows reducing dose in most OAR without compromising target coverage, keeping delivery time well below 5 minutes.

  2. Fan-beam intensity modulated proton therapy

    SciTech Connect

    Hill, Patrick; Westerly, David; Mackie, Thomas

    2013-11-15

    Purpose: This paper presents a concept for a proton therapy system capable of delivering intensity modulated proton therapy using a fan beam of protons. This system would allow present and future gantry-based facilities to deliver state-of-the-art proton therapy with the greater normal tissue sparing made possible by intensity modulation techniques.Methods: A method for producing a divergent fan beam of protons using a pair of electromagnetic quadrupoles is described and particle transport through the quadrupole doublet is simulated using a commercially available software package. To manipulate the fan beam of protons, a modulation device is developed. This modulator inserts or retracts acrylic leaves of varying thickness from subsections of the fan beam. Each subsection, or beam channel, creates what effectively becomes a beam spot within the fan area. Each channel is able to provide 0–255 mm of range shift for its associated beam spot, or stop the beam and act as an intensity modulator. Results of particle transport simulations through the quadrupole system are incorporated into the MCNPX Monte Carlo transport code along with a model of the range and intensity modulation device. Several design parameters were investigated and optimized, culminating in the ability to create topotherapy treatment plans using distal-edge tracking on both phantom and patient datasets.Results: Beam transport calculations show that a pair of electromagnetic quadrupoles can be used to create a divergent fan beam of 200 MeV protons over a distance of 2.1 m. The quadrupole lengths were 30 and 48 cm, respectively, with transverse field gradients less than 20 T/m, which is within the range of water-cooled magnets for the quadrupole radii used. MCNPX simulations of topotherapy treatment plans suggest that, when using the distal edge tracking delivery method, many delivery angles are more important than insisting on narrow beam channel widths in order to obtain conformal target coverage

  3. Fan-beam intensity modulated proton therapy

    PubMed Central

    Hill, Patrick; Westerly, David; Mackie, Thomas

    2013-01-01

    Purpose: This paper presents a concept for a proton therapy system capable of delivering intensity modulated proton therapy using a fan beam of protons. This system would allow present and future gantry-based facilities to deliver state-of-the-art proton therapy with the greater normal tissue sparing made possible by intensity modulation techniques. Methods: A method for producing a divergent fan beam of protons using a pair of electromagnetic quadrupoles is described and particle transport through the quadrupole doublet is simulated using a commercially available software package. To manipulate the fan beam of protons, a modulation device is developed. This modulator inserts or retracts acrylic leaves of varying thickness from subsections of the fan beam. Each subsection, or beam channel, creates what effectively becomes a beam spot within the fan area. Each channel is able to provide 0–255 mm of range shift for its associated beam spot, or stop the beam and act as an intensity modulator. Results of particle transport simulations through the quadrupole system are incorporated into the MCNPX Monte Carlo transport code along with a model of the range and intensity modulation device. Several design parameters were investigated and optimized, culminating in the ability to create topotherapy treatment plans using distal-edge tracking on both phantom and patient datasets. Results: Beam transport calculations show that a pair of electromagnetic quadrupoles can be used to create a divergent fan beam of 200 MeV protons over a distance of 2.1 m. The quadrupole lengths were 30 and 48 cm, respectively, with transverse field gradients less than 20 T/m, which is within the range of water-cooled magnets for the quadrupole radii used. MCNPX simulations of topotherapy treatment plans suggest that, when using the distal edge tracking delivery method, many delivery angles are more important than insisting on narrow beam channel widths in order to obtain conformal target coverage

  4. Impact of gantry rotation time on plan quality and dosimetric verification--volumetric modulated arc therapy (VMAT) vs. intensity modulated radiotherapy (IMRT).

    PubMed

    Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes

    2011-12-01

    To compare plan quality criteria and dosimetric accuracy of step-and-shoot intensity-modulated radiotherapy (ss-IMRT) and volumetric modulated arc radiotherapy (VMAT) using two different gantry rotation times. This retrospective planning study based on 20 patients was comprised of 10 prostate cancer (PC) and 10 head and neck (HN) cancer cases. Each plan contained two target volumes: a primary planning target volume (PTV) and a boost volume. For each patient, one ss-IMRT plan and two VMAT plans at 90 s (VMAT90) and 120 s (VMAT120) per arc were generated with the Pinnacle© planning system. Two arcs were provided for the PTV plans and a single arc for boost volumes. Dosimetric verification of the plans was performed using a 2D ionization chamber array placed in a full scatter phantom. VMAT reduced delivery time and monitor units for both treatment sites compared to IMRT. VMAT120 vs. VMAT90 increased delivery time and monitor units in PC plans without improving plan quality. For HN cases, VMAT120 provided comparable organs at risk sparing and better target coverage and conformity than VMAT90. In the VMAT plan verification, an average of 97.1% of the detector points passed the 3 mm, 3% γ criterion, while in IMRT verification it was 98.8%. VMAT90, VMAT120, and IMRT achieved comparable treatment plans. Slower gantry movement in VMAT120 plans only improves dosimetric quality for highly complex targets.

  5. Treatment Plan Technique and Quality for Single-Isocenter Stereotactic Ablative Radiotherapy of Multiple Lung Lesions with Volumetric-Modulated Arc Therapy or Intensity-Modulated Radiosurgery

    PubMed Central

    Quan, Kimmen; Xu, Karen M.; Lalonde, Ron; Horne, Zachary D.; Bernard, Mark E.; McCoy, Chuck; Clump, David A.; Burton, Steven A.; Heron, Dwight E.

    2015-01-01

    The aim of this study is to provide a practical approach to the planning technique and evaluation of plan quality for the multi-lesion, single-isocenter stereotactic ablative radiotherapy (SABR) of the lung. Eleven patients with two or more lung lesions underwent single-isocenter volumetric-modulated arc therapy (VMAT) radiosurgery or IMRS. All plans were normalized to the target maximum dose. For each plan, all targets were treated to the same dose. Plan conformity and dose gradient were maximized with dose-control tuning structures surrounding targets. For comparison, multi-isocenter plans were retrospectively created for four patients. Conformity index (CI), homogeneity index (HI), gradient index (GI), and gradient distance (GD) were calculated for each plan. V5, V10, and V20 of the lung and organs at risk (OARs) were collected. Treatment time and total monitor units (MUs) were also recorded. One patient had four lesions and the remainder had two lesions. Six patients received VMAT and five patients received intensity-modulated radiosurgery (IMRS). For those treated with VMAT, two patients received 3-arc VMAT and four received 2-arc VMAT. For those treated with IMRS, two patients were treated with 10 and 11 beams, respectively, and the rest received 12 beams. Prescription doses ranged from 30 to 54 Gy in three to five fractions. The median prescribed isodose line was 84% (range: 80–86%). The median maximum dose was 57.1 Gy (range: 35.7–65.1 Gy). The mean combined PTV was 49.57 cm3 (range: 14.90–87.38 cm3). For single-isocenter plans, the median CI was 1.15 (range: 0.97–1.53). The median HI was 1.19 (range: 1.16–1.28). The median GI was 4.60 (range: 4.16–7.37). The median maximum radiation dose (Dmax) to total lung was 55.6 Gy (range: 35.7–62.0 Gy). The median mean radiation dose to the lung (Dmean) was 4.2 Gy (range: 1.1–9.3 Gy). The median lung V5 was 18.7% (range: 3.8–41.3%). There was no significant difference in CI, HI, GI

  6. Volumetric-modulated arc therapy vs conventional fixed-field intensity-modulated radiotherapy in a whole-ventricular irradiation: A planning comparison study

    SciTech Connect

    Sakanaka, Katsuyuki; Mizowaki, Takashi; Sato, Sayaka; Ogura, Kengo; Hiraoka, Masahiro

    2013-07-01

    This study evaluated the dosimetric difference between volumetric-modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (cIMRT) in whole-ventricular irradiation. Computed tomography simulation data for 13 patients were acquired to create plans for VMAT and cIMRT. In both plans, the same median dose (100% = 24 Gy) was prescribed to the planning target volume (PTV), which comprised a tumor bed and whole ventricles. During optimization, doses to the normal brain and body were reduced, provided that the dose constraints of the target coverage were satisfied. The dose-volume indices of the PTV, normal brain, and body as well as monitor units were compared between the 2 techniques by using paired t-tests. The results showed no significant difference in the homogeneity index (0.064 vs 0.065; p = 0.824) of the PTV and conformation number (0.78 vs 0.77; p = 0.065) between the 2 techniques. In the normal brain and body, the dose-volume indices showed no significant difference between the 2 techniques, except for an increase in the volume receiving a low dose in VMAT; the absolute volume of the normal brain and body receiving 1 Gy of radiation significantly increased in VMAT by 1.6% and 8.3%, respectively, compared with that in cIMRT (1044 vs 1028 mL for the normal brain and 3079.2 vs 2823.3 mL for the body; p<0.001). The number of monitor units to deliver a 2.0-Gy fraction was significantly reduced in VMAT compared with that in cIMRT (354 vs 873, respectively; p<0.001). In conclusion, VMAT delivers IMRT to complex target volumes such as whole ventricles with fewer monitor units, while maintaining target coverage and conformal isodose distribution comparable to cIMRT; however, in addition to those characteristics, the fact that the volume of the normal brain and body receiving a low dose would increase in VMAT should be considered.

  7. SU-E-T-417: The Impact of Normal Tissue Constraints On PTV Dose Homogeneity for Intensity Modulated Radiotherapy (IMRT), Volume Modulated Arc Therapy (VMAT) and Tomotherapy

    SciTech Connect

    Peng, J; McDonald, D; Ashenafi, M; Ellis, A; Vanek, K

    2014-06-01

    Purpose: Complex intensity modulated arc therapy tends to spread low dose to normal tissue(NT)regions to obtain improved target conformity and homogeneity and OAR sparing.This work evaluates the trade-offs between PTV homogeneity and reduction of the maximum dose(Dmax)spread to NT while planning of IMRT,VMAT and Tomotherapy. Methods: Ten prostate patients,previously planned with step-and-shoot IMRT,were selected.To fairly evaluate how PTV homogeneity was affected by NT Dmax constraints,original IMRT DVH objectives for PTV and OARs(femoral heads,and rectal and bladder wall)applied to 2 VMAT plans in Pinnacle(V9.0), and Tomotherapy(V4.2).The only constraint difference was the NT which was defined as body contours excluding targets,OARs and dose rings.NT Dmax constraint for 1st VMAT was set to the prescription dose(Dp).For 2nd VMAT(VMAT-NT)and Tomotherapy,it was set to the Dmax achieved in IMRT(~70-80% of Dp).All NT constraints were set to the lowest priority.Three common homogeneity indices(HI),RTOG-HI=Dmax/Dp,moderated-HI=D95%/D5% and complex-HI=(D2%-D98%)/Dp*100 were calculated. Results: All modalities with similar dosimetric endpoints for PTV and OARs.The complex-HI shows the most variability of indices,with average values of 5.9,4.9,9.3 and 6.1 for IMRT,VMAT,VMAT-NT and Tomotherapy,respectively.VMAT provided the best PTV homogeneity without compromising any OAR/NT sparing.Both VMAT-NT and Tomotherapy,planned with more restrictive NT constraints,showed reduced homogeneity,with VMAT-NT showing the worst homogeneity(P<0.0001)for all HI.Tomotherapy gave the lowest NT Dmax,with slightly decreased homogeneity compared to VMAT. Finally, there was no significant difference in NT Dmax or Dmean between VMAT and VMAT-NT. Conclusion: PTV HI is highly dependent on permitted NT constraints. Results demonstrated that VMAT-NT with more restrictive NT constraints does not reduce Dmax NT,but significantly receives higher Dmax and worse target homogeneity.Therefore, it is critical

  8. Dosimetric comparison of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in total scalp irradiation: a single institutional experience

    PubMed Central

    Ostheimer, Christian; Hübsch, Patrick; Janich, Martin; Gerlach, Reinhard; Vordermark, Dirk

    2016-01-01

    Purpose Total scalp irradiation (TSI) is a rare but challenging indication. We previously reported that non-coplanar intensity-modulated radiotherapy (IMRT) was superior to coplanar IMRT in organ-at-risk (OAR) protection and target dose distribution. This consecutive treatment planning study compared IMRT with volumetric-modulated arc therapy (VMAT). Materials and Methods A retrospective treatment plan databank search was performed and 5 patient cases were randomly selected. Cranial imaging was restored from the initial planning computed tomography (CT) and target volumes and OAR were redelineated. For each patients, three treatment plans were calculated (coplanar/non-coplanar IMRT, VMAT; prescribed dose 50 Gy, single dose 2 Gy). Conformity, homogeneity and dose volume histograms were used for plan. Results VMAT featured the lowest monitor units and the sharpest dose gradient (1.6 Gy/mm). Planning target volume (PTV) coverage and homogeneity was better in VMAT (coverage, 0.95; homogeneity index [HI], 0.118) compared to IMRT (coverage, 0.94; HI, 0.119) but coplanar IMRT produced the most conformal plans (conformity index [CI], 0.43). Minimum PTV dose range was 66.8% –88.4% in coplanar, 77.5%–88.2% in non-coplanar IMRT and 82.8%–90.3% in VMAT. Mean dose to the brain, brain stem, optic system (maximum dose) and lenses were 18.6, 13.2, 9.1, and 5.2 Gy for VMAT, 21.9, 13.4, 14.5, and 6.3 Gy for non-coplanar and 22.8, 16.5, 11.5, and 5.9 Gy for coplanar IMRT. Maximum optic chiasm dose was 7.7, 8.4, and 11.1 Gy (non-coplanar IMRT, VMAT, and coplanar IMRT). Conclusion Target coverage, homogeneity and OAR protection, was slightly superior in VMAT plans which also produced the sharpest dose gradient towards healthy tissue. PMID:27951625

  9. Treatment planning strategy for whole-brain radiotherapy with hippocampal sparing and simultaneous integrated boost for multiple brain metastases using intensity-modulated arc therapy.

    PubMed

    Pokhrel, Damodar; Sood, Sumit; McClinton, Christopher; Shen, Xinglei; Lominska, Christopher; Saleh, Habeeb; Badkul, Rajeev; Jiang, Hongyu; Mitchell, Melissa; Wang, Fen

    2016-01-01

    To retrospectively evaluate the accuracy, plan quality and efficiency of intensity-modulated arc therapy (IMAT) for hippocampal sparing whole-brain radiotherapy (HS-WBRT) with simultaneous integrated boost (SIB) in patients with multiple brain metastases (m-BM). A total of 5 patients with m-BM were retrospectively replanned for HS-WBRT with SIB using IMAT treatment planning. The hippocampus was contoured on diagnostic T1-weighted magnetic resonance imaging (MRI) which had been fused with the planning CT image set. The hippocampal avoidance zone (HAZ) was generated using a 5-mm uniform margin around the paired hippocampi. The m-BM planning target volumes (PTVs) were contoured on T1/T2-weighted MRI registered with the 3D planning computed tomography (CT). The whole-brain planning target volume (WB-PTV) was defined as the whole-brain tissue volume minus HAZ and m-BM PTVs. Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis-TX linear accelerator consisting of high-definition multileaf collimators (HD-MLCs: 2.5-mm leaf width at isocenter) and 6-MV beam. Prescription dose was 30Gy for WB-PTV and 45Gy for each m-BM in 10 fractions. Three full coplanar arcs with orbit avoidance sectors were used. Treatment plans were evaluated using homogeneity (HI) and conformity indices (CI) for target coverage and dose to organs at risk (OAR). Dose delivery efficiency and accuracy of each IMAT plan was assessed via quality assurance (QA) with a MapCHECK device. Actual beam-on time was recorded and a gamma index was used to compare dose agreement between the planned and measured doses. All 5 HS-WBRT with SIB plans met WB-PTV D2%, D98%, and V30Gy NRG-CC001 requirements. The plans demonstrated highly conformal and homogenous coverage of the WB-PTV with mean HI and CI values of 0.33 ± 0.04 (range: 0.27 to 0.36), and 0.96 ± 0.01 (range: 0.95 to 0.97), respectively. All 5 hippocampal sparing patients met protocol guidelines with maximum dose and

  10. Evaluation of the trade-offs encountered in planning and treating locally advanced head and neck cancer: intensity-modulated radiation therapy vs dual-arc volumetric-modulated arc therapy

    PubMed Central

    Oliver, M; McConnell, D; Romani, M; McAllister, A; Pearce, A; Andronowski, A; Wang, X; Leszczynski, K

    2012-01-01

    Objective The primary purpose of this study was to assess the practical trade-offs between intensity-modulated radiation therapy (IMRT) and dual-arc volumetric-modulated arc therapy (DA-VMAT) for locally advanced head and neck cancer (HNC). Methods For 15 locally advanced HNC data sets, nine-field step-and-shoot IMRT plans and two full-rotation DA-VMAT treatment plans were created in the Pinnacle3 v. 9.0 (Philips Medical Systems, Fitchburg, WI) treatment planning environment and then delivered on a Clinac iX (Varian Medical Systems, Palo Alto, CA) to a cylindrical detector array. The treatment planning goals were organised into four groups based on their importance: (1) spinal cord, brainstem, optical structures; (2) planning target volumes; (3) parotids, mandible, larynx and brachial plexus; and (4) normal tissues. Results Compared with IMRT, DA-VMAT plans were of equal plan quality (p>0.05 for each group), able to be delivered in a shorter time (3.1 min vs 8.3 min, p<0.0001), delivered fewer monitor units (on average 28% fewer, p<0.0001) and produced similar delivery accuracy (p>0.05 at γ2%/2mm and γ3%/3mm). However, the VMAT plans took more planning time (28.9 min vs 7.7 min per cycle, p<0.0001) and required more data for a three-dimensional dose (20 times more, p<0.0001). Conclusions Nine-field step-and-shoot IMRT and DA-VMAT are both capable of meeting the majority of planning goals for locally advanced HNC. The main trade-offs between the techniques are shorter treatment time for DA-VMAT but longer planning time and the additional resources required for implementation of a new technology. Based on this study, our clinic has incorporated DA-VMAT for locally advanced HNC. Advances in knowledge DA-VMAT is a suitable alternative to IMRT for locally advanced HNC. PMID:22806619

  11. A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer

    SciTech Connect

    Elith, Craig A; Dempsey, Shane E; Warren-Forward, Helen M

    2013-09-15

    The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6). Twenty prostate cancer cases were retrospectively planned using v10.0 of Varian's Eclipse and RapidArc software. Three planning techniques were performed: a 5-field IMRT, VMAT using one arc (VMAT-1A), and VMAT with two arcs (VMAT-2A). Plan quality was assessed by examining homogeneity, conformity, the number of monitor units (MUs) utilized, and dose to the organs at risk (OAR). Resource implications were assessed by examining planning and treatment times. The results obtained using v10.0 were also compared to those previously reported by our group for v8.6. In v10.0, each technique was able to produce a dose distribution that achieved the departmental planning guidelines. The IMRT plans were produced faster than VMAT plans and displayed improved homogeneity. The VMAT plans provided better conformity to the target volume, improved dose to the OAR, and required fewer MUs. Treatments using VMAT-1A were significantly faster than both IMRT and VMAT-2A. Comparison between versions 8.6 and 10.0 revealed that in the newer version, VMAT planning was significantly faster and the quality of the VMAT dose distributions produced were of a better quality. VMAT (v10.0) using one or two arcs provides an acceptable alternative to IMRT for the treatment of prostate cancer. VMAT-1A has the greatest impact on reducing treatment time.

  12. SU-E-T-810: Volumetric Modulated Arc Therapy and Conventional Intensity-Modulated Radiotherapy for Non-Small-Cell Lung Cancer with Simultaneously Integrated Boost Radiation Therapy: A Planning Comparison Study

    SciTech Connect

    Liu, T; Chen, J; Zhang, G; Sun, T

    2015-06-15

    Purpose: To compare and analyze the characteristics of intensity-modulated arc therapy(IMAT) versus fixed-gantry intensity-modulated radiotherapy(IMRT) in treatment of non-small-cell lung cancer. Methods: Twelve patients treated in our radiotherapy center were selected for this study. The patient subsequently underwent 4D-CT simulation.Margins of 5mm and 10mm were added to the ITV to generate the CTV and PTV respectively. Three treatment plans (IMRT,one single arc (RA1),double arcs (RA2))were generated with Eclipse ver.8.6 planning systems. Using a dose level of 75Gy in 15fractions to the ITV,60Gy in 15fractions to the CTV and 45Gy in 15fractions to the PTV respectively. The target and normol tissue volumes were compared,as were the dosimetry parameters. Results: There were no significant differences in CI of ITV,PTV,HI of ITV,CTV and PTV, V5,V10,V15,V20,V25,V30,V45,V50 of total-lung and mean lung dose (all p>0.05). However, the differences were significant in terms of CI of CTV,V5 of B-P (all p<0.05). On the MU, IMRT=1540MU,RA1=1006 MU and RA2=1096 MU. (F=12.00,P=0.000).On the treatment time, IMRT= 13.5min,RA1= 1.5min,and RA2=2.5 min (F= 30.11,P=0.000 ). Conclusion: IMAT is equal to IMRT in dosimetril evaluation. Due to much less Mu and delivery time,IMAT is an ideal technique in treating patients by reduceing the uncomfortable influnce which could effect the treatment.

  13. Dosimetric difference amongst 3 techniques: TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC).

    PubMed

    Lee, Francis Kar-ho; Yip, Celia Wai-yi; Cheung, Frankie Chun-hung; Leung, Alex Kwok-cheung; Chau, Ricky Ming-chun; Ngan, Roger Kai-cheong

    2014-01-01

    To investigate the dosimetric difference amongst TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC). Ten patients with late-stage (Stage III or IV) NPC treated with TomoTherapy or IMRT were selected for the study. Treatment plans with these 3 techniques were devised according to departmental protocol. Dosimetric parameters for organ at risk and treatment targets were compared between TomoTherapy and IMRT, TomoTherapy and RapidArc, and IMRT and RapidArc. Comparison amongst the techniques was done by statistical tests on the dosimetric parameters, total monitor unit (MU), and expected delivery time. All 3 techniques achieved similar target dose coverage. TomoTherapy achieved significantly lower doses in lens and mandible amongst the techniques. It also achieved significantly better dose conformity to the treatment targets. RapidArc achieved significantly lower dose to the eye and normal tissue, lower total MU, and less delivery time. The dosimetric advantages of the 3 techniques were identified in the treatment of late-stage NPC. This may serve as a guideline for selection of the proper technique for different clinical cases. © 2013 American Association of Medical Dosimetrists Published by American Association of Medical Dosimetrists All rights reserved.

  14. Dosimetric difference amongst 3 techniques: TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC)

    SciTech Connect

    Lee, Francis Kar-ho Yip, Celia Wai-yi; Cheung, Frankie Chun-hung; Leung, Alex Kwok-cheung; Chau, Ricky Ming-chun; Ngan, Roger Kai-cheong

    2014-04-01

    To investigate the dosimetric difference amongst TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC). Ten patients with late-stage (Stage III or IV) NPC treated with TomoTherapy or IMRT were selected for the study. Treatment plans with these 3 techniques were devised according to departmental protocol. Dosimetric parameters for organ at risk and treatment targets were compared between TomoTherapy and IMRT, TomoTherapy and RapidArc, and IMRT and RapidArc. Comparison amongst the techniques was done by statistical tests on the dosimetric parameters, total monitor unit (MU), and expected delivery time. All 3 techniques achieved similar target dose coverage. TomoTherapy achieved significantly lower doses in lens and mandible amongst the techniques. It also achieved significantly better dose conformity to the treatment targets. RapidArc achieved significantly lower dose to the eye and normal tissue, lower total MU, and less delivery time. The dosimetric advantages of the 3 techniques were identified in the treatment of late-stage NPC. This may serve as a guideline for selection of the proper technique for different clinical cases.

  15. Potential for reduced radiation-induced toxicity using intensity-modulated arc therapy for whole-brain radiotherapy with hippocampal sparing.

    PubMed

    Pokhrel, Damodar; Sood, Sumit; Lominska, Christopher; Kumar, Parvesh; Badkul, Rajeev; Jiang, Hongyu; Wang, Fen

    2015-09-01

    The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity-modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole-brain radiotherapy (NC-WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1-weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole-brain planning target volume (WB-PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high-definition multileaf collimators (HD-MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam-on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB-PTV, mean WB-PTV D2%, and mean WB-PTV D98% were 34.9±0.3 Gy,33.2±0.4 Gy, and 26.0±0.4 Gy, respectively. Accordingly, WB-PTV received the prescription dose of 30 Gy and mean V30 was 90.5%±0.5%. The D100%, and mean

  16. Potential for reduced radiation-induced toxicity using intensity-modulated arc therapy for whole-brain radiotherapy with hippocampal sparing.

    PubMed

    Pokhrel, Damodar; Sood, Sumit; Lominska, Christopher; Kumar, Pravesh; Badkul, Rajeev; Jiang, Hongyu; Wang, Fen

    2015-09-08

    The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity-modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole-brain radiotherapy (NC-WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1-weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole-brain planning target volume (WB-PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high-definition multileaf collimators (HD-MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam-on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB-PTV, mean WB-PTV D2%, and mean WB-PTV D98% were 34.9 ± 0.3 Gy, 33.2 ± 0.4 Gy, and 26.0± 0.4Gy, respectively. Accordingly, WB-PTV received the prescription dose of 30Gy and mean V30 was 90.5% ± 0.5%. The D100%, and

  17. Film Dosimetry for Intensity Modulated Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Benites-Rengifo, J.; Martínez-Dávalos, A.; Celis, M.; Lárraga, J.

    2004-09-01

    Intensity Modulated Radiation Therapy (IMRT) is an oncology treatment technique that employs non-uniform beam intensities to deliver highly conformal radiation to the targets while minimizing doses to normal tissues and critical organs. A key element for a successful clinical implementation of IMRT is establishing a dosimetric verification process that can ensure that delivered doses are consistent with calculated ones for each patient. To this end we are developing a fast quality control procedure, based on film dosimetry techniques, to be applied to the 6 MV Novalis linear accelerator for IMRT of the Instituto Nacional de Neurología y Neurocirugía (INNN) in Mexico City. The procedure includes measurements of individual fluence maps for a limited number of fields and dose distributions in 3D using extended dose-range radiographic film. However, the film response to radiation might depend on depth, energy and field size, and therefore compromise the accuracy of measurements. In this work we present a study of the dependence of Kodak EDR2 film's response on the depth, field size and energy, compared with those of Kodak XV2 film. The first aim is to devise a fast and accurate method to determine the calibration curve of film (optical density vs. doses) commonly called a sensitometric curve. This was accomplished by using three types of irradiation techniques: Step-and-shoot, dynamic and static fields.

  18. Virtual micro-intensity modulated radiation therapy.

    PubMed

    Siochi, R A

    2000-11-01

    Virtual micro-intensity modulated radiation therapy (VMIMRT) combines a 10 x 5 mm2 intensity map with a 5 x 10 mm2 intensity map, delivered at orthogonal collimator settings. The superposition of these component maps (CM) yields a 5 x 5 mm2 virtual micro-intensity map (VMIM) that can be delivered with a 1 cm leaf width MLC. A pair of CMs with optimal delivery efficiency and quality must be chosen, since a given VMIM can be delivered using several different pairs. This is possible since, for each group of four VMIM cells that can be covered by an MLC leaf in either collimator orientation, the minimum intensity can be delivered from either collimator setting. By varying the proportions of the minimum values that go into each CM, one can simultaneously minimize the number of potential junction effects and the number of segments required to deliver the VMIM. The minimization is achieved by reducing high leaf direction gradients in the CMs. Several pseudoclinical and random VMIMs were studied to determine the applicability of this new technique. A nine level boost map was also studied to investigate dosimetric and spatial resolution issues. Finally, clinical issues for this technique are discussed.

  19. Comparison of intensity modulated x-ray therapy and intensity modulated proton therapy for selective subvolume boosting: a phantom study

    PubMed Central

    Flynn, R T; Barbee, D L; Mackie, T R; Jeraj, R

    2009-01-01

    Selective subvolume boosting can theoretically improve tumour control probability while maintaining normal tissue complication probabilities similar to those of uniform dose distributions. In this work the abilities of intensity modulated x-ray therapy (IMXT) and intensity modulated proton therapy (IMPT) to deliver boosts to multiple subvolumes of varying size and proximities are compared in a thorough phantom study. IMXT plans were created using the step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) methods. IMPT plans were created with the spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT) methods. IMPT-DGT is a generalization of the distal edge tracking method designed to reduce the number of proton beam spots required to deliver non-uniform dose distributions relative to IMPT-SS. The IMPT methods were delivered over both 180° and 360° arcs. The IMXT-SAS and IMPT-SS methods least and most optimally satisfied the non-uniform dose prescriptions, respectively. The IMPT delivery methods reduced normal tissue integral dose by a factor of about two relative to the IMXT delivery methods, regardless of the delivery arc. The IMPT-DGT method reduced the number of proton beam spots by a factor of about three relative to the IMPT-SS method. PMID:17921573

  20. Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

    SciTech Connect

    Wang, Xin; Li, Guangjun; Zhang, Yingjie; Bai, Sen; Xu, Feng; Wei, Yuquan; Gong, Youling

    2013-01-01

    To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patient's case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMAT plans successfully achieved better target dose conformity, reduced the V{sub 20/30}, and mean dose of the left kidney, as well as the V{sub 20/30} of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V{sub 20} of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6 Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future.

  1. SU-E-T-338: Dosimetric Study of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) for Stereotactic Body Radiation Therapy (SBRT) in Early Stage Lung Cancer

    SciTech Connect

    Ahmad, I; Quinn, K; Seebach, A; Wang, H; Yah, R

    2015-06-15

    Purpose: This study evaluates the dosimetric differences using volumetric modulated arc therapy (VMAT) in patients previously treated with intensity modulated radiation therapy IMRT for stereotactic body radiotherapy (SBRT) in early stage lung cancer. Methods: We evaluated 9 consecutive medically inoperable lung cancer patients at the start of the SBRT program who were treated with IMRT from November 2010 to October 2011. These patients were treated using 6 MV energy. The 9 cases were then re-planned with VMAT performed with arc therapy using 6 MV flattening filter free (FFF) energy with the same organs at risk (OARS) constraints. Data collected for the treatment plans included target coverage, beam on time, dose to OARS and gamma pass rate. Results: Five patients were T1N0 and four patients were T2N0 with all tumors less than 5 cm. The average GTV was 13.02 cm3 (0.83–40.87) and average PTV was 44.65 cm3 (14.06–118.08). The IMRT plans had a mean of 7.2 angles (6–9) and 5.4 minutes (3.6–11.1) per plan. The VMAT plans had a mean of 2.8 arcs (2–3) and 4.0 minutes (2.2–6.0) per plan. VMAT had slightly more target coverage than IMRT with average increase in D95 of 2.68% (1.24–5.73) and D99 of 3.65% (0.88–8.77). VMAT produced lower doses to all OARs. The largest reductions were in maximum doses to the spinal cord with an average reduction of 24.1%, esophagus with an average reduction of 22.1%, and lung with an average reduction in the V20 of 16.3% The mean gamma pass rate was 99.8% (99.2–100) at 3 mm and 3% for VMAT with comparable values for IMRT. Conclusion: These findings suggest that using VMAT for SBRT in early stage lung cancer is superior to IMRT in terms of dose coverage, OAR dose and a lower treatment delivery time with a similar gamma pass rate.

  2. Single arc volumetric-modulated arc therapy is sufficient for nasopharyngeal carcinoma: a dosimetric comparison with dual arc VMAT and dynamic MLC and step-and-shoot intensity-modulated radiotherapy

    PubMed Central

    2013-01-01

    Background The performance of single arc VMAT (VMAT1) for nasopharyngeal carcinoma (NPC) on the Axesse linac has not been well described in previous studies. The purpose of this study is to assess the feasibility of VMAT1 for NPC by comparing the dosimetry, delivery efficiency, and accuracy with dual arc VMAT (VMAT2), dynamic MLC intensity-modulated radiotherapy (dIMRT), and step-and-shoot intensity-modulated radiotherapy (ssIMRT). Methods Twenty consecutive patients with non-metastatic NPC were selected to be planned with VMAT1, VMAT2, dIMRT and ssIMRT using Monaco 3.2 TPS on the Axesse™ linear accelerator. Three planning target volumes (PTVs), contoured as high risk, moderate risk and low risk regions, were set to receive median absorbed-dose (D50%) of 72.6 Gy, 63.6 Gy and 54 Gy, respectively. The Homogeneity Index (HI), Conformity Index (CI), Dose Volume Histograms (DVHs), delivery efficiency and accuracy were all evaluated. Results Mean HI of PTV72.6 is better with VMAT1(0.07) and VMAT2(0.07) than dIMRT(0.09) and ssIMRT(0.09). Mean HI of PTV63.6 is better with VMAT1(0.21) and VMAT2(0.21) than dIMRT and ssIMRT. Mean CI of PTV72.6 is also better with VMAT1(0.57) and VMAT2(0.57) than dIMRT(0.49) and ssIMRT(0.5). Mean CI of PTV63.6 is better with VMAT1(0.76) and VMAT2(0.76) than dIMRT(0.73) and ssIMRT(0.73). VMAT had significantly improved homogeneity and conformity compared with IMRT. There was no significant difference between VMAT1 and VMAT2 in PTV coverage. Dose to normal tissues was acceptable for all four plan groups. VMAT1 and VMAT2 showed no significant difference in normal tissue sparring, whereas the mean dose of the parotid gland of dIMRT was significantly reduced compared to VMAT1 and VMAT2. The mean delivery time for VMAT1, VMAT2, dIMRT and ssIMRT was 2.7 min, 3.9 min, 5.7 min and 14.1 min, respectively. VMAT1 reduced the average delivery time by 29.8%, 51.1% and 80.8% compared with VMAT2, dIMRT and ssIMRT, respectively. VMAT and IMRT could all be

  3. Robust optimization of intensity modulated proton therapy

    SciTech Connect

    Liu Wei; Zhang Xiaodong; Li Yupeng; Mohan, Radhe

    2012-02-15

    Purpose: Intensity modulated proton therapy (IMPT) is highly sensitive to range uncertainties and uncertainties caused by setup variation. The conventional inverse treatment planning of IMPT optimized based on the planning target volume (PTV) is not often sufficient to ensure robustness of treatment plans. In this paper, a method that takes the uncertainties into account during plan optimization is used to mitigate the influence of uncertainties in IMPT. Methods: The authors use the so-called ''worst-case robust optimization'' to render IMPT plans robust in the face of uncertainties. For each iteration, nine different dose distributions are computed--one each for {+-} setup uncertainties along anteroposterior (A-P), lateral (R-L) and superior-inferior (S-I) directions, for {+-} range uncertainty, and the nominal dose distribution. The worst-case dose distribution is obtained by assigning the lowest dose among the nine doses to each voxel in the clinical target volume (CTV) and the highest dose to each voxel outside the CTV. Conceptually, the use of worst-case dose distribution is similar to the dose distribution achieved based on the use of PTV in traditional planning. The objective function value for a given iteration is computed using this worst-case dose distribution. The objective function used has been extended to further constrain the target dose inhomogeneity. Results: The worst-case robust optimization method is applied to a lung case, a skull base case, and a prostate case. Compared with IMPT plans optimized using conventional methods based on the PTV, our method yields plans that are considerably less sensitive to range and setup uncertainties. An interesting finding of the work presented here is that, in addition to reducing sensitivity to uncertainties, robust optimization also leads to improved optimality of treatment plans compared to the PTV-based optimization. This is reflected in reduction in plan scores and in the lower normal tissue doses for the

  4. Volumetric modulated arc therapy versus step-and-shoot intensity modulated radiation therapy in the treatment of large nerve perineural spread to the skull base: a comparative dosimetric planning study

    SciTech Connect

    Gorayski, Peter; Fitzgerald, Rhys; Barry, Tamara; Burmeister, Elizabeth; Foote, Matthew

    2014-06-15

    Cutaneous squamous cell carcinoma with large nerve perineural (LNPN) infiltration of the base of skull is a radiotherapeutic challenge given the complex target volumes to nearby organs at risk (OAR). A comparative planning study was undertaken to evaluate dosimetric differences between volumetric modulated arc therapy (VMAT) versus intensity modulated radiation therapy (IMRT) in the treatment of LNPN. Five consecutive patients previously treated with IMRT for LNPN were selected. VMAT plans were generated for each case using the same planning target volumes (PTV), dose prescriptions and OAR constraints as IMRT. Comparative parameters used to assess target volume coverage, conformity and homogeneity included V95 of the PTV (volume encompassed by the 95% isodose), conformity index (CI) and homogeneity index (HI). In addition, OAR maximum point doses, V20, V30, non-target tissue (NTT) point max doses, NTT volume above reference dose, monitor units (MU) were compared. IMRT and VMAT plans generated were comparable for CI (P = 0.12) and HI (P = 0.89). VMAT plans achieved better V95 (P = < 0.001) and reduced V20 and V30 by 652 cubic centimetres (cc) (28.5%) and 425.7 cc (29.1%), respectively. VMAT increased MU delivered by 18% without a corresponding increase in NTT dose. Compared with IMRT plans for LNPN, VMAT achieved comparable HI and CI.

  5. Simultaneous integrated boost plan comparison of volumetric-modulated arc therapy and sliding window intensity-modulated radiotherapy for whole pelvis irradiation of locally advanced prostate cancer.

    PubMed

    Riou, Olivier; Regnault de la Mothe, Pauline; Azria, David; Aillères, Norbert; Dubois, Jean-Bernard; Fenoglietto, Pascal

    2013-07-08

    Concurrent radiotherapy to the pelvis plus a prostate boost with long-term androgen deprivation is a standard of care for locally advanced prostate cancer. IMRT has the ability to deliver highly conformal dose to the target while lowering irradiation of critical organs around the prostate. Volumetric-modulated arc therapy is able to reduce treatment time, but its impact on organ sparing is still controversial when compared to static gantry IMRT. We compared the two techniques in simultaneous integrated boost plans. Ten patients with locally advanced prostate cancer were included. The planning target volume (PTV) 1 was defined as the pelvic lymph nodes, the prostate, and the seminal vesicles plus setup margins. The PTV2 consisted of the prostate with setup margins. The prescribed doses to PTV1 and PTV2 were 54 Gy in 37 fractions and 74 Gy in 37 fractions, respectively. We compared simultaneous integrated boost plans by means of either a seven coplanar static split fields IMRT, or a one-arc (RA1) and a two-arc (RA2) RapidArc planning. All three techniques allowed acceptable homogeneity and PTV coverage. Static IMRT enabled a better homogeneity for PTV2 than RapidArc techniques. Sliding window IMRT and VMAT permitted to maintain doses to OAR within acceptable levels with a low risk of side effects for each organ. VMAT plans resulted in a clinically and statistically significant reduction in doses to bladder (mean dose IMRT: 50.1 ± 4.6Gy vs. mean dose RA2: 47.1 ± 3.9 Gy, p = 0.037), rectum (mean dose IMRT: 44± 4.5 vs. mean dose RA2: 41.6 ± 5.5 Gy, p = 0.006), and small bowel (V30 IMRT: 76.47 ± 14.91% vs. V30 RA2: 47.49 ± 16.91%, p = 0.002). Doses to femoral heads were higher with VMAT but within accepted constraints. Our findings suggest that simultaneous integrated boost plans using VMAT and sliding window IMRT allow good OAR sparing while maintaining PTV coverage within acceptable levels.

  6. SU-E-T-309: Dosimetric Comparison of Simultaneous Integrated Boost Treatment Plan Between Intensity Modulated Radiotherapies (IMRTs), Dual Arc Volumetric Modulated Arc Therapy (DA-VMAT) and Single Arc Volumetric Modulated Arc Therapy (SA-VMAT) for Nasopharyngeal Carcinoma (NPC)

    SciTech Connect

    Sivakumar, R; Janardhan, N; Bhavani, P; Surendran, J; Saranganathan, B; Ibrahim, S; Jhonson, B; Madhuri, B; Anuradha, C

    2015-06-15

    Purpose: To compare the plan quality and performance of Simultaneous Integrated Boost (SIB) Treatment plan between Seven field (7F) and Nine field(9F) Intensity Modulated Radiotherapies and Single Arc (SA) and Dual Arc (DA) Volumetric Modulated Arc Therapy( VMAT). Methods: Retrospective planning study of 16 patients treated in Elekta Synergy Platform (mlci2) by 9F-IMRT were replanned with 7F-IMRT, Single Arc VMAT and Dual Arc VMAT using CMS, Monaco Treatment Planning System (TPS) with Monte Carlo simulation. Target delineation done as per Radiation Therapy Oncology Protocols (RTOG 0225&0615). Dose Prescribed as 70Gy to Planning Target Volumes (PTV70) and 61Gy to PTV61 in 33 fraction as a SIB technique. Conformity Index(CI), Homogeneity Index(HI) were used as analysis parameter for Target Volumes as well as Mean dose and Max dose for Organ at Risk(OAR,s).Treatment Delivery Time(min), Monitor unit per fraction (MU/fraction), Patient specific quality assurance were also analysed. Results: A Poor dose coverage and Conformity index (CI) was observed in PTV70 by 7F-IMRT among other techniques. SA-VMAT achieved poor dose coverage in PTV61. No statistical significance difference observed in OAR,s except Spinal cord (P= 0.03) and Right optic nerve (P=0.03). DA-VMAT achieved superior target coverage, higher CI (P =0.02) and Better HI (P=0.03) for PTV70 other techniques (7F-IMRT/9F-IMRT/SA-VMAT). A better dose spare for Parotid glands and spinal cord were seen in DA-VMAT. The average treatment delivery time were 5.82mins, 6.72mins, 3.24mins, 4.3mins for 7F-IMRT, 9F-IMRT, SA-VMAT and DA-VMAT respectively. Significance difference Observed in MU/fr (P <0.001) and Patient quality assurance pass rate were >95% (Gamma analysis (Γ3mm, 3%). Conclusion: DA-VAMT showed better target dose coverage and achieved better or equal performance in sparing OARs among other techniques. SA-VMAT offered least Treatment Time than other techniques but achieved poor target coverage. DA-VMAT offered

  7. Under conditions of large geometric miss, tumor control probability can be higher for static gantry intensity-modulated radiation therapy compared to volume-modulated arc therapy for prostate cancer

    SciTech Connect

    Balderson, Michael Brown, Derek; Johnson, Patricia; Kirkby, Charles

    2016-07-01

    The purpose of this work was to compare static gantry intensity-modulated radiation therapy (IMRT) with volume-modulated arc therapy (VMAT) in terms of tumor control probability (TCP) under scenarios involving large geometric misses, i.e., those beyond what are accounted for when margin expansion is determined. Using a planning approach typical for these treatments, a linear-quadratic–based model for TCP was used to compare mean TCP values for a population of patients who experiences a geometric miss (i.e., systematic and random shifts of the clinical target volume within the planning target dose distribution). A Monte Carlo approach was used to account for the different biological sensitivities of a population of patients. Interestingly, for errors consisting of coplanar systematic target volume offsets and three-dimensional random offsets, static gantry IMRT appears to offer an advantage over VMAT in that larger shift errors are tolerated for the same mean TCP. For example, under the conditions simulated, erroneous systematic shifts of 15 mm directly between or directly into static gantry IMRT fields result in mean TCP values between 96% and 98%, whereas the same errors on VMAT plans result in mean TCP values between 45% and 74%. Random geometric shifts of the target volume were characterized using normal distributions in each Cartesian dimension. When the standard deviations were doubled from those values assumed in the derivation of the treatment margins, our model showed a 7% drop in mean TCP for the static gantry IMRT plans but a 20% drop in TCP for the VMAT plans. Although adding a margin for error to a clinical target volume is perhaps the best approach to account for expected geometric misses, this work suggests that static gantry IMRT may offer a treatment that is more tolerant to geometric miss errors than VMAT.

  8. Under conditions of large geometric miss, tumor control probability can be higher for static gantry intensity-modulated radiation therapy compared to volume-modulated arc therapy for prostate cancer.

    PubMed

    Balderson, Michael; Brown, Derek; Johnson, Patricia; Kirkby, Charles

    2016-01-01

    The purpose of this work was to compare static gantry intensity-modulated radiation therapy (IMRT) with volume-modulated arc therapy (VMAT) in terms of tumor control probability (TCP) under scenarios involving large geometric misses, i.e., those beyond what are accounted for when margin expansion is determined. Using a planning approach typical for these treatments, a linear-quadratic-based model for TCP was used to compare mean TCP values for a population of patients who experiences a geometric miss (i.e., systematic and random shifts of the clinical target volume within the planning target dose distribution). A Monte Carlo approach was used to account for the different biological sensitivities of a population of patients. Interestingly, for errors consisting of coplanar systematic target volume offsets and three-dimensional random offsets, static gantry IMRT appears to offer an advantage over VMAT in that larger shift errors are tolerated for the same mean TCP. For example, under the conditions simulated, erroneous systematic shifts of 15mm directly between or directly into static gantry IMRT fields result in mean TCP values between 96% and 98%, whereas the same errors on VMAT plans result in mean TCP values between 45% and 74%. Random geometric shifts of the target volume were characterized using normal distributions in each Cartesian dimension. When the standard deviations were doubled from those values assumed in the derivation of the treatment margins, our model showed a 7% drop in mean TCP for the static gantry IMRT plans but a 20% drop in TCP for the VMAT plans. Although adding a margin for error to a clinical target volume is perhaps the best approach to account for expected geometric misses, this work suggests that static gantry IMRT may offer a treatment that is more tolerant to geometric miss errors than VMAT. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  9. Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients.

    PubMed

    Penoncello, Gregory P; Ding, George X

    2016-01-01

    The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, and 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2cm(3) for head and neck plans and brain plans and a contiguous volume of 5cm(3) for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens.

  10. Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients

    SciTech Connect

    Penoncello, Gregory P.; Ding, George X.

    2016-04-01

    The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, and 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2 cm{sup 3} for head and neck plans and brain plans and a contiguous volume of 5 cm{sup 3} for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens.

  11. Comparison of the performance between portal dosimetry and a commercial two-dimensional array system on pretreatment quality assurance for volumetric-modulated arc and intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Kim, Yon-Lae; Chung, Jin-Beom; Kim, Jae-Sung; Lee, Jeong-Woo; Choi, Kyoung-Sik

    2014-04-01

    The aim of this study was to compare the dosimetric performance and to evaluate the pretreatment quality assurance (QA) of a portal dosimetry and a commercial two-dimensional (2-D) array system. In the characteristics comparison study, the measured values for the dose linearity, dose rate response, reproducibility, and field size dependence for 6-MV photon beams were analyzed for both detector systems. To perform the qualitative evaluations of the 10 IMRT and the 10 VMAT plans, we used the Gamma index for quantifying the agreement between calculations and measurements. The performance estimates for both systems show that overall, minimal differences in the dosimetric characteristics exist between the Electron portal imaging device (EPID) and 2-D array system. In the qualitative analysis for pretreatment quality assurance, the EPID and 2-D array system yield similar passing rate results for the majority of clinical Intensity-modulated radiation therapy (IMRT) and Volumetric-modulated arc therapy (VMAT) cases. These results were satisfactory for IMRT and VMAT fields and were within the acceptable criteria of γ%≤1, γ avg <0.5. The EPDI and the 2-D array systems showed comparable dosimetric results. In this study, the results revealed both systems to be suitable for patient-specific QA measurements for IMRT and VMAT. We conclude that, depending on the status of clinic, both systems can be used interchangeably for routine pretreatment QA.

  12. Stochastic versus deterministic kernel-based superposition approaches for dose calculation of intensity-modulated arcs

    NASA Astrophysics Data System (ADS)

    Tang, Grace; Earl, Matthew A.; Luan, Shuang; Wang, Chao; Cao, Daliang; Yu, Cedric X.; Naqvi, Shahid A.

    2008-09-01

    Dose calculations for radiation arc therapy are traditionally performed by approximating continuous delivery arcs with multiple static beams. For 3D conformal arc treatments, the shape and weight variation per degree is usually small enough to allow arcs to be approximated by static beams separated by 5°-10°. But with intensity-modulated arc therapy (IMAT), the variation in shape and dose per degree can be large enough to require a finer angular spacing. With the increase in the number of beams, a deterministic dose calculation method, such as collapsed-cone convolution/superposition, will require proportionally longer computational times, which may not be practical clinically. We propose to use a homegrown Monte Carlo kernel-superposition technique (MCKS) to compute doses for rotational delivery. The IMAT plans were generated with 36 static beams, which were subsequently interpolated into finer angular intervals for dose calculation to mimic the continuous arc delivery. Since MCKS uses random sampling of photons, the dose computation time only increased insignificantly for the interpolated-static-beam plans that may involve up to 720 beams. Ten past IMRT cases were selected for this study. Each case took approximately 15-30 min to compute on a single CPU running Mac OS X using the MCKS method. The need for a finer beam spacing is dictated by how fast the beam weights and aperture shapes change between the adjacent static planning beam angles. MCKS, however, obviates the concern by allowing hundreds of beams to be calculated in practically the same time as for a few beams. For more than 43 beams, MCKS usually takes less CPU time than the collapsed-cone algorithm used by the Pinnacle3 planning system.

  13. Leaf position error during conformal dynamic arc and intensity modulated arc treatments.

    PubMed

    Ramsey, C R; Spencer, K M; Alhakeem, R; Oliver, A L

    2001-01-01

    Conformal dynamic arc (CD-ARC) and intensity modulated arc treatments (IMAT) are both treatment modalities where the multileaf collimator (MLC) can change leaf position dynamically during gantry rotation. These treatment techniques can be used to generate complex isodose distributions, similar to those used in fix-gantry intensity modulation. However, a beam-hold delay cannot be used during CD-ARC or IMAT treatments to reduce spatial error. Consequently, a certain amount of leaf position error will have to be accepted in order to make the treatment deliverable. Measurements of leaf position accuracy were taken with leaf velocities ranging from 0.3 to 3.0 cm/s. The average and maximum leaf position errors were measured, and a least-squares linear regression analysis was performed on the measured data to determine the MLC velocity error coefficient. The average position errors range from 0.03 to 0.21 cm, with the largest deviations occurring at the maximum achievable leaf velocity (3.0 cm/s). The measured MLC velocity error coefficient was 0.0674 s for a collimator rotation of 0 degrees and 0.0681 s for a collimator rotation of 90 degrees. The distribution in leaf position error between the 0 degrees and 90 degrees collimator rotations was within statistical uncertainty. A simple formula was developed based on these results for estimating the velocity-dependent dosimetric error. Using this technique, a dosimetric error index for plan evaluation can be calculated from the treatment time and the dynamic MLC leaf controller file.

  14. A comparison of volumetric modulated arc therapy and sliding-window intensity-modulated radiotherapy in the treatment of Stage I-II nasal natural killer/T-cell lymphoma

    SciTech Connect

    Liu, Xianfeng; Yang, Yong; Jin, Fu; He, Yanan; Zhong, Mingsong; Luo, Huanli; Qiu, Da; Li, Chao; Yang, Han; He, Guanglei; Wang, Ying

    2016-04-01

    This article is aimed to compare the dosimetric differences between volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for Stage I-II nasal natural killer/T-cell lymphoma (NNKTL). Ten patients with Stage I-II NNKTL treated with IMRT were replanned with VMAT (2 arcs). The prescribed dose of the planning target volume (PTV) was 50 Gy in 25 fractions. The VMAT plans with the Anisotropic Analytical Algorithm (Version 8.6.15) were based on an Eclipse treatment planning system; the monitor units (MUs) and treatment time (T) were scored to measure the expected treatment efficiency. All the 10 patients under the study were subject to comparisons regarding the quality of target coverage, the efficiency of delivery, and the exposure of normal adjacent organs at risk (OARs). The study shows that VMAT was associated with a better conformal index (CI) and homogeneity index (HI) (both p < 0.05) but slightly higher dose to OARs than IMRT. The MUs with VMAT (650.80 ± 24.59) were fewer than with IMRT (1300.10 ± 57.12) (relative reduction of 49.94%, p = 0.00) when using 2-Gy dose fractions. The treatment time with VMAT (3.20 ± 0.02 minutes) was shorter than with IMRT (7.38 ± 0.18 minutes) (relative reduction of 56.64%, p = 0.00). We found that VMAT and IMRT both provide satisfactory target dosimetric coverage and OARs sparing clinically. Likely to deliver a bit higher dose to OARs, VMAT in comparison with IMRT, is still a better choice for treatment of patients with Stage I-II NNKTL, thanks to better dose distribution, fewer MUs, and shorter delivery time.

  15. A comparison of volumetric modulated arc therapy and sliding-window intensity-modulated radiotherapy in the treatment of Stage I-II nasal natural killer/T-cell lymphoma.

    PubMed

    Liu, Xianfeng; Yang, Yong; Jin, Fu; He, Yanan; Zhong, Mingsong; Luo, Huanli; Qiu, Da; Li, Chao; Yang, Han; He, Guanglei; Wang, Ying

    2016-01-01

    This article is aimed to compare the dosimetric differences between volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for Stage I-II nasal natural killer/T-cell lymphoma (NNKTL). Ten patients with Stage I-II NNKTL treated with IMRT were replanned with VMAT (2 arcs). The prescribed dose of the planning target volume (PTV) was 50Gy in 25 fractions. The VMAT plans with the Anisotropic Analytical Algorithm (Version 8.6.15) were based on an Eclipse treatment planning system; the monitor units (MUs) and treatment time (T) were scored to measure the expected treatment efficiency. All the 10 patients under the study were subject to comparisons regarding the quality of target coverage, the efficiency of delivery, and the exposure of normal adjacent organs at risk (OARs). The study shows that VMAT was associated with a better conformal index (CI) and homogeneity index (HI) (both p < 0.05) but slightly higher dose to OARs than IMRT. The MUs with VMAT (650.80 ± 24.59) were fewer than with IMRT (1300.10 ± 57.12) (relative reduction of 49.94%, p = 0.00) when using 2-Gy dose fractions. The treatment time with VMAT (3.20 ± 0.02 minutes) was shorter than with IMRT (7.38 ± 0.18 minutes) (relative reduction of 56.64%, p = 0.00). We found that VMAT and IMRT both provide satisfactory target dosimetric coverage and OARs sparing clinically. Likely to deliver a bit higher dose to OARs, VMAT in comparison with IMRT, is still a better choice for treatment of patients with Stage I-II NNKTL, thanks to better dose distribution, fewer MUs, and shorter delivery time. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  16. A comparative study of standard intensity-modulated radiotherapy and RapidArc planning techniques for ipsilateral and bilateral head and neck irradiation.

    PubMed

    Pursley, Jennifer; Damato, Antonio L; Czerminska, Maria A; Margalit, Danielle N; Sher, David J; Tishler, Roy B

    2017-01-01

    The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is

  17. Volumetric modulated arc therapy improves dosimetry and reduces treatment time compared to conventional intensity-modulated radiotherapy for locoregional radiotherapy of left-sided breast cancer and internal mammary nodes.

    PubMed

    Popescu, Carmen C; Olivotto, Ivo A; Beckham, Wayne A; Ansbacher, Will; Zavgorodni, Sergei; Shaffer, Richard; Wai, Elaine S; Otto, Karl

    2010-01-01

    Volumetric modulated arc therapy (VMAT) is a novel extension of conventional intensity-modulated radiotherapy (cIMRT), in which an optimized three-dimensional dose distribution may be delivered in a single gantry rotation. VMAT is the predecessor to RapidArc (Varian Medical System). This study compared VMAT with cIMRT and with conventional modified wide-tangent (MWT) techniques for locoregional radiotherapy for left-sided breast cancer, including internal mammary nodes. Therapy for 5 patients previously treated with 50 Gy/25 fractions using nine-field cIMRT was replanned with VMAT and MWT. Comparative endpoints were planning target volume (PTV) dose homogeneity, doses to surrounding structures, number of monitor units, and treatment delivery time. For VMAT, two 190 degrees arcs with 2-cm overlapping jaws were required to optimize over the large treatment volumes. Treatment plans generated using VMAT optimization resulted in PTV homogeneity similar to that of cIMRT and MWT. The average heart volumes receiving >30 Gy for VMAT, cIMRT, and MWT were 2.6% +/- 0.7%, 3.5% +/- 0.8%, and 16.4% +/- 4.3%, respectively, and the average ipsilateral lung volumes receiving >20 Gy were 16.9% +/- 1.1%, 17.3% +/- 0.9%, and 37.3% +/- 7.2%, respectively. The average mean dose to the contralateral medial breast was 3.2 +/- 0.6 Gy for VMAT, 4.3 +/- 0.4 Gy for cIMRT, and 4.4 +/- 4.7 Gy for MWT. The healthy tissue volume percentages receiving 5 Gy were significantly larger with VMAT (33.1% +/- 2.1%) and IMRT (45.3% +/- 3.1%) than with MWT (19.4% +/- 3.7%). VMAT reduced the number of monitor units by 30% and the treatment time by 55% compared with cIMRT. VMAT achieved similar PTV coverage and sparing of organs at risk, with fewer monitor units and shorter delivery time than cIMRT.

  18. Volumetric Modulated Arc Therapy Improves Dosimetry and Reduces Treatment Time Compared to Conventional Intensity-Modulated Radiotherapy for Locoregional Radiotherapy of Left-Sided Breast Cancer and Internal Mammary Nodes

    SciTech Connect

    Popescu, Carmen C.; Olivotto, Ivo A.; Beckham, Wayne A.; Ansbacher, Will; Zavgorodni, Sergei; Shaffer, Richard; Wai, Elaine S.; Otto, Karl

    2010-01-15

    Purpose: Volumetric modulated arc therapy (VMAT) is a novel extension of conventional intensity-modulated radiotherapy (cIMRT), in which an optimized three-dimensional dose distribution may be delivered in a single gantry rotation. VMAT is the predecessor to RapidArc (Varian Medical System). This study compared VMAT with cIMRT and with conventional modified wide-tangent (MWT) techniques for locoregional radiotherapy for left-sided breast cancer, including internal mammary nodes. Methods and Materials: Therapy for 5 patients previously treated with 50 Gy/25 fractions using nine-field cIMRT was replanned with VMAT and MWT. Comparative endpoints were planning target volume (PTV) dose homogeneity, doses to surrounding structures, number of monitor units, and treatment delivery time. Results: For VMAT, two 190 deg. arcs with 2-cm overlapping jaws were required to optimize over the large treatment volumes. Treatment plans generated using VMAT optimization resulted in PTV homogeneity similar to that of cIMRT and MWT. The average heart volumes receiving >30 Gy for VMAT, cIMRT, and MWT were 2.6% +- 0.7%, 3.5% +- 0.8%, and 16.4% +- 4.3%, respectively, and the average ipsilateral lung volumes receiving >20 Gy were 16.9% +- 1.1%, 17.3% +- 0.9%, and 37.3% +- 7.2%, respectively. The average mean dose to the contralateral medial breast was 3.2 +- 0.6 Gy for VMAT, 4.3 +- 0.4 Gy for cIMRT, and 4.4 +- 4.7 Gy for MWT. The healthy tissue volume percentages receiving 5 Gy were significantly larger with VMAT (33.1% +- 2.1%) and IMRT (45.3% +- 3.1%) than with MWT (19.4% +- 3.7%). VMAT reduced the number of monitor units by 30% and the treatment time by 55% compared with cIMRT. Conclusions: VMAT achieved similar PTV coverage and sparing of organs at risk, with fewer monitor units and shorter delivery time than cIMRT.

  19. SU-E-P-51: Dosimetric Comparison to Organs at Risk Sparing Using Volumetric-Modulated Arc Therapy Versus Intensity-Modulated Radiotherapy in Postoperative Radiotherapy of Left-Sided Breast Cancer

    SciTech Connect

    Qiao, L; Deng, G; Xie, J; Cheng, J; Liang, N; Zhang, J; Zhang, J; Luo, H

    2015-06-15

    Purpose: To compare the dosimetric characteristics of volumetric-modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for left-sided breast cancer patients with modified radical mastectomy. Methods: Twenty-four left-sided breast cancer patients treated with modified radical mastectomy were selected in this study. The planning target volume (PTV) was generated by using 7-mm uniform expansion of the clinical target volume (CTV) in all direction except the skin surface. The organs at risk (OARs) included heart, left lung, right lung, and right breast. Dose volume histograms (DVHs) were utilized to evaluate the dose distribution in PTV and OARs. Results: Both VMAT and IMRT plans met the requirement of PTV coverage. VMAT was superior to IMRT in terms of conformity, with a statistically significant difference (p=0.024). Mean doses, V5 and V10 of heart and both lungs in VMAT plans were significantly decreased compared to IMRT plans (P<0.05), but in terms of heart volume irradiated by high doses (V30 and V45), no significant differences were observed (P>0.05). For right breast, VMAT showed the reduction of V5 in comparison with IMRT (P<0.05). Additionally, the mean number of monitor units (MU) and treatment time in VMAT (357.21, 3.62 min) were significantly less than those in IMRT (1132.85, 8.74 min). Conclusion: VMAT showed similar PTV coverage and significant advantage in OARs sparing compared with IMRT, especially in terms of decreased volumes irradiated by low doses, while significantly reducing the treatment time and MU number.

  20. Linear algebraic methods applied to intensity modulated radiation therapy.

    PubMed

    Crooks, S M; Xing, L

    2001-10-01

    Methods of linear algebra are applied to the choice of beam weights for intensity modulated radiation therapy (IMRT). It is shown that the physical interpretation of the beam weights, target homogeneity and ratios of deposited energy can be given in terms of matrix equations and quadratic forms. The methodology of fitting using linear algebra as applied to IMRT is examined. Results are compared with IMRT plans that had been prepared using a commercially available IMRT treatment planning system and previously delivered to cancer patients.

  1. Dosimetric comparison for volumetric modulated arc therapy and intensity-modulated radiotherapy on the left-sided chest wall and internal mammary nodes irradiation in treating post-mastectomy breast cancer

    PubMed Central

    Zhang, Qian; Yu, Xiao Li; Hu, Wei Gang; Chen, Jia Yi; Wang, Jia Zhou; Ye, Jin Song; Guo, Xiao Mao

    2015-01-01

    Background The aim of the study was to evaluate the dosimetric benefit of applying volumetric modulated arc therapy (VMAT) on the post-mastectomy left-sided breast cancer patients, with the involvement of internal mammary nodes (IMN). Patients and methods The prescription dose was 50 Gy delivered in 25 fractions, and the clinical target volume included the left chest wall (CW) and IMN. VMAT plans were created and compared with intensity-modulated radiotherapy (IMRT) plans on Pinnacle treatment planning system. Comparative endpoints were dose homogeneity within planning target volume (PTV), target dose coverage, doses to the critical structures including heart, lungs and the contralateral breast, number of monitor units and treatment delivery time. Results VMAT and IMRT plans showed similar PTV dose homogeneity, but, VMAT provided a better dose coverage for IMN than IMRT (p = 0.017). The mean dose (Gy), V30 (%) and V10 (%) for the heart were 13.5 ± 5.0 Gy, 9.9% ± 5.9% and 50.2% ± 29.0% by VMAT, and 14.0 ± 5.4 Gy, 10.6% ± 5.8% and 55.7% ± 29.6% by IMRT, respectively. The left lung mean dose (Gy), V20 (%), V10 (%) and the right lung V5 (%) were significantly reduced from 14.1 ± 2.3 Gy, 24.2% ± 5.9%, 42.4% ± 11.9% and 41.2% ± 12.3% with IMRT to 12.8 ± 1.9 Gy, 21.0% ± 3.8%, 37.1% ± 8.4% and 32.1% ± 18.2% with VMAT, respectively. The mean dose to the contralateral breast was 1.7 ± 1.2 Gy with VMAT and 2.3 ± 1.6 Gy with IMRT. Finally, VMAT reduced the number of monitor units by 24% and the treatment time by 53%, as compared to IMRT. Conclusions Compared to 5-be am step-and-shot IMRT, VMAT achieves similar or superior target coverage and a better normal tissue sparing, with fewer monitor units and shorter delivery time. PMID:25810708

  2. [Dosimetric verification of the intensity modulated radiation therapy].

    PubMed

    Zhang, Yuhai; Gao, Yang

    2010-05-01

    To research the method of dosimetric verification of the intensity modulated radiation therapy (IMRT). The IMRT treatment plans were designed by Eclipse TPS and were implemented in Varian ClinacIX LA with 6MV X-ray. The absolute point doses were measured using a PTW 0.6 cc ion chamber with UNIDOS E dosimeter and the planes dose distributions were measured using PTW 2D-Array ion chamber in the phantom. The error between the measured dose and calculated dose in the interesting points was less than 3%. The points passed ratio was more than 90% in gamma analysis method (3 mm 13%) about the plane dose distribution verification. The method of dosimetric verification of IMRT is reliable and efficient in the implementation.

  3. Palliative intensity modulated radiation therapy for symptomatic adrenal metastasis.

    PubMed

    Mod, H; Patel, V

    2013-05-01

    Metastasis to the adrenal glands is quite common; especially from melanomas, breast, lung, renal and gastro-intestinal tumours. The most common tumour found in the adrenals in post mortem series is a metastatic tumour; incidence ranging from 13 to 27%. The diagnosis of adrenal metastasis is now more common and easier due to staging and subsequent follow up with Computed tomography /Magnetic resonance imaging and or positron emission tomography-computed tomography imaging studies. Most of the times these metastatic lesions are clinically occult and those that do have clinical symptoms complain of pain, nausea, vomiting and early satiety. We irradiated a patient of non small cell lung cancer with adrenal metastasis with palliative Intensity Modulated Radiation Therapy and achieved a good response in terms of pain relief, stable disease and no side effects of the treatment.

  4. Prone breast intensity modulated radiation therapy: 5-year results.

    PubMed

    Osa, Etin-Osa O; DeWyngaert, Keith; Roses, Daniel; Speyer, James; Guth, Amber; Axelrod, Deborah; Fenton Kerimian, Maria; Goldberg, Judith D; Formenti, Silvia C

    2014-07-15

    To report the 5-year results of a technique of prone breast radiation therapy delivered by a regimen of accelerated intensity modulated radiation therapy with a concurrent boost to the tumor bed. Between 2003 and 2006, 404 patients with stage I-II breast cancer were prospectively enrolled into 2 consecutive protocols, institutional trials 03-30 and 05-181, that used the same regimen of 40.5 Gy/15 fractions delivered to the index breast over 3 weeks, with a concomitant daily boost to the tumor bed of 0.5 Gy (total dose 48 Gy). All patients were treated after segmental mastectomy and had negative margins and nodal assessment. Patients were set up prone: only if lung or heart volumes were in the field was a supine setup attempted and chosen if found to better spare these organs. Ninety-two percent of patients were treated prone, 8% supine. Seventy-two percent had stage I, 28% stage II invasive breast cancer. In-field lung volume ranged from 0 to 228.27 cm(3), mean 19.65 cm(3). In-field heart volume for left breast cancer patients ranged from 0 to 21.24 cm(3), mean 1.59 cm(3). There was no heart in the field for right breast cancer patients. At a median follow-up of 5 years, the 5-year cumulative incidence of isolated ipsilateral breast tumor recurrence was 0.82% (95% confidence interval [CI] 0.65%-1.04%). The 5-year cumulative incidence of regional recurrence was 0.53% (95% CI 0.41%-0.69%), and the 5-year overall cumulative death rate was 1.28% (95% CI 0.48%-3.38%). Eighty-two percent (95% CI 77%-85%) of patients judged their final cosmetic result as excellent/good. Prone accelerated intensity modulated radiation therapy with a concomitant boost results in excellent local control and optimal sparing of heart and lung, with good cosmesis. Radiation Therapy Oncology Group protocol 1005, a phase 3, multi-institutional, randomized trial is ongoing and is evaluating the equivalence of a similar dose and fractionation approach to standard 6-week radiation therapy with a

  5. Prone Breast Intensity Modulated Radiation Therapy: 5-Year Results

    SciTech Connect

    Osa, Etin-Osa O.; DeWyngaert, Keith; Roses, Daniel; Speyer, James; Guth, Amber; Axelrod, Deborah; Fenton Kerimian, Maria; Goldberg, Judith D.; Formenti, Silvia C.

    2014-07-15

    Purpose: To report the 5-year results of a technique of prone breast radiation therapy delivered by a regimen of accelerated intensity modulated radiation therapy with a concurrent boost to the tumor bed. Methods and Materials: Between 2003 and 2006, 404 patients with stage I-II breast cancer were prospectively enrolled into 2 consecutive protocols, institutional trials 03-30 and 05-181, that used the same regimen of 40.5 Gy/15 fractions delivered to the index breast over 3 weeks, with a concomitant daily boost to the tumor bed of 0.5 Gy (total dose 48 Gy). All patients were treated after segmental mastectomy and had negative margins and nodal assessment. Patients were set up prone: only if lung or heart volumes were in the field was a supine setup attempted and chosen if found to better spare these organs. Results: Ninety-two percent of patients were treated prone, 8% supine. Seventy-two percent had stage I, 28% stage II invasive breast cancer. In-field lung volume ranged from 0 to 228.27 cm{sup 3}, mean 19.65 cm{sup 3}. In-field heart volume for left breast cancer patients ranged from 0 to 21.24 cm{sup 3}, mean 1.59 cm{sup 3}. There was no heart in the field for right breast cancer patients. At a median follow-up of 5 years, the 5-year cumulative incidence of isolated ipsilateral breast tumor recurrence was 0.82% (95% confidence interval [CI] 0.65%-1.04%). The 5-year cumulative incidence of regional recurrence was 0.53% (95% CI 0.41%-0.69%), and the 5-year overall cumulative death rate was 1.28% (95% CI 0.48%-3.38%). Eighty-two percent (95% CI 77%-85%) of patients judged their final cosmetic result as excellent/good. Conclusions: Prone accelerated intensity modulated radiation therapy with a concomitant boost results in excellent local control and optimal sparing of heart and lung, with good cosmesis. Radiation Therapy Oncology Group protocol 1005, a phase 3, multi-institutional, randomized trial is ongoing and is evaluating the equivalence of a similar dose and

  6. Commissioning of Peacock System for intensity-modulated radiation therapy.

    PubMed

    Saw, C B; Ayyangar, K M; Thompson, R B; Zhen, W; Enke, C A

    2001-01-01

    The Peacock System was introduced to perform tomographic intensity-modulated radiation therapy (IMRT). Commissioning of the Peacock System included the alignment of the multileaf intensity-modulating collimator (MIMiC) to the beam axis, the alignment of the RTA device for immobilization, and checking the integrity of the CRANE for indexing the treatment couch. In addition, the secondary jaw settings, couch step size, and transmission through the leaves were determined. The dosimetric data required for the CORVUS planning system were divided into linear accelerator-specific and MIMiC-specific. The linear accelerator-specific dosimetric data were relative output in air, relative output in phantom, percent depth dose for a range of field sizes, and diagonal dose profiles for a large field size. The MIMiC-specific dosimetric data were the in-plane and cross-plane dose profiles of a small and a large field size to derive the penumbra fit. For each treatment unit, the Beam Utility software requires the data be entered into the CORVUS planning system in modular forms. These modules were treatment unit information, angle definition, configuration, gantry and couch angles range, dosimetry, results, and verification plans. After the appropriate machine data were entered, CORVUS created a dose model. The dose model was used to create known simple dose distribution for evaluation using the verification tools of the CORVUS. The planned doses for phantoms were confirmed using an ion chamber for point dose measurement and film for relative dose measurement. The planning system calibration factor was initially set at 1.0 and will be changed after data on clinical cases are acquired. The treatment unit was released for clinical use after the approval icon was checked in the verification plans module.

  7. Planning and delivery of intensity-modulated radiation therapy.

    PubMed

    Yu, Cedric X; Amies, Christopher J; Svatos, Michelle

    2008-12-01

    Intensity modulated radiation therapy (IMRT) is an advanced form of external beam radiation therapy. IMRT offers an additional dimension of freedom as compared with field shaping in three-dimensional conformal radiation therapy because the radiation intensities within a radiation field can be varied according to the preferences of locations within a given beam direction from which the radiation is directed to the tumor. This added freedom allows the treatment planning system to better shape the radiation doses to conform to the target volume while sparing surrounding normal structures. The resulting dosimetric advantage has shown to translate into clinical advantages of improving local and regional tumor control. It also offers a valuable mechanism for dose escalation to tumors while simultaneously reducing radiation toxicities to the surrounding normal tissue and sensitive structures. In less than a decade, IMRT has become common practice in radiation oncology. Looking forward, the authors wonder if IMRT has matured to such a point that the room for further improvement has diminished and so it is pertinent to ask what the future will hold for IMRT. This article attempts to look from the perspective of the current state of the technology to predict the immediate trends and the future directions. This article will (1) review the clinical experience of IMRT; (2) review what we learned in IMRT planning; (3) review different treatment delivery techniques; and finally, (4) predict the areas of advancements in the years to come.

  8. 3D treatment planning and intensity-modulated radiation therapy.

    PubMed

    Purdy, J A

    1999-10-01

    Three-dimensional (3D) image-based treatment planning and new delivery technologies have spurred the implementation of external beam radiation therapy techniques, in which the high-dose region is conformed much more closely to the target volume than previously possible, thus reducing the volume of normal tissues receiving a high dose. This form of external beam irradiation is referred to as 3D conformal radiation therapy (3DCRT). 3DCRT is not just an add-on to the current radiation oncology process; it represents a radical change in practice, particularly for the radiation oncologist. Defining target volumes and organs at risk in 3D by drawing contours on CT images on a slice-by-slice basis, as opposed to drawing beam portals on a simulator radiograph, can be challenging, because radiation oncologists are generally not well trained in cross-sectional imaging. Currently, the 3DCRT approach will increase the time and effort required by physicians inexperienced with 3D treatment planning. Intensity-modulated radiation therapy (IMRT) is a more advanced form of 3DCRT, but there is considerable developmental work remaining. The instrumentation and methods used for IMRT quality assurance procedures and testing are not well established. Computer optimization cost functions are too simplistic, and thus time-consuming. Subjective plan evaluation by the radiation oncologist is still the norm. In addition, many fundamental questions regarding IMRT remain unanswered. For example, the radiobiophysical consequences of altered time-dose-fraction are unknown. Also, the fact that there is much greater dose heterogeneity for both the target and normal critical structures with IMRT compared to traditional irradiation techniques challenges current radiation oncology planning principles. However, this new process of planning and treatment delivery shows significant potential for improving the therapeutic ratio. In addition, while inefficient today, these systems, when fully developed

  9. The Effect of Flattening Filter Free on Three-dimensional Conformal Radiation Therapy (3D-CRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT) Plans for Metastatic Brain Tumors from Non-small Cell Lung Cancer.

    PubMed

    Shi, Li-Wan; Lai, You-Qun; Lin, Qin; Ha, Hui-Ming; Fu, Li-Rong

    2015-07-01

    Flattening filter free (FFF) may affect outcome measures of radiotherapy. The objective of this study is to compare the dosimetric parameters in three types of radiotherapy plans, three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT), with or without the flattening filter (FF), developed for the treatment of metastatic brain tumors from non-small cell lung cancer (NSCLC). From July 2013 to October 2013, 3D-CRT, IMRT, and VMAT treatment plans were designed using 6 MV and 10 MV, with and without FF, for 10 patients with brain metastasis from NSCLC. The evaluation of the treatment plans included homogeneity index (HI), conformity index (CI), monitor units (MU), mean dose (Dmean), treatment time, and the influence of FFF on volumes. There was no difference in CI or HI between FFF and FF models with 3D-CRT, IMRT, and VMAT plans. At 6 MV, a lower Dmean was seen in the FFF model of 3D-CRT and in the VMAT plan at 10 MV. In the IMRT 6 MV, IMRT 10 MV, and VMAT 10 MV plans, higher MUs were seen in the FFF models. FFF treatments are similar in quality to FF plans, generally lead to more monitor units, and are associated with shorter treatment times. FFF plans ranked by the order of superiority in terms of a time advantage are VMAT, 3D-CRT, and IMRT.

  10. Pitfalls in normalization for intensity-modulated radiation therapy planning

    SciTech Connect

    Williams, Greg . E-mail: greg.williams@hci.utah.edu; Tobler, Matt; Leavitt, Dennis

    2005-01-01

    Three-dimensional (3D) treatment planning often involves complex combinations of beam energies, treatment fields, and beam modifying devices. Even when a plan is devised that meets many treatment-planning objectives, limitations in the planner's ability to further adjust beam characteristics may require the radiation dose prescription to be normalized to an isodose level that best covers the target volume. While these normalizations help meet the volume coverage goals, they also result in adjustment of the dose delivered to the normal tissues and must be carefully evaluated. Intensity-modulated radiation therapy (IMRT) treatment planning allows combinations of complex dose patterns, in order to achieve the desired treatment planning goals. These dose patterns are created by defining a set of treatment planning objectives and then allowing the treatment planning computer to create intensity patterns, through the use of moving multileaf collimation that will meet the requested goals. Often, when an IMRT treatment plan is created that meets many of the treatment planning goals but falls short of volume coverage requirements, the planner is tempted to apply normalization principles similar to those utilized with 3D treatment planning. Again, these normalizations help meet the volume coverage goals, but unlike 3D planning situations, may result in avoidable delivery of additional doses to the normal tissues. The focus of this study is to evaluate the effect of application of normalization for IMRT planning using multiple patient situations. Recommendations would favor re-optimization over normalization in most planning situations.

  11. Intensity-Modulated Radiation Therapy in Childhood Ependymoma

    SciTech Connect

    Schroeder, Thomas M.; Chintagumpala, Murali; Okcu, M. Fatih; Chiu, J. Kam; Teh, Bin S.; Woo, Shiao Y.; Paulino, Arnold C.

    2008-07-15

    Purpose: To determine the patterns of failure after intensity-modulated radiation therapy (IMRT) for localized intracranial ependymoma. Methods and Materials: From 1994 to 2005, 22 children with pathologically proven, localized, intracranial ependymoma were treated with adjuvant IMRT. Of the patients, 12 (55%) had an infratentorial tumor and 14 (64%) had anaplastic histology. Five patients had a subtotal resection (STR), as evidenced by postoperative magnetic resonance imaging. The clinical target volume encompassed the tumor bed and any residual disease plus margin (median dose 54 Gy). Median follow-up for surviving patients was 39.8 months. Results: The 3-year overall survival rate was 87% {+-} 9%. The 3-year local control rate was 68% {+-} 12%. There were six local recurrences, all in the high-dose region of the treatment field. Median time to recurrence was 21.7 months. Of the 5 STR patients, 4 experienced recurrence and 3 died. Patients with a gross total resection had significantly better local control (p = 0.024) and overall survival (p = 0.008) than those with an STR. At last follow-up, no patient had developed visual loss, brain necrosis, myelitis, or a second malignancy. Conclusions: Treatment with IMRT provides local control and survival rates comparable with those in historic publications using larger treatment volumes. All failures were within the high-dose region, suggesting that IMRT does not diminish local control. The degree of surgical resection was shown to be significant for local control and survival.

  12. Intensity modulated radiation therapy for breast cancer: current perspectives

    PubMed Central

    Buwenge, Milly; Cammelli, Silvia; Ammendolia, Ilario; Tolento, Giorgio; Zamagni, Alice; Arcelli, Alessandra; Macchia, Gabriella; Deodato, Francesco; Cilla, Savino; Morganti, Alessio G

    2017-01-01

    Background Owing to highly conformed dose distribution, intensity modulated radiation therapy (IMRT) has the potential to improve treatment results of radiotherapy (RT). Postoperative RT is a standard adjuvant treatment in conservative treatment of breast cancer (BC). The aim of this review is to analyze available evidence from randomized controlled trials (RCTs) on IMRT in BC, particularly in terms of reduction of side effects. Methods A literature search of the bibliographic database PubMed, from January 1990 through November 2016, was performed. Only RCTs published in English were included. Results Ten articles reporting data from 5 RCTs fulfilled the selection criteria and were included in our review. Three out of 5 studies enrolled only selected patients in terms of increased risk of toxicity. Three studies compared IMRT with standard tangential RT. One study compared the results of IMRT in the supine versus the prone position, and one study compared standard treatment with accelerated partial breast IMRT. Three studies reported reduced acute and/or late toxicity using IMRT compared with standard RT. No study reported improved quality of life. Conclusion IMRT seems able to reduce toxicity in selected patients treated with postoperative RT for BC. Further analyses are needed to better define patients who are candidates for this treatment modality. PMID:28293119

  13. Robust PET-guided intensity-modulated radiation therapy

    SciTech Connect

    Li, H.; Bissonnette, J. P.; Purdie, T.; Chan, T. C. Y.

    2015-08-15

    Purpose: Functional image guided intensity-modulated radiation therapy has the potential to improve cancer treatment quality by basing treatment parameters such as heterogeneous dose distributions information derived from imaging. However, such heterogeneous dose distributions are subject to imaging uncertainty. In this paper, the authors develop a robust optimization model to design plans that are desensitized to imaging uncertainty. Methods: Starting from the pretreatment fluorodeoxyglucose-positron emission tomography scans, the authors use the raw voxel standard uptake values (SUVs) as input into a series of intermediate functions to transform the SUV into a desired dose. The calculated desired doses were used as an input into a robust optimization model to generate beamlet intensities. For each voxel, the authors assume that the true SUV cannot be observed but instead resides in an interval centered on the nominal (i.e., observed) SUV. Then the authors evaluated the nominal and robust solutions through a simulation study. The simulation considered the effect of the true SUV being different from the nominal SUV on the quality of the treatment plan. Treatment plans were compared on the metrics of objective function value and tumor control probability (TCP). Results: Computational results demonstrate the potential for improvements in tumor control probability and deviation from the desired dose distribution compared to a nonrobust model while maintaining acceptable tissue dose. Conclusions: Robust optimization can help design treatment plans that are more stable in the presence of image value uncertainties.

  14. A comparison of intensity modulated x-ray therapy to intensity modulated proton therapy for the delivery of non-uniform dose distributions

    NASA Astrophysics Data System (ADS)

    Flynn, Ryan

    2007-12-01

    The distribution of biological characteristics such as clonogen density, proliferation, and hypoxia throughout tumors is generally non-uniform, therefore it follows that the optimal dose prescriptions should also be non-uniform and tumor-specific. Advances in intensity modulated x-ray therapy (IMXT) technology have made the delivery of custom-made non-uniform dose distributions possible in practice. Intensity modulated proton therapy (IMPT) has the potential to deliver non-uniform dose distributions as well, while significantly reducing normal tissue and organ at risk dose relative to IMXT. In this work, a specialized treatment planning system was developed for the purpose of optimizing and comparing biologically based IMXT and IMPT plans. The IMXT systems of step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) and the IMPT systems of intensity modulated spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT), were simulated. A thorough phantom study was conducted in which several subvolumes, which were contained within a base tumor region, were boosted or avoided with IMXT and IMPT. Different boosting situations were simulated by varying the size, proximity, and the doses prescribed to the subvolumes, and the size of the phantom. IMXT and IMPT were also compared for a whole brain radiation therapy (WBRT) case, in which a brain metastasis was simultaneously boosted and the hippocampus was avoided. Finally, IMXT and IMPT dose distributions were compared for the case of non-uniform dose prescription in a head and neck cancer patient that was based on PET imaging with the Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone (Cu-ATSM) hypoxia marker. The non-uniform dose distributions within the tumor region were comparable for IMXT and IMPT. IMPT, however, was capable of delivering the same non-uniform dose distributions within a tumor using a 180° arc as for a full 360° rotation, which resulted in the reduction of normal tissue integral dose by a factor of

  15. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    SciTech Connect

    Lim, Karen; Stewart, James; Kelly, Valerie; Xie, Jason; Brock, Kristy K.; Moseley, Joanne; Cho, Young-Bin; Fyles, Anthony; Lundin, Anna; Rehbinder, Henrik; Löf, Johan; Jaffray, David A.; Milosevic, Michael

    2014-09-01

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost.

  16. [Modalities of breast cancer irradiation in 2016: Aims and indications of intensity modulated radiation therapy].

    PubMed

    Bourgier, C; Fenoglietto, P; Lemanski, C; Ducteil, A; Charissoux, M; Draghici, R; Azria, D

    2016-10-01

    Irradiation techniques for breast cancer (arctherapy, tomotherapy) are evolving and intensity-modulated radiation therapy is being increasingly considered for the management of these tumours. Here, we propose a review of intensity-modulated radiation therapy planning issues, clinical toxicities and indications for breast cancer.

  17. Survey of resident education in intensity-modulated radiation therapy.

    PubMed

    Malik, Renuka; Oh, Julia L; Roeske, John C; Mundt, Arno J

    2005-06-01

    Intensity-modulated radiation therapy (IMRT) has been gaining increasing popularity among practicing physicians in the U.S., but the extent to which radiation oncology residents are taught the principles of this technology and are trained to use IMRT remains unknown. In this paper, we assessed the current level of resident education in IMRT in the United States. Chief residents at all 77 accredited radiation oncology programs were sent a 13-question survey addressing formal didactics and hands-on experience in IMRT. The survey assessed the frequency, subject, and format of IMRT didactics. Questions also addressed the number of IMRT patients and anatomical sites treated, resident involvement in the IMRT process, and the intent of IMRT use. Finally, residents were asked for their opinions on their IMRT education. Sixty-one surveys (79%) were completed. Overall, forty-three respondents (71%) reported receiving formal IMRT didactics, with nearly one-third reporting extensive didactics (> or = 3 lectures/seminars et cetera per year). The most common didactic formats were lectures (95%) and journal clubs (63%), most commonly supervised by physicists (98%). Involvement by physicians and radiobiologists were reported by 63% and 7% of respondents, respectively. Overall, 87% of respondents had hands-on IMRT training, with nearly one-half having treated > 25 patients. The most common sites treated were head and neck (94%) and prostate (81%). Involvement in all aspects of the IMRT process was common, particularly target and tissue delineation (98%) and plan evaluation (93%). Most respondents (79%) with hands-on experience reported receiving formal didactics. However, nearly one-third received no or only minimal formal didactics. The percentage of respondents desiring increased IMRT didactics and hands-on experience were 70% and 47%, respectively. Our results suggest that the great majority of radiation oncology residents in the United States are currently exposed to didactics

  18. Intensity Modulated Radiation Therapy With Dose Painting to Treat Rhabdomyosarcoma

    SciTech Connect

    Yang, Joanna C.; Dharmarajan, Kavita V.; Wexler, Leonard H.; La Quaglia, Michael P.; Happersett, Laura; Wolden, Suzanne L.

    2012-11-01

    Purpose: To examine local control and patterns of failure in rhabdomyosarcoma patients treated with intensity modulated radiation therapy (RT) with dose painting (DP-IMRT). Patients and Methods: A total of 41 patients underwent DP-IMRT with chemotherapy for definitive treatment. Nineteen also underwent surgery with or without intraoperative RT. Fifty-six percent had alveolar histologic features. The median interval from beginning chemotherapy to RT was 17 weeks (range, 4-25). Very young children who underwent second-look procedures with or without intraoperative RT received reduced doses of 24-36 Gy in 1.4-1.8-Gy fractions. Young adults received 50.4 Gy to the primary tumor and lower doses of 36 Gy in 1.8-Gy fractions to at-risk lymph node chains. Results: With 22 months of median follow-up, the actuarial local control rate was 90%. Patients aged {<=}7 years who received reduced overall and fractional doses had 100% local control, and young adults had 79% (P=.07) local control. Three local failures were identified in young adults whose primary target volumes had received 50.4 Gy in 1.8-Gy fractions. Conclusions: DP-IMRT with lower fractional and cumulative doses is feasible for very young children after second-look procedures with or without intraoperative RT. DP-IMRT is also feasible in adolescents and young adults with aggressive disease who would benefit from prophylactic RT to high-risk lymph node chains, although dose escalation might be warranted for improved local control. With limited follow-up, it appears that DP-IMRT produces local control rates comparable to those of sequential IMRT in patients with rhabdomyosarcoma.

  19. Prioritized efficiency optimization for intensity modulated proton therapy.

    PubMed

    Müller, Birgit S; Wilkens, Jan J

    2016-12-07

    A high dosimetric quality and short treatment time are major goals in radiotherapy planning. Intensity modulated proton therapy (IMPT) plans obtain dose distributions of great conformity but often result in long delivery times which are typically not incorporated into the optimization process. We present an algorithm to optimize delivery efficiency of IMPT plans while maintaining plan quality, and study the potential trade-offs of these interdependent objectives. The algorithm is based on prioritized optimization, a stepwise approach to implemented objectives. First the quality of the plan is optimized. The second step of the prioritized efficiency optimization (PrEfOpt) routine offers four alternatives for reducing delivery time: minimization of the total spot weight sum (A), maximization of the lowest spot intensity of each energy layer (B), elimination of low-weighted spots (C) or energy layers (D). The trade-off between dosimetric quality (step I) and treatment time (step II) is controlled during the optimization by option-dependent parameters. PrEfOpt was applied to a clinical patient case, and plans for different trade-offs were calculated. Delivery times were simulated for two virtual facilities with constant and variable proton current, i.e. independent and dependent on the optimized spot weight distributions. Delivery times decreased without major degradation of plan quality; absolute time reductions varied with the applied method and facility type. Minimizing the total spot weight sum (A) reduced times by 28% for a similar plan quality at a constant current (changes of minimum dose in the target  <1%). For a variable proton current, eliminating low-weighted spots (C) led to remarkably faster delivery (16%). The implementation of an efficiency-optimization step into the optimization process can yield reduced delivery times with similar plan qualities. A potential clinical application of PrEfOpt is the generation of multiple plans with different trade

  20. Prioritized efficiency optimization for intensity modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Müller, Birgit S.; Wilkens, Jan J.

    2016-12-01

    A high dosimetric quality and short treatment time are major goals in radiotherapy planning. Intensity modulated proton therapy (IMPT) plans obtain dose distributions of great conformity but often result in long delivery times which are typically not incorporated into the optimization process. We present an algorithm to optimize delivery efficiency of IMPT plans while maintaining plan quality, and study the potential trade-offs of these interdependent objectives. The algorithm is based on prioritized optimization, a stepwise approach to implemented objectives. First the quality of the plan is optimized. The second step of the prioritized efficiency optimization (PrEfOpt) routine offers four alternatives for reducing delivery time: minimization of the total spot weight sum (A), maximization of the lowest spot intensity of each energy layer (B), elimination of low-weighted spots (C) or energy layers (D). The trade-off between dosimetric quality (step I) and treatment time (step II) is controlled during the optimization by option-dependent parameters. PrEfOpt was applied to a clinical patient case, and plans for different trade-offs were calculated. Delivery times were simulated for two virtual facilities with constant and variable proton current, i.e. independent and dependent on the optimized spot weight distributions. Delivery times decreased without major degradation of plan quality; absolute time reductions varied with the applied method and facility type. Minimizing the total spot weight sum (A) reduced times by 28% for a similar plan quality at a constant current (changes of minimum dose in the target  <1%). For a variable proton current, eliminating low-weighted spots (C) led to remarkably faster delivery (16%). The implementation of an efficiency-optimization step into the optimization process can yield reduced delivery times with similar plan qualities. A potential clinical application of PrEfOpt is the generation of multiple plans with different trade

  1. A Phase II Trial of Arc-Based Hypofractionated Intensity-Modulated Radiotherapy in Localized Prostate Cancer

    SciTech Connect

    Lock, Michael; Best, Lara; Wong, Eugene; Bauman, Glenn; D'Souza, David; Venkatesan, Varagur; Sexton, Tracy; Ahmad, Belal; Izawa, Jonathan; Rodrigues, George

    2011-08-01

    Purpose: To evaluate acute and late genitourinary (GU) and gastrointestinal (GI) toxicity and biochemical control of hypofractionated, image-guided (fiducial markers or ultrasound guidance), simplified intensity-modulated arc therapy for localized prostate cancer. Methods and Materials: This Phase II prospective clinical trial for T1a-2cNXM0 prostate cancer enrolled 66 patients who received 63.2 Gy in 20 fractions over 4 weeks. Fiducial markers were used for image guidance in 30 patients and daily ultrasound for the remainder. Toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: Median follow-up was 36 months. Acute Phase Grade 2 and 3 toxicity was 34% and 9% for GU vs. 25% and 10% for GI symptoms. One Grade 4 acute GI toxicity occurred in a patient with unrecognized Crohn's disease. Late Grade 2 and 3 toxicity for GU was 14% and 5%, and GI toxicity was 25% and 3%. One late GI Grade 4 toxicity was observed in a patient with significant comorbidities (anticoagulation, vascular disease). Acute GI toxicity {>=}Grade 2 was shown to be a predictor for late toxicity Grade {>=}2 (p < 0.001). The biochemical disease-free survival at 3 years was 95%. Conclusions: Hypofractionated simplified intensity-modulated arc therapy radiotherapy given as 63.2 Gy in 20 fractions demonstrated promising biochemical control rates; however, higher rates of acute Grade 3 GU and GI toxicity and higher late Grade 2 GU and GI toxicity were noted. Ongoing randomized controlled trials should ultimately clarify issues regarding patient selection and the true rate of severe toxicity that can be directly attributed to hypofractionated radiotherapy.

  2. Comparative analysis of 60Co intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Fox, Christopher; Romeijn, H. Edwin; Lynch, Bart; Men, Chunhua; Aleman, Dionne M.; Dempsey, James F.

    2008-06-01

    In this study, we perform a scientific comparative analysis of using 60Co beams in intensity-modulated radiation therapy (IMRT). In particular, we evaluate the treatment plan quality obtained with (i) 6 MV, 18 MV and 60Co IMRT; (ii) different numbers of static multileaf collimator (MLC) delivered 60Co beams and (iii) a helical tomotherapy 60Co beam geometry. We employ a convex fluence map optimization (FMO) model, which allows for the comparison of plan quality between different beam energies and configurations for a given case. A total of 25 clinical patient cases that each contain volumetric CT studies, primary and secondary delineated targets, and contoured structures were studied: 5 head-and-neck (H&N), 5 prostate, 5 central nervous system (CNS), 5 breast and 5 lung cases. The DICOM plan data were anonymized and exported to the University of Florida optimized radiation therapy (UFORT) treatment planning system. The FMO problem was solved for each case for 5-71 equidistant beams as well as a helical geometry for H&N, prostate, CNS and lung cases, and for 3-7 equidistant beams in the upper hemisphere for breast cases, all with 6 MV, 18 MV and 60Co dose models. In all cases, 95% of the target volumes received at least the prescribed dose with clinical sparing criteria for critical organs being met for all structures that were not wholly or partially contained within the target volume. Improvements in critical organ sparing were found with an increasing number of equidistant 60Co beams, yet were marginal above 9 beams for H&N, prostate, CNS and lung. Breast cases produced similar plans for 3-7 beams. A helical 60Co beam geometry achieved similar plan quality as static plans with 11 equidistant 60Co beams. Furthermore, 18 MV plans were initially found not to provide the same target coverage as 6 MV and 60Co plans; however, adjusting the trade-offs in the optimization model allowed equivalent target coverage for 18 MV. For plans with comparable target coverage

  3. Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy

    SciTech Connect

    Li, Ruijiang; Xing, Lei

    2011-09-15

    Purpose: To propose an alternative radiation therapy (RT) planning and delivery scheme with optimal angular beam sampling and intrabeam modulation for improved dose distribution while maintaining high delivery efficiency. Methods: In the proposed approach, coined as dense angularly sampled and sparse intensity modulated RT (DASSIM-RT), a large number of beam angles are used to increase the angular sampling, leading to potentially more conformal dose distributions as compared to conventional IMRT. At the same time, intensity modulation of the incident beams is simplified to eliminate the dispensable segments, compensating the increase in delivery time caused by the increased number of beams and facilitating the plan delivery. In a sense, the proposed approach shifts and transforms, in an optimal fashion, some of the beam segments in conventional IMRT to the added beams. For newly available digital accelerators, the DASSIM-RT delivery can be made very efficient by concatenating the beams so that they can be delivered sequentially without operator's intervention. Different from VMAT, the level of intensity modulation in DASSIS-RT is field specific and optimized to meet the need of each beam direction. Three clinical cases (a head and neck (HN) case, a pancreas case, and a lung case) are used to evaluate the proposed RT scheme. DASSIM-RT, VMAT, and conventional IMRT plans are compared quantitatively in terms of the conformality index (CI) and delivery efficiency. Results: Plan quality improves generally with the number and intensity modulation of the incident beams. For a fixed number of beams or fixed level of intensity modulation, the improvement saturates after the intensity modulation or number of beams reaches to a certain level. An interplay between the two variables is observed and the saturation point depends on the values of both variables. For all the cases studied here, the CI of DASSIM-RT with 15 beams and 5 intensity levels (0.90, 0.79, and 0.84 for the HN

  4. Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy

    PubMed Central

    Li, Ruijiang; Xing, Lei

    2011-01-01

    Purpose: To propose an alternative radiation therapy (RT) planning and delivery scheme with optimal angular beam sampling and intrabeam modulation for improved dose distribution while maintaining high delivery efficiency. Methods: In the proposed approach, coined as dense angularly sampled and sparse intensity modulated RT (DASSIM-RT), a large number of beam angles are used to increase the angular sampling, leading to potentially more conformal dose distributions as compared to conventional IMRT. At the same time, intensity modulation of the incident beams is simplified to eliminate the dispensable segments, compensating the increase in delivery time caused by the increased number of beams and facilitating the plan delivery. In a sense, the proposed approach shifts and transforms, in an optimal fashion, some of the beam segments in conventional IMRT to the added beams. For newly available digital accelerators, the DASSIM-RT delivery can be made very efficient by concatenating the beams so that they can be delivered sequentially without operator’s intervention. Different from VMAT, the level of intensity modulation in DASSIS-RT is field specific and optimized to meet the need of each beam direction. Three clinical cases (a head and neck (HN) case, a pancreas case, and a lung case) are used to evaluate the proposed RT scheme. DASSIM-RT, VMAT, and conventional IMRT plans are compared quantitatively in terms of the conformality index (CI) and delivery efficiency. Results: Plan quality improves generally with the number and intensity modulation of the incident beams. For a fixed number of beams or fixed level of intensity modulation, the improvement saturates after the intensity modulation or number of beams reaches to a certain level. An interplay between the two variables is observed and the saturation point depends on the values of both variables. For all the cases studied here, the CI of DASSIM-RT with 15 beams and 5 intensity levels (0.90, 0.79, and 0.84 for the

  5. Aperture modulated arc therapy

    NASA Astrophysics Data System (ADS)

    Crooks, S. M.; Wu, Xiaodong; Takita, C.; Watzich, M.; Xing, Lei

    2003-05-01

    We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machine output of the accelerator has a constant value. Dose was calculated using the CORVUS 4.0 IMRT system, which uses a pencil beam dose algorithm, and treatments were delivered using a Varian 2100C/D Clinac. Results are presented for a head and neck and a prostate case, showing the equivalence of the IMRT and the translated AMAT delivery. For a prostate AMAT delivery, coronal plane film dose for the IMRT and AMAT deliveries agreed within 7.19 +/- 6.62%. For a meningioma the coronal plane dose distributions were similar to a value of 4.6 +/- 6.62%. Dose to the isocentre was measured as being within 2% of the planned value in both cases.

  6. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

    PubMed Central

    Crowe, Scott B; Kairn, Tanya; Middlebrook, Nigel; Hill, Brendan; Christie, David R H; Knight, Richard T; Kenny, John; Langton, Christian M; Trapp, Jamie V

    2013-01-01

    Introduction This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Methods Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. Results The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. Conclusions This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT. PMID:26229621

  7. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

    SciTech Connect

    Crowe, Scott B; Kairn, Tanya; Middlebrook, Nigel; Hill, Brendan; Christie, David R H; Knight, Richard T; Kenny, John; Langton, Christian M; Trapp, Jamie V

    2013-12-15

    This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT.

  8. Intrafractional 3D localization using kilovoltage digital tomosynthesis for sliding-window intensity modulated radiation therapy

    PubMed Central

    Zhang, Pengpeng; Hunt, Margie; Pham, Hai; Tang, Grace; Mageras, Gig

    2016-01-01

    Purpose To implement novel imaging sequences integrated into intensity modulated radiation therapy (IMRT) and determine 3D positions for intrafractional patient motion monitoring and management. Method In one method, we converted a static gantry IMRT beam into a series of arcs in which dose index and multileaf collimator positions for all control points were unchanged, but gantry angles were modified to oscillate ±3° around the original angle. Kilovoltage (kV) projections were acquired continuously throughout delivery and reconstructed to provide a series of 6° arc digital tomosynthesis (DTS) images which served to evaluate the in-plane positions of embedded-fiducials/vertebral-body. To obtain out-of-plane positions via triangulation, a 20° gantry rotation with beam hold-off was inserted during delivery to produce a pair of 6° DTS images separated by 14°. In a second method, the gantry remained stationary, but both kV source and detector moved over a 15° longitudinal arc using pitch and translational adjustment of the robotic arms. Evaluation of localization accuracy in an anthropomorphic Rando phantom during simulated intrafractional motion used programmed couch translations from customized scripts. Purpose-built software was used to reconstruct DTS images, register them to reference template images and calculate 3D fiducial positions. Result No significant dose difference (<0.5%) was found between the original and converted IMRT beams. For a typical hypofractionated spine treatment, 200 single DTS (6° arc) and 10 paired DTS (20° arc) images were acquired for each IMRT beam, providing in-plane and out-of-plane monitoring every 1.6 and 34.5 seconds, respectively. Mean ± standard deviation error in predicted position was −0.3±0.2 mm, −0.1±0.1 mm in-plane, and 0.2±0.4 mm out-of-plane with rotational gantry, 0.8±0.1 mm, −0.7±0.3 mm in-plane and 1.1±0.1 mm out-of-plane with translational source/detector. Conclusion Acquiring 3D fiducial positions

  9. Intrafractional 3D localization using kilovoltage digital tomosynthesis for sliding-window intensity modulated radiation therapy.

    PubMed

    Zhang, Pengpeng; Hunt, Margie; Pham, Hai; Tang, Grace; Mageras, Gig

    2015-09-07

    To implement novel imaging sequences integrated into intensity modulated radiation therapy (IMRT) and determine 3D positions for intrafractional patient motion monitoring and management.In one method, we converted a static gantry IMRT beam into a series of arcs in which dose index and multileaf collimator positions for all control points were unchanged, but gantry angles were modified to oscillate ± 3° around the original angle. Kilovoltage (kV) projections were acquired continuously throughout delivery and reconstructed to provide a series of 6° arc digital tomosynthesis (DTS) images which served to evaluate the in-plane positions of embedded-fiducials/vertebral-body. To obtain out-of-plane positions via triangulation, a 20° gantry rotation with beam hold-off was inserted during delivery to produce a pair of 6° DTS images separated by 14°. In a second method, the gantry remained stationary, but both kV source and detector moved over a 15° longitudinal arc using pitch and translational adjustment of the robotic arms. Evaluation of localization accuracy in an anthropomorphic Rando phantom during simulated intrafractional motion used programmed couch translations from customized scripts. Purpose-built software was used to reconstruct DTS images, register them to reference template images and calculate 3D fiducial positions.No significant dose difference (<0.5%) was found between the original and converted IMRT beams. For a typical hypofractionated spine treatment, 200 single DTS (6° arc) and 10 paired DTS (20° arc) images were acquired for each IMRT beam, providing in-plane and out-of-plane monitoring every 1.6 and 34.5 s, respectively. Mean ± standard deviation error in predicted position was -0.3 ± 0.2 mm, -0.1 ± 0.1 mm in-plane, and 0.2 ± 0.4 mm out-of-plane with rotational gantry, 0.8 ± 0.1 mm, -0.7 ± 0.3 mm in-plane and 1.1 ± 0.1 mm out-of-plane with translational source/detector.Acquiring 3D fiducial positions from kV-DTS during fixed gantry

  10. Strategies for quality assurance of intensity modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Benedek, Hunor; Isacsson, Ulf; Olevik-Dunder, Maria; Westermark, Mathias; Hållström, Per; Olofsson, Jörgen; Gustafsson, Magnus

    2015-01-01

    In late 2011 The Swedish Society of Radiation Physics formed a working group to concentrate on the Quality Assurance of modern radiation therapy techniques. The given task was to identify and summarise the different QA strategies in Sweden and also the international recommendations. This was used to formulate recommendations for practical guidelines within Sweden. In this paper a brief summery of the group's work is presented. All the Swedish radiation therapy centres do a pre treatment verification measurement as QA for every new IMRT and VMAT plan. Physicists do it and they believe it to be time consuming. A general standpoint from all the centres was that new guidelines and legislation is needed to allow QA that does not require a measurement. Based on various international publications and recommendations the working group has presented two strategies, one where all new plans are checked through measurement and one where no measurement is needed. The measurement- based strategy is basically the same as the one used today with an extended machine QA part. The other presented strategy is process oriented where all the different parts of the treatment chain are checked separately. The final report can be found in Swedish on http://www.radiofysik.org.

  11. Dosimetric study of volumetric arc modulation with RapidArc and intensity-modulated radiotherapy in patients with cervical cancer and comparison with 3-dimensional conformal technique for definitive radiotherapy in patients with cervical cancer

    SciTech Connect

    Guy, Jean-Baptiste; Falk, Alexander T.; Auberdiac, Pierre; Cartier, Lysian; Vallard, Alexis; Ollier, Edouard; Trone, Jane-Chloé; Khodri, Moustapha; Chargari, Cyrus; Magné, Nicolas

    2016-04-01

    Introduction: For patients with cervical cancer, intensity-modulated radiation therapy (IMRT) improves target coverage and allows dose escalation while reducing the radiation dose to organs at risk (OARs). In this study, we compared dosimetric parameters among 3-dimensional conformal radiotherapy (3D-CRT), “step-and-shoot” IMRT, and volumetric intensity-modulated arc radiotherapy (VMAT) in a series of patients with cervical cancer receiving definitive radiotherapy. Computed tomography (CT) scans of 10 patients with histologically proven cervical cancer treated with definitive radiation therapy (RT) from December 2008 to March 2010 at our department were selected for this study. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated following the guidelines of the Gyn IMRT consortium that included cervix, uterus, parametrial tissues, and the pelvic nodes including presacral. The median age was 57 years (range: 30 to 85 years). All 10 patients had squamous cell carcinoma with Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB. All patients were treated by VMAT. OAR doses were significantly reduced for plans with intensity-modulated technique compared with 3D-CRT except for the dose to the vagina. Between the 2 intensity-modulated techniques, significant difference was observed for the mean dose to the small intestine, to the benefit of VMAT (p < 0.001). There was no improvement in terms of OARs sparing for VMAT although there was a tendency for a slightly decreased average dose to the rectum: − 0.65 Gy but not significant (p = 0.07). The intensity modulation techniques have many advantages in terms of quality indexes, and particularly OAR sparing, compared with 3D-CRT. Following the ongoing technologic developments in modern radiotherapy, it is essential to evaluate the intensity-modulated techniques on prospective studies of a larger scale.

  12. Quantification of beam complexity in intensity-modulated radiation therapy treatment plans

    SciTech Connect

    Du, Weiliang Cho, Sang Hyun; Zhang, Xiaodong; Kudchadker, Rajat J.; Hoffman, Karen E.

    2014-02-15

    Purpose: Excessive complexity in intensity-modulated radiation therapy (IMRT) plans increases the dose uncertainty, prolongs the treatment time, and increases the susceptibility to changes in patient or target geometry. To date, the tools for quantitative assessment of IMRT beam complexity are still lacking. In this study, The authors have sought to develop metrics to characterize different aspects of beam complexity and investigate the beam complexity for IMRT plans of different disease sites. Methods: The authors evaluated the beam complexity scores for 65 step-and-shoot IMRT plans from three sites (prostate, head and neck, and spine) and 26 volumetric-modulated arc therapy (VMAT) plans for the prostate. On the basis of the beam apertures and monitor unit weights of all segments, the authors calculated the mean aperture area, extent of aperture shape irregularity, and degree of beam modulation for each beam. Then the beam complexity values were averaged to obtain the complexity metrics of the IMRT plans. The authors studied the correlation between the beam complexity metrics and the quality assurance (QA) results. Finally, the effects of treatment planning parameters on beam complexity were studied. Results: The beam complexity scores were not uniform among the prostate IMRT beams from different gantry angles. The lateral beams had larger monitor units and smaller shape irregularity, while the anterior-posterior beams had larger modulation values. On average, the prostate IMRT plans had the smallest aperture irregularity, beam modulation, and normalized monitor units; the head and neck IMRT plans had large beam irregularity and beam modulation; and the spine stereotactic radiation therapy plans often had small beam apertures, which may have been associated with the relatively large discrepancies between planned and QA measured doses. There were weak correlations between the beam complexity scores and the measured dose errors. The prostate VMAT beams showed

  13. Dosimetric Comparison between Single and Dual Arc-Volumetric Modulated Arc Radiotherapy and Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma Using a Simultaneous Integrated Boost Technique

    PubMed Central

    Radhakrishnan, Sivakumar; Chandrasekaran, Anuradha; Sarma, Yugandhar; Balakrishnan, Saranganathan; Nandigam, Janardhan

    2017-01-01

    Backround: Plan quality and performance of dual arc (DA) volumetric modulated arc therapy (VMAT), single arc (SA) VMAT and nine field (9F) intensity modulated radiotherapy were compared using a simultaneous integrated boost (SIB) technique. Methods: Twelve patients treated in Elekta Synergy Platform (mlci2) by 9F-IMRT were replanned with SA/DA-VMAT using a CMS Monaco Treatment Planning System (TPS) with Monte Carlo simulation. Target delineation was conducted as per Radiation Therapy Oncology Protocols (RTOG0225 and 0615). A 70Gy dose prescribed to PTV70 and 61Gy to PTV61 in 33 fractions was applied for the SIB technique. The conformity index (CI) and homogeneity index (HI) for targets and the mean dose and maximum dose for OAR’s, treatment delivery time (min), monitor units (MUs) per fraction, normal tissue integral dose and patient specific quality assurance were analysed. Results: Acceptable target coverage was achieved for PTV70 and PTV61 with all the planning techniques. No significant differences were observed except for D98 (PTV61), CI(PTV70) and HI(PTV61). Maximum dose (Dmax) to the spinal cord was lower in DA-VMAT than 9F-IMRT (p=0.002) and SA-VMAT (p=0.001). D50 (%) of parotid glands was better controlled by 9F-IMRT (p=0.001) and DA-VMAT (p=0.001) than SA-VMAT. A lower mean dose to the larynx was achieved with 9F-IMRT (P=0.001) and DA-VMAT (p=0.001) than with SA-VMAT. DA-VMAT achieved higher CI of PTV70 (P= 0.005) than SA-VMAT. For PTV61, DA-VMAT (P=0.001) and 9F-IMRT (P=0.001) achieved better HI than SA-VMAT. The average treatment delivery times were 7.67mins, 3.35 mins, 4.65 mins for 9F-IMRT, SA-VMAT and DA-VMAT, respectively. No significant difference were observed in MU/fr (p=0.9) and NTID (P=0.90) and the patient quality assurance pass rates were >95% (gamma analysis I3mm, 3%). Conclusion: DA-VMAT showed better conformity over target dose and spared the OARs better or equal to IMRT. SA-VMAT could not spare the OARs well. DA-VMAT offered shorter

  14. Extrapleural pneumonectomy, photodynamic therapy and intensity modulated radiation therapy for the treatment of malignant pleural mesothelioma.

    PubMed

    Du, Kevin L; Both, Stefan; Friedberg, Joseph S; Rengan, Ramesh; Hahn, Stephen M; Cengel, Keith A

    2010-09-01

    Intensity modulated radiation therapy (IMRT) has recently been proposed for the treatment of malignant pleural mesothelioma (MPM). Here, we describe our experience with a multimodality approach for the treatment of mesothelioma, incorporating extrapleural pneumonectomy, intraoperative photodynamic therapy and postoperative hemithoracic IMRT. From 2004-2007, we treated 11 MPM patients with hemithoracic IMRT, 7 of whom had undergone porfimer sodium-mediated PDT as an intraoperative adjuvant to surgical debulking. The median radiation dose to the planning treatment volume (PTV) ranged from 45.4-54.5 Gy. For the contralateral lung, V20 ranged from 1.4-28.5%, V5 from 42-100% and MLD from 6.8-16.5 Gy. In our series, 1 patient experienced respiratory failure secondary to radiation pneumonitis that did not require mechanical ventilation. Multimodality therapy combining surgery with increased doses of radiation using IMRT, and newer treatment modalities such as PDT , appears safe. Future prospective analysis will be needed to demonstrate efficacy of this approach in the treatment of malignant mesothelioma. Efforts to reduce lung toxicity and improve dose delivery are needed and provide the promise of improved local control and quality of life in a carefully chosen multidisciplinary approach.

  15. Dosimetric benefit of DMLC tracking for conventional and sub-volume boosted prostate intensity-modulated arc radiotherapy

    PubMed Central

    Pommer, Tobias; Falk, Marianne; Poulsen, Per R.; Keall, Paul J.; O’Brien, Ricky T.; Petersen, Peter Meidahl; Rosenschöld, Per Munck af

    2013-01-01

    This study investigated the dosimetric impact of uncompensated motion and motion compensation with dynamic multileaf collimator (DMLC) tracking for prostate intensity modulated arc therapy. Two treatment approaches were investigated; a conventional approach with a uniform radiation dose to the target volume and an intraprostatic lesion (IPL) boosted approach with an increased dose to a subvolume of the prostate. The impact on plan quality of optimizations with a leaf position constraint, which limited the distance between neighbouring adjacent MLC leaves, was also investigated. Deliveries were done with and without DMLC tracking on a linear acceleration with a high-resolution MLC. A cylindrical phantom containing two orthogonal diode arrays was used for dosimetry. A motion platform reproduced six patient-derived prostate motion traces, with the average displacement ranging from 1.0 to 8.9 mm during the first 75 seconds. A research DMLC tracking system was used for real-time motion compensation with optical monitoring for position input. The gamma index was used for evaluation, with measurements with a static phantom or the planned dose as reference, using 2% and 2 mm gamma criteria. The average pass rate with DMLC tracking was 99.9% (range 98.7–100%, measurement as reference), whereas the pass rate for untracked deliveries decreased distinctly as the average displacement increased, with an average pass rate of 61.3% (range 32.7–99.3%). Dose-volume histograms showed that DMLC tracking maintained the planned dose distributions in the presence of motion whereas traces with > 3 mm average displacement caused clear plan degradation for untracked deliveries. The dose to the rectum and bladder had an evident dependence on the motion direction and amplitude for untracked deliveries, and the dose to the rectum was slightly increased for IPL boosted plans compared to conventional plans for anterior motion with large amplitude. In conclusion, optimization using a leaf

  16. Dosimetric benefit of DMLC tracking for conventional and sub-volume boosted prostate intensity-modulated arc radiotherapy

    NASA Astrophysics Data System (ADS)

    Pommer, Tobias; Falk, Marianne; Poulsen, Per R.; Keall, Paul J.; O'Brien, Ricky T.; Meidahl Petersen, Peter; Rosenschöld, Per Munck af

    2013-04-01

    This study investigated the dosimetric impact of uncompensated motion and motion compensation with dynamic multileaf collimator (DMLC) tracking for prostate intensity modulated arc therapy. Two treatment approaches were investigated; a conventional approach with a uniform radiation dose to the target volume and an intraprostatic lesion (IPL) boosted approach with an increased dose to a subvolume of the prostate. The impact on plan quality of optimizations with a leaf position constraint, which limited the distance between neighbouring adjacent MLC leaves, was also investigated. Deliveries were done with and without DMLC tracking on a linear acceleration with a high-resolution MLC. A cylindrical phantom containing two orthogonal diode arrays was used for dosimetry. A motion platform reproduced six patient-derived prostate motion traces, with the average displacement ranging from 1.0 to 8.9 mm during the first 75 s. A research DMLC tracking system was used for real-time motion compensation with optical monitoring for position input. The gamma index was used for evaluation, with measurements with a static phantom or the planned dose as reference, using 2% and 2 mm gamma criteria. The average pass rate with DMLC tracking was 99.9% (range 98.7-100%, measurement as reference), whereas the pass rate for untracked deliveries decreased distinctly as the average displacement increased, with an average pass rate of 61.3% (range 32.7-99.3%). Dose-volume histograms showed that DMLC tracking maintained the planned dose distributions in the presence of motion whereas traces with >3 mm average displacement caused clear plan degradation for untracked deliveries. The dose to the rectum and bladder had an evident dependence on the motion direction and amplitude for untracked deliveries, and the dose to the rectum was slightly increased for IPL boosted plans compared to conventional plans for anterior motion with large amplitude. In conclusion, optimization using a leaf position

  17. Introducing an on-line adaptive procedure for prostate image guided intensity modulate proton therapy.

    PubMed

    Zhang, M; Westerly, D C; Mackie, T R

    2011-08-07

    With on-line image guidance (IG), prostate shifts relative to the bony anatomy can be corrected by realigning the patient with respect to the treatment fields. In image guided intensity modulated proton therapy (IG-IMPT), because the proton range is more sensitive to the material it travels through, the realignment may introduce large dose variations. This effect is studied in this work and an on-line adaptive procedure is proposed to restore the planned dose to the target. A 2D anthropomorphic phantom was constructed from a real prostate patient's CT image. Two-field laterally opposing spot 3D-modulation and 24-field full arc distal edge tracking (DET) plans were generated with a prescription of 70 Gy to the planning target volume. For the simulated delivery, we considered two types of procedures: the non-adaptive procedure and the on-line adaptive procedure. In the non-adaptive procedure, only patient realignment to match the prostate location in the planning CT was performed. In the on-line adaptive procedure, on top of the patient realignment, the kinetic energy for each individual proton pencil beam was re-determined from the on-line CT image acquired after the realignment and subsequently used for delivery. Dose distributions were re-calculated for individual fractions for different plans and different delivery procedures. The results show, without adaptive, that both the 3D-modulation and the DET plans experienced delivered dose degradation by having large cold or hot spots in the prostate. The DET plan had worse dose degradation than the 3D-modulation plan. The adaptive procedure effectively restored the planned dose distribution in the DET plan, with delivered prostate D(98%), D(50%) and D(2%) values less than 1% from the prescription. In the 3D-modulation plan, in certain cases the adaptive procedure was not effective to reduce the delivered dose degradation and yield similar results as the non-adaptive procedure. In conclusion, based on this 2D phantom

  18. Clinical outcomes of intensity-modulated pelvic radiation therapy for carcinoma of the cervix.

    PubMed

    Hasselle, Michael D; Rose, Brent S; Kochanski, Joel D; Nath, Sameer K; Bafana, Rounak; Yashar, Catheryn M; Hasan, Yasmin; Roeske, John C; Mundt, Arno J; Mell, Loren K

    2011-08-01

    To evaluate disease outcomes and toxicity in cervical cancer patients treated with pelvic intensity-modulated radiation therapy (IMRT). We included all patients with Stage I-IVA cervical carcinoma treated with IMRT at three different institutions from 2000-2007. Patients treated with extended field or conventional techniques were excluded. Intensity-modulated radiation therapy plans were designed to deliver 45 Gy in 1.8-Gy daily fractions to the planning target volume while minimizing dose to the bowel, bladder, and rectum. Toxicity was graded according to the Radiation Therapy Oncology Group system. Overall survival and disease-free survival were estimated by use of the Kaplan-Meier method. Pelvic failure, distant failure, and late toxicity were estimated by use of cumulative incidence functions. The study included 111 patients. Of these, 22 were treated with postoperative IMRT, 8 with IMRT followed by intracavitary brachytherapy and adjuvant hysterectomy, and 81 with IMRT followed by planned intracavitary brachytherapy. Of the patients, 63 had Stage I-IIA disease and 48 had Stage IIB-IVA disease. The median follow-up time was 27 months. The 3-year overall survival rate and the disease-free survival rate were 78% (95% confidence interval [CI], 68-88%) and 69% (95% CI, 59-81%), respectively. The 3-year pelvic failure rate and the distant failure rate were 14% (95% CI, 6-22%) and 17% (95% CI, 8-25%), respectively. Estimates of acute and late Grade 3 toxicity or higher were 2% (95% CI, 0-7%) and 7% (95% CI, 2-13%), respectively. Intensity-modulated radiation therapy is associated with low toxicity and favorable outcomes, supporting its safety and efficacy for cervical cancer. Prospective clinical trials are needed to evaluate the comparative efficacy of IMRT vs. conventional techniques. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Clinical Outcomes of Intensity-Modulated Pelvic Radiation Therapy for Carcinoma of the Cervix

    SciTech Connect

    Hasselle, Michael D.; Rose, Brent S.; Kochanski, Joel D.; Nath, Sameer K.; Bafana, Rounak; Yashar, Catheryn M.; Hasan, Yasmin; Roeske, John C.; Mundt, Arno J.; Mell, Loren K.

    2011-08-01

    Purpose: To evaluate disease outcomes and toxicity in cervical cancer patients treated with pelvic intensity-modulated radiation therapy (IMRT). Methods and Materials: We included all patients with Stage I-IVA cervical carcinoma treated with IMRT at three different institutions from 2000-2007. Patients treated with extended field or conventional techniques were excluded. Intensity-modulated radiation therapy plans were designed to deliver 45 Gy in 1.8-Gy daily fractions to the planning target volume while minimizing dose to the bowel, bladder, and rectum. Toxicity was graded according to the Radiation Therapy Oncology Group system. Overall survival and disease-free survival were estimated by use of the Kaplan-Meier method. Pelvic failure, distant failure, and late toxicity were estimated by use of cumulative incidence functions. Results: The study included 111 patients. Of these, 22 were treated with postoperative IMRT, 8 with IMRT followed by intracavitary brachytherapy and adjuvant hysterectomy, and 81 with IMRT followed by planned intracavitary brachytherapy. Of the patients, 63 had Stage I-IIA disease and 48 had Stage IIB-IVA disease. The median follow-up time was 27 months. The 3-year overall survival rate and the disease-free survival rate were 78% (95% confidence interval [CI], 68-88%) and 69% (95% CI, 59-81%), respectively. The 3-year pelvic failure rate and the distant failure rate were 14% (95% CI, 6-22%) and 17% (95% CI, 8-25%), respectively. Estimates of acute and late Grade 3 toxicity or higher were 2% (95% CI, 0-7%) and 7% (95% CI, 2-13%), respectively. Conclusions: Intensity-modulated radiation therapy is associated with low toxicity and favorable outcomes, supporting its safety and efficacy for cervical cancer. Prospective clinical trials are needed to evaluate the comparative efficacy of IMRT vs. conventional techniques.

  20. SU-E-T-503: Intensity Modulated Proton Therapy (IMPT) Versus Intensity Modulated X-Ray Therapy (IMRT) for Patient with Hepatocellular Carcinoma: A Dosimetric Comparison

    SciTech Connect

    Singh, H; Zhao, L; Prabhu, K; Rana, S; Zheng, Y

    2015-06-15

    Purpose This study compares the dosimetric parameters in treatment of unresectable hepatocellular carcinoma between intensity modulated proton therapy (IMPT) and intensity modulated x-ray radiation therapy (IMRT). Methods and Materials: We studied four patients treated at our institution. All patients were simulated supine with 4D-CT using a GE light speed simulator with a maximum slice thickness of 3mm. The average CT and an internal target volume to account for respiration motion were used for planning. Both IMRT and IMPT plans were created using Elekta’s CMSXiO treatment planning system (TPS). The prescription dose was 58.05 CGE in 15 fractions. The IMRT plans had five beams with combination of co-planar and non-co-planar. The IMPT plans had 2 to 3 beams. Dose comparison was performed based on the averaged results of the four patients. Results The mean dose and V95% to PTV were 58.24CGE, 98.57% for IMPT, versus 57.34CGE and 96.68% for IMRT, respectively. The V10, V20, V30 and mean dose of the normal liver for IMPT were 23.10%, 18.61%, 13.75% and 9.78 CGE; and 47.19%, 37.55%, 22.73% and 17.12CGE for IMRT. The spinal cord didn’t receive any dose in IMPT technique, but received a maximum of 18.77CGE for IMRT. The IMPT gave lower maximum dose to the stomach as compared to IMRT (19.26 vs 26.35CGE). V14 for left and right kidney was 0% and 2.32% for IMPT and 3.89% and 29.54% for IMRT. The mean dose, V35, V40 and V45 for small bowl were similar in both techniques, 0.74CGE, 6.27cc, 4.85cc and 3.53 cc for IMPT, 3.47CGE, 9.73cc, 7.61cc 5.35cc for IMRT. Conclusion Based on this study, IMPT plans gave less dose to the critical structures such as normal liver, kidney, stomach and spinal cord as compared to IMRT plans, potentially leading to less toxicity and providing better quality of life for patients.

  1. Optimization of intensity-modulated very high energy (50-250 MeV) electron therapy

    NASA Astrophysics Data System (ADS)

    Yeboah, C.; Sandison, G. A.; Moskvin, V.

    2002-04-01

    This work evaluates the potential of very high energy (50-250 MeV) electron beams for dose conformation and identifies those variables that influence optimized dose distributions for this modality. Intensity-modulated plans for a prostate cancer model were optimized as a function of the importance factors, beam energy and number of energy bins, number of beams, and the beam orientations. A trial-and-error-derived constellation of importance factors for target and sensitive structures to achieve good conformal dose distributions was 500, 50, 10 and 1 for the target, rectum, bladder and normal tissues respectively. Electron energies greater than 100 MeV were found to be desirable for intensity-modulated very high energy electron therapy (VHEET) of prostate cancer. Plans generated for lower energy beams had relatively poor conformal dose distributions about the target region and delivered high doses to sensitive structures. Fixed angle beam treatments utilizing a large number of fields in the range 9-21 provided acceptable plans. Using more than 21 beams at fixed gantry angles had an insignificant effect on target coverage, but resulted in an increased dose to sensitive structures and an increased normal tissue integral dose. Minor improvements in VHEET plans utilizing a `small' number (=<9) of beams may be achieved if, in addition to intensity modulation, energy modulation is implemented using a small number (=<3) of beam energies separated by 50 to 100 MeV. Rotation therapy provided better target dose homogeneity but unfortunately resulted in increased rectal dose, bladder dose and normal tissue integral dose relative to the 21-field fixed angle treatment plan. Modulation of the beam energy for rotation therapy had no beneficial consequences on the optimized dose distributions. Lastly, selection of beam orientations influenced the optimized treatment plan even when a large number of beams (approximately 15) were employed.

  2. Thyroid storm after intensity-modulated radiation therapy: a case report and discussion.

    PubMed

    Diaz, Roberto; Blakey, Marc D; Murphy, Patrick B; Cryar, A Keith; Cmelak, Anthony J

    2009-03-01

    A 43-year-old man with locally advanced squamous cell carcinoma of the base of tongue was treated with induction chemotherapy followed by intensity-modulated radiation therapy (IMRT). Within 20 days post-treatment, the patient developed clinical symptoms highly suggestive of hyperthyroidism. Two and one half months after completion of therapy, the patient developed severe thyrotoxicosis, which, in retrospect, appears to have met the criteria for thyroid storm. This case history illustrates a previously unreported, life-threatening complication of external-beam radiation that should be considered in patients receiving IMRT therapy involving the thyroid. Diagnosis of the patient's hyperthyroidism and probable thyroid storm was difficult to recognize because of the significant overlap between the signs and symptoms of severe thyrotoxicosis and the expected toxicities of his cancer therapy.

  3. Radiation-Induced Cancers From Modern Radiotherapy Techniques: Intensity-Modulated Radiotherapy Versus Proton Therapy

    SciTech Connect

    Yoon, Myonggeun; Ahn, Sung Hwan; Kim, Jinsung; Shin, Dong Ho; Park, Sung Yong; Lee, Se Byeong; Shin, Kyung Hwan; Cho, Kwan Ho

    2010-08-01

    Purpose: To assess and compare secondary cancer risk resulting from intensity-modulated radiotherapy (IMRT) and proton therapy in patients with prostate and head-and-neck cancer. Methods and Materials: Intensity-modulated radiotherapy and proton therapy in the scattering mode were planned for 5 prostate caner patients and 5 head-and-neck cancer patients. The secondary doses during irradiation were measured using ion chamber and CR-39 detectors for IMRT and proton therapy, respectively. Organ-specific radiation-induced cancer risk was estimated by applying organ equivalent dose to dose distributions. Results: The average secondary doses of proton therapy for prostate cancer patients, measured 20-60cm from the isocenter, ranged from 0.4 mSv/Gy to 0.1 mSv/Gy. The average secondary doses of IMRT for prostate patients, however, ranged between 3 mSv/Gy and 1 mSv/Gy, approximately one order of magnitude higher than for proton therapy. Although the average secondary doses of IMRT were higher than those of proton therapy for head-and-neck cancers, these differences were not significant. Organ equivalent dose calculations showed that, for prostate cancer patients, the risk of secondary cancers in out-of-field organs, such as the stomach, lungs, and thyroid, was at least 5 times higher for IMRT than for proton therapy, whereas the difference was lower for head-and-neck cancer patients. Conclusions: Comparisons of organ-specific organ equivalent dose showed that the estimated secondary cancer risk using scattering mode in proton therapy is either significantly lower than the cases in IMRT treatment or, at least, does not exceed the risk induced by conventional IMRT treatment.

  4. Empowering Intensity Modulated Proton Therapy Through Physics and Technology: An Overview.

    PubMed

    Mohan, Radhe; Das, Indra J; Ling, Clifton C

    2017-10-01

    Considering the clinical potential of protons attributable to their physical characteristics, interest in proton therapy has increased greatly in this century, as has the number of proton therapy installations. Until recently, passively scattered proton therapy was used almost entirely. Notably, the overall clinical results to date have not shown a convincing benefit of protons over photons. A rapid transition is now occurring with the implementation of the most advanced form of proton therapy, intensity modulated proton therapy (IMPT). IMPT is superior to passively scattered proton therapy and intensity modulated radiation therapy (IMRT) dosimetrically. However, numerous limitations exist in the present IMPT methods. In particular, compared with IMRT, IMPT is highly vulnerable to various uncertainties. In this overview we identify three major areas of current limitations of IMPT: treatment planning, treatment delivery, and motion management, and discuss current and future efforts for improvement. For treatment planning, we need to reduce uncertainties in proton range and in computed dose distributions, improve robust planning and optimization, enhance adaptive treatment planning and delivery, and consider how to exploit the variability in the relative biological effectiveness of protons for clinical benefit. The quality of proton therapy also depends on the characteristics of the IMPT delivery systems and image guidance. Efforts are needed to optimize the beamlet spot size for both improved dose conformality and faster delivery. For the latter, faster energy switching time and increased dose rate are also needed. Real-time in-room volumetric imaging for guiding IMPT is in its early stages with cone beam computed tomography (CT) and CT-on-rails, and continued improvements are anticipated. In addition, imaging of the proton beams themselves, using, for instance, prompt γ emissions, is being developed to determine the proton range and to reduce range uncertainty

  5. An integral quality monitoring system for real-time verification of intensity modulated radiation therapy

    SciTech Connect

    Islam, Mohammad K.; Norrlinger, Bernhard D.; Smale, Jason R.; Heaton, Robert K.; Galbraith, Duncan; Fan, Cary; Jaffray, David A.

    2009-12-15

    Purpose: To develop an independent and on-line beam monitoring system, which can validate the accuracy of segment-by-segment energy fluence delivery for each treatment field. The system is also intended to be utilized for pretreatment dosimetric quality assurance of intensity modulated radiation therapy (IMRT), on-line image-guided adaptive radiation therapy, and volumetric modulated arc therapy. Methods: The system, referred to as the integral quality monitor (IQM), utilizes an area integrating energy fluence monitoring sensor (AIMS) positioned between the final beam shaping device [i.e., multileaf collimator (MLC)] and the patient. The prototype AIMS consists of a novel spatially sensitive large area ionization chamber with a gradient along the direction of the MLC motion. The signal from the AIMS provides a simple output for each beam segment, which is compared in real time to the expected value. The prototype ionization chamber, with a physical area of 22x22 cm{sup 2}, has been constructed out of aluminum with the electrode separations varying linearly from 2 to 20 mm. A calculation method has been developed to predict AIMS signals based on an elementwise integration technique, which takes into account various predetermined factors, including the spatial response function of the chamber, MLC characteristics, beam transmission through the secondary jaws, and field size factors. The influence of the ionization chamber on the beam has been evaluated in terms of transmission, surface dose, beam profiles, and depth dose. The sensitivity of the system was tested by introducing small deviations in leaf positions. A small set of IMRT fields for prostate and head and neck plans was used to evaluate the system. The ionization chamber and the data acquisition software systems were interfaced to two different types of linear accelerators: Elekta Synergy and Varian iX. Results: For a 10x10 cm{sup 2} field, the chamber attenuates the beam intensity by 7% and 5% for 6 and 18

  6. Dosimetric research on intensity-modulated arc radiotherapy planning for left breast cancer after breast-preservation surgery

    SciTech Connect

    Yin Yong; Chen Jinhu; Sun Tao; Ma Changsheng; Lu Jie; Liu Tonghai; Wang Ruozheng

    2012-10-01

    Intensity-modulated radiotherapy (IMRT) has played an important role in breast cancer radiotherapy after breast-preservation surgery. Our aim was to study the dosimetric and implementation features/feasibility between IMRT and intensity-modulated arc radiotherapy (Varian RapidArc, Varian, Palo Alto, CA). The forward IMRT plan (f-IMRT), the inverse IMRT, and the RapidArc plan (RA) were generated for 10 patients. Afterward, we compared the target dose distribution of the 3 plans, radiation dose on organs at risk, monitor units, and treatment time. All 3 plans met clinical requirements, with RA performing best in target conformity. In target homogeneity, there was no statistical significance between RA and IMRT, but both of homogeneity were less than f-IMRT's. With regard to the V{sub 5} and V{sub 10} of the left lung, those in RA were higher than in f-IMRT but were lower than in IMRT; for V{sub 20} and V{sub 30}, the lowest was observed in RA; and in the V{sub 5} and V{sub 10} of the right lung, as well as the mean dose in normal-side breast and right lung, there was no statistically significance difference between RA and IMRT, and the lowest value was observed in f-IMRT. As for the maximum dose in the normal-side breast, the lowest value was observed in RA. Regarding monitor units (MUs), those in RA were higher than in f-IMRT but were lower than in IMRT. Treatment time of RA was 84.6% and 88.23% shorter than f-IMRT and IMRT, respectively, on average. Compared with f-IMRT and IMRT, RA performed better in target conformity and can reduce high-dose volume in the heart and left lung-which are related to complications-significantly shortening treatment time as well. Compared with IMRT, RA can also significantly reduce low-dose volume and MUs of the afflicted lung.

  7. Dosimetric comparison between intensity-modulated radiotherapy and RapidArc with single arc and dual arc for malignant glioma involving the parietal lobe

    PubMed Central

    YUAN, JUN; LEI, MINGJUN; YANG, ZHEN; FU, JUN; HUO, LEI; HONG, JIDONG

    2016-01-01

    The aim of the present study was to evaluate the difference in treatment plan quality, monitor units (MUs) per fraction and dosimetric parameters between IMRT (intensity-modulated radiotherapy) and RapidArc with single arc (RA1) and dual arc (RA2) for malignant glioma involving the parietal lobe. Treatment plans for IMRT and RA1 and RA2 were prepared for 10 patients with malignant gliomas involving the parietal lobe. The Wilcoxon matched-pair signed-rank test was used to compare the plan quality, monitor units and dosimetric parameters between IMRT and RA1 and RA2 through dose-volume histograms. Dnear-max (D2%) to the left lens, right lens and left optical nerve in RA1 were less compared with those in IMRT; D2% to the right lens and right optic nerve in RA2 were less compared with those in IMRT. D2% to the optic chiasma in RA2 was small compared with that in RA1. The median dose (D50%) to the right lens and right optic nerve in RA1 and RA2 was less compared with the identical parameters in IMRT, and D50% to the brain stem in RA2 was less compared with that in RA1. The volume receiving at least 45 Gy (V45) or V50 in normal brain tissue (whole brain minus the planning target volume 2; B-P) in RA1 was less compared with that in IMRT. V30, V35, V40, V45, or V50 in B-P in RA2 was less compared with that in IMRT. The MUs per fraction in RA1 and RA2 were significantly less compared with those in IMRT. All differences with a P-value<0.05 were considered to be significantly different. In conclusion, RA1 and RA2 markedly reduced the MUs per fraction, and spared partial organs at risk and B-P compared with IMRT. PMID:27330795

  8. Dosimetric comparison between intensity-modulated radiotherapy and RapidArc with single arc and dual arc for malignant glioma involving the parietal lobe.

    PubMed

    Yuan, Jun; Lei, Mingjun; Yang, Zhen; Fu, Jun; Huo, Lei; Hong, Jidong

    2016-07-01

    The aim of the present study was to evaluate the difference in treatment plan quality, monitor units (MUs) per fraction and dosimetric parameters between IMRT (intensity-modulated radiotherapy) and RapidArc with single arc (RA1) and dual arc (RA2) for malignant glioma involving the parietal lobe. Treatment plans for IMRT and RA1 and RA2 were prepared for 10 patients with malignant gliomas involving the parietal lobe. The Wilcoxon matched-pair signed-rank test was used to compare the plan quality, monitor units and dosimetric parameters between IMRT and RA1 and RA2 through dose-volume histograms. Dnear-max (D2%) to the left lens, right lens and left optical nerve in RA1 were less compared with those in IMRT; D2% to the right lens and right optic nerve in RA2 were less compared with those in IMRT. D2% to the optic chiasma in RA2 was small compared with that in RA1. The median dose (D50%) to the right lens and right optic nerve in RA1 and RA2 was less compared with the identical parameters in IMRT, and D50% to the brain stem in RA2 was less compared with that in RA1. The volume receiving at least 45 Gy (V45) or V50 in normal brain tissue (whole brain minus the planning target volume 2; B-P) in RA1 was less compared with that in IMRT. V30, V35, V40, V45, or V50 in B-P in RA2 was less compared with that in IMRT. The MUs per fraction in RA1 and RA2 were significantly less compared with those in IMRT. All differences with a P-value<0.05 were considered to be significantly different. In conclusion, RA1 and RA2 markedly reduced the MUs per fraction, and spared partial organs at risk and B-P compared with IMRT.

  9. Optimization in Radiation Therapy: Applications in Brachytherapy and Intensity Modulated Radiation Therapy

    NASA Astrophysics Data System (ADS)

    McGeachy, Philip David

    Over 50% of cancer patients require radiation therapy (RT). RT is an optimization problem requiring maximization of the radiation damage to the tumor while minimizing the harm to the healthy tissues. This dissertation focuses on two main RT optimization problems: 1) brachytherapy and 2) intensity modulated radiation therapy (IMRT). The brachytherapy research involved solving a non-convex optimization problem by creating an open-source genetic algorithm optimizer to determine the optimal radioactive seed distribution for a given set of patient volumes and constraints, both dosimetric- and implant-based. The optimizer was tested for a set of 45 prostate brachytherapy patients. While all solutions met the clinical standards, they also benchmarked favorably with those generated by a standard commercial solver. Compared to its compatriot, the salient features of the generated solutions were: slightly reduced prostate coverage, lower dose to the urethra and rectum, and a smaller number of needles required for an implant. Historically, IMRT requires modulation of fluence while keeping the photon beam energy fixed. The IMRT-related investigation in this thesis aimed at broadening the solution space by varying photon energy. The problem therefore involved simultaneous optimization of photon beamlet energy and fluence, denoted by XMRT. Formulating the problem as convex, linear programming was applied to obtain solutions for optimal energy-dependent fluences, while achieving all clinical objectives and constraints imposed. Dosimetric advantages of XMRT over single-energy IMRT in the improved sparing of organs at risk (OARs) was demonstrated in simplified phantom studies. The XMRT algorithm was improved to include clinical dose-volume constraints and clinical studies for prostate and head and neck cancer patients were investigated. Compared to IMRT, XMRT provided improved dosimetric benefit in the prostate case, particularly within intermediate- to low-dose regions (≤ 40 Gy

  10. A compact linac for intensity modulated proton therapy based on a dielectric wall accelerator.

    PubMed

    Caporaso, G J; Mackie, T R; Sampayan, S; Chen, Y-J; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Nelson, S; Paul, A; Poole, B; Rhodes, M; Sanders, D; Sullivan, J; Wang, L; Watson, J; Reckwerdt, P J; Schmidt, R; Pearson, D; Flynn, R W; Matthews, D; Purdy, J

    2008-06-01

    A novel compact CT-guided intensity modulated proton radiotherapy (IMPT) system is described. The system is being designed to deliver fast IMPT so that larger target volumes and motion management can be accomplished. The system will be ideal for large and complex target volumes in young patients. The basis of the design is the dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL). The DWA uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system will produce individual pulses that can be varied in intensity, energy and spot width. The IMPT planning system will optimize delivery characteristics. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. Feasibility tests of an optimization system for selecting the position, energy, intensity and spot size for a collection of spots comprising the treatment are underway. A prototype is being designed and concept designs of the envelope and environmental needs of the unit are beginning. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, SiC photoconductive switches and compact proton sources.

  11. Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy

    SciTech Connect

    Kavanaugh, James A.; Hogstrom, Kenneth R.; Fontenot, Jonas P.; Henkelmann, Gregory; Chu, Connel; Carver, Robert A.

    2013-02-15

    Purpose: The purpose of this study was to demonstrate that a bolus electron conformal therapy (ECT) dose plan and a mixed beam plan, composed of an intensity modulated x-ray therapy (IMXT) dose plan optimized on top of the bolus ECT plan, can be accurately delivered. Methods: Calculated dose distributions were compared with measured dose distributions for parotid and chest wall (CW) bolus ECT and mixed beam plans, each simulated in a cylindrical polystyrene phantom that allowed film dose measurements. Bolus ECT plans were created for both parotid and CW PTVs (planning target volumes) using 20 and 16 MeV beams, respectively, whose 90% dose surface conformed to the PTV. Mixed beam plans consisted of an IMXT dose plan optimized on top of the bolus ECT dose plan. The bolus ECT, IMXT, and mixed beam dose distributions were measured using radiographic films in five transverse and one sagittal planes for a total of 36 measurement conditions. Corrections for film dose response, effects of edge-on photon irradiation, and effects of irregular phantom optical properties on the Cerenkov component of the film signal resulted in high precision measurements. Data set consistency was verified by agreement of depth dose at the intersections of the sagittal plane with the five measured transverse planes. For these same depth doses, results for the mixed beam plan agreed with the sum of the individual depth doses for the bolus ECT and IMXT plans. The six mean measured planar dose distributions were compared with those calculated by the treatment planning system for all modalities. Dose agreement was assessed using the 4% dose difference and 0.2 cm distance to agreement. Results: For the combined high-dose region and low-dose region, pass rates for the parotid and CW plans were 98.7% and 96.2%, respectively, for the bolus ECT plans and 97.9% and 97.4%, respectively, for the mixed beam plans. For the high-dose gradient region, pass rates for the parotid and CW plans were 93.1% and 94

  12. Strategies for improved accuracy and efficiency with advanced intensity modulated radiation therapy techniques

    NASA Astrophysics Data System (ADS)

    Westerly, David C.

    2009-11-01

    The development of advanced intensity modulated radiation therapy (IMRT) techniques has led to significant improvements in our ability to treat complicated target volumes with minimal collateral damage to the surrounding healthy tissue. These techniques however, come at the cost of increased complexity; which translates into increased sensitivity of the optimized treatment plans to inaccuracies in the planning and delivery processes, and can also result in longer treatment times. The aim of this work is investigate various strategies designed to improve the accuracy and efficiency of two advanced forms of IMRT: helical tomotherapy and intensity modulated proton therapy (IMPT). Helical tomotherapy is form of X-ray IMRT that uses a compact linear accelerator mounted on a CT ring gantry to rotationally deliver intensity modulated fan-beams of radiation to a patient for treatment. Failure to select judicious values for certain planning parameters can result in plans with long treatment times that are difficult for the machine to accurately deliver. This situation was observed for a series of patients scheduled for treatment at the University of Wisconsin. Treatment planning methods designed to avoid these difficulties have been investigated and are discussed. While the vast majority of IMRT treatments are performed using mega-voltage X-rays, there has recently been a great deal of interest in the use of IMPT for a variety of clinical indications. Current methods of IMPT are limited in their applicability however, due to restrictions imposed by the current delivery paradigm. An alternative method for IMPT delivery using a fan-beam geometry has been examined. Another challenge with IMPT pertains to the accuracy of proton dose calculations in the presence of complex tissue heterogeneities. Monte Carlo methods provide the most accurate means of dose calculation; however, the computational requirements of current radiation transport codes makes Monte Carlo methods

  13. Simple tool for prediction of parotid gland sparing in intensity-modulated radiation therapy

    SciTech Connect

    Gensheimer, Michael F.; Hummel-Kramer, Sharon M.; Cain, David; Quang, Tony S.

    2015-10-01

    Sparing one or both parotid glands is a key goal when planning head and neck cancer radiation treatment. If the planning target volume (PTV) overlaps one or both parotid glands substantially, it may not be possible to achieve adequate gland sparing. This finding results in physicians revising their PTV contours after an intensity-modulated radiation therapy (IMRT) plan has been run and reduces workflow efficiency. We devised a simple formula for predicting mean parotid gland dose from the overlap of the parotid gland and isotropically expanded PTV contours. We tested the tool using 44 patients from 2 institutions and found agreement between predicted and actual parotid gland doses (mean absolute error = 5.3 Gy). This simple method could increase treatment planning efficiency by improving the chance that the first plan presented to the physician will have optimal parotid gland sparing.

  14. Balancing control and simplicity: A variable aggregation method in intensity modulated radiation therapy planning*

    PubMed Central

    Süss, Philipp; Küfer, Karl-Heinz

    2008-01-01

    It is commonly believed that not all degrees of freedom are needed to produce good solutions for the treatment planning problem in intensity modulated radiation therapy (IMRT). However, typical methods to exploit this fact either increase the complexity of the optimization problem or are heuristic in nature. In this work we introduce a technique based on adaptively refining variable clusters to successively attain better treatment plans. The approach creates approximate solutions based on smaller models that may come arbitrarily close to the optimal solution. Although the method is illustrated using a specific treatment planning model, the components constituting the variable clustering and the adaptive refinement are independent of the particular optimization problem. PMID:19255600

  15. Matching Intensity-Modulated Radiation Therapy to an Anterior Low Neck Field

    SciTech Connect

    Amdur, Robert J. Liu, Chihray; Li, Jonathan; Mendenhall, William; Hinerman, Russell

    2007-10-01

    When using intensity-modulated radiation therapy (IMRT) to treat head and neck cancer with the primary site above the level of the larynx, there are two basic options for the low neck lymphatics: to treat the entire neck with IMRT, or to match the IMRT plan to a conventional anterior 'low neck' field. In view of the potential advantages of using a conventional low neck field, it is important to look for ways to minimize or manage the problems of matching IMRT to a conventional radiotherapy field. Treating the low neck with a single anterior field and the standard larynx block decreases the dose to the larynx and often results in a superior IMRT plan at the primary site. The purpose of this article is to review the most applicable studies and to discuss our experience with implementing a technique that involves moving the position of the superior border of the low neck field several times during a single treatment fraction.

  16. Intensity Modulated Radiation Therapy for Primary Soft Tissue Sarcoma of the Extremity: Preliminary Results

    SciTech Connect

    Alektiar, Kaled M. . E-mail: alektiak@mskcc.org; Hong, Linda; Brennan, Murray F.; Della-Biancia, Cesar; Singer, Samuel

    2007-06-01

    Purpose: To report preliminary results on using intensity modulated radiation therapy (IMRT) as an adjuvant treatment in primary soft tissue sarcoma (STS) of the extremity. Methods and Materials: Between February 2002 and March 2005, 31 adult patients with primary STS of the extremity were treated with surgery and adjuvant IMRT. Tumor size was >10 cm in 74% of patients and grade was high in 77%. Preoperative IMRT was given to 7 patients (50 Gy) and postoperative IMRT (median dose, 63 Gy) was given to 24 patients. Complete gross resection including periosteal stripping or bone resection was required in 10, and neurolysis or nerve resection in 20. The margins were positive or within 1 mm in 17. Complications from surgery and radiation therapy (RT) were assessed using the Common Terminology Criteria for Adverse Events grading system. Results: Median follow-up time was 23 months. Grade 1 RT dermatitis developed in 71% of patients, Grade 2 in 16%, and Grade 3 in 10%. Infectious wound complications developed in 13% and noninfectious complications in 10%. Two patients (6.4%) developed fractures. Grade 1 neuropathy developed in 28% of patients and Grade 2 in 5%. The rates of Grade 1 and 2 joint stiffness were each 19%. Grade 1 edema was observed in 19% of patients and Grade 2 in 13%. The 2-year local control, distant control, and overall survival were 95%, 65%, and 81%, respectively. Conclusion: Intensity modulated RT appears to provide excellent local control in a difficult group of high-risk patients. The morbidity profile is also favorable, but longer follow-up is needed to confirm the results from this study.

  17. Robust Intensity Modulated Proton Therapy (IMPT) Increases Estimated Clinical Benefit in Head and Neck Cancer Patients

    PubMed Central

    van Dijk, Lisanne V.; Steenbakkers, Roel J. H. M.; ten Haken, Bennie; van der Laan, Hans Paul; van ‘t Veld, Aart A.; Langendijk, Johannes A.; Korevaar, Erik W.

    2016-01-01

    Purpose To compare the clinical benefit of robust optimized Intensity Modulated Proton Therapy (minimax IMPT) with current photon Intensity Modulated Radiation Therapy (IMRT) and PTV-based IMPT for head and neck cancer (HNC) patients. The clinical benefit is quantified in terms of both Normal Tissue Complication Probability (NTCP) and target coverage in the case of setup and range errors. Methods and Materials For 10 HNC patients, PTV-based IMRT (7 fields), minimax and PTV-based IMPT (2, 3, 4, 5 and 7 fields) plans were tested on robustness. Robust optimized plans differed from PTV-based plans in that they target the CTV and penalize possible error scenarios, instead of using the static isotropic CTV-PTV margin. Perturbed dose distributions of all plans were acquired by simulating in total 8060 setup (±3.5 mm) and range error (±3%) combinations. NTCP models for xerostomia and dysphagia were used to predict the clinical benefit of IMPT versus IMRT. Results The robustness criterion was met in the IMRT and minimax IMPT plans in all error scenarios, but this was only the case in 1 of 40 PTV-based IMPT plans. Seven (out of 10) patients had relatively large NTCP reductions in minimax IMPT plans compared to IMRT. For these patients, xerostomia and dysphagia NTCP values were reduced by 17.0% (95% CI; 13.0–21.1) and 8.1% (95% CI; 4.9–11.2) on average with minimax IMPT. Increasing the number of fields did not contribute to plan robustness, but improved organ sparing. Conclusions The estimated clinical benefit in terms of NTCP of robust optimized (minimax) IMPT is greater than that of IMRT and PTV-based IMPT in HNC patients. Furthermore, the target coverage of minimax IMPT plans in the presence of errors was comparable to IMRT plans. PMID:27030987

  18. A comparison of three optimization algorithms for intensity modulated radiation therapy.

    PubMed

    Pflugfelder, Daniel; Wilkens, Jan J; Nill, Simeon; Oelfke, Uwe

    2008-01-01

    In intensity modulated treatment techniques, the modulation of each treatment field is obtained using an optimization algorithm. Multiple optimization algorithms have been proposed in the literature, e.g. steepest descent, conjugate gradient, quasi-Newton methods to name a few. The standard optimization algorithm in our in-house inverse planning tool KonRad is a quasi-Newton algorithm. Although this algorithm yields good results, it also has some drawbacks. Thus we implemented an improved optimization algorithm based on the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) routine. In this paper the improved optimization algorithm is described. To compare the two algorithms, several treatment plans are optimized using both algorithms. This included photon (IMRT) as well as proton (IMPT) intensity modulated therapy treatment plans. To present the results in a larger context the widely used conjugate gradient algorithm was also included into this comparison. On average, the improved optimization algorithm was six times faster to reach the same objective function value. However, it resulted not only in an acceleration of the optimization. Due to the faster convergence, the improved optimization algorithm usually terminates the optimization process at a lower objective function value. The average of the observed improvement in the objective function value was 37%. This improvement is clearly visible in the corresponding dose-volume-histograms. The benefit of the improved optimization algorithm is particularly pronounced in proton therapy plans. The conjugate gradient algorithm ranked in between the other two algorithms with an average speedup factor of two and an average improvement of the objective function value of 30%.

  19. Intensity-modulated radiation therapy, protons, and the risk of second cancers

    SciTech Connect

    Hall, Eric J. . E-mail: ejh1@columbia.edu

    2006-05-01

    Intensity-modulated radiation therapy (IMRT) allows dose to be concentrated in the tumor volume while sparing normal tissues. However, the downside to IMRT is the potential to increase the number of radiation-induced second cancers. The reasons for this potential are more monitor units and, therefore, a larger total-body dose because of leakage radiation and, because IMRT involves more fields, a bigger volume of normal tissue is exposed to lower radiation doses. Intensity-modulated radiation therapy may double the incidence of solid cancers in long-term survivors. This outcome may be acceptable in older patients if balanced by an improvement in local tumor control and reduced acute toxicity. On the other hand, the incidence of second cancers is much higher in children, so that doubling it may not be acceptable. IMRT represents a special case for children for three reasons. First, children are more sensitive to radiation-induced cancer than are adults. Second, radiation scattered from the treatment volume is more important in the small body of the child. Third, the question of genetic susceptibility arises because many childhood cancers involve a germline mutation. The levels of leakage radiation in current Linacs are not inevitable. Leakage can be reduced but at substantial cost. An alternative strategy is to replace X-rays with protons. However, this change is only an advantage if the proton machine employs a pencil scanning beam. Many proton facilities use passive modulation to produce a field of sufficient size, but the use of a scattering foil produces neutrons, which results in an effective dose to the patient higher than that characteristic of IMRT. The benefit of protons is only achieved if a scanning beam is used in which the doses are 10 times lower than with IMRT.

  20. Dosimetric Comparison of Three-Dimensional Conformal Proton Radiotherapy, Intensity-Modulated Proton Therapy, and Intensity-Modulated Radiotherapy for Treatment of Pediatric Craniopharyngiomas

    SciTech Connect

    Boehling, Nicholas S.; Grosshans, David R.; Bluett, Jaques B.; Palmer, Matthew T.; Song, Xiaofei; Amos, Richard A.; Sahoo, Narayan; Meyer, Jeffrey J.; Mahajan, Anita; Woo, Shiao Y.

    2012-02-01

    Purpose: Cranial irradiation in pediatric patients is associated with serious long-term adverse effects. We sought to determine whether both three-dimensional conformal proton radiotherapy (3D-PRT) and intensity-modulated proton therapy (IMPT) compared with intensity-modulated radiotherapy (IMRT) decrease integral dose to brain areas known to harbor neuronal stem cells, major blood vessels, and other normal brain structures for pediatric patients with craniopharyngiomas. Methods and Materials: IMRT, forward planned, passive scattering proton, and IMPT plans were generated and optimized for 10 pediatric patients. The dose was 50.4 Gy (or cobalt Gy equivalent) delivered in 28 fractions with the requirement for planning target volume (PTV) coverage of 95% or better. Integral dose data were calculated from differential dose-volume histograms. Results: The PTV target coverage was adequate for all modalities. IMRT and IMPT yielded the most conformal plans in comparison to 3D-PRT. Compared with IMRT, 3D-PRT and IMPT plans had a relative reduction of integral dose to the hippocampus (3D-PRT, 20.4; IMPT, 51.3%{sup Asterisk-Operator }), dentate gyrus (27.3, 75.0%{sup Asterisk-Operator }), and subventricular zone (4.5, 57.8%{sup Asterisk-Operator }). Vascular organs at risk also had reduced integral dose with the use of proton therapy (anterior cerebral arteries, 33.3{sup Asterisk-Operator }, 100.0%{sup Asterisk-Operator }; middle cerebral arteries, 25.9%{sup Asterisk-Operator }, 100%{sup Asterisk-Operator }; anterior communicating arteries, 30.8{sup Asterisk-Operator }, 41.7%{sup Asterisk-Operator }; and carotid arteries, 51.5{sup Asterisk-Operator }, 77.6{sup Asterisk-Operator }). Relative reduction of integral dose to the infratentorial brain (190.7{sup Asterisk-Operator }, 109.7%{sup Asterisk-Operator }), supratentorial brain without PTV (9.6, 26.8%{sup Asterisk-Operator }), brainstem (45.6, 22.4%{sup Asterisk-Operator }), and whole brain without PTV (19.4{sup Asterisk

  1. Three-Phase Adaptive Radiation Therapy for Patients With Nasopharyngeal Carcinoma Undergoing Intensity-Modulated Radiation Therapy: Dosimetric Analysis.

    PubMed

    Deng, Shan; Liu, Xu; Lu, Heming; Huang, Huixian; Shu, Liuyang; Jiang, Hailan; Cheng, Jinjian; Peng, Luxing; Pang, Qiang; Gu, Junzhao; Qin, Jian; Lu, Zhiping; Mo, Ying; Wu, Danling; Wei, Yinglin

    2017-01-01

    Patients with nasopharyngeal carcinoma undergoing intensity-modulated radiation therapy may experience significant anatomic changes throughout the entire treatment course, and adaptive radiation therapy may be necessary to maintain optimal dose delivered both to the targets and to the critical structures. The timing of adaptive radiation therapy, however, is largely unknown. This study was to evaluate the dosimetric benefits of a 3-phase adaptive radiation therapy technique for nasopharyngeal carcinoma. Twenty patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy were recruited prospectively. After fractions 5 and 15, each patient had repeat computed tomography scans, and adaptive replans with recontouring the targets and organs at risk on the new computed tomography images were generated and used for subsequent treatment (replan 1 and replan 2). Two hybrid intensity-modulated radiation therapy plans (plan 1 and plan 2) were generated by superimposing the initial plan (plan 0) to each repeated new computed tomography image, reflecting the actual dose delivered to the targets and organs at risk if no changes were made to the original plan. Dosimetric comparisons were made between the adaptive replans (adaptive radiation therapy plans: plan 0 + replan 1 + replan 2) and their corresponding nonadaptive radiation therapy plans (plan 0 + plan 1 + plan 2). Comparing with the nonadaptive radiation therapy plans, the adaptive radiation therapy plans resulted in a significant improvement in conformity index for planning target volumes for primary disease, involved lymph node, high-risk clinical target volume, and low-risk clinical target volume (PTVnx, PTVnd, PTV1, and PTV2, respectively). Median V95 for PTVnx; D95, D99, V100, V95, and V93 for PTVnd; D99 and V100 for PTV1; and D95, D99, V100, V95, and V93 for PTV2 were increased significantly. There were significant dose-volume reductions, including maximum doses to the brainstem and

  2. Volumetric Modulation Arc Radiotherapy Compared With Static Gantry Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma Tumor: A Feasibility Study

    SciTech Connect

    Scorsetti, Marta; Bignardi, Mario; Clivio, Alessandro

    2010-07-01

    Purpose: A planning study was performed to evaluate RapidArc (RA), a volumetric modulated arc technique, on malignant pleural mesothelioma. The benchmark was conventional fixed-field intensity-modulated radiotherapy (IMRT). Methods and materials: The computed tomography data sets of 6 patients were included. The plans for IMRT with nine fixed beams were compared against double-modulated arcs with a single isocenter. All plans were optimized for 15-MV photon beams. The dose prescription was 54 Gy to the planning target volume. The planning objectives for the planning target volume were a minimal dose of >95% and maximal dose of <107%. For the organs at risk, the parameters were as follows: contralateral lung, percentage of volume receiving 5 Gy (V{sub 5Gy}) <60%, V{sub 20Gy} < 10%, mean <10.0 Gy; liver, V{sub 30Gy} <33%, mean <31 Gy; heart, V{sub 45Gy} <30%, V{sub 50Gy} <20%, dose received by 1% of the volume (D{sub 1%}) <60 Gy; contralateral kidney, V{sub 15Gy} <20%; spine, D{sub 1%} <45 Gy; esophagus, V{sub 55Gy} <30%; and spleen, V{sub 40Gy} <50%. The monitor units (MUs) and delivery time were scored to measure the treatment efficiency. The pretreatment portal dosimetry scored delivery to the calculation agreement with the Gamma Agreement Index. Results: RA and IMRT provided equivalent coverage and homogeneity. Both techniques fulfilled objectives on organs at risk with a tendency of RA to improve sparing. The conformity index was 1.9 {+-} 0.1 for RA and IMRT. The number of MU/2Gy was 734 {+-} 82 for RA and 2,195 {+-} 317 for IMRT. The planning vs. delivery agreement revealed a Gamma Agreement Index for IMRT of 96.0% {+-} 2.6% and for RA of 95.7% {+-} 1.5%. The treatment time was 3.7 {+-} 0.3min for RA and 13.4 {+-} 0.1min for IMRT. Conclusion: RA demonstrated compared with conventional IMRT, similar target coverage and better dose sparing to the organs at risks. The number of MUs and the time required to deliver a 2-Gy fraction were much lower for RA, allowing

  3. Intensity-modulated radiation therapy for oropharyngeal cancer: radiation dosage constraint at the anterior mandible.

    PubMed

    Verdonck, Henk W D; de Jong, Jos M A; Granzier, Marlies E P G; Nieman, Fred H; de Baat, Cees; Stoelinga, Paul J W

    2009-06-01

    Because the survival of endosseous implants in irradiated bone is lower than in non-irradiated bone, particularly if the irradiation dose exceeds 50Gy, a study was carried out to assess the irradiation dose in the anterior mandible, when intensity modulated radiation therapy (IMRT) is used. The hypothesis was that adequate IMRT planning in oropharyngeal cancer patients is allowing sufficiently low anterior mandibular bone radiation dosages to safely insert endosseous implants. Ten randomly selected patients with oropharyngeal cancer, primarily treated by intensity-modulated radiotherapy (IMRT), were included in this study. First, at five determined positions distributed over the anterior mandible, the appropriate radiation dosages were calculated according to the originally arranged fractionated radiation schedule. Second, for each patient an adjusted fractionated radiation schedule was established with an extra dose constraint which allowed a lower dose in the mandible taking into account that the anterior mandible needs protection against radiation-induced osteoradionecrosis. The goal for the adjusted fractionated radiation schedule was similar as that of the original fractionated radiation schedule, including a desired tumour target dosage of 70Gy and maximum mean local dosages for organs at risk. The data revealed a considerable and statistically significant, irradiation dose reduction in the anterior mandible without compromising the other constraints. As a result of this study it is strongly advised to maximize dose constraint to the anterior mandible when planning irradiation for oropharyngeal cancer patients, using IMRT. This would greatly facilitate successful implant treatment for this group of patients. The fractionated radiation schedules used, should also be used for the planning of the best implant positions by integrating them in the implant planning software.

  4. MAGIC-type polymer gel for three-dimensional dosimetry: intensity-modulated radiation therapy verification.

    PubMed

    Gustavsson, Helen; Karlsson, Anna; Bäck, Sven A J; Olsson, Lars E; Haraldsson, Pia; Engström, Per; Nyström, Håkan

    2003-06-01

    A new type of polymer gel dosimeter, which responds well to absorbed dose even when manufactured in the presence of normal levels of oxygen, was recently described by Fong et al. [Phys. Med. Biol. 46, 3105-3113 (2001)] and referred to by the acronym MAGIC. The aim of this study was to investigate the feasibility of using this new type of gel for intensity-modulated radiation therapy (IMRT) verification. Gel manufacturing was carried out in room atmosphere under normal levels of oxygen. IMRT inverse treatment planning was performed using the Helios software. The gel was irradiated using a linear accelerator equipped with a dynamic multileaf collimator, and intensity modulation was achieved using sliding window technique. The response to absorbed dose was evaluated using magnetic resonance imaging. Measured and calculated dose distributions were compared with regard to in-plane isodoses and dose volume histograms. In addition, the spatial and dosimetric accuracy was evaluated using the gamma formalism. Good agreement between calculated and measured data was obtained. In the isocenter plane, the 70% and 90% isodoses acquired using the different methods are mostly within 2 mm, with up to 3 mm disagreement at isolated points. For the planning target volume (PTV), the calculated mean relative dose was 96.8 +/- 2.5% (1 SD) and the measured relative mean dose was 98.6 +/- 2.2%. Corresponding data for an organ at risk was 34.4 +/- 0.9% and 32.7 +/- 0.7%, respectively. The gamma criterion (3 mm spatial/3% dose deviation) was fulfilled for 94% of the pixels in the target region. Discrepancies were found in hot spots the upper and lower parts of the PTV, where the measured dose was up to 11% higher than calculated. This was attributed to sub optimal scatter kernels used in the treatment planning system dose calculations. Our results indicate great potential for IMRT verification using MAGIC-type polymer gel.

  5. A Comparison of Helical Intensity-Modulated Radiotherapy, Intensity-Modulated Radiotherapy, and 3D-Conformal Radiation Therapy for Pancreatic Cancer

    SciTech Connect

    Poppe, Matthew M.; Narra, Venkat; Yue, Ning J.; Zhou Jinghao; Nelson, Carl; Jabbour, Salma K.

    2011-01-01

    We assessed dosimetric differences in pancreatic cancer radiotherapy via helical intensity-modulated radiotherapy (HIMRT), linac-based IMRT, and 3D-conformal radiation therapy (3D-CRT) with regard to successful plan acceptance and dose to critical organs. Dosimetric analysis was performed in 16 pancreatic cases that were planned to 54 Gy; both post-pancreaticoduodenectomy (n = 8) and unresected (n = 8) cases were compared. Without volume modification, plans met constraints 75% of the time with HIMRT and IMRT and 13% with 3D-CRT. There was no statistically significantly improvement with HIMRT over conventional IMRT in reducing liver V35, stomach V45, or bowel V45. HIMRT offers improved planning target volume (PTV) dose homogeneity compared with IMRT, averaging a lower maximum dose and higher volume receiving the prescription dose (D100). HIMRT showed an increased mean dose over IMRT to bowel and liver. Both HIMRT and IMRT offer a statistically significant improvement over 3D-CRT in lowering dose to liver, stomach, and bowel. The results were similar for both unresected and resected patients. In pancreatic cancer, HIMRT offers improved dose homogeneity over conventional IMRT and several significant benefits to 3D-CRT. Factors to consider before incorporating IMRT into pancreatic cancer therapy are respiratory motion, dose inhomogeneity, and mean dose.

  6. P13.25A RADIOBIOLOGICAL COMPARISON BETWEEN THE INVERSE INTENSITY MODULATED RADIATION THERAPY AND THE FIELD IN FIELD INTENSITY MODULATED RADIATION THERAPY FOR THE TREATMENT OF GLIOBLASTOMA

    PubMed Central

    Yazici, A.; Dirican, B.; Kara, E.

    2014-01-01

    For critical structures the use of maximum or mean dose limits in the intensity modulated radiation therapy (IMRT) optimization is not very meaningful. The dose-volume limits and equivalent uniform dose (EUD) which is defined as the uniform dose that would lead to the same effect as the given non-uniform dose in as particular organ are combined to analyze the volume effect. The normal tissue complication probability (NTCP) is a predictor of radiobiological effect for organs at risk (OAR). The calculation of the NTCP is based on the DVH which is generated by the treatment planning system after calculation of the 3D dose distribution. Uniform EUD irradiation of an OAR results in the same NTCP as the original non-homogeneous distribution. The NTCP equation is therefore represented as a function of EUD. The inverse equation expresses EUD as a function of NTCP. Expressing NTCP in terms of EUD represents a step toward simplifying the conceptual framework for modeling probability of expected complications. The aim of this study is to compare radiobiological effects between the fif IMRT and inverse IMRT for treatment of Glioblastoma (GBM) using the equivalent uniform dose (EUD) and normal tissue complication probability (NTCP). Five representative patients treated with definitive radiation using IMRT at our clinic in the last two year were selected for treatment planning study. Criteria for inclusion were glioblastoma . The normal tissues (Organ at Risk, OaR) contoured included brain-stem, optic chiasm, optic nerves, right-left cohclea and whole brain. Brain was defined as total brain tissue minus the PTV. Two different radiation therapy techniques; inverse IMRT and FiF IMRT treatment plans were optimised with the prescription dose 60 Gy/30 fractions. All those calculations and IMRT optimizations were performed using the Prowess Panther DAQ TPS with 6 MV,Siemens Artiste, MLC with 160 leaves and evaluated by using EUD and NTCP models. In the present study, target dose

  7. Intensity-modulated radiation therapy to bilateral lower limb extremities concurrently: a planning case study

    SciTech Connect

    Fitzgerald, Emma Miles, Wesley; Fenton, Paul; Frantzis, Jim

    2014-09-15

    Non-melanomatous skin cancers represent 80% of all newly diagnosed cancers in Australia with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being the most common. A previously healthy 71-year-old woman presented with widespread and tender superficial skin cancers on the lower bilateral limbs. External beam radiation therapy through the use of intensity-modulated radiation therapy (IMRT) was employed as the treatment modality of choice as this technique provides conformal dose distribution to a three-dimensional treatment volume while reducing toxicity to surrounding tissues. The patient was prescribed a dose of 60 Gy to the planning target volume (PTV) with 1.0 cm bolus over the ventral surface of each limb. The beam arrangement consisted of six treatment fields that avoided entry and exit through the contralateral limb. The treatment plans met the International Commission on Radiation Units and Measurements (ICRU) guidelines and produced highly conformal dosimetric results. Skin toxicity was measured against the National Cancer Institute: Common Terminology Criteria for Adverse Events (NCI: CTCAE) version 3. A well-tolerated treatment was delivered with excellent results given the initial extent of the disease. This case study has demonstrated the feasibility and effectiveness of IMRT for skin cancers as an alternative to surgery and traditional superficial radiation therapy, utilising a complex PTV of the extremities for patients with similar presentations.

  8. Compact Dielectric Wall Accelerator Development For Intensity Modulated Proton Therapy And Homeland Security Applications

    SciTech Connect

    Chen, Y -; Caporaso, G J; Guethlein, G; Sampayan, S; Akana, G; Anaya, R; Blackfield, D; Cook, E; Falabella, S; Gower, E; Harris, J; Hawkins, S; Hickman, B; Holmes, C; Horner, A; Nelson, S; Paul, A; Pearson, D; Poole, B; Richardson, R; Sanders, D; Stanley, J; Sullivan, J; Wang, L; Watson, J; Weir, J

    2009-06-17

    Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, SiC photoconductive switches and compact proton sources. Applications of the DWA accelerator to problems in homeland security will also be discussed.

  9. Improved outcomes with intensity modulated radiation therapy combined with temozolomide for newly diagnosed glioblastoma multiforme.

    PubMed

    Aherne, Noel J; Benjamin, Linus C; Horsley, Patrick J; Silva, Thomaz; Wilcox, Shea; Amalaseelan, Julan; Dwyer, Patrick; Tahir, Abdul M R; Hill, Jacques; Last, Andrew; Hansen, Carmen; McLachlan, Craig S; Lee, Yvonne L; McKay, Michael J; Shakespeare, Thomas P

    2014-01-01

    Purpose. Glioblastoma multiforme (GBM) is optimally treated by maximal debulking followed by combined chemoradiation. Intensity modulated radiation therapy (IMRT) is gaining widespread acceptance in other tumour sites, although evidence to support its use over three-dimensional conformal radiation therapy (3DCRT) in the treatment of gliomas is currently lacking. We examined the survival outcomes for patients with GBM treated with IMRT and Temozolomide. Methods and Materials. In all, 31 patients with GBM were treated with IMRT and 23 of these received chemoradiation with Temozolomide. We correlated survival outcomes with patient functional status, extent of surgery, radiation dose, and use of chemotherapy. Results. Median survival for all patients was 11.3 months, with a median survival of 7.2 months for patients receiving 40.05 Gray (Gy) and a median survival of 17.4 months for patients receiving 60 Gy. Conclusions. We report one of the few series of IMRT in patients with GBM. In our group, median survival for those receiving 60 Gy with Temozolomide compared favourably to the combined therapy arm of the largest randomised trial of chemoradiation versus radiation to date (17.4 months versus 14.6 months). We propose that IMRT should be considered as an alternative to 3DCRT for patients with GBM.

  10. [Intensity-modulated radiation therapy and stereotactic body radiation therapy for head and neck tumors: evidence-based medicine].

    PubMed

    Lapierre, A; Martin, F; Lapeyre, M

    2014-10-01

    Over the last decade, there have been many technical advances in radiation therapy, such as the spread of intensity-modulated conformal radiotherapy, and the rise of stereotactic body radiation therapy. By allowing better dose-to-target conformation and thus better organs at risk-sparing, these techniques seem very promising, particularly in the field of head and neck tumors. The present work aims at analyzing the level of evidence and recommendation supporting the use of high-technology radiotherapy in head and neck neoplasms, by reviewing the available literature.

  11. Fatal pneumonitis associated with intensity-modulated radiation therapy for mesothelioma

    SciTech Connect

    Allen, Aaron M. . E-mail: aallen@lroc.harvard.edu; Czerminska, Maria; Jaenne, Pasi A.; Sugarbaker, David J.; Bueno, Raphael; Harris, Jay R.; Court, Laurence; Baldini, Elizabeth H.

    2006-07-01

    Purpose: To describe the initial experience at Dana-Farber Cancer Institute/Brigham and Women's Hospital with intensity-modulated radiation therapy (IMRT) as adjuvant therapy after extrapleural pneumonectomy (EPP) and adjuvant chemotherapy. Methods and Materials: The medical records of patients treated with IMRT after EPP and adjuvant chemotherapy were retrospectively reviewed. IMRT was given to a dose of 54 Gy to the clinical target volume in 1.8 Gy daily fractions. Treatment was delivered with a dynamic multileaf collimator using a sliding window technique. Eleven of 13 patients received heated intraoperative cisplatin chemotherapy (225 mg/m{sup 2}). Two patients received neoadjuvant intravenous cisplatin/pemetrexed, and 10 patients received adjuvant cisplatin/pemetrexed chemotherapy after EPP but before radiation therapy. All patients received at least 2 cycles of intravenous chemotherapy. The contralateral lung was limited to a V20 (volume of lung receiving 20 Gy or more) of 20% and a mean lung dose (MLD) of 15 Gy. All patients underwent fluorodeoxyglucose positron emission tomography (FDG-PET) for staging, and any FDG-avid areas in the hemithorax were given a simultaneous boost of radiotherapy to 60 Gy. Statistical comparisons were done using two-sided t test. Results: Thirteen patients were treated with IMRT from December 2004 to September 2005. Six patients developed fatal pneumonitis after treatment. The median time from completion of IMRT to the onset of radiation pneumonitis was 30 days (range 5-57 days). Thirty percent of patients (4 of 13) developed acute Grade 3 nausea and vomiting. One patient developed acute Grade 3 thrombocytopenia. The median V20, MLD, and V5 (volume of lung receiving 5 Gy or more) for the patients who developed pneumonitis was 17.6% (range, 15.3-22.3%), 15.2 Gy (range, 13.3-17 Gy), and 98.6% (range, 81-100%), respectively, as compared with 10.9% (range, 5.5-24.7%) (p = 0.08), 12.9 Gy (range, 8.7-16.9 Gy) (p = 0.07), and 90% (range

  12. Treatment planning, optimization, and beam delivery technqiues for intensity modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Sengbusch, Evan R.

    , beamlet weight, the number of delivered beamlets, and the number of delivery angles. These methods are evaluated via treatment planning studies including left-sided whole breast irradiation, lung stereotactic body radiotherapy, nasopharyngeal carcinoma, and whole brain radiotherapy with hippocampal avoidance. Improvements in efficiency and efficacy relative to traditional proton therapy and intensity modulated photon radiation therapy are discussed.

  13. [Vestibular disorders and nausea during head and neck intensity-modulated radiation therapy].

    PubMed

    Berta, É; Righini, C A; Chamorey, E; Villa, J; Atallah, I; Reyt, É; Coffre, A; Schmerber, S

    2016-06-01

    We studied whether there is a relationship between nausea and vestibular disorders in patients treated with intensity modulated radiation therapy (IMRT) for head and neck cancer. We performed a prospective single-centre study that enrolled 31 patients. A videonystagmography was carried out before and within 15 days after radiation therapy for each patient. Nausea was assessed at baseline, every week, and at the post-radiotherapy videonystagmography visit. Twenty-six patients had benefited from a complete interpretable videonystagmography. For 14 of these patients vestibular damage was diagnosed post-radiotherapy. During irradiation, six patients felt nauseous, but without dizziness. In univariate analysis, we found a relationship statistically significant between the average dose received by the vestibules and vestibular disorder videonystagmography (P=0.001, odds ratio [OR]: 1.08 [1.025-.138]), but there was no relationship between vestibular disorder videonystagmography and nausea (P=0.701). Irradiation of the vestibular system during IMRT does not seem to explain the nausea. Copyright © 2016 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  14. Intensity modulated radiation therapy with field rotation--a time-varying fractionation study.

    PubMed

    Dink, Delal; Langer, Mark P; Rardin, Ronald L; Pekny, Joseph F; Reklaitis, Gintaras V; Saka, Behlul

    2012-06-01

    This paper proposes a novel mathematical approach to the beam selection problem in intensity modulated radiation therapy (IMRT) planning. The approach allows more beams to be used over the course of therapy while limiting the number of beams required in any one session. In the proposed field rotation method, several sets of beams are interchanged throughout the treatment to allow a wider selection of beam angles than would be possible with fixed beam orientations. The choice of beamlet intensities and the number of identical fractions for each set are determined by a mixed integer linear program that controls jointly for the distribution per fraction and the cumulative dose distribution delivered to targets and critical structures. Trials showed the method allowed substantial increases in the dose objective and/or sparing of normal tissues while maintaining cumulative and fraction size limits. Trials for a head and neck site showed gains of 25%-35% in the objective (average tumor dose) and for a thoracic site gains were 7%-13%, depending on how strict the fraction size limits were set. The objective did not rise for a prostate site significantly, but the tolerance limits on normal tissues could be strengthened with the use of multiple beam sets.

  15. Comparison of intensity modulated radiotherapy (IMRT) with intensity modulated particle therapy (IMPT) using fixed beams or an ion gantry for the treatment of patients with skull base meningiomas

    PubMed Central

    2012-01-01

    Background To examine the potential improvement in treatment planning for patients with skull base meningioma using IMRT compared to carbon ion or proton beams with and without a gantry. Methods Five patients originally treated with photon IMRT were selected for the study. Ion beams were chosen using a horizontal beam or an ion gantry. Intensity controlled raster scanning and the intensity modulated particle therapy mode were used for plan optimization. The evaluation included analysis of dose-volume histograms of the target volumes and organs at risk. Results In comparison with carbon and proton beams only with horizontal beams, carbon ion treatment plans could spare the OARs more and concentrated on the target volumes more than proton and photon IMRT treatment plans. Using only a horizontal fixed beam, satisfactory plans could be achieved for skull base tumors. Conclusion The results of the case studies showed that using IMPT has the potential to overcome the lack of a gantry for skull base tumors. Carbon ion plans offered slightly better dose distributions than proton plans, but the differences were not clinically significant with established dose prescription concepts. PMID:22439607

  16. Computer-assisted selection of coplanar beam orientations in intensity-modulated radiation therapy*

    NASA Astrophysics Data System (ADS)

    Pugachev, A.; Xing, L.

    2001-09-01

    In intensity-modulated radiation therapy (IMRT), the incident beam orientations are often determined by a trial and error search. The conventional beam's-eye view (BEV) tool becomes less helpful in IMRT because it is frequently required that beams go through organs at risk (OARs) in order to achieve a compromise between the dosimetric objectives of the planning target volume (PTV) and the OARs. In this paper, we report a beam's-eye view dosimetrics (BEVD) technique to assist in the selection of beam orientations in IMRT. In our method, each beam portal is divided into a grid of beamlets. A score function is introduced to measure the `goodness' of each beamlet at a given gantry angle. The score is determined by the maximum PTV dose deliverable by the beamlet without exceeding the tolerance doses of the OARs and normal tissue located in the path of the beamlet. The overall score of the gantry angle is given by a sum of the scores of all beamlets. For a given patient, the score function is evaluated for each possible beam orientation. The directions with the highest scores are then selected as the candidates for beam placement. This procedure is similar to the BEV approach used in conventional radiation therapy, except that the evaluation by a human is replaced by a score function to take into account the intensity modulation. This technique allows one to select beam orientations without the excessive computing overhead of computer optimization of beam orientation. It also provides useful insight into the problem of selection of beam orientation and is especially valuable for complicated cases where the PTV is surrounded by several sensitive structures and where it is difficult to select a set of `good' beam orientations. Several two-dimensional (2D) model cases were used to test the proposed technique. The plans obtained using the BEVD-selected beam orientations were compared with the plans obtained using equiangular spaced beams. For all the model cases investigated

  17. Clinical response of advanced cancer patients to cellular immunotherapy and intensity-modulated radiation therapy

    PubMed Central

    Hasumi, Kenichiro; Aoki, Yukimasa; Wantanabe, Ryuko; Mann, Dean L

    2013-01-01

    Patients afflicted with advanced cancers were treated with the intratumoral injection of autologous immature dendritic cells (iDCs) followed by activated T-cell infusion and intensity-modulated radiation therapy (IMRT). A second round of iDCs and activated T cells was then administered to patients after the last radiation cycle. This complete regimen was repeated for new and recurring lesions after 6 weeks of follow-up. One year post therapy, outcome analyses were performed to evaluate treatment efficacy. Patients were grouped according to both the number and size of tumors and clinical parameters at treatment initiation, including recurrent disease after standard cancer therapy, Stage IV disease, and no prior therapy. Irrespective of prior treatment status, 23/37 patients with ≤ 5 neoplastic lesions that were ≤ 3 cm in diameter achieved complete responses (CRs), and 5/37 exhibited partial responses (PRs). Among 130 individuals harboring larger and more numerous lesions, CRs were observed in 7/74 patients that had received prior SCT and in 2/56 previously untreated patients. Some patients manifested immune responses including an increase in CD8+CD56+ lymphocytes among circulating mononuclear cells in the course of treatment. To prospectively explore the therapeutic use of these cells, CD8+ cells were isolated from patients that had been treated with cellular immunotherapy and IMRT, expanded in vitro, and injected into recurrent metastatic sites in 13 individuals who underwent the same immunoradiotherapeutic regimens but failed to respond. CRs were achieved in 34 of 58 of such recurrent lesions while PRs in 17 of 58. These data support the expanded use of immunoradiotherapy in advanced cancer patients exhibiting progressive disease. PMID:24349874

  18. TH-A-BRE-01: The Status of Intensity Modulated Proton and Ion Therapy

    SciTech Connect

    Dong, L; Zhu, X; Unkelbach, J; Schulte, R

    2014-06-15

    IMRT with photons has become a radiation therapy standard of care for many cancer treatment sites. The situation is quite different with intensity modulated particle (protons and ion) radiation therapy (IMPT). With the rapid development of beam scanning techniques and many of the newer proton facilities exclusively offering active beam scanning as their radiation delivery technique, it is timely to give an update on the status and challenges of IMPT. The leading principle in IMPT is to aim at the target from several, not necessarily coplanar, directions with multiple pencil beams that are modulated in their intensity and adjusted in their energy such that a desired dose distribution or, more generally, a desired bio-effective dose distribution is achieved. Different from low-LET photons, the varying relative biological effectiveness (RBE) along the beam path adds an additional dimension to the treatment planning process and will require biophysical modeling at least for carbon ion therapy. IMPT involves computationally challenging tasks, yet it needs to be very fast in order to be clinically relevant. To make IMPT computationally tractable, robust and efficient optimization methods are required. Lastly, IMPT planning is very sensitive to accurate knowledge of relative stopping and scattering powers of the intervening tissues as well as intra- and inter-fraction motion. Robust planning methods are being developed in order to obtain IMPT plans that are less sensitive against such uncertainties. This therapy symposium will present an update on the current status and emerging developments of IMPT from the medical physics perspective. Learning Objectives: Become familiar with current delivery techniques for IMPT and their limitations. Understand the basics of dose calculational algorithms and commissioning of IMPT. Learn how to assess the accuracy of planning and delivery of IMPT treatments. Get an overview of currently used and emerging optimization techniques. Learn

  19. Dose-Volume Comparison of Proton Therapy and Intensity-Modulated Radiotherapy for Prostate Cancer

    SciTech Connect

    Vargas, Carlos Fryer, Amber; Mahajan, Chaitali; Indelicato, Daniel; Horne, David C.; Chellini, Angela; McKenzie, Craig C.; Lawlor, Paula C.; Henderson, Randal; Li Zuofeng; Lin Liyong; Olivier, Kenneth; Keole, Sameer

    2008-03-01

    Purpose: The contrast in dose distribution between proton radiotherapy (RT) and intensity-modulated RT (IMRT) is unclear, particularly in regard to critical structures such as the rectum and bladder. Methods and Materials: Between August and November 2006, the first 10 consecutive patients treated in our Phase II low-risk prostate proton protocol (University of Florida Proton Therapy Institute protocol 0001) were reviewed. The double-scatter proton beam plans used in treatment were analyzed for various dosimetric endpoints. For all plans, each beam dose distribution, angle, smearing, and aperture margin were optimized. IMRT plans were created for all patients and simultaneously analyzed. The IMRT plans were optimized through multiple volume objectives, beam weighting, and individual leaf movement. The patients were treated to 78 Gray-equivalents (GE) in 2-GE fractions with a biologically equivalent dose of 1.1. Results: All rectal and rectal wall volumes treated to 10-80 GE (percentage of volume receiving 10-80 GE [V{sub 10}-V{sub 80}]) were significantly lower with proton therapy (p < 0.05). The rectal V{sub 50} was reduced from 31.3% {+-} 4.1% with IMRT to 14.6% {+-} 3.0% with proton therapy for a relative improvement of 53.4% and an absolute benefit of 16.7% (p < 0.001). The mean rectal dose decreased 59% with proton therapy (p < 0.001). For the bladder and bladder wall, proton therapy produced significantly smaller volumes treated to doses of 10-35 GE (p < 0.05) with a nonsignificant advantage demonstrated for the volume receiving {<=}60 GE. The bladder V{sub 30} was reduced with proton therapy for a relative improvement of 35.3% and an absolute benefit of 15.1% (p = 0.02). The mean bladder dose decreased 35% with proton therapy (p = 0.002). Conclusion: Compared with IMRT, proton therapy reduced the dose to the dose-limiting normal structures while maintaining excellent planning target volume coverage.

  20. Dose verification in intensity modulation radiation therapy: a fractal dimension characteristics study.

    PubMed

    Wu, Jia-Ming; Kuo, Chung-Ming; Chen, Ching-Jiang

    2013-01-01

    This study describes how to identify the coincidence of desired planning isodose curves with film experimental results by using a mathematical fractal dimension characteristic method to avoid the errors caused by visual inspection in the intensity modulation radiation therapy (IMRT). The isodose curves of the films delivered by linear accelerator according to Plato treatment planning system were acquired using Osiris software to aim directly at a single interested dose curve for fractal characteristic analysis. The results were compared with the corresponding planning desired isodose curves for fractal dimension analysis in order to determine the acceptable confidence level between the planning and the measurement. The film measured isodose curves and computer planning curves were deemed identical in dose distribution if their fractal dimensions are within some criteria which suggested that the fractal dimension is a unique fingerprint of a curve in checking the planning and film measurement results. The dose measured results of the film were presumed to be the same if their fractal dimension was within 1%. This quantitative rather than qualitative comparison done by fractal dimension numerical analysis helps to decrease the quality assurance errors in IMRT dosimetry verification.

  1. Intensity-modulated radiation therapy for malignancies of the nasal cavity and paranasal sinuses

    SciTech Connect

    Daly, Megan E.; Chen, Allen M. . E-mail: allenmchen@yahoo.com; Bucci, M. Kara; El-Sayed, Ivan; Xia Ping; Kaplan, Michael J.; Eisele, David W.

    2007-01-01

    Purpose: To report the clinical outcome of patients treated with intensity-modulated radiation therapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 1998 and 2004, 36 patients with malignancies of the sinonasal region were treated with IMRT. Thirty-two patients (89%) were treated in the postoperative setting after gross total resection. Treatment plans were designed to provide a dose of 70 Gy to 95% or more of the gross tumor volume (GTV) and 60 Gy to 95% or more of the clinical tumor volume (CTV) while sparing neighboring critical structures including the optic chiasm, optic nerves, eyes, and brainstem. The primary sites were: 13 ethmoid sinus, 10 maxillary sinus, 7 nasal cavity, and 6 other. Histology was: 12 squamous cell, 7 esthesioneuroblastoma, 5 adenoid cystic, 5 undifferentiated, 5 adenocarcinoma, and 2 other. Median follow-up was 51 months among surviving patients (range, 9-82 months). Results: The 2-year and 5-year estimates of local control were 62% and 58%, respectively. One patient developed isolated distant metastasis, and none developed isolated regional failure. The 5-year rates of disease-free and overall survival were 55% and 45%, respectively. The incidence of ocular toxicity was minimal with no patients reporting decreased vision. Late complications included xerophthalmia (1 patient), lacrimal stenosis (1 patient), and cataract (1 patient). Conclusion: Although IMRT for malignancies of the sinonasal region does not appear to lead to significant improvements in disease control, the low incidence of complications is encouraging.

  2. Dosimetric comparison of tools for intensity modulated radiation therapy with gamma analysis: a phantom study

    NASA Astrophysics Data System (ADS)

    Akbas, Ugur; Okutan, Murat; Demir, Bayram; Koksal, Canan

    2015-07-01

    Dosimetry of the Intensity Modulated Radiation Therapy (IMRT) is very important because of the complex dose distributions. Diode arrays are the most common and practical measurement tools for clinical usage for IMRT. Phantom selection is critical for QA process. IMRT treatment plans are recalculated for the phantom irradiation in QA. Phantoms are made in different geometrical shapes to measure the doses of different types of irradiation techniques. Comparison of measured and calculated dose distributions for IMRT can be made by using gamma analysis. In this study, 10 head-and-neck IMRT QA plans were created with Varian Eclipse 8.9 treatment planning system. Water equivalent RW3-slab phantoms, Octavius-2 phantom and PTW Seven29 2D-array were used for QA measurements. Gantry, collimator and couch positions set to 00 and QA plans were delivered to RW3 and Octavius phantoms. Then the positions set to original angles and QA plans irradiated again. Measured and calculated fluence maps were evaluated with gamma analysis for different DD and DTA criteria. The effect of different set-up conditions for RW3 and Octavius phantoms in QA plan delivery evaluated by gamma analysis. Results of gamma analysis show that using RW3-slab phantoms with setting parameters to 00 is more appropriate for IMRT QA.

  3. Rational use of intensity-modulated radiation therapy: the importance of clinical outcome.

    PubMed

    De Neve, Wilfried; De Gersem, Werner; Madani, Indira

    2012-01-01

    During the last 2 decades, intensity-modulated radiation therapy (IMRT) became a standard technique despite its drawbacks of volume delineation, planning, robustness of delivery, challenging quality assurance, and cost as compared with non-IMRT. The theoretic advantages of IMRT dose distributions are generally accepted, but the clinical advantages remain debatable because of the lack of clinical assessment of the effort that is required to overshadow the disadvantages. Rational IMRT use requires a positive advantage/drawback balance. Only 5 randomized clinical trials (RCTs), 3 in the breast and 2 in the head and neck, which compare IMRT with non-IMRT (2-dimensional technique in four fifths of the trials), have been published (as of March 2011), and all had toxicity as the primary endpoint. More than 50 clinical trials compared results of IMRT-treated patients with a non-IMRT group, mostly historical controls. RCTs systematically showed a lower toxicity in IMRT-treated patients, and the non-RCTs confirmed these findings. Toxicity reduction, counterbalancing the drawbacks of IMRT, was convincing for breast and head and neck IMRT. For other tumor sites, the arguments favoring IMRT are weaker because of the inability to control bias outside the randomized setting. For anticancer efficacy endpoints, like survival, disease-specific survival, or locoregional control, the balance between advantages and drawbacks is fraught with uncertainties because of the absence of robust clinical data.

  4. Compact multileaf collimator for conformal and intensity modulated fast neutron therapy: Electromechanical design and validation

    SciTech Connect

    Farr, J. B.; Maughan, R. L.; Yudelev, M.; Blosser, E.; Brandon, J.; Horste, T.; Forman, J. D.

    2006-09-15

    The electromechanical properties of a 120-leaf, high-resolution, computer-controlled, fast neutron multileaf collimator (MLC) are presented. The MLC replaces an aging, manually operated multirod collimator. The MLC leaves project 5 mm in the isocentric plane perpendicular to the beam axis. A taper is included on the leaves matching beam divergence along one axis. The 5-mm leaf projection width is chosen to give high-resolution conformality across the entire field. The maximum field size provided is 30x30 cm{sup 2}. To reduce the interleaf transmission a 0.254-mm blocking step is included. End-leaf steps totaling 0.762 mm are also provided allowing opposing leaves to close off within the primary radiation beam. The neutron MLC also includes individual 45 deg. and 60 deg. automated universal tungsten wedges. The automated high-resolution neutron collimation provides an increase in patient throughput capacity, enables a new modality, intensity modulated neutron therapy, and limits occupational radiation exposure by providing remote operation from a shielded console area.

  5. A novel linear programming approach to fluence map optimization for intensity modulated radiation therapy treatment planning.

    PubMed

    Romeijn, H Edwin; Ahuja, Ravindra K; Dempsey, James F; Kumar, Arvind; Li, Jonathan G

    2003-11-07

    We present a novel linear programming (LP) based approach for efficiently solving the intensity modulated radiation therapy (IMRT) fluence-map optimization (FMO) problem to global optimality. Our model overcomes the apparent limitations of a linear-programming approach by approximating any convex objective function by a piecewise linear convex function. This approach allows us to retain the flexibility offered by general convex objective functions, while allowing us to formulate the FMO problem as a LP problem. In addition, a novel type of partial-volume constraint that bounds the tail averages of the differential dose-volume histograms of structures is imposed while retaining linearity as an alternative approach to improve dose homogeneity in the target volumes, and to attempt to spare as many critical structures as possible. The goal of this work is to develop a very rapid global optimization approach that finds high quality dose distributions. Implementation of this model has demonstrated excellent results. We found globally optimal solutions for eight 7-beam head-and-neck cases in less than 3 min of computational time on a single processor personal computer without the use of partial-volume constraints. Adding such constraints increased the running times by a factor of 2-3, but improved the sparing of critical structures. All cases demonstrated excellent target coverage (> 95%), target homogeneity (< 10% overdosing and < 7% underdosing) and organ sparing using at least one of the two models.

  6. Combining segment generation with direct step-and-shoot optimization in intensity-modulated radiation therapy

    SciTech Connect

    Carlsson, Fredrik

    2008-09-15

    A method for generating a sequence of intensity-modulated radiation therapy step-and-shoot plans with increasing number of segments is presented. The objectives are to generate high-quality plans with few, large and regular segments, and to make the planning process more intuitive. The proposed method combines segment generation with direct step-and-shoot optimization, where leaf positions and segment weights are optimized simultaneously. The segment generation is based on a column generation approach. The method is evaluated on a test suite consisting of five head-and-neck cases and five prostate cases, planned for delivery with an Elekta SLi accelerator. The adjustment of segment shapes by direct step-and-shoot optimization improves the plan quality compared to using fixed segment shapes. The improvement in plan quality when adding segments is larger for plans with few segments. Eventually, adding more segments contributes very little to the plan quality, but increases the plan complexity. Thus, the method provides a tool for controlling the number of segments and, indirectly, the delivery time. This can support the planner in finding a sound trade-off between plan quality and treatment complexity.

  7. Meningioma Causing Visual Impairment: Outcomes and Toxicity After Intensity Modulated Radiation Therapy

    SciTech Connect

    Maclean, Jillian; Fersht, Naomi; Bremner, Fion; Stacey, Chris; Sivabalasingham, Suganya; Short, Susan

    2013-03-15

    Purpose: To evaluate ophthalmologic outcomes and toxicity of intensity modulated radiation therapy (IMRT) in patients with meningiomas causing visual deficits. Methods and Materials: A prospective observational study with formal ophthalmologic and clinical assessment of 30 consecutive cases of meningioma affecting vision treated with IMRT from 2007 to 2011. Prescriptions were 50.4 Gy to mean target dose in 28 daily fractions. The median follow-up time was 28 months. Twenty-six meningiomas affected the anterior visual pathway (including 3 optic nerve sheath meningiomas); 4 were posterior to the chiasm. Results: Vision improved objectively in 12 patients (40%). Improvements were in visual field (5/16 patients), color vision (4/9 patients), acuity (1/15 patients), extraocular movements (3/11 patients), ptosis (1/5 patients), and proptosis (2/6 patients). No predictors of clinical response were found. Two patients had minor reductions in tumor dimensions on magnetic resonance imaging, 1 patient had radiological progression, and the other patients were stable. One patient experienced grade 2 keratitis, 1 patient had a minor visual field loss, and 5 patients had grade 1 dry eye. Conclusion: IMRT is an effective method for treating meningiomas causing ophthalmologic deficits, and toxicity is minimal. Thorough ophthalmologic assessment is important because clinical responses often occur in the absence of radiological change.

  8. SU-E-P-18: Intensity-Modulated Radiation Therapy for Cervical Esophageal Squamous Cell Carcinoma

    SciTech Connect

    Bai, W; Qiao, X; Zhou, Z; Song, Y; Zhang, R; Zhen, C

    2015-06-15

    Purpose: To retrospectively analyze the outcomes and prognostic factors of cervical esophageal squamous cell carcinoma (SCC) treated with intensity modulated radiation therapy (IMRT). Methods: Thirty-seven patients with cervical esophageal SCC treated with IMRT were analyzed retrospectively. They received 54–66 Gy in 27–32 fractions. Nineteen patients received concurrent (n=12) or sequential (n=7) platinum-based two drugs chemoradiotherapy. Overall survival (OS), local control rates (LCR) and prognostic factors were evaluated. Acute toxicities and patterns of first failures were observed. Results: The median follow-up was 46 months for alive patients. The l-, 3-, 4- and 5-year OS of the all patients were 83.8%, 59.1%, 47.5% and 32.6% respectively. The median survival time was 46 months. The l-, 3-,4- and 5-year LCR were 82.9%, 63.0%, 54.5% and 54.5%, respectively. Univariate and Multivariate analysis all showed that size of GTV was an independent prognostic factor (p=0.033, p=0.039). There were no patients with Grade 3 acute radiation esophagitis and Grade 2–4 acute pneumonitis. The local failure accounted for 70.0% of all treatment-related failures. Conclusion: IMRT is safe and effective in the treatment of cervical esophageal squamous cell carcinoma. Size of GTV is an independent prognostic factor. Local failure still remains the main reason of treatment failures. The authors declare no conflicts of interest in preparing this article.

  9. Feasibility of atlas-based active bone marrow sparing intensity modulated radiation therapy for cervical cancer.

    PubMed

    Li, Nan; Noticewala, Sonal S; Williamson, Casey W; Shen, Hanjie; Sirak, Igor; Tarnawski, Rafal; Mahantshetty, Umesh; Hoh, Carl K; Moore, Kevin L; Mell, Loren K

    2017-05-01

    To test the hypothesis that atlas-based active bone marrow (ABM)-sparing intensity modulated radiation therapy (IMRT) yields similar dosimetric results compared to custom ABM-sparing IMRT for cervical cancer patients. We sampled 62 cervical cancer patients with pre-treatment FDG-PET/CT in training (n=32) or test (n=30) sets. ABM was defined as the subvolume of the pelvic bone marrow (PBM) with standardized uptake value (SUV) above the mean on the average FDG-PET image (ABMAtlas) vs. the individual's PET (ABMCustom). Both were deformed to the planning CT. Overlap between the two subvolumes was measured using the Dice coefficient. Three IMRT plans designed to spare PBM, ABMAtlas, or ABMCustom were compared for 30 test patients. Dosimetric parameters were used to evaluate plan quality. ABMAtlas and ABMCustom volumes were not significantly different (p=0.90), with a mean Dice coefficient of 0.75, indicating good agreement. Compared to IMRT plans designed to spare PBM and ABMCustom, ABMAtlas-sparing IMRT plans achieved excellent target coverage and normal tissue sparing, without reducing dose to ABMCustom (mean ABMCustom dose 29.4Gy vs. 27.1Gyvs. 26.9Gy, respectively; p=0.10); however, PTV coverage and bowel sparing were slightly reduced. Atlas-based ABM sparing IMRT is clinically feasible and may obviate the need for customized ABM-sparing as a strategy to reduce hematologic toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study.

    PubMed

    Yepes, Pablo P; Eley, John G; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

    2016-04-07

    Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

  11. A fast optimization algorithm for multicriteria intensity modulated proton therapy planning

    SciTech Connect

    Chen Wei; Craft, David; Madden, Thomas M.; Zhang, Kewu; Kooy, Hanne M.; Herman, Gabor T.

    2010-09-15

    Purpose: To describe a fast projection algorithm for optimizing intensity modulated proton therapy (IMPT) plans and to describe and demonstrate the use of this algorithm in multicriteria IMPT planning. Methods: The authors develop a projection-based solver for a class of convex optimization problems and apply it to IMPT treatment planning. The speed of the solver permits its use in multicriteria optimization, where several optimizations are performed which span the space of possible treatment plans. The authors describe a plan database generation procedure which is customized to the requirements of the solver. The optimality precision of the solver can be specified by the user. Results: The authors apply the algorithm to three clinical cases: A pancreas case, an esophagus case, and a tumor along the rib cage case. Detailed analysis of the pancreas case shows that the algorithm is orders of magnitude faster than industry-standard general purpose algorithms (MOSEK's interior point optimizer, primal simplex optimizer, and dual simplex optimizer). Additionally, the projection solver has almost no memory overhead. Conclusions: The speed and guaranteed accuracy of the algorithm make it suitable for use in multicriteria treatment planning, which requires the computation of several diverse treatment plans. Additionally, given the low memory overhead of the algorithm, the method can be extended to include multiple geometric instances and proton range possibilities, for robust optimization.

  12. The Accuracy of Inhomogeneity Corrections in Intensity Modulated Radiation Therapy Planning in Philips Pinnacle System

    SciTech Connect

    Alaei, Parham; Higgins, Patrick D.

    2011-10-01

    The degree of accuracy of inhomogeneity corrections in a treatment planning system is dependent on the algorithm used by the system. The choice of field size, however, could have an effect on the calculation accuracy as well. There have been several evaluation studies on the accuracy of inhomogeneity corrections used by different algorithms. Most of these studies, however, focus on evaluating the dose in phantom using simplified geometry and open/static fields. This work focuses on evaluating the degree of dose accuracy in calculations involving intensity-modulated radiation therapy (IMRT) fields incident on a phantom containing both lung- and bone-equivalent heterogeneities using 6 and 10 MV beams. IMRT treatment plans were generated using the Philips Pinnacle treatment planning system and delivered to a phantom containing 55 thermoluminescent dosimeter (TLD) locations within the lung and bone and near the lung and bone interfaces with solid water. The TLD readings were compared with the dose predicted by the planning system. We find satisfactory agreement between planned and delivered doses, with an overall absolute average difference between measurement and calculation of 1.2% for the 6 MV and 3.1% for the 10 MV beam with larger variations observed near the interfaces and in areas of high-dose gradient. The results presented here demonstrate that the convolution algorithm used in the Pinnacle treatment planning system produces accurate results in IMRT plans calculated and delivered to inhomogeneous media, even in regions that potentially lack electronic equilibrium.

  13. Intelligence-guided beam angle optimization in treatment planning of intensity-modulated radiation therapy.

    PubMed

    Yan, Hui; Dai, Jian-Rong

    2016-10-01

    An intelligence guided approach based on fuzzy inference system (FIS) was proposed to automate beam angle optimization in treatment planning of intensity-modulated radiation therapy (IMRT). The model of FIS is built on inference rules in describing the relationship between dose quality of IMRT plan and irradiated region of anatomical structure. Dose quality of IMRT plan is quantified by the difference between calculated and constraint doses of the anatomical structures in an IMRT plan. Irradiated region of anatomical structure is characterized by the metric, covered region of interest, which is the region of an anatomical structure under radiation field while beam's eye-view is conform to target volume. Initially, an IMRT plan is created with a single beam. The dose difference is calculated for the input of FIS and the output of FIS is obtained with processing of fuzzy inference. Later, a set of candidate beams is generated for replacing the current beam. This process continues until no candidate beams is found. Then the next beam is added to the IMRT plan and optimized in the same way as the previous beam. The new beam keeps adding to the IMRT plan until the allowed beam number is reached. Two spinal cases were investigated in this study. The preliminary results show that dose quality of IMRT plans achieved by this approach is better than those achieved by the default approach with equally spaced beam setting. It is effective to find the optimal beam combination of IMRT plan with the intelligence-guided approach.

  14. Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

    NASA Astrophysics Data System (ADS)

    Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

    2016-04-01

    Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

  15. Selective robust optimization: A new intensity-modulated proton therapy optimization strategy

    SciTech Connect

    Li, Yupeng; Niemela, Perttu; Siljamaki, Sami; Vanderstraeten, Reynald; Liao, Li; Jiang, Shengpeng; Li, Heng; Poenisch, Falk; Zhu, X. Ronald; Sahoo, Narayan; Gillin, Michael; Zhang, Xiaodong

    2015-08-15

    Purpose: To develop a new robust optimization strategy for intensity-modulated proton therapy as an important step in translating robust proton treatment planning from research to clinical applications. Methods: In selective robust optimization, a worst-case-based robust optimization algorithm is extended, and terms of the objective function are selectively computed from either the worst-case dose or the nominal dose. Two lung cancer cases and one head and neck cancer case were used to demonstrate the practical significance of the proposed robust planning strategy. The lung cancer cases had minimal tumor motion less than 5 mm, and, for the demonstration of the methodology, are assumed to be static. Results: Selective robust optimization achieved robust clinical target volume (CTV) coverage and at the same time increased nominal planning target volume coverage to 95.8%, compared to the 84.6% coverage achieved with CTV-based robust optimization in one of the lung cases. In the other lung case, the maximum dose in selective robust optimization was lowered from a dose of 131.3% in the CTV-based robust optimization to 113.6%. Selective robust optimization provided robust CTV coverage in the head and neck case, and at the same time improved controls over isodose distribution so that clinical requirements may be readily met. Conclusions: Selective robust optimization may provide the flexibility and capability necessary for meeting various clinical requirements in addition to achieving the required plan robustness in practical proton treatment planning settings.

  16. Direct-aperture optimization applied to selection of beam orientations in intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Bedford, J. L.; Webb, S.

    2007-01-01

    Direct-aperture optimization (DAO) was applied to iterative beam-orientation selection in intensity-modulated radiation therapy (IMRT), so as to ensure a realistic segmental treatment plan at each iteration. Nested optimization engines dealt separately with gantry angles, couch angles, collimator angles, segment shapes, segment weights and wedge angles. Each optimization engine performed a random search with successively narrowing step sizes. For optimization of segment shapes, the filtered backprojection (FBP) method was first used to determine desired fluence, the fluence map was segmented, and then constrained direct-aperture optimization was used thereafter. Segment shapes were fully optimized when a beam angle was perturbed, and minimally re-optimized otherwise. The algorithm was compared with a previously reported method using FBP alone at each orientation iteration. An example case consisting of a cylindrical phantom with a hemi-annular planning target volume (PTV) showed that for three-field plans, the method performed better than when using FBP alone, but for five or more fields, neither method provided much benefit over equally spaced beams. For a prostate case, improved bladder sparing was achieved through the use of the new algorithm. A plan for partial scalp treatment showed slightly improved PTV coverage and lower irradiated volume of brain with the new method compared to FBP alone. It is concluded that, although the method is computationally intensive and not suitable for searching large unconstrained regions of beam space, it can be used effectively in conjunction with prior class solutions to provide individually optimized IMRT treatment plans.

  17. Direct-aperture optimization applied to selection of beam orientations in intensity-modulated radiation therapy.

    PubMed

    Bedford, J L; Webb, S

    2007-01-21

    Direct-aperture optimization (DAO) was applied to iterative beam-orientation selection in intensity-modulated radiation therapy (IMRT), so as to ensure a realistic segmental treatment plan at each iteration. Nested optimization engines dealt separately with gantry angles, couch angles, collimator angles, segment shapes, segment weights and wedge angles. Each optimization engine performed a random search with successively narrowing step sizes. For optimization of segment shapes, the filtered backprojection (FBP) method was first used to determine desired fluence, the fluence map was segmented, and then constrained direct-aperture optimization was used thereafter. Segment shapes were fully optimized when a beam angle was perturbed, and minimally re-optimized otherwise. The algorithm was compared with a previously reported method using FBP alone at each orientation iteration. An example case consisting of a cylindrical phantom with a hemi-annular planning target volume (PTV) showed that for three-field plans, the method performed better than when using FBP alone, but for five or more fields, neither method provided much benefit over equally spaced beams. For a prostate case, improved bladder sparing was achieved through the use of the new algorithm. A plan for partial scalp treatment showed slightly improved PTV coverage and lower irradiated volume of brain with the new method compared to FBP alone. It is concluded that, although the method is computationally intensive and not suitable for searching large unconstrained regions of beam space, it can be used effectively in conjunction with prior class solutions to provide individually optimized IMRT treatment plans.

  18. On Linear Infeasibility Arising in Intensity-Modulated Radiation Therapy Inverse Planning.

    PubMed

    Censor, Yair; Ben-Israel, Adi; Xiao, Ying; Galvin, James M

    2008-03-01

    Intensity-modulated radiation therapy (IMRT) gives rise to systems of linear inequalities, representing the effects of radiation on the irradiated body. These systems are often infeasible, in which case one settles for an approximate solution, such as an {α, β}-relaxation, meaning that no more than α percent of the inequalities are violated by no more than β percent. For real-world IMRT problems, there is a feasible {α, β}-relaxation for sufficiently large α, β > 0, however large values of these parameters may be unacceptable medically.The {α, β}-relaxation problem is combinatorial, and for given values of the parameters can be solved exactly by Mixed Integer Programming (MIP), but this may be impractical because of problem size, and the need for repeated solutions as the treatment progresses.As a practical alternative to the MIP approach we present a heuristic non-combinatorial method for finding an approximate relaxation. The method solves a Linear Program (LP) for each pair of values of the parameters {α, β} and progresses through successively increasing values until an acceptable solution is found, or is determined non-existent. The method is fast and reliable, since it consists of solving a sequence of LP's.

  19. Comparison of optimization algorithms in intensity-modulated radiation therapy planning

    NASA Astrophysics Data System (ADS)

    Kendrick, Rachel

    Intensity-modulated radiation therapy is used to better conform the radiation dose to the target, which includes avoiding healthy tissue. Planning programs employ optimization methods to search for the best fluence of each photon beam, and therefore to create the best treatment plan. The Computational Environment for Radiotherapy Research (CERR), a program written in MATLAB, was used to examine some commonly-used algorithms for one 5-beam plan. Algorithms include the genetic algorithm, quadratic programming, pattern search, constrained nonlinear optimization, simulated annealing, the optimization method used in Varian EclipseTM, and some hybrids of these. Quadratic programing, simulated annealing, and a quadratic/simulated annealing hybrid were also separately compared using different prescription doses. The results of each dose-volume histogram as well as the visual dose color wash were used to compare the plans. CERR's built-in quadratic programming provided the best overall plan, but avoidance of the organ-at-risk was rivaled by other programs. Hybrids of quadratic programming with some of these algorithms seems to suggest the possibility of better planning programs, as shown by the improved quadratic/simulated annealing plan when compared to the simulated annealing algorithm alone. Further experimentation will be done to improve cost functions and computational time.

  20. Accounting for range uncertainties in the optimization of intensity modulated proton therapy.

    PubMed

    Unkelbach, Jan; Chan, Timothy C Y; Bortfeld, Thomas

    2007-05-21

    Treatment plans optimized for intensity modulated proton therapy (IMPT) may be sensitive to range variations. The dose distribution may deteriorate substantially when the actual range of a pencil beam does not match the assumed range. We present two treatment planning concepts for IMPT which incorporate range uncertainties into the optimization. The first method is a probabilistic approach. The range of a pencil beam is assumed to be a random variable, which makes the delivered dose and the value of the objective function a random variable too. We then propose to optimize the expectation value of the objective function. The second approach is a robust formulation that applies methods developed in the field of robust linear programming. This approach optimizes the worst case dose distribution that may occur, assuming that the ranges of the pencil beams may vary within some interval. Both methods yield treatment plans that are considerably less sensitive to range variations compared to conventional treatment plans optimized without accounting for range uncertainties. In addition, both approaches--although conceptually different--yield very similar results on a qualitative level.

  1. Compact multileaf collimator for conformal and intensity modulated fast neutron therapy: electromechanical design and validation.

    PubMed

    Farr, J B; Maughan, R L; Yudelev, M; Blosser, E; Brandon, J; Horste, T; Forman, J D

    2006-09-01

    The electromechanical properties of a 120-leaf, high-resolution, computer-controlled, fast neutron multileaf collimator (MLC) are presented. The MLC replaces an aging, manually operated multirod collimator. The MLC leaves project 5 mm in the isocentric plane perpendicular to the beam axis. A taper is included on the leaves matching beam divergence along one axis. The 5-mm leaf projection width is chosen to give high-resolution conformality across the entire field. The maximum field size provided is 30 x 30 cm2. To reduce the interleaf transmission a 0.254-mm blocking step is included. End-leaf steps totaling 0.762 mm are also provided allowing opposing leaves to close off within the primary radiation beam. The neutron MLC also includes individual 45 degrees and 60 degrees automated universal tungsten wedges. The automated high-resolution neutron collimation provides an increase in patient throughput capacity, enables a new modality, intensity modulated neutron therapy, and limits occupational radiation exposure by providing remote operation from a shielded console area.

  2. Acute Esophagus Toxicity in Lung Cancer Patients After Intensity Modulated Radiation Therapy and Concurrent Chemotherapy

    SciTech Connect

    Kwint, Margriet; Uyterlinde, Wilma; Nijkamp, Jasper; Chen, Chun; Bois, Josien de; Sonke, Jan-Jakob; Heuvel, Michel van den; Knegjens, Joost; Herk, Marcel van; Belderbos, Jose

    2012-10-01

    Purpose: The purpose of this study was to investigate the dose-effect relation between acute esophageal toxicity (AET) and the dose-volume parameters of the esophagus after intensity modulated radiation therapy (IMRT) and concurrent chemotherapy for patients with non-small cell lung cancer (NSCLC). Patients and Methods: One hundred thirty-nine patients with inoperable NSCLC treated with IMRT and concurrent chemotherapy were prospectively analyzed. The fractionation scheme was 66 Gy in 24 fractions. All patients received concurrently a daily dose of cisplatin (6 mg/m Superscript-Two ). Maximum AET was scored according to Common Toxicity Criteria 3.0. Dose-volume parameters V5 to V70, D{sub mean} and D{sub max} of the esophagus were calculated. A logistic regression analysis was performed to analyze the dose-effect relation between these parameters and grade {>=}2 and grade {>=}3 AET. The outcome was compared with the clinically used esophagus V35 prediction model for grade {>=}2 after radical 3-dimensional conformal radiation therapy (3DCRT) treatment. Results: In our patient group, 9% did not experience AET, and 31% experienced grade 1 AET, 38% grade 2 AET, and 22% grade 3 AET. The incidence of grade 2 and grade 3 AET was not different from that in patients treated with CCRT using 3DCRT. The V50 turned out to be the most significant dosimetric predictor for grade {>=}3 AET (P=.012). The derived V50 model was shown to predict grade {>=}2 AET significantly better than the clinical V35 model (P<.001). Conclusions: For NSCLC patients treated with IMRT and concurrent chemotherapy, the V50 was identified as most accurate predictor of grade {>=}3 AET. There was no difference in the incidence of grade {>=}2 AET between 3DCRT and IMRT in patients treated with concurrent chemoradiation therapy.

  3. Intensity-Modulated Radiation Therapy With Concurrent Chemotherapy as Preoperative Treatment for Localized Gastric Adenocarcinoma

    SciTech Connect

    Chakravarty, Twisha; Crane, Christopher H.; Ajani, Jaffer A.; Mansfield, Paul F.; Briere, Tina M.; Beddar, A. Sam; Mok, Henry; Reed, Valerie K.; Krishnan, Sunil; Delclos, Marc E.; Das, Prajnan

    2012-06-01

    Purpose: The goal of this study was to evaluate dosimetric parameters, acute toxicity, pathologic response, and local control in patients treated with preoperative intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy for localized gastric adenocarcinoma. Methods: Between November 2007 and April 2010, 25 patients with localized gastric adenocarcinoma were treated with induction chemotherapy, followed by preoperative IMRT and concurrent chemotherapy and, finally, surgical resection. The median radiation therapy dose was 45 Gy. Concurrent chemotherapy was 5-fluorouracil and oxaliplatin in 18 patients, capecitabine in 3, and other regimens in 4. Subsequently, resection was performed with total gastrectomy in 13 patients, subtotal gastrectomy in 7, and other surgeries in 5. Results: Target coverage, expressed as the ratio of the minimum dose received by 99% of the planning target volume to the prescribed dose, was a median of 0.97 (range, 0.92-1.01). The median V{sub 30} (percentage of volume receiving at least 30 Gy) for the liver was 26%; the median V{sub 20} (percentage of volume receiving at least 20 Gy) for the right and left kidneys was 14% and 24%, respectively; and the median V{sub 40} (percentage of volume receiving at least 40 Gy) for the heart was 18%. Grade 3 acute toxicity developed in 14 patients (56%), including dehydration in 10, nausea in 8, and anorexia in 5. Grade 4 acute toxicity did not develop in any patient. There were no significant differences in the rates of acute toxicity, hospitalization, or feeding tube use in comparison to those in a group of 50 patients treated with preoperative three-dimensional conformal radiation therapy with concurrent chemotherapy. R0 resection was obtained in 20 patients (80%), and pathologic complete response occurred in 5 (20%). Conclusions: Preoperative IMRT for gastric adenocarcinoma was well tolerated, accomplished excellent target coverage and normal structure sparing, and led to appropriate

  4. Adoption of Intensity Modulated Radiation Therapy For Early-Stage Breast Cancer From 2004 Through 2011

    SciTech Connect

    Wang, Elyn H.; Mougalian, Sarah S.; Soulos, Pamela R.; Smith, Benjamin D.; Haffty, Bruce G.; Gross, Cary P.; Yu, James B.

    2015-02-01

    Purpose: Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. Methods and Materials: We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). Results: We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. Conclusions: The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status.

  5. Intensity-modulated radiation therapy with dose-painting for pediatric sarcomas with pulmonary metastases.

    PubMed

    Yang, Joanna C; Wexler, Leonard H; Meyers, Paul A; Happersett, Laura; La Quaglia, Michael P; Wolden, Suzanne L

    2013-10-01

    We examined patterns of failure in pediatric patients with thoracic sarcoma and pulmonary metastases treated with intensity-modulated radiation therapy with dose-painting (DP-IMRT). Eleven pediatric patients, five with Ewing sarcoma family tumors (ESFT) and six with rhabdomyosarcoma (RMS), with primary thoracic tumors and pulmonary metastases underwent DP-IMRT with chemotherapy for definitive treatment. Eight patients also underwent surgery. Median time to RT was 21 (15-31) weeks. Nine patients received 45-50.4-Gy in 1.8 Gy fractions to the primary tumor (n = 3) or post-operative tumor bed (n = 6). Two patients ≤4 years received 12 Gy intraoperative radiation therapy and 30.6-36 Gy IMRT postoperatively to the tumor bed. All patients received 14-16.8 Gy in 0.54-0.88 Gy fractions to the whole lungs (n = 6) or hemithorax (n = 5) using dose-painting technique. A representative case was re-planned with IMRT plus standard AP/PA whole lung irradiation (WLI) for dosimetric comparison. With 27-month median follow-up, 3-year pulmonary relapse-free survival in all patients was 61%: 80% for RMS and 40% for ESFT. Five patients (4 ESFT and 1 RMS) experienced pulmonary relapse at median 16 (9-41) months. There were no local failures. Our representative case demonstrated more homogeneous target volume coverage of the whole lungs and decreased mean dose to esophagus (15%), heart (31%), spinal cord (15%), and liver (19%) with DP-IMRT. The treatment of children with a primary thoracic tumor and pulmonary metastases poses a significant challenge. DP-IMRT is one solution to this technical problem. Initial data from this small series suggest DP-IMRT is feasible and produces superior sparing of critical normal tissues. Copyright © 2013 Wiley Periodicals, Inc.

  6. Adoption of intensity modulated radiation therapy for early-stage breast cancer from 2004 through 2011.

    PubMed

    Wang, Elyn H; Mougalian, Sarah S; Soulos, Pamela R; Smith, Benjamin D; Haffty, Bruce G; Gross, Cary P; Yu, James B

    2015-02-01

    Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method

    NASA Astrophysics Data System (ADS)

    Rocha, Humberto; Dias, Joana M.; Ferreira, Brígida C.; Lopes, Maria C.

    2013-05-01

    Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better organ sparing and to improve tumor coverage. However, in clinical practice, most of the time, beam directions continue to be manually selected by the treatment planner without objective and rigorous criteria. The goal of this paper is to introduce a novel approach that uses beam’s-eye-view dose ray tracing metrics within a pattern search method framework in the optimization of the highly non-convex BAO problem. Pattern search methods are derivative-free optimization methods that require a few function evaluations to progress and converge and have the ability to better avoid local entrapment. The pattern search method framework is composed of a search step and a poll step at each iteration. The poll step performs a local search in a mesh neighborhood and ensures the convergence to a local minimizer or stationary point. The search step provides the flexibility for a global search since it allows searches away from the neighborhood of the current iterate. Beam’s-eye-view dose metrics assign a score to each radiation beam direction and can be used within the pattern search framework furnishing a priori knowledge of the problem so that directions with larger dosimetric scores are tested first. A set of clinical cases of head-and-neck tumors treated at the Portuguese Institute of Oncology of Coimbra is used to discuss the potential of this approach in the optimization of the BAO problem.

  8. Replanning During Intensity Modulated Radiation Therapy Improved Quality of Life in Patients With Nasopharyngeal Carcinoma

    SciTech Connect

    Yang Haihua; Hu Wei; Wang Wei; Chen Peifang; Ding Weijun; Luo Wei

    2013-01-01

    Purpose: Anatomic and dosimetric changes have been reported during intensity modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the effects of replanning on quality of life (QoL) and clinical outcomes during the course of IMRT for NPC patients. Methods and Materials: Between June 2007 and August 2011, 129 patients with NPC were enrolled. Forty-three patients received IMRT without replanning, while 86 patients received IMRT replanning after computed tomography (CT) images were retaken part way through therapy. Chinese versions of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 and Head and Neck Quality of Life Questionnaire 35 were completed before treatment began and at the end of treatment and at 1, 3, 6, and 12 months after the completion of treatment. Overall survival (OS) data were compared using the Kaplan-Meier method. Results: IMRT replanning had a profound impact on the QoL of NPC patients, as determined by statistically significant changes in global QoL and other QoL scales. Additionally, the clinical outcome comparison indicates that replanning during IMRT for NPC significantly improved 2-year local regional control (97.2% vs 92.4%, respectively, P=.040) but did not improve 2-year OS (89.8% vs 82.2%, respectively, P=.475). Conclusions: IMRT replanning improves QoL as well as local regional control in patients with NPC. Future research is needed to determine the criteria for replanning for NPC patients undergoing IMRT.

  9. Expert Consensus Contouring Guidelines for Intensity Modulated Radiation Therapy in Esophageal and Gastroesophageal Junction Cancer

    SciTech Connect

    Wu, Abraham J.; Bosch, Walter R.; Chang, Daniel T.; Hong, Theodore S.; Jabbour, Salma K.; Kleinberg, Lawrence R.; Mamon, Harvey J.; Thomas, Charles R.; Goodman, Karyn A.

    2015-07-15

    Purpose/Objective(s): Current guidelines for esophageal cancer contouring are derived from traditional 2-dimensional fields based on bony landmarks, and they do not provide sufficient anatomic detail to ensure consistent contouring for more conformal radiation therapy techniques such as intensity modulated radiation therapy (IMRT). Therefore, we convened an expert panel with the specific aim to derive contouring guidelines and generate an atlas for the clinical target volume (CTV) in esophageal or gastroesophageal junction (GEJ) cancer. Methods and Materials: Eight expert academically based gastrointestinal radiation oncologists participated. Three sample cases were chosen: a GEJ cancer, a distal esophageal cancer, and a mid-upper esophageal cancer. Uniform computed tomographic (CT) simulation datasets and accompanying diagnostic positron emission tomographic/CT images were distributed to each expert, and the expert was instructed to generate gross tumor volume (GTV) and CTV contours for each case. All contours were aggregated and subjected to quantitative analysis to assess the degree of concordance between experts and to generate draft consensus contours. The panel then refined these contours to generate the contouring atlas. Results: The κ statistics indicated substantial agreement between panelists for each of the 3 test cases. A consensus CTV atlas was generated for the 3 test cases, each representing common anatomic presentations of esophageal cancer. The panel agreed on guidelines and principles to facilitate the generalizability of the atlas to individual cases. Conclusions: This expert panel successfully reached agreement on contouring guidelines for esophageal and GEJ IMRT and generated a reference CTV atlas. This atlas will serve as a reference for IMRT contours for clinical practice and prospective trial design. Subsequent patterns of failure analyses of clinical datasets using these guidelines may require modification in the future.

  10. Intensity-Modulated Radiation Therapy Significantly Improves Acute Gastrointestinal Toxicity in Pancreatic and Ampullary Cancers

    SciTech Connect

    Yovino, Susannah; Poppe, Matthew; Jabbour, Salma; David, Vera; Garofalo, Michael; Pandya, Naimesh; Alexander, Richard; Hanna, Nader; Regine, William F.

    2011-01-01

    Purpose: Among patients with upper abdominal malignancies, intensity-modulated radiation therapy (IMRT) can improve dose distributions to critical dose-limiting structures near the target. Whether these improved dose distributions are associated with decreased toxicity when compared with conventional three-dimensional treatment remains a subject of investigation. Methods and Materials: 46 patients with pancreatic/ampullary cancer were treated with concurrent chemoradiation (CRT) using inverse-planned IMRT. All patients received CRT based on 5-fluorouracil in a schema similar to Radiation Therapy Oncology Group (RTOG) 97-04. Rates of acute gastrointestinal (GI) toxicity for this series of IMRT-treated patients were compared with those from RTOG 97-04, where all patients were treated with three-dimensional conformal techniques. Chi-square analysis was used to determine if there was a statistically different incidence in acute GI toxicity between these two groups of patients. Results: The overall incidence of Grade 3-4 acute GI toxicity was low in patients receiving IMRT-based CRT. When compared with patients who had three-dimensional treatment planning (RTOG 97-04), IMRT significantly reduced the incidence of Grade 3-4 nausea and vomiting (0% vs. 11%, p = 0.024) and diarrhea (3% vs. 18%, p = 0.017). There was no significant difference in the incidence of Grade 3-4 weight loss between the two groups of patients. Conclusions: IMRT is associated with a statistically significant decrease in acute upper and lower GI toxicity among patients treated with CRT for pancreatic/ampullary cancers. Future clinical trials plan to incorporate the use of IMRT, given that it remains a subject of active investigation.

  11. Disease-Control Rates Following Intensity-Modulated Radiation Therapy for Small Primary Oropharyngeal Carcinoma

    PubMed Central

    Garden, Adam S.; Morrison, William H.; Wong, Pei-Fong; Tung, Sam S.; Rosenthal, David I.; Dong, Lei; Mason, Brian; Perkins, George H.; Ang, K. Kian

    2014-01-01

    Background The purpose of this study was to assess the ability of intensity-modulated radiation therapy (IMRT) to achieve favorable disease-control rates while minimizing parotid gland doses in patients treated for small primary tumors of the oropharynx. Methods We retrospectively identified all patients who received IMRT as treatment for a small (< 4 cm) primary tumor of the oropharynx from October 2000 through June 2002. Tumor characteristics, IMRT parameters, and patient outcomes were assessed. Results Fifty-one patients met the criteria for our study. All patients had treatment to gross disease with margin (CTV1), and all but 1 had treatment to the bilateral necks. The most common treatment schedule (39 patients) was a once-daily fractionation of prescribed doses of 63 - 66 Gy to the CTV1 and 54 Gy to subclinical sites, delivered in 30 fractions. Twenty-one patients (40%) had gastrostomy tubes placed during therapy; in 4 patients, the tube remained in place for more than 6 months following completion of IMRT. The median follow-up was 45 months. The 2-year actuarial local-regional control, recurrence-free, and overall survival rates were 94%, 88%, and 94%, respectively. Conclusions These preliminary data suggest that treatment with IMRT results in favorable local-regional control of small primary oropharynx tumors. IMRT did not appear to have a more favorable acute toxicity profile in this group with respect to the use of a feeding tube; however, the mean dose of radiation delivered to the parotid gland by IMRT was decreased, as 95% of patients had a mean dose of < 30 Gy to at least one gland. PMID:17141972

  12. Disease-control rates following intensity-modulated radiation therapy for small primary oropharyngeal carcinoma

    SciTech Connect

    Garden, Adam S. . E-mail: agarden@mdanderson.org; Morrison, William H.; Wong, P.-F.; Tung, Sam S.; Rosenthal, David I.; Dong Lei; Mason, Brian M.S.; Perkins, George H.; Ang, K. Kian

    2007-02-01

    Background: The purpose of this study was to assess the ability of intensity-modulated radiation therapy (IMRT) to achieve favorable disease-control rates while minimizing parotid gland doses in patients treated for small primary tumors of the oropharynx. Methods and Materials: We retrospectively identified all patients who received IMRT as treatment for a small (<4 cm) primary tumor of the oropharynx between October 2000 and June 2002. Tumor characteristics, IMRT parameters, and patient outcomes were assessed. Results: Fifty-one patients met the criteria for our study. All patients had treatment to gross disease with margin (CTV1), and all but 1 had treatment to the bilateral necks. The most common treatment schedule (39 patients) was a once-daily fractionation of prescribed doses of 63-66 Gy to the CTV1 and 54 Gy to subclinical sites, delivered in 30 fractions. Twenty-one patients (40%) had gastrostomy tubes placed during therapy; in 4 patients, the tube remained in place for more than 6 months after completion of IMRT. The median follow-up was 45 months. The 2-year actuarial locoregional control, recurrence-free, and overall survival rates were 94%, 88%, and 94%, respectively. Conclusions: These preliminary data suggest that treatment with IMRT results in favorable locoregional control of small primary oropharynx tumors. IMRT did not appear to have a more favorable acute toxicity profile in this group with respect to the use of a feeding tube; however, the mean dose of radiation delivered to the parotid gland by IMRT was decreased, because 95% of patients had a mean dose of <30 Gy to at least one gland.

  13. Lymphatic atlas-based target volume definition for intensity-modulated radiation therapy planning

    NASA Astrophysics Data System (ADS)

    Qatarneh, S. M.; Kiricuta, I. C.; Brahme, A.; Noz, M. E.; Ferreira, B.; Kim, W. C.; Lind, B. K.

    2007-10-01

    Despite the improvements in current imaging modalities such as CT and MRI, the detection of normal or malignant lymph nodes remains a challenge due to the large variability in lymph node characteristics and the variation in imaging quality and the limited imaging resolution. A computerized lymph node atlas could be the ideal tool for target volume definition based on the distribution of normal lymph nodes surrounding the verified malignant nodes to improve the accuracy of intensity-modulated radiation therapy planning. The standard lymph node topography in the newly constructed 3D lymph node atlas offers a detailed topographical distribution of discrete nodal locations in relation to surrounding organs at risk. In the present paper, the recently developed lymph node atlas is used for selection and delineation of target volumes in the head and neck, thorax and pelvic region. Image registration techniques were implemented to integrate the topography of the lymph node atlas into the patient's data set. By combining the knowledge-based lymph node distribution with the patient's data set, more detailed definitions of the target volumes were obtained to facilitate biologically based treatment plan optimization. The response values of the biologically optimized treatment plans were used to derive the probability of tumor control and the probability of complications in organs at risk. The treatment outcome of the lung reference plan showed a lower probability of recurrence in comparison to planning without the lymph node atlas. The lymph node atlas can improve and standardize the target volume definition by including more accurate anatomical knowledge for target volume definition and biologically optimized radiation therapy planning.

  14. SU-E-T-124: Dosimetric Comparison of HDR Brachytherapy and Intensity Modulated Proton Therapy

    SciTech Connect

    Wu, J; Wu, H; Das, I

    2014-06-01

    Purpose: Brachytherapy is known to be able to deliver more radiation dose to tumor while minimizing radiation dose to surrounding normal tissues. Proton therapy also provides superior dose distribution due to Bragg peak. Since both HDR and Intensity Modulated Proton Therapy (IMPT) are beneficial for their quick dose drop off, our goal in this study is to compare the pace of dose gradient drop-off between HDR and IMPT plans based on the same CT image data-set. In addition, normal tissues sparing were also compared among HDR, IMPT and SBRT. Methods: Five cervical cancer cases treated with EBRT + HDR boost combination with Tandem and Ovoid applicator were used for comparison purpose. Original HDR plans with prescribed dose of 5.5 Gy x 5 fractions were generated and optimized. The 100% isodose line of HDR plans was converted to a dose volume, and treated as CTV for IMPT and SBRT planning. The same HDR CT scans were also used for IMPT plan and SBRT plan for direct comparison. The philosophy of the IMPT and SBRT planning was to create the same CTV coverage as HDR plans. All three modalities treatment plans were compared to each other with a set of predetermined criteria. Results: With similar target volume coverage in cervix cancer boost treatment, HDR provides a slightly sharper dose drop-off from 100% to 50% isodose line, averagely in all directions compared to IMPT. However, IMPT demonstrated more dose gradient drop-off at the junction of the target and normal tissues by providing more normal tissue sparing and superior capability to reduce integral dose. Conclusion: IMPT is capable of providing comparable dose drop-off as HDR. IMPT can be explored as replacement for HDR brachytherapy in various applications.

  15. Intensity-Modulated Radiation Therapy for Anal Malignancies: A Preliminary Toxicity and Disease Outcomes Analysis

    SciTech Connect

    Pepek, Joseph M.; Willett, Christopher G.; Wu, Q. Jackie; Yoo, Sua; Clough, Robert W.; Czito, Brian G.

    2010-12-01

    Purpose: Intensity-modulated radiation therapy (IMRT) has the potential to reduce toxicities associated with chemoradiotherapy in the treatment of anal cancer. This study reports the results of using IMRT in the treatment of anal cancer. Methods and Materials: Records of patients with anal malignancies treated with IMRT at Duke University were reviewed. Acute toxicity was graded using the NCI CTCAEv3.0 scale. Overall survival (OS), metastasis-free survival (MFS), local-regional control (LRC) and colostomy-free survival (CFS) were calculated using the Kaplan-Meier method. Results: Forty-seven patients with anal malignancy (89% canal, 11% perianal skin) were treated with IMRT between August 2006 and September 2008. Median follow-up was 14 months (19 months for SCC patients). Median radiation dose was 54 Gy. Eight patients (18%) required treatment breaks lasting a median of 5 days (range, 2-7 days). Toxicity rates were as follows: Grade 4: leukopenia (7%), thrombocytopenia (2%); Grade 3: leukopenia (18%), diarrhea (9%), and anemia (4%); Grade 2: skin (93%), diarrhea (24%), and leukopenia (24%). The 2-year actuarial overall OS, MFS, LRC, and CFS rates were 85%, 78%, 90% and 82%, respectively. For SCC patients, the 2-year OS, MFS, LRC, and CFS rates were 100%, 100%, 95%, and 91%, respectively. Conclusions: IMRT-based chemoradiotherapy for anal cancer results in significant reductions in normal tissue dose and acute toxicities versus historic controls treated without IMRT, leading to reduced rates of toxicity-related treatment interruption. Early disease-related outcomes seem encouraging. IMRT is emerging as a standard therapy for anal cancer.

  16. Fast voxel and polygon ray-tracing algorithms in intensity modulated radiation therapy treatment planning.

    PubMed

    Fox, Christopher; Romeijn, H Edwin; Dempsey, James F

    2006-05-01

    We present work on combining three algorithms to improve ray-tracing efficiency in radiation therapy dose computation. The three algorithms include: An improved point-in-polygon algorithm, incremental voxel ray tracing algorithm, and stereographic projection of beamlets for voxel truncation. The point-in-polygon and incremental voxel ray-tracing algorithms have been used in computer graphics and nuclear medicine applications while the stereographic projection algorithm was developed by our group. These algorithms demonstrate significant improvements over the current standard algorithms in peer reviewed literature, i.e., the polygon and voxel ray-tracing algorithms of Siddon for voxel classification (point-in-polygon testing) and dose computation, respectively, and radius testing for voxel truncation. The presented polygon ray-tracing technique was tested on 10 intensity modulated radiation therapy (IMRT) treatment planning cases that required the classification of between 0.58 and 2.0 million voxels on a 2.5 mm isotropic dose grid into 1-4 targets and 5-14 structures represented as extruded polygons (a.k.a. Siddon prisms). Incremental voxel ray tracing and voxel truncation employing virtual stereographic projection was tested on the same IMRT treatment planning cases where voxel dose was required for 230-2400 beamlets using a finite-size pencil-beam algorithm. Between a 100 and 360 fold cpu time improvement over Siddon's method was observed for the polygon ray-tracing algorithm to perform classification of voxels for target and structure membership. Between a 2.6 and 3.1 fold reduction in cpu time over current algorithms was found for the implementation of incremental ray tracing. Additionally, voxel truncation via stereographic projection was observed to be 11-25 times faster than the radial-testing beamlet extent approach and was further improved 1.7-2.0 fold through point-classification using the method of translation over the cross product technique.

  17. Intensity-Modulated Radiation Therapy in the Salvage of Locally Recurrent Nasopharyngeal Carcinoma

    SciTech Connect

    Qiu Sufang; Lin Shaojun; Tham, Ivan W.K.; Pan Jianji; Lu Jun; Lu, Jiade J.

    2012-06-01

    Purpose: Local recurrences of nasopharyngeal carcinoma (NPC) may be salvaged by reirradiation with conventional techniques, but with significant morbidity. Intensity-modulated radiation therapy (IMRT) may improve the therapeutic ratio by reducing doses to normal tissue. The aim of this study was to address the efficacy and toxicity profile of IMRT for a cohort of patients with locally recurrent NPC. Methods and Materials: Between August 2003 and June 2009, 70 patients with radiologic or pathologically proven locally recurrent NPC were treated with IMRT. The median time to recurrence was 30 months after the completion of conventional radiation to definitive dose. Fifty-seven percent of the tumors were classified asrT3-4. The minimum planned doses were 59.4 to 60 Gy in 1.8- to 2-Gy fractions per day to the gross disease with margins, with or without chemotherapy. Results: The median dose to the recurrent tumor was 70 Gy (range, 50-77.4 Gy). Sixty-five patients received the planned radiation therapy; 5 patients received between 50 and 60 Gy because of acute side effects. With a median follow-up time of 25 months, the rates of 2-year locoregional recurrence-free survival, disease-free survival, and overall survival were 65.8%, 65.8%, and 67.4%, respectively. Moderate to severe late toxicities were noted in 25 patients (35.7%). Eleven patients (15.7%) had posterior nasal space ulceration, 17 (24.3%) experienced cranial nerve palsies, 12 (17.1%) had trismus, and 12 (17.1%) experienced deafness. Extended disease-free interval (relative risk 2.049) and advanced T classification (relative risk 3.895) at presentation were adverse prognostic factors. Conclusion: Reirradiation with IMRT provides reasonable long-term control in patients with locally recurrent NPC.

  18. Linear energy transfer-guided optimization in intensity modulated proton therapy: feasibility study and clinical potential.

    PubMed

    Giantsoudi, Drosoula; Grassberger, Clemens; Craft, David; Niemierko, Andrzej; Trofimov, Alexei; Paganetti, Harald

    2013-09-01

    To investigate the feasibility and potential clinical benefit of linear energy transfer (LET) guided plan optimization in intensity modulated proton therapy (IMPT). A multicriteria optimization (MCO) module was used to generate a series of Pareto-optimal IMPT base plans (BPs), corresponding to defined objectives, for 5 patients with head-and-neck cancer and 2 with pancreatic cancer. A Monte Carlo platform was used to calculate dose and LET distributions for each BP. A custom-designed MCO navigation module allowed the user to interpolate between BPs to produce deliverable Pareto-optimal solutions. Differences among the BPs were evaluated for each patient, based on dose-volume and LET-volume histograms and 3-dimensional distributions. An LET-based relative biological effectiveness (RBE) model was used to evaluate the potential clinical benefit when navigating the space of Pareto-optimal BPs. The mean LET values for the target varied up to 30% among the BPs for the head-and-neck patients and up to 14% for the pancreatic cancer patients. Variations were more prominent in organs at risk (OARs), where mean LET values differed by a factor of up to 2 among the BPs for the same patient. An inverse relation between dose and LET distributions for the OARs was typically observed. Accounting for LET-dependent variable RBE values, a potential improvement on RBE-weighted dose of up to 40%, averaged over several structures under study, was noticed during MCO navigation. We present a novel strategy for optimizing proton therapy to maximize dose-averaged LET in tumor targets while simultaneously minimizing dose-averaged LET in normal tissue structures. MCO BPs show substantial LET variations, leading to potentially significant differences in RBE-weighted doses. Pareto-surface navigation, using both dose and LET distributions for guidance, provides the means for evaluating a large variety of deliverable plans and aids in identifying the clinically optimal solution. Copyright © 2013

  19. Intensity-modulated radiation therapy (IMRT) in the treatment of anal cancer: Toxicity and clinical outcome

    SciTech Connect

    Milano, Michael T.; Jani, Ashesh B.; Farrey, Karl J.; Rash, Carla C.; Heimann, Ruth; Chmura, Steven J. . E-mail: schmura@radonc.uchicago.edu

    2005-10-01

    Purpose: To assess survival, local control, and toxicity of intensity modulated radiation therapy (IMRT) in squamous cell carcinoma of the anal canal. Methods and Materials: Seventeen patients were treated with nine-field IMRT plans. Thirteen received concurrent 5-fluorouracil and mitomycin C, whereas 1 patient received 5-fluorouracil alone. Seven patients were planned with three-dimensional anteroposterior/posterior-anterior (AP/PA) fields for dosimetric comparison to IMRT. Results: Compared with AP/PA, IMRT reduced the mean and threshold doses to small bowel, bladder, and genitalia. Treatment was well tolerated, with no Grade {>=}3 acute nonhematologic toxicity. There were no treatment breaks attributable to gastrointestinal or skin toxicity. Of patients who received mitomycin C, 38% experienced Grade 4 hematologic toxicity. IMRT did not afford bone marrow sparing, possibly resulting from the clinical decision to prescribe 45 Gy to the whole pelvis in most patients, vs. the Radiation Therapy Oncology Group-recommended 30.6 Gy whole pelvic dose. Three of 17 patients, who did not achieve a complete response, proceeded to an abdominoperineal resection and colostomy. At a median follow-up of 20.3 months, there were no other local failures. Two-year overall survival, disease-free survival, and colostomy-free survival are: 91%, 65%, and 82% respectively. Conclusions: In this hypothesis-generating analysis, the acute toxicity and clinical outcome with IMRT in the treatment of anal cancer is encouraging. Compared with historical controls, local control is not compromised despite efforts to increase conformality and reduce normal structure dose.

  20. Linear Energy Transfer-Guided Optimization in Intensity Modulated Proton Therapy: Feasibility Study and Clinical Potential

    SciTech Connect

    Giantsoudi, Drosoula; Grassberger, Clemens; Craft, David; Niemierko, Andrzej; Trofimov, Alexei; Paganetti, Harald

    2013-09-01

    Purpose: To investigate the feasibility and potential clinical benefit of linear energy transfer (LET) guided plan optimization in intensity modulated proton therapy (IMPT). Methods and Materials: A multicriteria optimization (MCO) module was used to generate a series of Pareto-optimal IMPT base plans (BPs), corresponding to defined objectives, for 5 patients with head-and-neck cancer and 2 with pancreatic cancer. A Monte Carlo platform was used to calculate dose and LET distributions for each BP. A custom-designed MCO navigation module allowed the user to interpolate between BPs to produce deliverable Pareto-optimal solutions. Differences among the BPs were evaluated for each patient, based on dose–volume and LET–volume histograms and 3-dimensional distributions. An LET-based relative biological effectiveness (RBE) model was used to evaluate the potential clinical benefit when navigating the space of Pareto-optimal BPs. Results: The mean LET values for the target varied up to 30% among the BPs for the head-and-neck patients and up to 14% for the pancreatic cancer patients. Variations were more prominent in organs at risk (OARs), where mean LET values differed by a factor of up to 2 among the BPs for the same patient. An inverse relation between dose and LET distributions for the OARs was typically observed. Accounting for LET-dependent variable RBE values, a potential improvement on RBE-weighted dose of up to 40%, averaged over several structures under study, was noticed during MCO navigation. Conclusions: We present a novel strategy for optimizing proton therapy to maximize dose-averaged LET in tumor targets while simultaneously minimizing dose-averaged LET in normal tissue structures. MCO BPs show substantial LET variations, leading to potentially significant differences in RBE-weighted doses. Pareto-surface navigation, using both dose and LET distributions for guidance, provides the means for evaluating a large variety of deliverable plans and aids in

  1. Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

    SciTech Connect

    Frank, Steven J.; Cox, James D.; Gillin, Michael; Mohan, Radhe; Garden, Adam S.; Rosenthal, David I.; Gunn, G. Brandon; Weber, Randal S.; Kies, Merrill S.; Lewin, Jan S.; Munsell, Mark F.; Palmer, Matthew B.; Sahoo, Narayan; Zhang, Xiaodong; Liu, Wei; Zhu, X. Ronald

    2014-07-15

    Background: We report the first clinical experience and toxicity of multifield optimization (MFO) intensity modulated proton therapy (IMPT) for patients with head and neck tumors. Methods and Materials: Fifteen consecutive patients with head and neck cancer underwent MFO-IMPT with active scanning beam proton therapy. Patients with squamous cell carcinoma (SCC) had comprehensive treatment extending from the base of the skull to the clavicle. The doses for chemoradiation therapy and radiation therapy alone were 70 Gy and 66 Gy, respectively. The robustness of each treatment plan was also analyzed to evaluate sensitivity to uncertainties associated with variations in patient setup and the effect of uncertainties with proton beam range in patients. Proton beam energies during treatment ranged from 72.5 to 221.8 MeV. Spot sizes varied depending on the beam energy and depth of the target, and the scanning nozzle delivered the spot scanning treatment “spot by spot” and “layer by layer.” Results: Ten patients presented with SCC and 5 with adenoid cystic carcinoma. All 15 patients were able to complete treatment with MFO-IMPT, with no need for treatment breaks and no hospitalizations. There were no treatment-related deaths, and with a median follow-up time of 28 months (range, 20-35 months), the overall clinical complete response rate was 93.3% (95% confidence interval, 68.1%-99.8%). Xerostomia occurred in all 15 patients as follows: grade 1 in 10 patients, grade 2 in 4 patients, and grade 3 in 1 patient. Mucositis within the planning target volumes was seen during the treatment of all patients: grade 1 in 1 patient, grade 2 in 8 patients, and grade 3 in 6 patients. No patient experienced grade 2 or higher anterior oral mucositis. Conclusions: To our knowledge, this is the first clinical report of MFO-IMPT for head and neck tumors. Early clinical outcomes are encouraging and warrant further investigation of proton therapy in prospective clinical trials.

  2. Total Marrow Irradiation With RapidArc Volumetric Arc Therapy

    SciTech Connect

    Aydogan, Bulent; Yeginer, Mete; Kavak, Gulbin O.; Fan, John; Radosevich, James A.; Gwe-Ya, Kim

    2011-10-01

    Purpose: To develop a volumetric arc therapy (VMAT)-total marrow irradiation (TMI) technique for patients with hematologic malignancies. Methods and Materials: VMAT planning was performed for 6 patients using RapidArc technology. The planning target volume consisted of all the bones in the body from the head to the mid-femur, excluding the extremities, except for the humerus, plus a 3.0-mm margin. The organs at risk included the lungs, heart, liver, kidneys, bowels, brain, eyes, and oral cavity. The VMAT-TMI technique consisted of three plans: the head and neck, the chest, and the pelvis, each with three 330{sup o} arcs. The plans were prescribed to ensure, at a minimum, 95% planning target volume dose coverage with the prescription dose (percentage of volume receiving dose of {>=}12 Gy was 95%). The treatments were delivered and verified using MapCheck and ion chamber measurements. Results: The VMAT-TMI technique reported in the present study provided comparable dose distributions with respect to the fixed gantry linear accelerator intensity-modulated TMI. RapidArc planning was less subjective and easier, and, most importantly, the delivery was more efficient. RapidArc reduced the treatment delivery time to approximately 18 min from 45 min with the fixed gantry linear accelerator intensity-modulated TMI. When the prescription dose coverage was reduced to 85% from 95% and the mandible and maxillary structures were not included in the planning target volume as reported in a tomotherapy study, a considerable organ at risk dose reduction of 4.2-51% was observed. The average median dose for the lungs and lenses was reduced to 5.6 Gy from 7.2 Gy and 2.4 Gy from 4.5 Gy, respectively. Conclusion: The RapidArc VMAT technique improved the treatment planning, dose conformality, and, most importantly, treatment delivery efficiency. The results from our study suggest that the RapidArc VMAT technology can be expected to facilitate the clinical transition of TMI.

  3. Whole Abdominopelvic Intensity-Modulated Radiation Therapy for Desmoplastic Small Round Cell Tumor After Surgery

    SciTech Connect

    Pinnix, Chelsea C.; Fontanilla, Hiral P.; Hayes-Jordan, Andrea; Subbiah, Vivek; Bilton, Stephen D.; Chang, Eric L.; Grosshans, David R.; McAleer, Mary F.; Sulman, Eric P.; Woo, Shiao Y.; Anderson, Peter; Green, Holly L.; Mahajan, Anita

    2012-05-01

    Purpose: Desmoplastic small round cell tumor (DSCRT) is an uncommon pediatric tumor with a poor prognosis. Aggressive multimodality therapy is the current treatment approach; however. treatment toxicity is of concern. We report our results with whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) as a component of multimodality therapy for DSCRT at a single institution. Materials/Methods: Medical records of all patients with DSCRT who received WAP-IMRT as part of definitive treatment at MD Anderson (2006-2010) were identified and reviewed. Results: Eight patients with DSRCT received WAP-IMRT with a median follow-up of 15.2 months. All patients received multiple courses of chemotherapy followed by surgical debulking of intra-abdominal disease; seven also had intraoperative hyperthermic cisplatin. WAP-IMRT was delivered to a total dose of 30 Gy postoperatively; four patients received a simultaneous boost (6-10 Gy) to sites of gross residual disease. Seven patients received concurrent chemotherapy during WAP-IMRT. No Radiation Therapy Oncology Group Grade 4 nausea, vomiting, or diarrhea occurred during RT. Red-cell transfusions were given to two patients to maintain hemoglobin levels >10 g/dL. Grade 4 cytopenia requiring growth factor support occurred in only one patient; no other significant cytopenias were noted. WAP-IMRT resulted in 25% lower radiation doses to the lumbosacral vertebral bodies and pelvic bones than conventional RT plans. The median time to local or distant failure after WAP-IMRT was 8.73 months in seven patients. One patient who had completed RT 20 months before the last follow-up remains alive without evidence of disease. Five patients (63%) experienced treatment failure in the abdomen. Distant failure occurred in three patients (37.5%). Conclusions: WAP-IMRT with concurrent radiosensitizing chemotherapy was well tolerated after aggressive surgery for DSCRT. Enhanced bone sparing with IMRT probably accounts for the low hematologic

  4. Disease Control After Reduced Volume Conformal and Intensity Modulated Radiation Therapy for Childhood Craniopharyngioma

    SciTech Connect

    Merchant, Thomas E.; Kun, Larry E.; Hua, Chia-Ho; Wu, Shengjie; Xiong, Xiaoping; Sanford, Robert A.; Boop, Frederick A.

    2013-03-15

    Purpose: To estimate the rate of disease control after conformal radiation therapy using reduced clinical target volume (CTV) margins and to determine factors that predict for tumor progression. Methods and Materials: Eighty-eight children (median age, 8.5 years; range, 3.2-17.6 years) received conformal or intensity modulated radiation therapy between 1998 and 2009. The study group included those prospectively treated from 1998 to 2003, using a 10-mm CTV, defined as the margin surrounding the solid and cystic tumor targeted to receive the prescription dose of 54 Gy. The CTV margin was subsequently reduced after 2003, yielding 2 groups of patients: those treated with a CTV margin greater than 5 mm (n=26) and those treated with a CTV margin less than or equal to 5 mm (n=62). Disease progression was estimated on the basis of additional variables including sex, race, extent of resection, tumor interventions, target volume margins, and frequency of weekly surveillance magnetic resonance (MR) imaging during radiation therapy. Median follow-up was 5 years. Results: There was no difference between progression-free survival rates based on CTV margins (>5 mm vs ≤5 mm) at 5 years (88.1% ± 6.3% vs 96.2% ± 4.4% [P=.6386]). There were no differences based on planning target volume (PTV) margins (or combined CTV plus PTV margins). The PTV was systematically reduced from 5 to 3 mm during the time period of the study. Factors predictive of superior progression-free survival included Caucasian race (P=.0175), no requirement for cerebrospinal fluid shunting (P=.0066), and number of surveillance imaging studies during treatment (P=.0216). Patients whose treatment protocol included a higher number of weekly surveillance MR imaging evaluations had a lower rate of tumor progression. Conclusions: These results suggest that targeted volume reductions for radiation therapy using smaller margins are feasible and safe but require careful monitoring. We are currently investigating

  5. Multibeam tomotherapy: A new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy

    SciTech Connect

    Achterberg, Nils; Mueller, Reinhold G.

    2007-10-15

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of {+-}36 deg. . Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of 'step and shoot' MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as 'multibeam tomotherapy.' Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The 'Multifocal MLC-positioning' algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better

  6. Multibeam tomotherapy: a new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy.

    PubMed

    Achterberg, Nils; Müller, Reinhold G

    2007-10-01

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of +/- 36 degrees. Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of "step and shoot" MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as "multibeam tomotherapy." Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The "Multifocal MLC-positioning" algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better

  7. Vulvar Recurrences After Intensity-modulated Radiation Therapy for Squamous Cell Carcinoma of the Anus.

    PubMed

    Bagshaw, Hilary P; Sause, William T; Gawlick, Ute; Kim, H Tae; Whisenant, Jonathan; Cannon, George M

    2016-07-19

    The objective is to determine localregional control (LRC), distant metastasis free survival, disease-free survival, overall survival (OS), and toxicity for patients with squamous cell carcinoma of the anus treated with definitive chemotherapy and intensity-modulated radiation therapy (IMRT). We conducted a retrospective review of patients treated using IMRT for squamous cell carcinoma of the anus at our institution since 2005. Patients with local recurrences were identified and reviewed. The Kaplan-Meier curves were used for LRC and OS. From 2005 to 2014, 52 patients were treated with IMRT-based chemoradiation for squamous cell carcinoma of the anus. Median dose to the primary tumor was 54 Gy. LRC, distant metastasis free survival, OS, and disease-free survival were 92.3%, 88.5%, 86.5%, and 84.6%, respectively, with a median follow-up of 20 months. Two local failures occurred at the anal primary site and 2 in the vulva. Despite subsequent palliative radiotherapy and chemotherapy, neither patient with a vulvar recurrence achieved disease control. In a cohort of patients treated with IMRT-based chemoradiation, 2 vulvar recurrences were identified within the avoided external genitalia despite limited recurrence rates within the cohort overall. This experience suggests that for patients with a locally advanced primary tumor and bulky bilateral inguinal or pelvic disease, the in-transit vulvar dermal lymphatics may be at risk for subclinical involvement and subsequent recurrence. If substantiated by a similar pattern of recurrence at other institutions, the external genitalia may need to be reclassified from an avoidance structure to a clinical treatment volume in patients with locally advanced anal cancer.

  8. Vaginal Motion and Bladder and Rectal Volumes During Pelvic Intensity-Modulated Radiation Therapy After Hysterectomy

    SciTech Connect

    Jhingran, Anuja; Salehpour, Mohammad; Sam, Marianne; Levy, Larry; Eifel, Patricia J.

    2012-01-01

    Purpose: To evaluate variations in bladder and rectal volume and the position of the vaginal vault during a 5-week course of pelvic intensity-modulated radiation therapy (IMRT) after hysterectomy. Methods and Materials: Twenty-four patients were instructed how to fill their bladders before simulation and treatment. These patients underwent computed tomography simulations with full and empty bladders and then underwent rescanning twice weekly during IMRT; patients were asked to have full bladder for treatment. Bladder and rectal volumes and the positions of vaginal fiducial markers were determined, and changes in volume and position were calculated. Results: The mean full and empty bladder volumes at simulation were 480 cc (range, 122-1,052) and 155 cc (range, 49-371), respectively. Bladder volumes varied widely during IMRT: the median difference between the maximum and minimum volumes was 247 cc (range, 96-585). Variations in rectal volume during IMRT were less pronounced. For the 16 patients with vaginal fiducial markers in place throughout IMRT, the median maximum movement of the markers during IMRT was 0.59 cm in the right-left direction (range, 0-0.9), 1.46 cm in the anterior-posterior direction (range, 0.8-2.79), and 1.2 cm in the superior-inferior direction (range, 0.6-2.1). Large variations in rectal or bladder volume frequently correlated with significant displacement of the vaginal apex. Conclusion: Although treatment with a full bladder is usually preferred because of greater sparing of small bowel, our data demonstrate that even with detailed instruction, patients are unable to maintain consistent bladder filling. Variations in organ position during IMRT can result in marked changes in the position of the target volume and the volume of small bowel exposed to high doses of radiation.

  9. Automation and Intensity Modulated Radiation Therapy for Individualized High-Quality Tangent Breast Treatment Plans

    SciTech Connect

    Purdie, Thomas G.; Dinniwell, Robert E.; Fyles, Anthony; Sharpe, Michael B.

    2014-11-01

    Purpose: To demonstrate the large-scale clinical implementation and performance of an automated treatment planning methodology for tangential breast intensity modulated radiation therapy (IMRT). Methods and Materials: Automated planning was used to prospectively plan tangential breast IMRT treatment for 1661 patients between June 2009 and November 2012. The automated planning method emulates the manual steps performed by the user during treatment planning, including anatomical segmentation, beam placement, optimization, dose calculation, and plan documentation. The user specifies clinical requirements of the plan to be generated through a user interface embedded in the planning system. The automated method uses heuristic algorithms to define and simplify the technical aspects of the treatment planning process. Results: Automated planning was used in 1661 of 1708 patients receiving tangential breast IMRT during the time interval studied. Therefore, automated planning was applicable in greater than 97% of cases. The time for treatment planning using the automated process is routinely 5 to 6 minutes on standard commercially available planning hardware. We have shown a consistent reduction in plan rejections from plan reviews through the standard quality control process or weekly quality review multidisciplinary breast rounds as we have automated the planning process for tangential breast IMRT. Clinical plan acceptance increased from 97.3% using our previous semiautomated inverse method to 98.9% using the fully automated method. Conclusions: Automation has become the routine standard method for treatment planning of tangential breast IMRT at our institution and is clinically feasible on a large scale. The method has wide clinical applicability and can add tremendous efficiency, standardization, and quality to the current treatment planning process. The use of automated methods can allow centers to more rapidly adopt IMRT and enhance access to the documented

  10. Vaginal motion and bladder and rectal volumes during pelvic intensity-modulated radiation therapy after hysterectomy.

    PubMed

    Jhingran, Anuja; Salehpour, Mohammad; Sam, Marianne; Levy, Larry; Eifel, Patricia J

    2012-01-01

    To evaluate variations in bladder and rectal volume and the position of the vaginal vault during a 5-week course of pelvic intensity-modulated radiation therapy (IMRT) after hysterectomy. Twenty-four patients were instructed how to fill their bladders before simulation and treatment. These patients underwent computed tomography simulations with full and empty bladders and then underwent rescanning twice weekly during IMRT; patients were asked to have full bladder for treatment. Bladder and rectal volumes and the positions of vaginal fiducial markers were determined, and changes in volume and position were calculated. The mean full and empty bladder volumes at simulation were 480 cc (range, 122-1,052) and 155 cc (range, 49-371), respectively. Bladder volumes varied widely during IMRT: the median difference between the maximum and minimum volumes was 247 cc (range, 96-585). Variations in rectal volume during IMRT were less pronounced. For the 16 patients with vaginal fiducial markers in place throughout IMRT, the median maximum movement of the markers during IMRT was 0.59 cm in the right-left direction (range, 0-0.9), 1.46 cm in the anterior-posterior direction (range, 0.8-2.79), and 1.2 cm in the superior-inferior direction (range, 0.6-2.1). Large variations in rectal or bladder volume frequently correlated with significant displacement of the vaginal apex. Although treatment with a full bladder is usually preferred because of greater sparing of small bowel, our data demonstrate that even with detailed instruction, patients are unable to maintain consistent bladder filling. Variations in organ position during IMRT can result in marked changes in the position of the target volume and the volume of small bowel exposed to high doses of radiation. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. DICOM-based computer-aided evaluation of intensity modulated radiation therapy (IMRT) treatment plans

    NASA Astrophysics Data System (ADS)

    Cheung, Fion W. K.; Law, Maria Y. Y.

    2011-03-01

    Intensity-modulated radiation therapy (IMRT) has gained popularity in the treatment of cancers because of its excellent local control with decreased normal tissue complications. Yet, computer planning for the treatment relies heavily on human inspection of resultant radiation dose distribution within the irradiated region of the body. Even for experienced planners, comparison of IMRT plans is definitely cumbersome and not error-free. To solve this problem, a computer-aided decision-support system was built for automatic evaluation of IMRT plans based on the DICOM standard. A DICOM based IMRT plan with DICOM and DICOM-RT objects including CT images, RT Structure Set, RT Dose and RT Plan were retrieved from the Treatment Planning System for programming. Utilizing the MATLAB program language, the decoding-encoding software applications were developed on the basis of the DICOM information object definitions. After tracing the clinical workflow and understanding the needs and expectations from radiation oncologists, a set of routines were written to parse key data items such as isodose curves, region of interests, dose-volume histogram from the DICOM-RT objects. Then graphical user interfaces (GUIs) were created to allow planners to query for parameters such as overdose or underdose areas. A total of 30 IMRT plans were collected in a Department of Clinical Oncology for systematic testing of the DICOM-based decision-support system. Both structural and functional tests were implemented as a major step on the road to software maturity. With promising test results, this decision-support system could represent a major breakthrough in the routine IMRT planning workflow.

  12. An Anatomically Validated Brachial Plexus Contouring Method for Intensity Modulated Radiation Therapy Planning

    SciTech Connect

    Van de Velde, Joris; Audenaert, Emmanuel; Speleers, Bruno; Vercauteren, Tom; Mulliez, Thomas; Vandemaele, Pieter; Achten, Eric; Kerckaert, Ingrid; D'Herde, Katharina; De Neve, Wilfried; Van Hoof, Tom

    2013-11-15

    Purpose: To develop contouring guidelines for the brachial plexus (BP) using anatomically validated cadaver datasets. Magnetic resonance imaging (MRI) and computed tomography (CT) were used to obtain detailed visualizations of the BP region, with the goal of achieving maximal inclusion of the actual BP in a small contoured volume while also accommodating for anatomic variations. Methods and Materials: CT and MRI were obtained for 8 cadavers positioned for intensity modulated radiation therapy. 3-dimensional reconstructions of soft tissue (from MRI) and bone (from CT) were combined to create 8 separate enhanced CT project files. Dissection of the corresponding cadavers anatomically validated the reconstructions created. Seven enhanced CT project files were then automatically fitted, separately in different regions, to obtain a single dataset of superimposed BP regions that incorporated anatomic variations. From this dataset, improved BP contouring guidelines were developed. These guidelines were then applied to the 7 original CT project files and also to 1 additional file, left out from the superimposing procedure. The percentage of BP inclusion was compared with the published guidelines. Results: The anatomic validation procedure showed a high level of conformity for the BP regions examined between the 3-dimensional reconstructions generated and the dissected counterparts. Accurate and detailed BP contouring guidelines were developed, which provided corresponding guidance for each level in a clinical dataset. An average margin of 4.7 mm around the anatomically validated BP contour is sufficient to accommodate for anatomic variations. Using the new guidelines, 100% inclusion of the BP was achieved, compared with a mean inclusion of 37.75% when published guidelines were applied. Conclusion: Improved guidelines for BP delineation were developed using combined MRI and CT imaging with validation by anatomic dissection.

  13. Incorporation of gantry angle correction for 3D dose prediction in intensity-modulated radiation therapy

    PubMed Central

    Sumida, Iori; Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Yagi, Masashi; Ogawa, Kazuhiko

    2015-01-01

    Pretreatment dose verification with beam-by-beam analysis for intensity-modulated radiation therapy (IMRT) is commonly performed with a gantry angle of 0° using a 2D diode detector array. Any changes in multileaf collimator (MLC) position between the actual treatment gantry angle and 0° may result in deviations from the planned dose. We evaluated the effects of MLC positioning errors between the actual treatment gantry angles and nominal gantry angles. A gantry angle correction (GAC) factor was generated by performing a non-gap test at various gantry angles using an electronic portal imaging device (EPID). To convert pixel intensity to dose at the MLC abutment positions, a non-gap test was performed using an EPID and a film at 0° gantry angle. We then assessed the correlations between pixel intensities and doses. Beam-by-beam analyses for 15 prostate IMRT cases as patient-specific quality assurance were performed with a 2D diode detector array at 0° gantry angle to determine the relative dose error for each beam. The resulting relative dose error with or without GAC was added back to the original dose grid for each beam. We compared the predicted dose distributions with or without GAC for film measurements to validate GAC effects. A gamma pass rate with a tolerance of 2%/2 mm was used to evaluate these dose distributions. The gamma pass rate with GAC was higher than that without GAC (P = 0.01). The predicted dose distribution improved with GAC, although the dosimetric effect to a patient was minimal. PMID:25742866

  14. Three-Year Outcomes of Breast Intensity-Modulated Radiation Therapy With Simultaneous Integrated Boost

    SciTech Connect

    McDonald, Mark W.; Godette, Karen D.; Whitaker, Daisy J.; Davis, Lawrence W.; Johnstone, Peter A.S.

    2010-06-01

    Purpose: To report our clinical experience using breast intensity-modulated radiation therapy with simultaneous integrated boost (SIB-IMRT). Methods and Materials: Retrospective review identified 354 Stage 0 to III breast cancer patients treated with SIB-IMRT after conservative surgery between 2003 and 2006. The most common fractionation (89%) simultaneously delivered 1.8 Gy to the ipsilateral breast tissue and 2.14 Gy to the resection cavity, yielding a breast dose of 45 Gy (25 fractions) and cavity dose 59.92 Gy (28 fractions), biologically equivalent for tumor control to 45 Gy to the breast with sequential 16-Gy boost (33 fractions). Results: A total of 356 breasts in 354 patients were treated: 282 with invasive breast cancer, and 74 with ductal carcinoma in situ (DCIS). For left breast radiation, median cardiac V{sub 15} was 2.9% and left ventricular V{sub 15} 1.7%. Median follow-up was 33 months (range, 4-73 months). Acute toxicity was Grade 1 in 57% of cases, Grade 2 in 43%, and Grade 3 in <1%. For invasive breast cancer, the 3-year overall survival was 97.6% and risk of any locoregional recurrence was 2.8%. For ductal carcinoma in situ, 3-year overall survival was 98% and risk of locoregional recurrence 1.4%. In 142 cases at a minimum of 3 years follow-up, global breast cosmesis was judged by physicians as good or excellent in 96.5% and fair in 3.5%. Conclusions: Breast SIB-IMRT reduced treatment duration by five fractions with a favorable acute toxicity profile and low cardiac dose for left breast treatment. At 3 years, locoregional control was excellent, and initial assessment suggested good or excellent cosmesis in a high percentage of evaluable patients.

  15. Incorporation of gantry angle correction for 3D dose prediction in intensity-modulated radiation therapy.

    PubMed

    Sumida, Iori; Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Yagi, Masashi; Ogawa, Kazuhiko

    2015-05-01

    Pretreatment dose verification with beam-by-beam analysis for intensity-modulated radiation therapy (IMRT) is commonly performed with a gantry angle of 0° using a 2D diode detector array. Any changes in multileaf collimator (MLC) position between the actual treatment gantry angle and 0° may result in deviations from the planned dose. We evaluated the effects of MLC positioning errors between the actual treatment gantry angles and nominal gantry angles. A gantry angle correction (GAC) factor was generated by performing a non-gap test at various gantry angles using an electronic portal imaging device (EPID). To convert pixel intensity to dose at the MLC abutment positions, a non-gap test was performed using an EPID and a film at 0° gantry angle. We then assessed the correlations between pixel intensities and doses. Beam-by-beam analyses for 15 prostate IMRT cases as patient-specific quality assurance were performed with a 2D diode detector array at 0° gantry angle to determine the relative dose error for each beam. The resulting relative dose error with or without GAC was added back to the original dose grid for each beam. We compared the predicted dose distributions with or without GAC for film measurements to validate GAC effects. A gamma pass rate with a tolerance of 2%/2 mm was used to evaluate these dose distributions. The gamma pass rate with GAC was higher than that without GAC (P = 0.01). The predicted dose distribution improved with GAC, although the dosimetric effect to a patient was minimal.

  16. Gamma evaluation combined with isocenter optimal matching in intensity modulated radiation therapy quality assurance

    NASA Astrophysics Data System (ADS)

    Bak, Jino; Choi, Jin Hwa; Park, Suk Won; Park, Kwangwoo; Park, Sungho

    2015-12-01

    Two-dimensional (2D) dose comparisons are widely performed by using a gamma evaluation with patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) or dose delivery quality assurance (DQA). In this way, a pass/fail determination is made for a particular treatment plan. When gamma evaluation results are close to the failure criterion, the pass/fail decision may change applying a small shift to the center of the 2D dose distribution. In this study, we quantitatively evaluated the meaning of such a small relative shift in a 2D dose distribution comparison. In addition, we propose the use of a small shift for a pass/fail criterion in gamma analysis, where the concept of isocenter optimal matching (IOM) is applied to IMRT QA of 20 patients. Gamma evaluations were performed to compare two dose distributions, one with and the other without IOM. In-house software was developed in C++ in order to find IOM values including both translational and rotational shifts. Upon gamma evaluation failure, further investigation was initiated using IOM. In this way, three groups were categorized: group 1 for `pass' on gamma evaluation, group 21 for `fail' on the gamma evaluation and `pass' on the gamma the evaluation with IOM, and group 22 for `fail' on the both gamma evaluations and the IOM calculation. IOM results revealed that some failures could be considered as a `pass'. In group 21, 88.98% (fail) of the averaged gamma pass rate changed to 90.45% (pass) when IOM was applied. On average, a ratio of γ ≥ 1 was reduced by 11.06% in 20 patients. We propose that gamma evaluations that do not pass with a rate of 85% to 90% may be augmented with IOM to reveal a potential pass result.

  17. Individualized Selection of Beam Angles and Treatment Isocenter in Tangential Breast Intensity Modulated Radiation Therapy.

    PubMed

    Penninkhof, Joan; Spadola, Sara; Breedveld, Sebastiaan; Baaijens, Margreet; Lanconelli, Nico; Heijmen, Ben

    2017-06-01

    Propose a novel method for individualized selection of beam angles and treatment isocenter in tangential breast intensity modulated radiation therapy (IMRT). For each patient, beam and isocenter selection starts with the fully automatic generation of a large database of IMRT plans (up to 847 in this study); each of these plans belongs to a unique combination of isocenter position, lateral beam angle, and medial beam angle. The imposed hard planning constraint on patient maximum dose may result in plans with unacceptable target dose delivery. Such plans are excluded from further analyses. Owing to differences in beam setup, database plans differ in mean doses to organs at risk (OARs). These mean doses are used to construct 2-dimensional graphs, showing relationships between: (1) contralateral breast dose and ipsilateral lung dose; and (2) contralateral breast dose and heart dose (analyzed only for left-sided). The graphs can be used for selection of the isocenter and beam angles with the optimal, patient-specific tradeoffs between the mean OAR doses. For 30 previously treated patients (15 left-sided and 15 right-sided tumors), graphs were generated considering only the clinically applied isocenter with 121 tangential beam angle pairs. For 20 of the 30 patients, 6 alternative isocenters were also investigated. Computation time for automatic generation of 121 IMRT plans took on average 30 minutes. The generated graphs demonstrated large variations in tradeoffs between conflicting OAR objectives, depending on beam angles and patient anatomy. For patients with isocenter optimization, 847 IMRT plans were considered. Adding isocenter position optimization next to beam angle optimization had a small impact on the final plan quality. A method is proposed for individualized selection of beam angles in tangential breast IMRT. This may be especially important for patients with cardiac risk factors or an enhanced risk for the development of contralateral breast cancer

  18. A 2-D diode array and analysis software for verification of intensity modulated radiation therapy delivery.

    PubMed

    Jursinic, Paul A; Nelms, Ben E

    2003-05-01

    An analysis is made of a two-dimensional array of diodes that can be used for measuring dose generated in a plane by a radiation beam. This measuring device is the MapCHECK Model 1175 (Sun Nuclear, Melbourne, FL). This device has 445 N-type diodes in a 22 x 22 cm2 2-D array with variable spacing. The entire array of diodes is easily calibrated to allow for measurements in absolute dose. For IMRT quality assurance, each beam is measured individually with the beam central axis oriented perpendicular to the plane of diodes. Software is available to do the analytical comparison of measurements versus dose distributions calculated by a treatment planning system. Comparison criteria of percent difference and distance-to-agreement are defined by the operator. Data are presented that show the diode array has linear response when beam fluence changes by over 300-fold, which is typical of the level of modulation in intensity modulated radiation therapy, IMRT, beams. A linear dependence is also shown for a 100-fold change in monitors units delivered. Methods for how this device can be used in the clinic for quality assurance of IMRT fields are described. Measurements of typical IMRT beams that are modulated by compensators and MLCs are presented with comparisons to treatment planning system dose calculations. A time analysis is done for typical IMRT quality assurance measurements. The setup, calibration, and analysis time for the 2-D diode array are on the order of 20 min, depending on numbers of fields. This is significantly less time than required to do similar analysis with radiographic film. The 2-D diode array is ideal for per-plan quality assurance after an IMRT system is fully commissioned.

  19. A critical evaluation of worst case optimization methods for robust intensity-modulated proton therapy planning

    SciTech Connect

    Fredriksson, Albin Bokrantz, Rasmus

    2014-08-15

    Purpose: To critically evaluate and compare three worst case optimization methods that have been previously employed to generate intensity-modulated proton therapy treatment plans that are robust against systematic errors. The goal of the evaluation is to identify circumstances when the methods behave differently and to describe the mechanism behind the differences when they occur. Methods: The worst case methods optimize plans to perform as well as possible under the worst case scenario that can physically occur (composite worst case), the combination of the worst case scenarios for each objective constituent considered independently (objectivewise worst case), and the combination of the worst case scenarios for each voxel considered independently (voxelwise worst case). These three methods were assessed with respect to treatment planning for prostate under systematic setup uncertainty. An equivalence with probabilistic optimization was used to identify the scenarios that determine the outcome of the optimization. Results: If the conflict between target coverage and normal tissue sparing is small and no dose-volume histogram (DVH) constraints are present, then all three methods yield robust plans. Otherwise, they all have their shortcomings: Composite worst case led to unnecessarily low plan quality in boundary scenarios that were less difficult than the worst case ones. Objectivewise worst case generally led to nonrobust plans. Voxelwise worst case led to overly conservative plans with respect to DVH constraints, which resulted in excessive dose to normal tissue, and less sharp dose fall-off than the other two methods. Conclusions: The three worst case methods have clearly different behaviors. These behaviors can be understood from which scenarios that are active in the optimization. No particular method is superior to the others under all circumstances: composite worst case is suitable if the conflicts are not very severe or there are DVH constraints whereas

  20. Planning Hybrid Intensity Modulated Radiation Therapy for Whole-breast Irradiation

    SciTech Connect

    Farace, Paolo; Zucca, Sergio; Solla, Ignazio; Fadda, Giuseppina; Durzu, Silvia; Porru, Sergio; Meleddu, Gianfranco; Deidda, Maria Assunta; Possanzini, Marco; Orru, Sivia; Lay, Giancarlo

    2012-09-01

    Purpose: To test tangential and not-tangential hybrid intensity modulated radiation therapy (IMRT) for whole-breast irradiation. Methods and Materials: Seventy-eight (36 right-, 42 left-) breast patients were randomly selected. Hybrid IMRT was performed by direct aperture optimization. A semiautomated method for planning hybrid IMRT was implemented using Pinnacle scripts. A plan optimization volume (POV), defined as the portion of the planning target volume covered by the open beams, was used as the target objective during inverse planning. Treatment goals were to prescribe a minimum dose of 47.5 Gy to greater than 90% of the POV and to minimize the POV and/or normal tissue receiving a dose greater than 107%. When treatment goals were not achieved by using a 4-field technique (2 conventional open plus 2 IMRT tangents), a 6-field technique was applied, adding 2 non tangential (anterior-oblique) IMRT beams. Results: Using scripts, manual procedures were minimized (choice of optimal beam angle, setting monitor units for open tangentials, and POV definition). Treatment goals were achieved by using the 4-field technique in 61 of 78 (78%) patients. The 6-field technique was applied in the remaining 17 of 78 (22%) patients, allowing for significantly better achievement of goals, at the expense of an increase of low-dose ({approx}5 Gy) distribution in the contralateral tissue, heart, and lungs but with no significant increase of higher doses ({approx}20 Gy) in heart and lungs. The mean monitor unit contribution to IMRT beams was significantly greater (18.7% vs 9.9%) in the group of patients who required 6-field procedure. Conclusions: Because hybrid IMRT can be performed semiautomatically, it can be planned for a large number of patients with little impact on human or departmental resources, promoting it as the standard practice for whole-breast irradiation.

  1. Ototoxicity After Intensity-Modulated Radiation Therapy and Cisplatin-Based Chemotherapy in Children With Medulloblastoma

    SciTech Connect

    Paulino, Arnold C.; Lobo, Mark; Teh, Bin S.; Okcu, M. Fatih; South, Michael; Butler, E. Brian; Su, Jack; Chintagumpala, Murali

    2010-12-01

    Purpose: To report the incidence of Pediatric Oncology Group (POG) Grade 3 or 4 ototoxicity in a cohort of patients treated with craniospinal irradiation (CSI) followed by posterior fossa (PF) and/or tumor bed (TB) boost using intensity-modulated radiation therapy (IMRT). Methods and Materials: From 1998 to 2006, 44 patients with medulloblastoma were treated with CSI followed by IMRT to the PF and/or TB and cisplatin-based chemotherapy. Patients with standard-risk disease were treated with 18 to 23.4 Gy CSI followed by either a (1) PF boost to 36 Gy and TB boost to 54 to 55.8 Gy or (2) TB boost to 55.8 Gy. Patients with high-risk disease received 36 to 39.6 Gy CSI followed by a (1) PF boost to 54 to 55.8 Gy, (2) PF boost to 45 Gy and TB boost to 55.8 Gy, or (3) TB boost to 55.8 Gy. Median audiogram follow-up was 41 months (range, 11-92.4 months). Results: POG Grade Ototoxicity 0, 1, 2, 3. and 4 was found in 29, 32, 11, 13. and 3 ears. respectively, with POG Grade 3 or 4 accounting for 18.2% of cases. There was a statistically significant difference in mean radiation dose (D{sub mean}) cochlea according to degree of ototoxicity, with D{sub mean} cochlea increasing with severity of hearing loss (p = 0.027). Conclusions: Severe ototoxicity was seen in 18.2% of ears in children treated with IMRT boost and cisplatin-based chemotherapy. Increasing dose to the cochlea was associated with increasing severity of hearing loss.

  2. Proton energy optimization and reduction for intensity-modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X. Ronald; Gomez, Daniel; Zhang, Xiaodong

    2014-10-01

    Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To ‘scan’ the target volume, the proton beam is controlled by varying its energy to penetrate the patient’s body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10-20 m s-1, changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%-18.9% for the prostate cancer cases, 11.0% for the lung cancer cases and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed.

  3. Proton energy optimization and reduction for intensity-modulated proton therapy.

    PubMed

    Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X Ronald; Gomez, Daniel; Zhang, Xiaodong

    2014-11-07

    Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To 'scan' the target volume, the proton beam is controlled by varying its energy to penetrate the patient's body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10-20 m s(-1), changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%-18.9% for the prostate cancer cases, 11.0% for the lung cancer cases and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed.

  4. Simultaneous integrated boost-intensity modulated radiation therapy for inoperable hepatocellular carcinoma.

    PubMed

    Kim, Tae Hyun; Park, Joong-Won; Kim, Yeon-Joo; Kim, Bo Hyun; Woo, Sang Myung; Moon, Sung Ho; Kim, Sang Soo; Lee, Woo Jin; Kim, Dae Yong; Kim, Chang-Min

    2014-10-01

    The aim of this work was to evaluate the clinical efficacy and safety of simultaneous integrated boost-intensity modulated radiation therapy (SIB-IMRT) in patients with inoperable hepatocellular carcinoma (HCC). A total of 53 patients with inoperable HCC underwent SIB-IMRT using two dose-fractionation schemes, depending on the proximity of gastrointestinal structures. The 41 patients in the low dose-fractionation (LD) group, with internal target volume (ITV) < 1 cm from gastrointestinal structures, received total doses of 55 and 44 Gy in 22 fractions to planning target volume 1 (PTV1) and 2 (PTV2), respectively. The 12 patients in the high dose-fractionation (HD) group, with ITV ≥ 1 cm from gastrointestinal structures, received total doses of 66 and 55 Gy in 22 fractions to the PTV1 and PTV2, respectively. Overall, treatment was well tolerated, with no grade > 3 toxicity. The LD group had larger sized tumors (median: 6 vs. 3.4 cm) and greater frequencies of vascular invasion (80.6 vs. 16.7 %) than patients in the HD group (p < 0.05 each). The median overall survival (OS) was 25.1 mKonzept ist machbar und sicheronths and the actuarial 2-year local progression-free survival (LPFS), relapse-free survival (RFS), and OS rates were 67.3, 14.7, and 54.7  %, respectively. The HD group tended to show better tumor response (100 vs. 62.2 %, p = 0.039) and 2-year LPFS (85.7 vs. 59  %, p = 0.119), RFS (38.1 vs. 7.3 %, p = 0.063), and OS (83.3 vs. 44.3 %, p = 0.037) rates than the LD group. Multivariate analysis showed that tumor response was significantly associated with OS. SIB-IMRT is feasible and safe for patients with inoperable HCC.

  5. Aichi Cancer Center Initial Experience of Intensity Modulated Radiation Therapy for Nasopharyngeal Cancer Using Helical Tomotherapy

    SciTech Connect

    Kodaira, Takeshi Tomita, Natsuo; Tachibana, Hiroyuki; Nakamura, Tatsuya; Nakahara, Rie; Inokuchi, Haruo; Fuwa, Nobukazu

    2009-03-15

    Purpose: To assess the feasibility of helical tomotherapy (HT) for patients with nasopharyngeal carcinoma. Methods and Materials: From June 2006 to June 2007, 20 patients with nasopharyngeal carcinoma were treated with HT with (n = 18) or without (n = 2) systemic chemotherapy. The primary tumor and involved lymph node (PTV1) were prescribed 70 Gy and the prophylactic region 54 Gy at D95, respectively. The majority of patients received 2 Gy per fraction for PTV1 in 35 fractions. Parotid function was evaluated using quantitative scintigraphy at pretreatment, and posttreatment at 3 months and 1 year later. Results: The median patient age was 53 years, ranging from 15 to 83. Our cohort included 5, 8, 4, 2, and 1 patients with disease Stages IIB, III, IVA, IVB, and IVC, respectively. Histopathological record revealed two for World Health Organization Type I and 18 for Type 2 or 3. The median duration time for treatment preparation was 9.5 days, and all plans were thought to be acceptable regarding dose constraints of both the planning target volume and organ at risk. All patients completed their treatment procedure of intensity-modulated radiation therapy (IMRT). All patients achieved clinical remission after IMRT. The majority of patients had Grade 3 or higher toxicity of skin, mucosa, and neutropenia. At the median follow-up of 10.9 months, two patients recurred, and one patient died from cardiac disease. Parotid gland function at 1 year after completion of IMRT was significantly improved compared with that at 3 months. Conclusion: HT was clinically effective in terms of IMRT planning and utility for patients with nasopharyngeal cancer.

  6. Intensity modulated radiation-therapy for preoperative posterior abdominal wall irradiation of retroperitoneal liposarcomas

    SciTech Connect

    Bossi, Alberto . E-mail: alberto.bossi@uz.kuleuven.ac.be; De Wever, Ivo; Van Limbergen, Erik; Vanstraelen, Bianca

    2007-01-01

    Purpose: Preoperative external-beam radiation therapy (preop RT) in the management of Retroperitoneal Liposarcomas (RPLS) typically involves the delivery of radiation to the entire tumor mass: yet this may not be necessary. The purpose of this study is to evaluate a new strategy of preop RT for RPLS in which the target volume is limited to the contact area between the tumoral mass and the posterior abdominal wall. Methods and Materials: Between June 2000 and Jan 2005, 18 patients with the diagnosis of RPLS have been treated following a pilot protocol of pre-op RT, 50 Gy in 25 fractions of 2 Gy/day. The Clinical Target Volume (CTV) has been limited to the posterior abdominal wall, region at higher risk for local relapse. A Three-Dimensional conformal (3D-CRT) and an Intensity Modulated (IMRT) plan were generated and compared; toxicity was reported following the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events v3.0. Results: All patients completed the planned treatment and the acute toxicity was tolerable: 2 patients experienced Grade 3 and 1 Grade 2 anorexia while 2 patients developed Grade 2 nausea. IMRT allows a better sparing of the ipsilateral and the contralateral kidney. All tumors were successfully resected without major complications. At a median follow-up of 27 months 2 patients developed a local relapse and 1 lung metastasis. Conclusions: Our strategy of preop RT is feasible and well tolerated: the rate of resectability is not compromised by limiting the preop CTV to the posterior abdominal wall and a better critical-structures sparing is obtained with IMRT.

  7. Hypofractionated Dose-Painting Intensity Modulated Radiation Therapy With Chemotherapy for Nasopharyngeal Carcinoma: A Prospective Trial

    SciTech Connect

    Bakst, Richard L.; Lee, Nancy; Pfister, David G.; Zelefsky, Michael J.; Hunt, Margie A.; Kraus, Dennis H.; Wolden, Suzanne L.

    2011-05-01

    Purpose: To evaluate the feasibility of dose-painting intensity-modulated radiation therapy (DP-IMRT) with a hypofractionated regimen to treat nasopharyngeal carcinoma (NPC) with concomitant toxicity reduction. Methods and Materials: From October 2002 through April 2007, 25 newly diagnosed NPC patients were enrolled in a prospective trial. DP-IMRT was prescribed to deliver 70.2 Gy using 2.34-Gy fractions to the gross tumor volume for the primary and nodal sites while simultaneously delivering 54 Gy in 1.8-Gy fractions to regions at risk of microscopic disease. Patients received concurrent and adjuvant platin-based chemotherapy similar to the Intergroup 0099 trial. Results: Patient and disease characteristics are as follows: median age, 46; 44% Asian; 68% male; 76% World Health Organization III; 20% T1, 52% T2, 16% T3, 12% T4; 20% N0, 36% N1, 36% N2, 8% N3. With median follow-up of 33 months, 3-year local control was 91%, regional control was 91%, freedom from distant metastases was 91%, and overall survival was 89%. The average mean dose to each cochlea was 43 Gy. With median audiogram follow-up of 14 months, only one patient had clinically significant (Grade 3) hearing loss. Twelve percent of patients developed temporal lobe necrosis; one patient required surgical resection. Conclusions: Preliminary findings using a hypofractionated DP-IMRT regimen demonstrated that local control, freedom from distant metastases, and overall survival compared favorably with other series of IMRT and chemotherapy. The highly conformal boost to the tumor bed resulted low rates of severe ototoxicity (Grade 3-4). However, the incidence of in-field brain radiation necrosis indicates that 2.34 Gy per fraction is not safe in this setting.

  8. Disease Control and Ototoxicity Using Intensity-Modulated Radiation Therapy Tumor-Bed Boost for Medulloblastoma

    SciTech Connect

    Polkinghorn, William R.; Dunkel, Ira J.; Souweidane, Mark M.; Khakoo, Yasmin; Lyden, David C.; Gilheeney, Stephen W.; Becher, Oren J.; Budnick, Amy S.; Wolden, Suzanne L.

    2011-11-01

    Purpose: We previously reported excellent local control for treating medulloblastoma with a limited boost to the tumor bed. In order to decrease ototoxicity, we subsequently implemented a tumor-bed boost using intensity-modulated radiation therapy (IMRT), the clinical results of which we report here. Patients and Methods: A total of 33 patients with newly diagnosed medulloblastoma, 25 with standard risk, and 8 with high risk, were treated on an IMRT tumor-bed boost following craniospinal irradiation (CSI). Six standard-risk patients were treated with an institutional protocol with 18 Gy CSI in conjunction with intrathecal iodine-131-labeled monoclonal antibody. The majority of patients received concurrent vincristine and standard adjuvant chemotherapy. Pure-tone audiograms were graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: Median age was 9 years old (range, 4-46 years old). Median follow-up was 63 months. Kaplan-Meier estimates of progression-free survival (PFS) and overall survival (OS) rates for standard-risk patients who received 23.4 or 36 Gy CSI (not including those who received 18 Gy CSI with radioimmunotherapy) were 81.4% and 88.4%, respectively, at 5 years; 5-year PFS and OS rates for high-risk patients were both 87.5%. There were no isolated posterior fossa failures outside of the boost volume. Posttreatment audiograms were available for 31 patients, of whom 6%, at a median follow-up of 19 months, had developed Grade 3 hearing loss. Conclusion: An IMRT tumor-bed boost results in excellent local control while delivering a low mean dose to the cochlea, resulting in a low rate of ototoxicity.

  9. Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

    SciTech Connect

    Garden, Adam S.; Dong, Lei; Morrison, William H.; Stugis, Erich M.; Glisson, Bonnie S.; Schwartz, David L.; Kies, Merill S.; Ang, K. Kian; Rosenthal, David I.

    2013-03-15

    Purpose: To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT). Methods and Materials: The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed. Results: The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Joint Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease. Conclusions: Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage.

  10. Intensity-Modulated Proton Therapy Versus Helical Tomotherapy in Nasopharynx Cancer: Planning Comparison and NTCP Evaluation

    SciTech Connect

    Widesott, Lamberto Pierelli, Alessio; Fiorino, Claudio; Dell'Oca, Italo; Broggi, Sara; Cattaneo, Giovanni Mauro; Di Muzio, Nadia; Fazio, Ferruccio; Calandrino, Riccardo; Schwarz, Marco

    2008-10-01

    Purpose: To compare intensity-modulated proton therapy (IMPT) and helical tomotherapy (HT) treatment plans for nasopharynx cancer using a simultaneous integrated boost approach. Methods and Materials: The data from 6 patients who had previously been treated with HT were used. A three-beam IMPT technique was optimized in the Hyperion treatment planning system, simulating a 'beam scanning' technique. HT was planned using the tomotherapy treatment planning system. Both techniques were optimized to simultaneously deliver 66 Gy in 30 fractions to planning target volume (PTV1; GTV and enlarged nodes) and 54 Gy to PTV2 subclinical, electively treated nodes. Normal tissue complication probability calculation was performed for the parotids and larynx. Results: Very similar PTVs coverage and homogeneity of the target dose distribution for IMPT and HT were found. The conformity index was significantly lower for protons than for photons (1.19 vs. 1.42, respectively). The mean dose to the ipsilateral and contralateral parotid glands decreased by 6.4 Gy and 5.6 Gy, respectively, with IMPT. The volume of mucosa and esophagus receiving {>=}20 Gy and {>=}30 Gy with IMPT was significantly lower than with HT. The average volume of larynx receiving {>=}50 Gy was significantly lower with HT, while for thyroid, it was comparable. The volume receiving {>=}30, {>=}20, and {>=}10 Gy in total body volume decreased with IMPT by 14.5%, 19.4%, and 23.1%, respectively. The normal tissue complication probability for the parotid glands was significantly lower with IMPT for all sets of parameters; however, we also estimated an almost full recovery of the contralateral parotid with HT. The normal tissue complication probability for the larynx was not significantly different between the two irradiation techniques. Conclusion: Excellent target coverage, homogeneity within the PTVs, and sparing of the organs at risk were reached with both modalities. IMPT allows for better sparing of most organs at

  11. Comparison of coplanar and noncoplanar intensity-modulated radiation therapy and helical tomotherapy for hepatocellular carcinoma

    PubMed Central

    2010-01-01

    Background To compare the differences in dose-volume data among coplanar intensity modulated radiotherapy (IMRT), noncoplanar IMRT, and helical tomotherapy (HT) among patients with hepatocellular carcinoma (HCC) and portal vein thrombosis (PVT). Methods Nine patients with unresectable HCC and PVT underwent step and shoot coplanar IMRT with intent to deliver 46 - 54 Gy to the tumor and portal vein. The volume of liver received 30Gy was set to keep less than 30% of whole normal liver (V30 < 30%). The mean dose to at least one side of kidney was kept below 23 Gy, and 50 Gy as for stomach. The maximum dose was kept below 47 Gy for spinal cord. Several parameters including mean hepatic dose, percent volume of normal liver with radiation dose at X Gy (Vx), uniformity index, conformal index, and doses to organs at risk were evaluated from the dose-volume histogram. Results HT provided better uniformity for the planning-target volume dose coverage than both IMRT techniques. The noncoplanar IMRT technique reduces the V10 to normal liver with a statistically significant level as compared to HT. The constraints for the liver in the V30 for coplanar IMRT vs. noncoplanar IMRT vs. HT could be reconsidered as 21% vs. 17% vs. 17%, respectively. When delivering 50 Gy and 60-66 Gy to the tumor bed, the constraints of mean dose to the normal liver could be less than 20 Gy and 25 Gy, respectively. Conclusion Noncoplanar IMRT and HT are potential techniques of radiation therapy for HCC patients with PVT. Constraints for the liver in IMRT and HT could be stricter than for 3DCRT. PMID:20492727

  12. Bile Acid Malabsorption After Pelvic and Prostate Intensity Modulated Radiation Therapy: An Uncommon but Treatable Condition

    SciTech Connect

    Harris, Victoria; Benton, Barbara; Sohaib, Aslam; Dearnaley, David; Andreyev, H. Jervoise N.

    2012-12-01

    Purpose: Intensity modulated radiation therapy (IMRT) is a significant therapeutic advance in prostate cancer, allowing increased tumor dose delivery and increased sparing of normal tissues. IMRT planning uses strict dose constraints to nearby organs to limit toxicity. Bile acid malabsorption (BAM) is a treatable disorder of the terminal ileum (TI) that presents with symptoms similar to radiation therapy toxicity. It has not been described in patients receiving RT for prostate cancer in the contemporary era. We describe new-onset BAM in men after IMRT for prostate cancer. Methods and Materials: Diagnosis of new-onset BAM was established after typical symptoms developed, selenium-75 homocholic acid taurine (SeHCAT) scanning showed 7-day retention of <15%, and patients' symptoms unequivocally responded to a bile acid sequestrant. The TI was identified on the original radiation therapy plan, and the radiation dose delivered was calculated and compared with accepted dose-volume constraints. Results: Five of 423 men treated in a prospective series of high-dose prostate and pelvic IMRT were identified with new onset BAM (median age, 65 years old). All reported having normal bowel habits before RT. The volume of TI ranged from 26-141 cc. The radiation dose received by the TI varied between 11.4 Gy and 62.1 Gy (uncorrected). Three of 5 patients had TI treated in excess of 45 Gy (equivalent dose calculated in 2-Gy fractions, using an {alpha}/{beta} ratio of 3) with volumes ranging from 1.6 cc-49.0 cc. One patient had mild BAM (SeHCAT retention, 10%-15%), 2 had moderate BAM (SeHCAT retention, 5%-10%), and 2 had severe BAM (SeHCAT retention, <5%). The 3 patients whose TI received {>=}45 Gy developed moderate to severe BAM, whereas those whose TI received <45 Gy had only mild to moderate BAM. Conclusions: Radiation delivered to the TI during IMRT may cause BAM. Identification of the TI from unenhanced RT planning computed tomography scans is difficult and may impede accurate

  13. Bile acid malabsorption after pelvic and prostate intensity modulated radiation therapy: an uncommon but treatable condition.

    PubMed

    Harris, Victoria; Benton, Barbara; Sohaib, Aslam; Dearnaley, David; Andreyev, H Jervoise N

    2012-12-01

    Intensity modulated radiation therapy (IMRT) is a significant therapeutic advance in prostate cancer, allowing increased tumor dose delivery and increased sparing of normal tissues. IMRT planning uses strict dose constraints to nearby organs to limit toxicity. Bile acid malabsorption (BAM) is a treatable disorder of the terminal ileum (TI) that presents with symptoms similar to radiation therapy toxicity. It has not been described in patients receiving RT for prostate cancer in the contemporary era. We describe new-onset BAM in men after IMRT for prostate cancer. Diagnosis of new-onset BAM was established after typical symptoms developed, selenium-75 homocholic acid taurine (SeHCAT) scanning showed 7-day retention of <15%, and patients' symptoms unequivocally responded to a bile acid sequestrant. The TI was identified on the original radiation therapy plan, and the radiation dose delivered was calculated and compared with accepted dose-volume constraints. Five of 423 men treated in a prospective series of high-dose prostate and pelvic IMRT were identified with new onset BAM (median age, 65 years old). All reported having normal bowel habits before RT. The volume of TI ranged from 26-141 cc. The radiation dose received by the TI varied between 11.4 Gy and 62.1 Gy (uncorrected). Three of 5 patients had TI treated in excess of 45 Gy (equivalent dose calculated in 2-Gy fractions, using an α/β ratio of 3) with volumes ranging from 1.6 cc-49.0 cc. One patient had mild BAM (SeHCAT retention, 10%-15%), 2 had moderate BAM (SeHCAT retention, 5%-10%), and 2 had severe BAM (SeHCAT retention, <5%). The 3 patients whose TI received ≥45 Gy developed moderate to severe BAM, whereas those whose TI received <45 Gy had only mild to moderate BAM. Radiation delivered to the TI during IMRT may cause BAM. Identification of the TI from unenhanced RT planning computed tomography scans is difficult and may impede accurate dosimetric evaluation. Thorough toxicity assessment and close

  14. The Feasibility Study of a Hybrid Coplanar Arc Technique Versus Hybrid Intensity-modulated Radiotherapy in Treatment of Early-stage Left-sided Breast Cancer with Simultaneous-integrated Boost

    PubMed Central

    Chen, Yuan-Gui; Li, An-Chuan; Li, Wen-Yao; Huang, Miao-Yun; Li, Xiao-Bo; Chen, Ming-Qiu; Zhang, Mutian; Xu, Ben-Hua

    2017-01-01

    This study demonstrated the feasibility and advantages of a hybrid, volumetric arc therapy technique that used two 90° coplanar arcs and two three-dimensional conformal tangential beams in the simultaneous-integrated boost radiotherapy of left-sided breast cancer after breast-conserving surgery. A total of nine patients with stage I, left-sided breast cancer who underwent breast-conserving surgery were selected for this retrospective study. For each patient, a hybrid arc plan was generated and then compared with two hybrid intensity-modulated radiotherapy plans. All plans were optimized using the same objectives and dose constraints. The prescription dose was 50.4 Gy to the planning target volume with simultaneous boost to 60 Gy to the expanded gross target volume in 28 fractions. The differences among these hybrid plans were analyzed by the Kolmogorov–Smirnov test or the Wilcoxon rank sum test. The hybrid arc plans achieved the clinical requirements of target dose coverage and normal tissue (NT) dose constraints. It was found that the hybrid arc plans showed advantages in the conformity index of the expanded gross target volume, the V5 of the heart, the D2 of the left ventricle, and the D2 and V50.4 of NTs. The average beam-on time and monitor units of the hybrid arc plans were significantly lower (P < 0.001). PMID:28405101

  15. Intensity-modulated radiation therapy for pancreatic and prostate cancer using pulsed low–dose rate delivery techniques

    SciTech Connect

    Li, Jie; Lang, Jinyi; Wang, Pei; Kang, Shengwei; Lin, Mu-han; Chen, Xiaoming; Chen, Fu; Guo, Ming; Chen, Lili; Ma, Chang-Ming Charlie

    2014-01-01

    Reirradiation of patients who were previously treated with radiotherapy is vastly challenging. Pulsed low–dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while providing significant tumor control for recurrent cancers. This work investigates treatment planning techniques for intensity-modulated radiation therapy (IMRT)-based PLDR treatment of various sites, including cases with pancreatic and prostate cancer. A total of 20 patients with clinical recurrence were selected for this study, including 10 cases with pancreatic cancer and 10 with prostate cancer. Large variations in the target volume were included to test the ability of IMRT using the existing treatment planning system and optimization algorithm to deliver uniform doses in individual gantry angles/fields for PLDR treatments. Treatment plans were generated with 10 gantry angles using the step-and-shoot IMRT delivery technique, which can be delivered in 3-minute intervals to achieve an effective low dose rate of 6.7 cGy/min. Instead of dose constraints on critical structures, ring structures were mainly used in PLDR-IMRT optimization. In this study, the PLDR-IMRT plans were compared with the PLDR-3-dimensional conformal radiation therapy (3DCRT) plans and the PLDR-RapidArc plans. For the 10 cases with pancreatic cancer that were investigated, the mean planning target volume (PTV) dose for each gantry angle in the PLDR-IMRT plans ranged from 17.6 to 22.4 cGy. The maximum doses ranged between 22.9 and 34.8 cGy. The minimum doses ranged from 8.2 to 17.5 cGy. For the 10 cases with prostate cancer that were investigated, the mean PTV doses for individual gantry angles ranged from 18.8 to 22.6 cGy. The maximum doses per gantry angle were between 24.0 and 34.7 cGy. The minimum doses per gantry angle ranged from 4.4 to 17.4 cGy. A significant reduction in the organ at risk (OAR) dose was observed with the PLDR-IMRT plan when compared with that using the PLDR-3DCRT

  16. Influence of robust optimization in intensity-modulated proton therapy with different dose delivery techniques

    SciTech Connect

    Liu Wei; Li Yupeng; Li Xiaoqiang; Cao Wenhua; Zhang Xiaodong

    2012-06-15

    Purpose: The distal edge tracking (DET) technique in intensity-modulated proton therapy (IMPT) allows for high energy efficiency, fast and simple delivery, and simple inverse treatment planning; however, it is highly sensitive to uncertainties. In this study, the authors explored the application of DET in IMPT (IMPT-DET) and conducted robust optimization of IMPT-DET to see if the planning technique's sensitivity to uncertainties was reduced. They also compared conventional and robust optimization of IMPT-DET with three-dimensional IMPT (IMPT-3D) to gain understanding about how plan robustness is achieved. Methods: They compared the robustness of IMPT-DET and IMPT-3D plans to uncertainties by analyzing plans created for a typical prostate cancer case and a base of skull (BOS) cancer case (using data for patients who had undergone proton therapy at our institution). Spots with the highest and second highest energy layers were chosen so that the Bragg peak would be at the distal edge of the targets in IMPT-DET using 36 equally spaced angle beams; in IMPT-3D, 3 beams with angles chosen by a beam angle optimization algorithm were planned. Dose contributions for a number of range and setup uncertainties were calculated, and a worst-case robust optimization was performed. A robust quantification technique was used to evaluate the plans' sensitivity to uncertainties. Results: With no uncertainties considered, the DET is less robust to uncertainties than is the 3D method but offers better normal tissue protection. With robust optimization to account for range and setup uncertainties, robust optimization can improve the robustness of IMPT plans to uncertainties; however, our findings show the extent of improvement varies. Conclusions: IMPT's sensitivity to uncertainties can be improved by using robust optimization. They found two possible mechanisms that made improvements possible: (1) a localized single-field uniform dose distribution (LSFUD) mechanism, in which the

  17. Influence of robust optimization in intensity-modulated proton therapy with different dose delivery techniques

    PubMed Central

    Liu, Wei; Li, Yupeng; Li, Xiaoqiang; Cao, Wenhua; Zhang, Xiaodong

    2012-01-01

    Purpose: The distal edge tracking (DET) technique in intensity-modulated proton therapy (IMPT) allows for high energy efficiency, fast and simple delivery, and simple inverse treatment planning; however, it is highly sensitive to uncertainties. In this study, the authors explored the application of DET in IMPT (IMPT-DET) and conducted robust optimization of IMPT-DET to see if the planning technique’s sensitivity to uncertainties was reduced. They also compared conventional and robust optimization of IMPT-DET with three-dimensional IMPT (IMPT-3D) to gain understanding about how plan robustness is achieved. Methods: They compared the robustness of IMPT-DET and IMPT-3D plans to uncertainties by analyzing plans created for a typical prostate cancer case and a base of skull (BOS) cancer case (using data for patients who had undergone proton therapy at our institution). Spots with the highest and second highest energy layers were chosen so that the Bragg peak would be at the distal edge of the targets in IMPT-DET using 36 equally spaced angle beams; in IMPT-3D, 3 beams with angles chosen by a beam angle optimization algorithm were planned. Dose contributions for a number of range and setup uncertainties were calculated, and a worst-case robust optimization was performed. A robust quantification technique was used to evaluate the plans’ sensitivity to uncertainties. Results: With no uncertainties considered, the DET is less robust to uncertainties than is the 3D method but offers better normal tissue protection. With robust optimization to account for range and setup uncertainties, robust optimization can improve the robustness of IMPT plans to uncertainties; however, our findings show the extent of improvement varies. Conclusions: IMPT’s sensitivity to uncertainties can be improved by using robust optimization. They found two possible mechanisms that made improvements possible: (1) a localized single-field uniform dose distribution (LSFUD) mechanism, in which the

  18. Improving intensity-modulated radiation therapy using the anatomic beam orientation optimization algorithm

    SciTech Connect

    Potrebko, Peter S.; McCurdy, Boyd M. C.; Butler, James B.; El-Gubtan, Adel S.

    2008-05-15

    A novel, anatomic beam orientation optimization (A-BOO) algorithm is proposed to significantly improve conventional intensity-modulated radiation therapy (IMRT). The A-BOO algorithm vectorially analyses polygonal surface mesh data of contoured patient anatomy. Five optimal (5-opt) deliverable beam orientations are selected based on (1) tangential orientation bisecting the target and adjacent organ's-at-risk (OARs) to produce precipitous dose gradients between them and (2) parallel incidence with polygon features of the target volume to facilitate conformal coverage. The 5-opt plans were compared to standard five, seven, and nine equiangular-spaced beam plans (5-equi, 7-equi, 9-equi) for: (1) gastric, (2) Radiation Therapy Oncology Group (RTOG) P-0126 prostate, and (3) RTOG H-0022 oropharyngeal (stage-III, IV) cancer patients. In the gastric case, the noncoplanar 5-opt plan reduced the right kidney V 20 Gy by 32.2%, 23.2%, and 20.6% compared to plans with five, seven, and nine equiangular-spaced beams. In the prostate case, the coplanar 5-opt plan produced similar rectal sparing as the 7-equi and 9-equi plans with a reduction of the V 75, V 70, V 65, and V 60 Gy of 2.4%, 5.3%, 7.0%, and 9.5% compared to the 5-equi plan. In the stage-III and IV oropharyngeal cases, the noncoplanar 5-opt plan substantially reduced the V 30 Gy and mean dose to the contralateral parotid compared to plans with five, seven, and nine equiangular-spaced beams: (stage-III) 7.1%, 5.2%, 6.8%, and 5.1, 3.5, 3.7 Gy and (stage-IV) 10.2%, 10.2%, 9.8% and 7.0, 7.1, 7.2 Gy. The geometry-based A-BOO algorithm has been demonstrated to be robust for application to a variety of IMRT treatment sites. Beam orientations producing significant improvements in OAR sparing over conventional IMRT can be automatically produced in minutes compared to hours with existing dose-based beam orientation optimization methods.

  19. Influence of jaw tracking in intensity-modulated and volumetric-modulated arc radiotherapy for head and neck cancers: a dosimetric study.

    PubMed

    Mani, Karthick Raj; Upadhayay, Sagar; Das, K J Maria

    2017-03-01

    To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. The conformity index average of all patients followed by standard deviation ([Formula: see text] ± [Formula: see text]) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65, and 1.85 ± 0.64, and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04, and 0.064 ± 0.05. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

  20. SU-E-T-394: The Use of Jaw Tracking in Intensity Modulated and Volumetric Modulated Arc Radiotherapy for Spine Stereotactic Radiosurgery

    SciTech Connect

    Chin, K; Wen, N; Huang, Y; Kim, J; Zhao, B; Siddiqui, S; Chetty, I; Ryu, S

    2014-06-01

    Purpose: To evaluate the potential advantages of jaw tracking for intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in spine radiosurgery. Methods: VMAT and IMRT plans were retrospectively generated for ten patients. Six plans for each patient were created in the Eclipse treatment planning system for a Varian Truebeam equipped with a Millennium 120 MLC. Plans were created to study IMRT and VMAT plans with and without jaw tracking, as well as IMRT plans of different flattening filter free (FFF) energies. Plans were prescribed to the 90% isodose line to 16 or 18 Gy in one fraction to cover 95% of the target. Planning target volume (PTV) coverage, conformity index (CI), dose to spinal cord, distance to fall off from the 90% to 50% isodose line (DTF), as well as delivery time were evaluated. Ion chamber and film measurements were performed to verify calculated and measured dose distributions. Results: Jaw tracking decreased the spinal cord dose for both IMRT and VMAT plans, but a larger decrease was seen with the IMRT plans (p=0.004 vs p=0.04). The average D10% for the spinal cord was least for the 6MV FFF IMRT plan with jaw tracking and was greatest for the 10MV FFF plan without jaw tracking. Treatment times between IMRT and VMAT plans with or without jaw tracking were not significantly different. Measured plans showed greater than 98.5% agreement for planar dose gamma analysis (3%/2 mm) and less than 2.5% for point dose analysis compared to calculated plans. Conclusion: Jaw tracking can be used to help decrease spinal cord dose without any change in treatment delivery or calculation accuracy. Lower dose to the spinal cord was achieved using 6 MV beams compared to 10 MV beams, though 10 MV may be justified in some cases to decrease skin dose.

  1. Continuous-time method and its discretization to inverse problem of intensity-modulated radiation therapy treatment planning

    NASA Astrophysics Data System (ADS)

    Fujimoto, Ken'ichi; Tanaka, Yoshihiro; Abou Al-Ola, Omar M.; Yoshinaga, Tetsuya

    2014-06-01

    We propose a novel approach for solving box-constrained inverse problems in intensity-modulated radiation therapy (IMRT) treatment planning based on the idea of continuous dynamical methods and split-feasibility algorithms. Our method can compute a feasible solution without the second derivative of an objective function, which is required for gradient-based optimization algorithms. We prove theoretically that a double Kullback-Leibler divergence can be used as the Lyapunov function for the IMRT planning system.

  2. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Kondoh, Takafumi; Kashima, Hiroaki; Yang, Jinfeng; Yoshida, Yoichi; Tagawa, Seiichi

    2008-10-01

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods.

  3. A GPU-accelerated and Monte Carlo-based intensity modulated proton therapy optimization system.

    PubMed

    Ma, Jiasen; Beltran, Chris; Seum Wan Chan Tseung, Hok; Herman, Michael G

    2014-12-01

    Conventional spot scanning intensity modulated proton therapy (IMPT) treatment planning systems (TPSs) optimize proton spot weights based on analytical dose calculations. These analytical dose calculations have been shown to have severe limitations in heterogeneous materials. Monte Carlo (MC) methods do not have these limitations; however, MC-based systems have been of limited clinical use due to the large number of beam spots in IMPT and the extremely long calculation time of traditional MC techniques. In this work, the authors present a clinically applicable IMPT TPS that utilizes a very fast MC calculation. An in-house graphics processing unit (GPU)-based MC dose calculation engine was employed to generate the dose influence map for each proton spot. With the MC generated influence map, a modified least-squares optimization method was used to achieve the desired dose volume histograms (DVHs). The intrinsic CT image resolution was adopted for voxelization in simulation and optimization to preserve spatial resolution. The optimizations were computed on a multi-GPU framework to mitigate the memory limitation issues for the large dose influence maps that resulted from maintaining the intrinsic CT resolution. The effects of tail cutoff and starting condition were studied and minimized in this work. For relatively large and complex three-field head and neck cases, i.e., >100,000 spots with a target volume of ∼ 1000 cm(3) and multiple surrounding critical structures, the optimization together with the initial MC dose influence map calculation was done in a clinically viable time frame (less than 30 min) on a GPU cluster consisting of 24 Nvidia GeForce GTX Titan cards. The in-house MC TPS plans were comparable to a commercial TPS plans based on DVH comparisons. A MC-based treatment planning system was developed. The treatment planning can be performed in a clinically viable time frame on a hardware system costing around 45,000 dollars. The fast calculation and

  4. Optimal beam design on intensity-modulated radiation therapy with simultaneous integrated boost in nasopharyngeal cancer

    SciTech Connect

    Cheng, Mei-Chun; Hu, Yu-Wen; Liu, Ching-Sheng; Lee, Jeun-Shenn; Huang, Pin-I; Yen, Sang-Hue; Lee, Yuh-Lin; Hsieh, Chun-Mei; Shiau, Cheng-Ying

    2014-10-01

    This study aims to determine the optimal beam design among various combinations of field numbers and beam trajectories for intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) technique for the treatment of nasopharyngeal cancer (NPC). We used 10 fields with gantry angles of 155°, 130°, 75°, 25°, 0° L, 0° R, 335°, 285°, 230°, and 205° denoted as F10. To decrease doses in the spinal cord, the F10 technique was designed by featuring 2 pairs of split-opposed beam fields at 155° to 335° and 205° to 25°, as well as one pair of manually split beam fields at 0°. The F10 technique was compared with 4 other common field arrangements: F7E, 7 fields with 50° equally spaced gantry angles; F7, the basis of F10 with 155°, 130°, 75°, 0°, 285°, 230°, and 205°; F9E, 9 fields with 40° equally spaced gantry angles; and FP, 7 posterior fields with 180°, 150°, 120°, 90°, 270°, 240°, and 210°. For each individual case of 10 patients, the customized constraints derived after optimization with the standard F10 technique were applied to 4 other field arrangements. The 4 new optimized plans of each individual case were normalized to achieve the same coverage of planning target volume (PTV){sub 63} {sub Gy} as that of the standard F10 technique. The F10 field arrangement exhibited the best coverage in PTV{sub 70} {sub Gy} and the least mean dose in the trachea-esophagus region. Furthermore, the F10 field arrangement demonstrated the highest level of conformity in the low-dose region and the least monitor unit. The F10 field arrangement performed more outstandingly than the other field arrangements in PTV{sub 70} {sub Gy} coverage and spared the central organ. This arrangement also exhibited the highest conformity and delivery efficiency. The F10 technique is recommended as the standard beam geometry for the SIB-IMRT of NPC.

  5. Treatment of Oral Cavity Squamous Cell Carcinoma With Adjuvant or Definitive Intensity-Modulated Radiation Therapy

    SciTech Connect

    Sher, David J.; Thotakura, Vijaya; Balboni, Tracy A.; Norris, Charles M.; Haddad, Robert I.; Posner, Marshall R.; Lorch, Jochen; Goguen, Laura A.; Annino, Donald J.; Tishler, Roy B.

    2011-11-15

    Purpose: The optimal management of oral cavity squamous cell carcinoma (OCSCC) typically involves surgical resection followed by adjuvant radiotherapy or chemoradiotherapy (CRT) in the setting of adverse pathologic features. Intensity-modulated radiation therapy (IMRT) is frequently used to treat oral cavity cancers, but published IMRT outcomes specific to this disease site are sparse. We report the Dana-Farber Cancer Institute experience with IMRT-based treatment for OCSCC. Methods and Materials: Retrospective study of all patients treated at Dana-Farber Cancer Institute for OCSCC with adjuvant or definitive IMRT between August 2004 and December 2009. The American Joint Committee on Cancer disease stage criteria distribution of this cohort included 5 patients (12%) with stage I; 10 patients (24%) with stage II (n = 10, 24%),; 14 patients (33%) with stage III (n = 14, 33%),; and 13 patients (31%) with stage IV. The primary endpoint was overall survival (OS); secondary endpoints were locoregional control (LRC) and acute and chronic toxicity. Results: Forty-two patients with OCSCC were included, 30 of whom were initially treated with surgical resection. Twenty-three (77%) of 30 surgical patients treated with adjuvant IMRT also received concurrent chemotherapy, and 9 of 12 (75%) patients treated definitively without surgery were treated with CRT or induction chemotherapy and CRT. With a median follow-up of 2.1 years (interquartile range, 1.1-3.1 years) for all patients, the 2-year actuarial rates of OS and LRC following adjuvant IMRT were 85% and 91%, respectively, and the comparable results for definitive IMRT were 63% and 64% for OS and LRC, respectively. Only 1 patient developed symptomatic osteoradionecrosis, and among patients without evidence of disease, 35% experienced grade 2 to 3 late dysphagia, with only 1 patient who was continuously gastrostomy-dependent. Conclusions: In this single-institution series, postoperative IMRT was associated with promising LRC

  6. An FMEA Evaluation of Intensity Modulated Radiation Therapy Dose Delivery Failures at Tolerance Criteria Levels.

    PubMed

    Faught, Jacqueline Tonigan; Balter, Peter A; Johnson, Jennifer L; Kry, Stephen F; Court, Laurence E; Stingo, Francesco C; Followill, David S

    2017-09-01

    The objective of this work was to assess both the perception of failure modes in Intensity Modulated Radiation Therapy (IMRT) when the linac is operated at the edge of tolerance given in AAPM TG-40(1) and TG-142(2) as well as the application of FMEA to this specific section of the IMRT process. An online survey was distributed to approximately 2000 physicists worldwide that participate in quality services provided by the Imaging and Radiation Oncology Core - Houston (IROC-H). The survey briefly described eleven different failure modes covered by basic quality assurance in step-and-shoot IMRT at or near TG-40(1) and TG-142(2) tolerance criteria levels. Respondents were asked to estimate the worst case scenario percent dose error that could be caused by each of these failure modes in a head and neck patient as well as the FMEA scores: Occurrence, Detectability, and Severity. Risk probability number (RPN) scores were calculated as the product of these scores. Demographic data was also collected. 181 individual and three group responses were submitted. 84% were from North America. Most (76%) individual respondents performed at least 80% clinical work and 92% were nationally certified. Respondent medical physics experience ranged from 2.5-45 years (average 18 years). 52% of individual respondents were at least somewhat familiar with FMEA, while 17% were not familiar. Several IMRT techniques, treatment planning systems, and linear accelerator manufacturers were represented. All failure modes received widely varying scores ranging from 1-10 for occurrence, at least 1-9 for detectability, and at least 1-7 for severity. Ranking failure modes by RPN scores also resulted in large variability, with each failure mode being ranked both most risky (1st) and least risky (11th) by different respondents. On average MLC modeling had the highest RPN scores. Individual estimated percent dose errors and severity scores positively correlated (p<0.01) for each FM as expected. No universal

  7. Including robustness in multi-criteria optimization for intensity-modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Unkelbach, Jan; Trofimov, Alexei; Madden, Thomas; Kooy, Hanne; Bortfeld, Thomas; Craft, David

    2012-02-01

    We present a method to include robustness in a multi-criteria optimization (MCO) framework for intensity-modulated proton therapy (IMPT). The approach allows one to simultaneously explore the trade-off between different objectives as well as the trade-off between robustness and nominal plan quality. In MCO, a database of plans each emphasizing different treatment planning objectives, is pre-computed to approximate the Pareto surface. An IMPT treatment plan that strikes the best balance between the different objectives can be selected by navigating on the Pareto surface. In our approach, robustness is integrated into MCO by adding robustified objectives and constraints to the MCO problem. Uncertainties (or errors) of the robust problem are modeled by pre-calculated dose-influence matrices for a nominal scenario and a number of pre-defined error scenarios (shifted patient positions, proton beam undershoot and overshoot). Objectives and constraints can be defined for the nominal scenario, thus characterizing nominal plan quality. A robustified objective represents the worst objective function value that can be realized for any of the error scenarios and thus provides a measure of plan robustness. The optimization method is based on a linear projection solver and is capable of handling large problem sizes resulting from a fine dose grid resolution, many scenarios, and a large number of proton pencil beams. A base-of-skull case is used to demonstrate the robust optimization method. It is demonstrated that the robust optimization method reduces the sensitivity of the treatment plan to setup and range errors to a degree that is not achieved by a safety margin approach. A chordoma case is analyzed in more detail to demonstrate the involved trade-offs between target underdose and brainstem sparing as well as robustness and nominal plan quality. The latter illustrates the advantage of MCO in the context of robust planning. For all cases examined, the robust optimization for

  8. A feedback constraint optimization method for intensity-modulated radiation therapy of nasopharyngeal carcinoma

    PubMed Central

    LI, YONGWU; SUN, XIAONAN; WANG, QI; ZHOU, QINXUAN; GU, BENXING; SHI, GUOZHI; JIANG, DONGLIANG

    2015-01-01

    Intensity-modulated radiation therapy (IMRT) is able to achieve good target conformance with a limited dose to organs at risk (OARs); however, IMRT increases the irradiation volume and monitor units (MUs) required. The present study aimed to evaluate the use of an IMRT plan with fewer segments and MUs, while maintaining quality in the treatment of nasopharyngeal carcinoma. In the present study, two types of IMRT plan were therefore compared: The direct machine parameter optimization (DMPO)-RT method and the feedback constraint DMPO-RT (fc_DMPO-RT) method, which utilizes compensative feedback constraint in DMPO-RT and maintains optimization. Plans for 23 patients were developed with identical dose prescriptions. Each plan involved synchronous delivery to various targets, with identical OAR constraints, by means of 7 coplanar fields. The average dose, maximum dose, dose-volume histograms of targets and the OAR, MUs of the plan, the number of segments, delivery time and accuracy were subsequently compared. The fc_DMPO-RT exhibited superior dose distribution in terms of the average, maximum and minimum doses to the gross tumor volume compared with that of DMPO-RT (t=62.7, 20.5 and 22.0, respectively; P<0.05). The fc_DMPO-RT also resulted in a smaller maximum dose to the spinal cord (t=7.3; P<0.05), as well as fewer MUs, fewer segments and decreased treatment times than that of the DMPO-RT (t=6.2, 393.4 and 244.3, respectively; P<0.05). The fc_DMPO-RT maintained plan quality with fewer segments and MUs, and the treatment time was significantly reduced, thereby resulting in reduced radiation leakage and an enhanced curative effect. Therefore, introducing feedback constraint into DMPO may result in improved IMRT planning. In nasopharyngeal carcinoma specifically, feedback constraint resulted in the improved protection of OARs in proximity of targets (such as the brainstem and parotid) due to sharp dose distribution and reduced MUs. PMID:26622793

  9. Particle swarm optimizer for weighting factor selection in intensity-modulated radiation therapy optimization algorithms.

    PubMed

    Yang, Jie; Zhang, Pengcheng; Zhang, Liyuan; Shu, Huazhong; Li, Baosheng; Gui, Zhiguo

    2017-01-01

    In inverse treatment planning of intensity-modulated radiation therapy (IMRT), the objective function is typically the sum of the weighted sub-scores, where the weights indicate the importance of the sub-scores. To obtain a high-quality treatment plan, the planner manually adjusts the objective weights using a trial-and-error procedure until an acceptable plan is reached. In this work, a new particle swarm optimization (PSO) method which can adjust the weighting factors automatically was investigated to overcome the requirement of manual adjustment, thereby reducing the workload of the human planner and contributing to the development of a fully automated planning process. The proposed optimization method consists of three steps. (i) First, a swarm of weighting factors (i.e., particles) is initialized randomly in the search space, where each particle corresponds to a global objective function. (ii) Then, a plan optimization solver is employed to obtain the optimal solution for each particle, and the values of the evaluation functions used to determine the particle's location and the population global location for the PSO are calculated based on these results. (iii) Next, the weighting factors are updated based on the particle's location and the population global location. Step (ii) is performed alternately with step (iii) until the termination condition is reached. In this method, the evaluation function is a combination of several key points on the dose volume histograms. Furthermore, a perturbation strategy - the crossover and mutation operator hybrid approach - is employed to enhance the population diversity, and two arguments are applied to the evaluation function to improve the flexibility of the algorithm. In this study, the proposed method was used to develop IMRT treatment plans involving five unequally spaced 6MV photon beams for 10 prostate cancer cases. The proposed optimization algorithm yielded high-quality plans for all of the cases, without human

  10. Evaluation of a fast method of EPID-based dosimetry for intensity modulated radiation therapy

    PubMed Central

    Nelms, Benjamin E.; Rasmussen, Karl H.; Tomé, Wolfgang A.

    2010-01-01

    Electronic portal imaging devices (EPIDs) could potentially be useful for Intensity Modulated Radiation Therapy (IMRT) QA. The data density, high resolution, large active area, and efficiency of the MV EPID make it an attractive option. However, EPIDs were designed to be effective imaging devices, but not dosimeters, and as a result they do not measure dose in tissue-equivalent materials. EPIDose (Sun Nuclear, Melbourne, FL) is a tool designed for the use of EPIDs in IMRT QA that uses raw MV EPID images (no additional build-up and independent of gantry angle, but with dark and flood field corrections applied) to estimate absolute dose planes normal to the beam axis in a homogeneous media, i.e. similar to conventional IMRT QA methods. However, because of the inherent challenges of the EPID-based dosimetry, validating and commissioning such a system must be done very carefully, exploring the range of use cases and using well-proven “standards” for comparison. In this work, a multi-institutional study was performed to verify accurate EPID image to dose plane conversion over a variety of conditions. Converted EPID images were compared to 2D diode array absolute dose measurements for one hundred and eighty eight (188) fields from twenty eight (28) clinical IMRT treatment plans generated using a number of commercially available treatment planning systems (TPS) covering various treatment sites including prostate, head and neck, brain, and lung. The data included three beam energies (6, 10, and 15 MV) and both step-and-shoot and dynamic MLC fields. Out of 26,207 points of comparison over 188 fields analyzed the average overall field pass rate was 99.7% when 3mm/3% DTA criteria were used (range 94.0-100 per field). The pass rates for more stringent criteria were 97.8% for 2mm/2% DTA (range 82.0-100 per field), and 84.6% for 1mm/1% DTA (range 54.7-100 per field). Individual patient specific sites as well as different beam energies followed similar trends to the overall

  11. Larynx-sparing techniques using intensity-modulated radiation therapy for oropharyngeal cancer.

    PubMed

    Bar Ad, Voichita; Lin, Haibo; Hwang, Wei-Ting; Deville, Curtiland; Dutta, Pinaki R; Tochner, Zelig; Both, Stefan

    2012-01-01

    The purpose of the current study was to explore whether the laryngeal dose can be reduced by using 2 intensity-modulated radiation therapy (IMRT) techniques: whole-neck field IMRT technique (WF-IMRT) vs. junctioned IMRT (J-IMRT). The effect on planning target volumes (PTVs) coverage and laryngeal sparing was evaluated. WF-IMRT technique consisted of a single IMRT plan, including the primary tumor and the superior and inferior neck to the level of the clavicular heads. The larynx was defined as an organ at risk extending superiorly to cover the arytenoid cartilages and inferiorly to include the cricoid cartilage. The J-IMRT technique consisted of an IMRT plan for the primary tumor and the superior neck, matched to conventional antero-posterior opposing lower neck fields at the level of the thyroid notch. A central block was used for the anterior lower neck field at the level of the larynx to restrict the dose to the larynx. Ten oropharyngeal cancer cases were analyzed. Both the primary site and bilateral regional lymphatics were included in the radiotherapy targets. The averaged V95 for the PTV57.6 was 99.2% for the WF-IMRT technique compared with 97.4% (p = 0.02) for J-IMRT. The averaged V95 for the PTV64 was 99.9% for the WF-IMRT technique compared with 98.9% (p = 0.02) for J-IMRT and the averaged V95 for the PT70 was 100.0% for WF-IMRT technique compared with 99.5% (p = 0.04) for J-IMRT. The averaged mean laryngeal dose was 18 Gy with both techniques. The averaged mean doses within the matchline volumes were 69.3 Gy for WF-MRT and 66.2 Gy for J-IMRT (p = 0.03). The WF-IMRT technique appears to offer an optimal coverage of the target volumes and a mean dose to the larynx similar with J-IMRT and should be further evaluated in clinical trials. Copyright © 2012. Published by Elsevier Inc.

  12. A GPU-accelerated and Monte Carlo-based intensity modulated proton therapy optimization system

    SciTech Connect

    Ma, Jiasen Beltran, Chris; Seum Wan Chan Tseung, Hok; Herman, Michael G.

    2014-12-15

    Purpose: Conventional spot scanning intensity modulated proton therapy (IMPT) treatment planning systems (TPSs) optimize proton spot weights based on analytical dose calculations. These analytical dose calculations have been shown to have severe limitations in heterogeneous materials. Monte Carlo (MC) methods do not have these limitations; however, MC-based systems have been of limited clinical use due to the large number of beam spots in IMPT and the extremely long calculation time of traditional MC techniques. In this work, the authors present a clinically applicable IMPT TPS that utilizes a very fast MC calculation. Methods: An in-house graphics processing unit (GPU)-based MC dose calculation engine was employed to generate the dose influence map for each proton spot. With the MC generated influence map, a modified least-squares optimization method was used to achieve the desired dose volume histograms (DVHs). The intrinsic CT image resolution was adopted for voxelization in simulation and optimization to preserve spatial resolution. The optimizations were computed on a multi-GPU framework to mitigate the memory limitation issues for the large dose influence maps that resulted from maintaining the intrinsic CT resolution. The effects of tail cutoff and starting condition were studied and minimized in this work. Results: For relatively large and complex three-field head and neck cases, i.e., >100 000 spots with a target volume of ∼1000 cm{sup 3} and multiple surrounding critical structures, the optimization together with the initial MC dose influence map calculation was done in a clinically viable time frame (less than 30 min) on a GPU cluster consisting of 24 Nvidia GeForce GTX Titan cards. The in-house MC TPS plans were comparable to a commercial TPS plans based on DVH comparisons. Conclusions: A MC-based treatment planning system was developed. The treatment planning can be performed in a clinically viable time frame on a hardware system costing around 45

  13. Postoperative Intensity Modulated Radiation Therapy in High Risk Prostate Cancer: A Dosimetric Comparison

    SciTech Connect

    Digesu, Cinzia; Cilla, Savino; De Gaetano, Andrea; Massaccesi, Mariangela; Macchia, Gabriella; Ippolito, Edy; Deodato, Francesco; Panunzi, Simona; Iapalucci, Chiara; Mattiucci, Gian Carlo; D'Angelo, Elisa; Padula, Gilbert D.A.; Valentini, Vincenzo; Cellini, Numa

    2011-10-01

    The aim of this study was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal technique (3D-CRT), with respect to target coverage and irradiation of organs at risk for high dose postoperative radiotherapy (PORT) of the prostate fossa. 3D-CRT and IMRT treatment plans were compared with respect to dose to the rectum and bladder. The dosimetric comparison was carried out in 15 patients considering 2 different scenarios: (1) exclusive prostate fossa irradiation, and (2) pelvic node irradiation followed by a boost on the prostate fossa. In scenario (1), a 3D-CRT plan (box technique) and an IMRT plan were calculated and compared for each patient. In scenario (2), 3 treatment plans were calculated and compared for each patient: (a) 3D-CRT box technique for both pelvic (prophylactic nodal irradiation) and prostate fossa irradiation (3D-CRT only); (b) 3D-CRT box technique for pelvic irradiation followed by an IMRT boost to the prostatic fossa (hybrid 3D-CRT and IMRT); and (c) IMRT for both pelvic and prostate fossa irradiation (IMRT only). For exclusive prostate fossa irradiation, IMRT significantly reduced the dose to the rectum (lower Dmean, V50%, V75%, V90%, V100%, EUD, and NTCP) and the bladder (lower Dmean, V50%, V90%, EUD and NTCP). When prophylactic irradiation of the pelvis was also considered, plan C (IMRT only) performed better than plan B (hybrid 3D-CRT and IMRT) as respect to both rectum and bladder irradiation (reduction of Dmean, V50%, V75%, V90%, equivalent uniform dose [EUD], and normal tissue complication probability [NTCP]). Plan (b) (hybrid 3D-CRT and IMRT) performed better than plan (a) (3D-CRT only) with respect to dose to the rectum (lower Dmean, V75%, V90%, V100%, EUD, and NTCP) and the bladder (Dmean, EUD, and NTCP). Postoperative IMRT in prostate cancer significantly reduces rectum and bladder irradiation compared with 3D-CRT.

  14. Factors influencing the incidence of sinusitis in nasopharyngeal carcinoma patients after intensity-modulated radiation therapy.

    PubMed

    Su, Yan-xia; Liu, Lan-ping; Li, Lei; Li, Xu; Cao, Xiu-juan; Dong, Wei; Yang, Xin-hua; Xu, Jin; Yu, Shui; Hao, Jun-fang

    2014-12-01

    The aim of the study was to investigate the incidence of sinusitis in nasopharyngeal carcinoma (NPC) patients before and after intensity-modulated radiation therapy (IMRT) and to analyze factors associated with the incidence of sinusitis following IMRT. We retrospectively analyzed 283 NPC patients who received IMRT in our hospital from March 2009 to May 2011. The diagnostic criteria for sinusitis are based on computed tomography (CT) or magnetic resonance imaging (MRI) findings. CT or MRI scans were performed before and after IMRT to evaluate the incidence of sinusitis. Factors influencing the incidence of sinusitis were analyzed by log-rank univariate and logistic multivariate analyses. Among the 283 NPC patients, 128 (45.2 %) suffered from sinusitis before radiotherapy. The incidence rates of sinusitis in patients with T1, T2, T3, and T4 NPC before radiotherapy were 22.6, 37.5, 46.8, and 61.3 %, respectively (χ 2 = 14.548, p = 0.002). Among the 155 NPC patients without sinusitis before radiotherapy, the incidence rates of sinusitis at the end of radiotherapy and at 1, 3, 6, 9, 12, and 18 months after radiotherapy were 32.9, 43.2, 61.3, 68.4, 73.5, 69.7, and 61.3 %, respectively (χ 2 = 86.461, p < 0.001). Univariate analysis showed that T stage, invasion of the nasal cavity, nasal irrigation, and radiation dose to the nasopharynx were associated with the incidence of sinusitis in NPC patients after IMRT (p = 0.003, 0.006, 0.002, and 0.020). Multivariate analysis showed that T stage, invasion of the nasal cavity, and nasal irrigation were influential factors for the incidence of sinusitis in NPC patients after IMRT (p = 0.002, 0.002, and 0.000). There was a higher incidence of sinusitis with higher T stage among NPC patients before radiotherapy, and the incidence of sinusitis in NPC patients after IMRT was high (45.2 %). The incidence of sinusitis increased rapidly within the first 3 months after IMRT, and the number of sinusitis cases peaked at 6-9 months after

  15. EBT GAFCHROMIC{sup TM} film dosimetry in compensator-based intensity modulated radiation therapy

    SciTech Connect

    Vaezzadeh, Seyedali; Allahverdi, Mahmoud; Nedaie, Hasan A.; Ay, Mohammadreza; Shirazi, Alireza; Yarahmadi, Mehran

    2013-07-01

    The electron benefit transfer (EBT) GAFCHROMIC films possess a number of features making them appropriate for high-quality dosimetry in intensity-modulated radiation therapy (IMRT). Compensators to deliver IMRT are known to change the beam-energy spectrum as well as to produce scattered photons and to contaminate electrons; therefore, the accuracy and validity of EBT-film dosimetry in compensator-based IMRT should be investigated. Percentage-depth doses and lateral-beam profiles were measured using EBT films in perpendicular orientation with respect to 6 and 18 MV photon beam energies for: (1) different thicknesses of cerrobend slab (open, 1.0, 2.0, 4.0, and 6.0 cm), field sizes (5×5, 10×10, and 20×20 cm{sup 2}), and measurement depths (D{sub max}, 5.0 and 10.0 cm); and (2) step-wedged compensator in a solid phantom. To verify results, same measurements were implemented using a 0.125 cm{sup 3} ionization chamber in a water phantom and also in Monte Carlo simulations using the Monte Carlo N-particle radiation transport computer code. The mean energy of photons was increased due to beam hardening in comparison with open fields at both 6 and 18 MV energies. For a 20×20 cm{sup 2} field size of a 6 MV photon beam and a 6.0 cm thick block, the surface dose decreased by about 12% and percentage-depth doses increased up to 3% at 30.0 cm depth, due to the beam-hardening effect induced by the block. In contrast, at 18 MV, the surface dose increased by about 8% and depth dose reduced by 3% at 30.0 cm depth. The penumbral widths (80% to 20%) increase with block thickness, field size, and beam energy. The EBT film results were in good agreement with the ionization chamber dose profiles and Monte Carlo N-particle radiation transport computer code simulation behind the step-wedged compensator. Also, there was a good agreement between the EBT-film and the treatment-planning results on the anthropomorphic phantom. The EBT films can be accurately used as a 2D dosimeter for dose

  16. Failure Patterns After Hemithoracic Pleural Intensity Modulated Radiation Therapy for Malignant Pleural Mesothelioma

    SciTech Connect

    Rimner, Andreas; Spratt, Daniel E.; Zauderer, Marjorie G.; Rosenzweig, Kenneth E.; Wu, Abraham J.; Foster, Amanda; Yorke, Ellen D.; Adusumilli, Prasad; Rusch, Valerie W.; Krug, Lee M.

    2014-10-01

    Purpose: We previously reported our technique for delivering intensity modulated radiation therapy (IMRT) to the entire pleura while attempting to spare the lung in patients with malignant pleural mesothelioma (MPM). Herein, we report a detailed pattern-of-failure analysis in patients with MPM who were unresectable or underwent pleurectomy/decortication (P/D), uniformly treated with hemithoracic pleural IMRT. Methods and Materials: Sixty-seven patients with MPM were treated with definitive or adjuvant hemithoracic pleural IMRT between November 2004 and May 2013. Pretreatment imaging, treatment plans, and posttreatment imaging were retrospectively reviewed to determine failure location(s). Failures were categorized as in-field (within the 90% isodose line), marginal (<90% and ≥50% isodose lines), out-of-field (outside the 50% isodose line), or distant. Results: The median follow-up was 24 months from diagnosis and the median time to in-field local failure from the end of RT was 10 months. Forty-three in-field local failures (64%) were found with a 1- and 2-year actuarial failure rate of 56% and 74%, respectively. For patients who underwent P/D versus those who received a partial pleurectomy or were deemed unresectable, the median time to in-field local failure was 14 months versus 6 months, respectively, with 1- and 2-year actuarial in-field local failure rates of 43% and 60% versus 66% and 83%, respectively (P=.03). There were 13 marginal failures (19%). Five of the marginal failures (38%) were located within the costomediastinal recess. Marginal failures decreased with increasing institutional experience (P=.04). Twenty-five patients (37%) had out-of-field failures. Distant failures occurred in 32 patients (48%). Conclusions: After hemithoracic pleural IMRT, local failure remains the dominant form of failure pattern. Patients treated with adjuvant hemithoracic pleural IMRT after P/D experience a significantly longer time to local and distant failure than

  17. Efficiency of analytical and sampling-based uncertainty propagation in intensity-modulated proton therapy.

    PubMed

    Wahl, N; Hennig, P; Wieser, H P; Bangert, M

    2017-06-26

    The sensitivity of intensity-modulated proton therapy (IMPT) treatment plans to uncertainties can be quantified and mitigated with robust/min-max and stochastic/probabilistic treatment analysis and optimization techniques. Those methods usually rely on sparse random, importance, or worst-case sampling. Inevitably, this imposes a trade-off between computational speed and accuracy of the uncertainty propagation. Here, we investigate analytical probabilistic modeling (APM) as an alternative for uncertainty propagation and minimization in IMPT that does not rely on scenario sampling. APM propagates probability distributions over range and setup uncertainties via a Gaussian pencil-beam approximation into moments of the probability distributions over the resulting dose in closed form. It supports arbitrary correlation models and allows for efficient incorporation of fractionation effects regarding random and systematic errors. We evaluate the trade-off between run-time and accuracy of APM uncertainty computations on three patient datasets. Results are compared against reference computations facilitating importance and random sampling. Two approximation techniques to accelerate uncertainty propagation and minimization based on probabilistic treatment plan optimization are presented. Runtimes are measured on CPU and GPU platforms, dosimetric accuracy is quantified in comparison to a sampling-based benchmark (5000 random samples). APM accurately propagates range and setup uncertainties into dose uncertainties at competitive run-times (GPU [Formula: see text] min). The resulting standard deviation (expectation value) of dose show average global [Formula: see text] pass rates between 94.2% and 99.9% (98.4% and 100.0%). All investigated importance sampling strategies provided less accuracy at higher run-times considering only a single fraction. Considering fractionation, APM uncertainty propagation and treatment plan optimization was proven to be possible at constant time

  18. Investigation of geometric uncertainty introduced dosimetric variation in intensity modulated proton therapy (IMPT) and its intervention

    NASA Astrophysics Data System (ADS)

    Zhang, Miao

    The intensity modulated proton therapy (IMPT) can generate plans with reduced normal tissue toxicity and increased target dose conformity. However, geometric uncertainty associated with the treatment process could introduce large dose variations between the delivered dose distribution and the planned. There are three common types of geometric uncertainty: setup uncertainty, inter-, and intra-fractional organ motion. This thesis work will investigate setup uncertainty and inter-fractional organ motion introduced dose variation and find solutions to minimize such variations. A proton treatment planning system was developed by using Geant4 Monte Carlo toolbox as the dose calculation engine. The setup uncertainty was studied on the head and neck cancer site. Plan delivery simulation shown large dose variation occurred even with small amount of setup uncertainty. Two intervention strategies were investigated: (i) different proton pencil beam sizes, and (ii) the energy margin. By varying proton pencil beam size, we found the larger the beam size the less the dose variation, nevertheless the higher normal tissue dose. The energy margin is a planning strategy incorporating the possible motion effect into the planning stage by assigning proton pencil beams an energy value large enough to guarantee protons will travel to where they are planned. The energy margin solution was tested to be effective to minimize the dose variation in the distal edge tracking (DET) based IMPT. The inter-fractional motion was studied by looking at the daily prostate shift in the prostate cancer treatment. Delivery simulation for prostate cancer IMPT shown large dose variation would result even if the image guidance (IG) technique was used to realign the prostate back to its original location on the planning CT. A novel on-line adaptive image guided IMPT (A-IG-IMPT) technique was proposed to minimize the dose variation. By updating the energy value for individual proton pencil beam from the on

  19. Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system

    NASA Astrophysics Data System (ADS)

    Petric, Martin Peter

    This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing field-by-field verification of IMRT plans. This work was motivated by an initial study comparing two IMRT treatment planning systems. The clinical functionality of BrainLAB's BrainSCAN and Varian's Helios IMRT treatment planning systems were compared in terms of implementation and commissioning, dose optimization, and plan assessment. Implementation and commissioning revealed differences in the beam data required to characterize the beam prior to use with the BrainSCAN system requiring higher resolution data compared to Helios. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. The dose optimization and plan assessment comparisons revealed that while both systems use considerably different optimization algorithms and user-control interfaces, they are both capable of producing substantially equivalent dose plans. The extensive use of dosimetric verification techniques in the IMRT treatment planning comparison study motivated the development and implementation of a novel IMRT dosimetric verification system. The system consists of a water-filled phantom with a tissue equivalent plastic scintillator sheet built into the top surface. Scintillation light is reflected by a plastic mirror within the phantom towards a viewing window where it is captured using a CCD camera. Optical photon spread is removed using a micro-louvre optical collimator and by deconvolving a glare kernel from the raw images. Characterization of this

  20. Efficiency of analytical and sampling-based uncertainty propagation in intensity-modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Wahl, N.; Hennig, P.; Wieser, H. P.; Bangert, M.

    2017-07-01

    The sensitivity of intensity-modulated proton therapy (IMPT) treatment plans to uncertainties can be quantified and mitigated with robust/min-max and stochastic/probabilistic treatment analysis and optimization techniques. Those methods usually rely on sparse random, importance, or worst-case sampling. Inevitably, this imposes a trade-off between computational speed and accuracy of the uncertainty propagation. Here, we investigate analytical probabilistic modeling (APM) as an alternative for uncertainty propagation and minimization in IMPT that does not rely on scenario sampling. APM propagates probability distributions over range and setup uncertainties via a Gaussian pencil-beam approximation into moments of the probability distributions over the resulting dose in closed form. It supports arbitrary correlation models and allows for efficient incorporation of fractionation effects regarding random and systematic errors. We evaluate the trade-off between run-time and accuracy of APM uncertainty computations on three patient datasets. Results are compared against reference computations facilitating importance and random sampling. Two approximation techniques to accelerate uncertainty propagation and minimization based on probabilistic treatment plan optimization are presented. Runtimes are measured on CPU and GPU platforms, dosimetric accuracy is quantified in comparison to a sampling-based benchmark (5000 random samples). APM accurately propagates range and setup uncertainties into dose uncertainties at competitive run-times (GPU ≤slant {5} min). The resulting standard deviation (expectation value) of dose show average global γ{3% / {3}~mm} pass rates between 94.2% and 99.9% (98.4% and 100.0%). All investigated importance sampling strategies provided less accuracy at higher run-times considering only a single fraction. Considering fractionation, APM uncertainty propagation and treatment plan optimization was proven to be possible at constant time complexity

  1. Origin of Tumor Recurrence After Intensity Modulated Radiation Therapy for Oropharyngeal Squamous Cell Carcinoma

    SciTech Connect

    Raktoe, Sawan A.S.; Dehnad, Homan; Raaijmakers, Cornelis P.J.; Braunius, Weibel; Terhaard, Chris H.J.

    2013-01-01

    Purpose: To model locoregional recurrences of oropharyngeal squamous cell carcinomas (OSCC) treated with primary intensity modulated radiation therapy (IMRT) in order to find the origins from which recurrences grow and relate their location to original target volume borders. Methods and Materials: This was a retrospective analysis of OSCC treated with primary IMRT between January 2002 and December 2009. Locoregional recurrence volumes were delineated on diagnostic scans and coregistered rigidly with treatment planning computed tomography scans. Each recurrence was analyzed with two methods. First, overlapping volumes of a recurrence and original target were measured ('volumetric approach') and assessed as 'in-field', 'marginal', or 'out-field'. Then, the center of mass (COM) of a recurrence volume was assumed as the origin from where a recurrence expanded, the COM location was compared with original target volume borders and assessed as 'in-field', 'marginal', or 'out-field'. Results: One hundred thirty-one OSCC were assessed. For all patients alive at the end of follow-up, the mean follow-up time was 40 months (range, 12-83 months); 2 patients were lost to follow-up. The locoregional recurrence rate was 27%. Of all recurrences, 51% were local, 23% were regional, and 26% had both local and regional recurrences. Of all recurrences, 74% had imaging available for assessment. Regarding volumetric analysis of local recurrences, 15% were in-field gross tumor volume (GTV), and 65% were in-field clinical tumor volume (CTV). Using the COM approach, we found that 70% of local recurrences were in-field GTV and 90% were in-field CTV. Of the regional recurrences, 25% were volumetrically in-field GTV, and using the COM approach, we found 54% were in-field GTV. The COM of local out-field CTV recurrences were maximally 16 mm outside CTV borders, whereas for regional recurrences, this was 17 mm. Conclusions: The COM model is practical and specific for recurrence assessment. Most

  2. Effectiveness of robust optimization in intensity-modulated proton therapy planning for head and neck cancers

    SciTech Connect

    Liu Wei; Li Xiaoqiang; Park, Peter C.; Ronald Zhu, X.; Mohan, Radhe; Frank, Steven J.; Li Yupeng; Dong Lei

    2013-05-15

    Purpose: Intensity-modulated proton therapy (IMPT) is highly sensitive to uncertainties in beam range and patient setup. Conventionally, these uncertainties are dealt using geometrically expanded planning target volume (PTV). In this paper, the authors evaluated a robust optimization method that deals with the uncertainties directly during the spot weight optimization to ensure clinical target volume (CTV) coverage without using PTV. The authors compared the two methods for a population of head and neck (H and N) cancer patients. Methods: Two sets of IMPT plans were generated for 14 H and N cases, one being PTV-based conventionally optimized and the other CTV-based robustly optimized. For the PTV-based conventionally optimized plans, the uncertainties are accounted for by expanding CTV to PTV via margins and delivering the prescribed dose to PTV. For the CTV-based robustly optimized plans, spot weight optimization was guided to reduce the discrepancy in doses under extreme setup and range uncertainties directly, while delivering the prescribed dose to CTV rather than PTV. For each of these plans, the authors calculated dose distributions under various uncertainty settings. The root-mean-square dose (RMSD) for each voxel was computed and the area under the RMSD-volume histogram curves (AUC) was used to relatively compare plan robustness. Data derived from the dose volume histogram in the worst-case and nominal doses were used to evaluate the plan optimality. Then the plan evaluation metrics were averaged over the 14 cases and were compared with two-sided paired t tests. Results: CTV-based robust optimization led to more robust (i.e., smaller AUCs) plans for both targets and organs. Under the worst-case scenario and the nominal scenario, CTV-based robustly optimized plans showed better target coverage (i.e., greater D{sub 95%}), improved dose homogeneity (i.e., smaller D{sub 5%}- D{sub 95%}), and lower or equivalent dose to organs at risk. Conclusions: CTV

  3. Larynx-sparing techniques using intensity-modulated radiation therapy for oropharyngeal cancer

    SciTech Connect

    Bar Ad, Voichita; Lin, Haibo; Hwang, Wei-Ting; Deville, Curtiland; Dutta, Pinaki R.; Tochner, Zelig; Both, Stefan

    2012-01-01

    The purpose of the current study was to explore whether the laryngeal dose can be reduced by using 2 intensity-modulated radiation therapy (IMRT) techniques: whole-neck field IMRT technique (WF-IMRT) vs. junctioned IMRT (J-IMRT). The effect on planning target volumes (PTVs) coverage and laryngeal sparing was evaluated. WF-IMRT technique consisted of a single IMRT plan, including the primary tumor and the superior and inferior neck to the level of the clavicular heads. The larynx was defined as an organ at risk extending superiorly to cover the arytenoid cartilages and inferiorly to include the cricoid cartilage. The J-IMRT technique consisted of an IMRT plan for the primary tumor and the superior neck, matched to conventional antero-posterior opposing lower neck fields at the level of the thyroid notch. A central block was used for the anterior lower neck field at the level of the larynx to restrict the dose to the larynx. Ten oropharyngeal cancer cases were analyzed. Both the primary site and bilateral regional lymphatics were included in the radiotherapy targets. The averaged V95 for the PTV57.6 was 99.2% for the WF-IMRT technique compared with 97.4% (p = 0.02) for J-IMRT. The averaged V95 for the PTV64 was 99.9% for the WF-IMRT technique compared with 98.9% (p = 0.02) for J-IMRT and the averaged V95 for the PT70 was 100.0% for WF-IMRT technique compared with 99.5% (p = 0.04) for J-IMRT. The averaged mean laryngeal dose was 18 Gy with both techniques. The averaged mean doses within the matchline volumes were 69.3 Gy for WF-MRT and 66.2 Gy for J-IMRT (p = 0.03). The WF-IMRT technique appears to offer an optimal coverage of the target volumes and a mean dose to the larynx similar with J-IMRT and should be further evaluated in clinical trials.

  4. SU-F-BRD-06: Robust Dose Calculation in Intensity Modulated Proton Therapy

    SciTech Connect

    Brosch, R; Liu, W

    2015-06-15

    Purpose: Commissioning data for intensity modulated proton therapy (IMPT) must be post-processed by fits to ad-hoc functions to derive the dose calculation kernel parameters in a treatment planning system (TPS). Whether from experimental measurement or Monte Carlo simulation, the limited and noisy nature of such data makes this task very challenging. We present a method to improve the modeling of the lateral dose distribution of clinical energy proton beams in water to commission an in-house IMPT dose calculation engine. Methods: A linear sum of three Gaussian distribution functions was fitted to the lateral dose data in logarithmic scale. Starting values of fitting solutions were determined from the Generalized Highland Approximation. We exhaustively optimized the combinations of data weights with upper bounds of the fitting solutions to minimize confidence intervals of the fitting solutions while maintaining the coefficient of determination (R{sup 2}). Results: Across all energies, average confidence bounds improved 72.88% [Max: 88.28%, Min: 55.05%] for small angle coulomb scattering, 114.25% [409.13%, 66.72%,] for nuclear scattering, and 68.66% [141.09%, 33.27%] for large angle coulomb scattering, while the coefficients of determination of the fits (R{sup 2}) remained comparable. On average R {sup 2} only changed 0.18% and were very close to 1 (approx. 0.999). Wilcoxon signed rank tests comparing unweighted/unbounded fits with weighted/bounded fits averaged 0.0146 (Max: 0.177, Min: 7.05×10−{sup 7}) for small angle Coulomb, 0.0903 (0.945, 7.05×10−{sup 7}) for nuclear, and 0.254 (0.871, 1.86×10−{sup 6}) for large angle Coulomb scattering. This allows rejection of the null hypothesis for small angle Coulomb scattering at the 0.015 level and nuclear interaction at the 0.1 level. Conclusion: Optimal weights assigned to IMPT lateral dose data minimized fitting to stochastic noise in the tail region. Optimizing the upper bounds of fitting parameters improved

  5. Examination of geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation therapy.

    PubMed

    Wiersma, R D; Xing, L

    2007-10-01

    Due to the complicated technical nature of gated radiation therapy, electronic and mechanical limitations may affect the precision of delivery. The purpose of this study is to investigate the geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation treatments (SS-IMRT). Unique segmental MLC plans are designed, which allow quantitative testing of the gating process. Both ungated and gated deliveries are investigated for different dose sizes, dose rates, and gating window times using a commercial treatment system (Varian Trilogy) together with a respiratory gating system [Varian Real-Time Position Management system]. Radiographic film measurements are used to study the geometric accuracy, where it is found that with both ungated and gated SS-IMRT deliveries the MLC leaf divergence away from planned is less than or equal to the MLC specified leaf tolerance value for all leafs (leaf tolerance being settable from 0.5-5 mm). Nevertheless, due to the MLC controller design, failure to define a specific leaf tolerance value suitable to the SS-IMRT plan can lead to undesired geometric effects, such as leaf motion of up to the maximum 5 mm leaf tolerance value occurring after the beam is turned on. In this case, gating may be advantageous over the ungated case, as it allows more time for the MLC to reach the intended leaf configuration. The dosimetric precision of gated SS-IMRT is investigated using ionization chamber methods. Compared with the ungated case, it is found that gating generally leads to increased dosimetric errors due to the interruption of the "overshoot phenomena." With gating the average timing deviation for intermediate segments is found to be 27 ms, compared to 18 ms for the ungated case. For a plan delivered at 600 MU/min this would correspond to an average segment dose error of approximately 0.27 MU and approximately 0.18 MU for gated and ungated deliveries, respectively. The maximum dosimetric errors for individual

  6. Optimal beam design on intensity-modulated radiation therapy with simultaneous integrated boost in nasopharyngeal cancer.

    PubMed

    Cheng, Mei-Chun; Hu, Yu-Wen; Liu, Ching-Sheng; Lee, Jeun-Shenn; Huang, Pin-I; Yen, Sang-Hue; Lee, Yuh-Lin; Hsieh, Chun-Mei; Shiau, Cheng-Ying

    2014-01-01

    This study aims to determine the optimal beam design among various combinations of field numbers and beam trajectories for intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) technique for the treatment of nasopharyngeal cancer (NPC). We used 10 fields with gantry angles of 155°, 130°, 75°, 25°, 0° L, 0° R, 335°, 285°, 230°, and 205° denoted as F10. To decrease doses in the spinal cord, the F10 technique was designed by featuring 2 pairs of split-opposed beam fields at 155° to 335° and 205° to 25°, as well as one pair of manually split beam fields at 0°. The F10 technique was compared with 4 other common field arrangements: F7E, 7 fields with 50° equally spaced gantry angles; F7, the basis of F10 with 155°, 130°, 75°, 0°, 285°, 230°, and 205°; F9E, 9 fields with 40° equally spaced gantry angles; and FP, 7 posterior fields with 180°, 150°, 120°, 90°, 270°, 240°, and 210°. For each individual case of 10 patients, the customized constraints derived after optimization with the standard F10 technique were applied to 4 other field arrangements. The 4 new optimized plans of each individual case were normalized to achieve the same coverage of planning target volume (PTV)63Gy as that of the standard F10 technique. The F10 field arrangement exhibited the best coverage in PTV70Gy and the least mean dose in the trachea-esophagus region. Furthermore, the F10 field arrangement demonstrated the highest level of conformity in the low-dose region and the least monitor unit. The F10 field arrangement performed more outstandingly than the other field arrangements in PTV70Gy coverage and spared the central organ. This arrangement also exhibited the highest conformity and delivery efficiency. The F10 technique is recommended as the standard beam geometry for the SIB-IMRT of NPC. Copyright © 2014 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  7. An immobilization system for claustrophobic patients in head-and-neck intensity-modulated radiation therapy.

    PubMed

    Kim, Siyong; Akpati, Hilary C; Li, Jonathan G; Liu, Chihray R; Amdur, Robert J; Palta, Jatinder R

    2004-08-01

    To evaluate the effectiveness of an immobilization treatment system used for claustrophobic patients in head-and-neck intensity-modulated radiation therapy (IMRT). Instead of the thermoplastic facemask, the Vac Fix (S & S Par Scientific, Odense, Denmark) mold is used for immobilization of claustrophobic patients at the University of Florida in head-and-neck IMRT. The immobilization procedure combines the use of commercial stereotactic infrared (IR) ExacTrac camera system (BrainLAB, Inc., Westchester, IL) for patient setup and monitoring. The Vac Fix mold is placed on the headrest and folded up as needed to provide support before the mold is hardened. For the camera system, a frame referred to as a "tattoo-free immobilization accessory" is fabricated, on which the IR markers can be placed. A patient-specific dental impression is made with the bite tray. The movement of the markers, connected through the dental impression of the patient, accurately represents the overall patient motion. Patient movement is continuously monitored and repositioning is performed whenever patient movement exceeds the predefined tolerance limit. Monitored patient movements are recorded at a certain frequency. Recorded data are analyzed and compared with those of patients immobilized with the thermoplastic facemask plus the camera system that is the standard immobilization system in our clinic. For three patients treated with the Vac Fix mold plus the camera system, on average, the histogram-based uncertainties, U(95)(5), U(95)(20), and mean displacement, R(mean) (mm) were 1.03, 1.08, and 0.60, respectively. These values are close to those obtained with the mask plus the camera system. The Vac Fix mold plus the camera system often requires more beam interruptions because of repositioning than the mask plus the camera system (on average, the Vac Fix mold plus the camera system required repositioning 7.7 times and the mask plus the camera system required repositioning 1.8 times during 20

  8. Motion mitigation in intensity modulated particle therapy by internal target volumes covering range changes.

    PubMed

    Graeff, Christian; Durante, Marco; Bert, Christoph

    2012-10-01

    Particle therapy offers benefits over conventional photon therapy but also introduces sensitivity to changes in the water-equivalent path length (WEPL) in case of target motion, e.g., breathing. Target motion can be addressed by the internal target volume (ITV) approach, defined as the CTV plus target movement. In photon therapy, the ITV can be constructed as the geometric union of CTVs in all motion states (GEO-ITV) of a 4D-CT, but this does not account for WEPL-changes. An ITV including WEPL-changes can be defined as the union of all CTVs transformed to a WEPL-equivalent axis along beam's eye view. The resulting WEPL-ITV is field-specific and thus unsuitable for intensity modulated particle therapy (IMPT). The purpose of this study was an IMPT-compatible ITV by splitting geometrical motion and field-specific WEPL changes, following ICRU 78 recommendations. For all fields, the GEO-ITV was used as a common target. This identical geometry for all fields was mapped to an enlarged WEPL extent with a field-specific transformation. As the dose distribution is determined by the WEPL, this is sufficient to achieve equivalent dose coverage as for a geometrically enlarged target volume. The WEPL enlargement is only visible to the specific field and therefore does not increase the target volume of other fields. This avoids unnecessary lateral field extensions, reducing the dose to normal tissue. Homogeneous dose coverage in IMPT is achieved only if the inhomogeneous doses from the individual fields match up during delivery. As the course of the WEPL within each motion phase differs, this cannot be guaranteed by optimizing the fields only in the reference phase. The WEPL-ITV for the reference phase can be amended by CTVs from a subset of motion phases (4D-WEPL-ITV). Here, end-exhale as the reference phase was combined with end-inhale to cover the whole motion range. The GEO-ITV, WEPL-ITV, and 4D-WEPL-ITV were applied in an IMPT simulation of a lung cancer patient case using a

  9. In vitro study of cell survival following dynamic MLC intensity-modulated radiation therapy dose delivery

    SciTech Connect

    Moiseenko, Vitali; Duzenli, Cheryl; Durand, Ralph E.

    2007-04-15

    The possibility of reduced cell kill following intensity-modulated radiation therapy (IMRT) compared to conventional radiation therapy has been debated in the literature. This potential reduction in cell kill relates to prolonged treatment times typical of IMRT dose delivery and consequently increased repair of sublethal lesions. While there is some theoretical support to this reduction in cell kill published in the literature, direct experimental evidence specific to IMRT dose delivery patterns is lacking. In this study we present cell survival data for three cell lines: Chinese hamster V79 fibroblasts, human cervical carcinoma, SiHa and colon adenocarcinoma, WiDr. Cell survival was obtained for 2.1 Gy delivered as acute dose with parallel-opposed pair (POP), irradiation time 75 s, which served as a reference; regular seven-field IMRT, irradiation time 5 min; and IMRT with a break for multiple leaf collimator (MLC) re-initialization after three fields were delivered, irradiation time 10 min. An actual seven-field dynamic MLC IMRT plan for a head and neck patient was used. The IMRT plan was generated for a Varian EX or iX linear accelerator with 120 leaf Millenium MLC. Survival data were also collected for doses 1x, 2x, 3x, 4x, and 5x 2.1 Gy to establish parameters of the linear-quadratic equation describing survival following acute dose delivery. Cells were irradiated inside an acrylic cylindrical phantom specifically designed for this study. Doses from both IMRT and POP were validated using ion chamber measurements. A reproducible increase in cell survival was observed following IMRT dose delivery. This increase varied from small for V79, with a surviving fraction of 0.8326 following POP vs 0.8420 following uninterrupted IMRT, to very pronounced for SiHa, with a surviving fraction of 0.3903 following POP vs 0.5330 for uninterrupted IMRT. When compared to IMRT or IMRT with a break for MLC initialization, cell survival following acute dose delivery was

  10. Treatment planning of intensity modulated composite particle therapy with dose and linear energy transfer optimization

    NASA Astrophysics Data System (ADS)

    Inaniwa, Taku; Kanematsu, Nobuyuki; Noda, Koji; Kamada, Tadashi

    2017-06-01

    The biological effect of charged-particle beams depends on both dose and particle spectrum. As one of the physical quantities describing the particle spectrum of charged-particle beams, we considered the linear energy transfer (LET) throughout this study. We investigated a new therapeutic technique using two or more ion species in one treatment session, which we call an intensity modulated composite particle therapy (IMPACT), for optimizing the physical dose and dose-averaged LET distributions in a patient as its proof of principle. Protons and helium, carbon, and oxygen ions were considered as ion species for IMPACT. For three cubic targets of 4  ×  4  ×  4, 8  ×  8  ×  8, and 12  ×  12  ×  12 cm3, defined at the center of the water phantom of 20  ×  20  ×  20 cm3, we made IMPACT plans of two composite fields with opposing and orthogonal geometries. The prescribed dose to the target was fixed at 1 Gy, while the prescribed LET to the target was varied from 1 keV µm-1 to 120 keV µm-1 to investigate the range of LET valid for prescription. The minimum and maximum prescribed LETs, (L T_min, L T_max), by the opposing-field geometry, were (3 keV µm-1, 115 keV µm-1), (2 keV µm-1, 84 keV µm-1),and (2 keV µm-1, 66 keV µm-1), while those by the orthogonal-field geometry were (8 keV µm-1, 98 keV µm-1), (7 keV µm-1, 72 keV µm-1), and (8 keV µm-1, 57 keV µm-1) for the three targets, respectively. To show the proof of principle of IMPACT in a clinical situation, we made IMPACT plans for a prostate case. In accordance with the prescriptions, the LETs in prostate, planning target volume (PTV), and rectum could be adjusted at 80 keV µm-1, at 50 keV µm-1, and below 30 keV µm-1, respectively, while keeping the dose to the PTV at 2 Gy uniformly. IMPACT enables the optimization of the dose and the LET distributions in a patient, which will maximize the

  11. Comparison of Rapid Arc and Intensity-modulated Radiotherapy Plans Using Unified Dosimetry Index and the Impact of Conformity Index on Unified Dosimetry Index Evaluation.

    PubMed

    Krishnan, Jayapalan; Shetty, Jayarama; Rao, Suresh; Hegde, Sanath; Shambhavi, C

    2017-01-01

    The aim of this study was to evaluate the impact of conformity index in the unified dosimetry index (UDI) score for two different planning techniques namely intensity-modulated radiotherapy (IMRT) and Rapid Arc. Rapid Arc and IMRT plans of 57 patients were evaluated and compared using UDI score which incorporates four indices. To determine the impact of conformity index on the IMRT and Rapid Arc plans, UDI at conformity index one of all plan (UDIunit_CI) score was calculated by assuming conformity index is equal to one. Mean and standard deviations of all indices were calculated. Rapid Arc technique plans of different treatment sites of all patients scored lesser UDI than IMRT plans, and the conformity index of Rapid Arc plan was significantly better than IMRT plan. The average dose gradient, homogeneity, coverage, and conformity index of all sites with Rapid Arc plans were 0.212 ± 0.05, 1.123 ± 0.03, 0.959 ± 0.03, and 1.056 ± 0.09; with IMRT plans were 0.190 ± 0.05, 1.113 ± 0.04, 0.950 ± 0.04, and 1.172 ± 0.16, respectively. UDI score value with actual conformity index of Rapid Arc and IMRT plans differed significantly (P < 0.001). However, UDIunit_CI score values with assumed conformity index equal to one did not differ significantly (P = 0.528). In the comparison of IMRT and Rapid Arc plans using the UDI score, the impact of conformity index was significant.

  12. Comparison of Rapid Arc and Intensity-modulated Radiotherapy Plans Using Unified Dosimetry Index and the Impact of Conformity Index on Unified Dosimetry Index Evaluation

    PubMed Central

    Krishnan, Jayapalan; Shetty, Jayarama; Rao, Suresh; Hegde, Sanath; Shambhavi, C

    2017-01-01

    The aim of this study was to evaluate the impact of conformity index in the unified dosimetry index (UDI) score for two different planning techniques namely intensity-modulated radiotherapy (IMRT) and Rapid Arc. Rapid Arc and IMRT plans of 57 patients were evaluated and compared using UDI score which incorporates four indices. To determine the impact of conformity index on the IMRT and Rapid Arc plans, UDI at conformity index one of all plan (UDIunit_CI) score was calculated by assuming conformity index is equal to one. Mean and standard deviations of all indices were calculated. Rapid Arc technique plans of different treatment sites of all patients scored lesser UDI than IMRT plans, and the conformity index of Rapid Arc plan was significantly better than IMRT plan. The average dose gradient, homogeneity, coverage, and conformity index of all sites with Rapid Arc plans were 0.212 ± 0.05, 1.123 ± 0.03, 0.959 ± 0.03, and 1.056 ± 0.09; with IMRT plans were 0.190 ± 0.05, 1.113 ± 0.04, 0.950 ± 0.04, and 1.172 ± 0.16, respectively. UDI score value with actual conformity index of Rapid Arc and IMRT plans differed significantly (P < 0.001). However, UDIunit_CI score values with assumed conformity index equal to one did not differ significantly (P = 0.528). In the comparison of IMRT and Rapid Arc plans using the UDI score, the impact of conformity index was significant. PMID:28405103

  13. Impact of geometric uncertainties on dose calculations for intensity modulated radiation therapy of prostate cancer

    NASA Astrophysics Data System (ADS)

    Jiang, Runqing

    Intensity-modulated radiation therapy (IMRT) uses non-uniform beam intensities within a radiation field to provide patient-specific dose shaping, resulting in a dose distribution that conforms tightly to the planning target volume (PTV). Unavoidable geometric uncertainty arising from patient repositioning and internal organ motion can lead to lower conformality index (CI) during treatment delivery, a decrease in tumor control probability (TCP) and an increase in normal tissue complication probability (NTCP). The CI of the IMRT plan depends heavily on steep dose gradients between the PTV and organ at risk (OAR). Geometric uncertainties reduce the planned dose gradients and result in a less steep or "blurred" dose gradient. The blurred dose gradients can be maximized by constraining the dose objective function in the static IMRT plan or by reducing geometric uncertainty during treatment with corrective verification imaging. Internal organ motion and setup error were evaluated simultaneously for 118 individual patients with implanted fiducials and MV electronic portal imaging (EPI). A Gaussian probability density function (PDF) is reasonable for modeling geometric uncertainties as indicated by the 118 patients group. The Gaussian PDF is patient specific and group standard deviation (SD) should not be used for accurate treatment planning for individual patients. In addition, individual SD should not be determined or predicted from small imaging samples because of random nature of the fluctuations. Frequent verification imaging should be employed in situations where geometric uncertainties are expected. Cumulative PDF data can be used for re-planning to assess accuracy of delivered dose. Group data is useful for determining worst case discrepancy between planned and delivered dose. The margins for the PTV should ideally represent true geometric uncertainties. The measured geometric uncertainties were used in this thesis to assess PTV coverage, dose to OAR, equivalent

  14. A novel conformity index for intensity modulated radiation therapy plan evaluation

    SciTech Connect

    Cheung, Fion W. K.; Law, Maria Y. Y.

    2012-09-15

    Purpose: Intensity modulated radiation therapy (IMRT) has gained popularity in the treatment of cancers. Manual evaluation of IMRT plans for head-and-neck cancers has been especially challenging necessitating efficient and objective assessment tools. In this work, the authors address this issue by developing a personalized conformity index (CI) for comparison of IMRT plans for head-and-neck cancers and evaluating its plan quality discerning power in comparison with other widely used CIs. Methods: A two-dimensional CI with dose and distance incorporated (CI{sub DD}) was developed using the MATLAB program language, to quantify the planning target volume (PTV) coverage. Valuable information contained in the digital imaging and communication in medicine (DICOM) RT objects were harvested for computation of each of the CI{sub DD} components. Apart from the dose penalty factor, a distance-based exponential function was employed by varying the penalty weight associated with the location of cold spots within the PTV. With the goal of deriving a customized penalty factor, the distances between individual pixel and its nearest PTV boundary was found. Using the exponential function, the impact of distance penalty was substantially larger for cold spots closer to the PTV centroid but petered out quickly wherever they were situated in the vicinity of PTV border. In order to evaluate the CI{sub DD} scoring system, three CT image data sets of nasopharyngeal carcinoma (NPC) patients were collected. Ten IMRT plans with degrading qualities were generated from each dataset and were ranked based on CI{sub DD} and other existing indices. The coefficient of variance was calculated for each dataset to compare the degree of variation. Results: The CI{sub DD} scoring system that considered spatial importance of each voxel within the PTV was successfully developed. The results demonstrated that the CI{sub DD} including four discrete factors could provide accurate rankings of plan quality by

  15. The impact of daily setup variations on head-and-neck intensity-modulated radiation therapy

    SciTech Connect

    Hong, Theodore S.; Tome, Wolfgang A.; Chappell, Richard J.; Chinnaiyan, Prakash; Mehta, Minesh P.; Harari, Paul M. . E-mail: harari@humonc.wisc.edu

    2005-03-01

    Purpose: Intensity-modulated radiation therapy (IMRT) in the treatment of head-and-neck (H and N) cancer provides the opportunity to diminish normal tissue toxicity profiles and thereby enhance patient quality of life. However, highly conformal treatment techniques commonly establish steep dose gradients between tumor and avoidance structures. Daily setup variations can therefore significantly compromise the ultimate precision of idealized H and N IMRT delivery. This study provides a detailed analysis regarding the potential impact of daily setup variations on the overall integrity of H and N IMRT. Methods and materials: A series of 10 patients with advanced H and N cancer were prospectively enrolled in a clinical trial to examine daily H and N radiation setup accuracy. These patients were treated with conventional shrinking field design using three-dimensional treatment planning techniques (not IMRT). Immobilization and alignment were performed using modern H and N practice techniques including conventional thermoplastic masking, baseplate fixation to the treatment couch, three-point laser alignment, and weekly portal film evaluation. After traditional laser alignment, setup accuracy was assessed daily for each patient by measuring 3 Cartesian and 3 angular deviations from the specified isocenter using a high-precision, optically guided patient localization system, which affords submillimeter setup accuracy. These positional errors were then applied to a distinct series of 10 H and N IMRT plans for detailed analysis regarding the impact of daily setup variation (without optical guidance) on the ultimate integrity of IMRT plans over a 30-day treatment course. Dose-volume histogram (DVH), equivalent uniform dose (EUD), mean total dose (mTd), and maximal total dose (MTD) for normal structures were analyzed for IMRT plans with and without incorporation of daily setup variation. Results: Using conventional H and N masking and laser alignment for daily positioning, the

  16. Application of Histogram Analysis in Radiation Therapy (HART) in Intensity Modulation Radiation Therapy (IMRT) Treatments

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-03-01

    A carcinoma is a malignant cancer that emerges from epithelial cells in structures through out the body.It invades the critical organs, could metastasize or spread to lymph nodes.IMRT is an advanced mode of radiation therapy treatment for cancer. It delivers more conformal doses to malignant tumors sparing the critical organs by modulating the intensity of radiation beam.An automated software, HART (S. Jang et al.,2008,Med Phys 35,p.2812) was used for efficient analysis of dose volume histograms (DVH) for multiple targets and critical organs in four IMRT treatment plans for each patient. IMRT data for ten head and neck cancer patients were exported as AAPM/RTOG format files from a commercial treatment planning system at Northwestern Memorial Hospital (NMH).HART extracted DVH statistics were used to evaluate plan indices and to analyze dose tolerance of critical structures at prescription dose (PD) for each patient. Mean plan indices (n=10) were found to be in good agreement with published results for Linac based plans. The least irradiated volume at tolerance dose (TD50) was observed for brainstem and the highest volume for larynx in SIB treatment techniques. Thus HART, an open source platform, has extensive clinical implications in IMRT treatments.

  17. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT)

    SciTech Connect

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    2013-12-15

    Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.

  18. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT)

    PubMed Central

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    2013-01-01

    Introduction Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. Methods A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. Results The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. Conclusion The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques. PMID:26229623

  19. Proton therapy versus intensity modulated x-ray therapy in the treatment of prostate cancer: Estimating secondary cancer risks

    NASA Astrophysics Data System (ADS)

    Fontenot, Jonas David

    External beam radiation therapy is used to treat nearly half of the more than 200,000 new cases of prostate cancer diagnosed in the United States each year. During a radiation therapy treatment, healthy tissues in the path of the therapeutic beam are exposed to high doses. In addition, the whole body is exposed to a low-dose bath of unwanted scatter radiation from the pelvis and leakage radiation from the treatment unit. As a result, survivors of radiation therapy for prostate cancer face an elevated risk of developing a radiogenic second cancer. Recently, proton therapy has been shown to reduce the dose delivered by the therapeutic beam to normal tissues during treatment compared to intensity modulated x-ray therapy (IMXT, the current standard of care). However, the magnitude of stray radiation doses from proton therapy, and their impact on this incidence of radiogenic second cancers, was not known. The risk of a radiogenic second cancer following proton therapy for prostate cancer relative to IMXT was determined for 3 patients of large, median, and small anatomical stature. Doses delivered to healthy tissues from the therapeutic beam were obtained from treatment planning system calculations. Stray doses from IMXT were taken from the literature, while stray doses from proton therapy were simulated using a Monte Carlo model of a passive scattering treatment unit and an anthropomorphic phantom. Baseline risk models were taken from the Biological Effects of Ionizing Radiation VII report. A sensitivity analysis was conducted to characterize the uncertainty of risk calculations to uncertainties in the risk model, the relative biological effectiveness (RBE) of neutrons for carcinogenesis, and inter-patient anatomical variations. The risk projections revealed that proton therapy carries a lower risk for radiogenic second cancer incidence following prostate irradiation compared to IMXT. The sensitivity analysis revealed that the results of the risk analysis depended only

  20. Outcomes for patients with cervical cancer treated with extended-field intensity-modulated radiation therapy and concurrent cisplatin.

    PubMed

    Jensen, Lindsay G; Hasselle, Michael D; Rose, Brent S; Nath, Sameer K; Hasan, Yasmin; Scanderbeg, Dan J; Yashar, Catheryn M; Mundt, Arno J; Mell, Loren K

    2013-01-01

    To evaluate disease outcomes and toxicity in patients with cervical cancer treated with extended-field intensity-modulated radiotherapy. We included all patients treated with extended-field intensity-modulated radiotherapy and concurrent weekly cisplatin from 2003 to 2010 at 2 institutions. Overall survival and disease-free survival were estimated using Kaplan-Meier method. Locoregional failure (LRF), distant failure, and competing mortality were calculated using cumulative incidence functions. Acute and late toxicity were graded using Common Terminology Criteria for Adverse Events (CTCAE) and Radiation Therapy Oncology Group late radiation morbidity scoring criteria, respectively. The study included 21 patients, 14 and 20 of which had positive para-aortic and pelvic nodes, respectively. The median follow-up was 22 months. Eighteen-month overall survival and disease-free survival were 59.7% (95% confidence interval [CI], 41.2%-86.4%) and 42.9% (95% CI, 26.2%-70.2%). Eighteen-month cumulative incidences of LRF, distant failure, and competing mortality were 9.5% (95% CI, 1.5-26.8%), 42.9% (95% CI, 21.3-62.9%), and 4.8% (95% CI, 0.3-20.2%), respectively. Eighteen-month cumulative incidences of late grade 3 or higher-grade genitourinary and gastrointestinal toxicity were 4.8% (95% CI, 0.2%-20.3%) and 0%, respectively. Intensity-modulated extended-field radiotherapy was associated with low rates of late toxicity and LRF. High rates of distant failure indicate that this group of patients could benefit from intensified systemic therapy.

  1. Simultaneous beam geometry and intensity map optimization in intensity-modulated radiation therapy.

    PubMed

    Lee, Eva K; Fox, Tim; Crocker, Ian

    2006-01-01

    In current intensity-modulated radiation therapy (IMRT) plan optimization, the focus is on either finding optimal beam angles (or other beam delivery parameters such as field segments, couch angles, gantry angles) or optimal beam intensities. In this article we offer a mixed integer programming (MIP) approach for simultaneously determining an optimal intensity map and optimal beam angles for IMRT delivery. Using this approach, we pursue an experimental study designed to (a) gauge differences in plan quality metrics with respect to different tumor sites and different MIP treatment planning models, and (b) test the concept of critical-normal-tissue-ring--a tissue ring of 5 mm thickness drawn around the planning target volume (PTV)--and its use for designing conformal plans. Our treatment planning models use two classes of decision variables to capture the beam configuration and intensities simultaneously. Binary (0/1) variables are used to capture "on" or "off" or "yes" or "no" decisions for each field, and nonnegative continuous variables are used to represent intensities of beamlets. Binary and continuous variables are also used for each voxel to capture dose level and dose deviation from target bounds. Treatment planning models were designed to explicitly incorporate the following planning constraints: (a) upper/lower/mean dose-based constraints, (b) dose-volume and equivalent-uniform-dose (EUD) constraints for critical structures, (c) homogeneity constraints (underdose/overdose) for PTV, (d) coverage constraints for PTV, and (e) maximum number of beams allowed. Within this constrained solution space, five optimization strategies involving clinical objectives were analyzed: optimize total intensity to PTV, optimize total intensity and then optimize conformity, optimize total intensity and then optimize homogeneity, minimize total dose to critical structures, minimize total dose to critical structures and optimize conformity simultaneously. We emphasize that the

  2. Imaging Changes in Pediatric Intracranial Ependymoma Patients Treated With Proton Beam Radiation Therapy Compared to Intensity Modulated Radiation Therapy

    SciTech Connect

    Gunther, Jillian R.; Sato, Mariko; Chintagumpala, Murali; Ketonen, Leena; Jones, Jeremy Y.; Allen, Pamela K.; Paulino, Arnold C.; Okcu, M. Fatih; Su, Jack M.; Weinberg, Jeffrey; Boehling, Nicholas S.; Khatua, Soumen; Adesina, Adekunle; Dauser, Robert; Whitehead, William E.; Mahajan, Anita

    2015-09-01

    Purpose: The clinical significance of magnetic resonance imaging (MRI) changes after radiation therapy (RT) in children with ependymoma is not well defined. We compared imaging changes following proton beam radiation therapy (PBRT) to those after photon-based intensity modulated RT (IMRT). Methods and Materials: Seventy-two patients with nonmetastatic intracranial ependymoma who received postoperative RT (37 PBRT, 35 IMRT) were analyzed retrospectively. MRI images were reviewed by 2 neuroradiologists. Results: Sixteen PBRT patients (43%) developed postradiation MRI changes at 3.8 months (median) with resolution by 6.1 months. Six IMRT patients (17%) developed changes at 5.3 months (median) with 8.3 months to resolution. Mean age at radiation was 4.4 and 6.9 years for PBRT and IMRT, respectively (P=.06). Age at diagnosis (>3 years) and time of radiation (≥3 years) was associated with fewer imaging changes on univariate analysis (odds ratio [OR]: 0.35, P=.048; OR: 0.36, P=.05). PBRT (compared to IMRT) was associated with more frequent imaging changes, both on univariate (OR: 3.68, P=.019) and multivariate (OR: 3.89, P=.024) analyses. Seven (3 IMRT, 4 PBRT) of 22 patients with changes had symptoms requiring intervention. Most patients were treated with steroids; some PBRT patients also received bevacizumab and hyperbaric oxygen therapy. None of the IMRT patients had lasting deficits, but 2 patients died from recurrent disease. Three PBRT patients had persistent neurological deficits, and 1 child died secondarily to complications from radiation necrosis. Conclusions: Postradiation MRI changes are more common with PBRT and in patients less than 3 years of age at diagnosis and treatment. It is difficult to predict causes for development of imaging changes that progress to clinical significance. These changes are usually self-limiting, but some require medical intervention, especially those involving the brainstem.

  3. Intensity-Modulated Radiation Therapy with Stereotactic Body Radiation Therapy Boost for Unfavorable Prostate Cancer: The Georgetown University Experience.

    PubMed

    Mercado, Catherine; Kress, Marie-Adele; Cyr, Robyn A; Chen, Leonard N; Yung, Thomas M; Bullock, Elizabeth G; Lei, Siyuan; Collins, Brian T; Satinsky, Andrew N; Harter, K William; Suy, Simeng; Dritschilo, Anatoly; Lynch, John H; Collins, Sean P

    2016-01-01

    Stereotactic body radiation therapy (SBRT) is emerging as a minimally invasive alternative to brachytherapy to deliver highly conformal, dose--escalated radiation therapy (RT) to the prostate. SBRT alone may not adequately cover the tumor extensions outside the prostate commonly seen in unfavorable prostate cancer. External beam radiation therapy (EBRT) with high dose rate brachytherapy boost is a proven effective therapy for unfavorable prostate cancer. This study reports on early prostate-specific antigen and prostate cancer-specific quality of life (QOL) outcomes in a cohort of unfavorable patients treated with intensity-modulated radiation therapy (IMRT) and SBRT boost. Prostate cancer patients treated with SBRT (19.5 Gy in three fractions) followed by fiducial-guided IMRT (45-50.4 Gy) from March 2008 to September 2012 were included in this retrospective review of prospectively collected data. Biochemical failure was assessed using the Phoenix definition. Patients completed the expanded prostate cancer index composite (EPIC)-26 at baseline, 1 month after the completion of RT, every 3 months for the first year, then every 6 months for a minimum of 2 years. One hundred eight patients (4 low-, 45 intermediate-, and 59 high-risk) with median age of 74 years completed treatment, with median follow-up of 4.4 years. Sixty-four percent of the patients received androgen deprivation therapy prior to the initiation of RT. The 3-year actuarial biochemical control rates were 100 and 89.8% for intermediate- and high-risk patients, respectively. At the initiation of RT, 9 and 5% of men felt their urinary and bowel function was a moderate to big problem, respectively. Mean EPIC urinary and bowel function and bother scores exhibited transient declines, with subsequent return to near baseline. At 2 years posttreatment, 13.7 and 5% of men felt their urinary and bowel function was a moderate to big problem, respectively. At 3-year follow-up, biochemical control

  4. Three-dimensional conformal intensity-modulated radiation therapy of left femur foci does not damage the sciatic nerve

    PubMed Central

    Xu, Wanlong; Zhao, Xibin; Wang, Qing; Sun, Jungang; Xu, Jiangbo; Zhou, Wenzheng; Wang, Hao; Yan, Shigui; Yuan, Hong

    2014-01-01

    During radiotherapy to kill femoral hydatid tapeworms, the sciatic nerve surrounding the focus can be easily damaged by the treatment. Thus, it is very important to evaluate the effects of radiotherapy on the surrounding nervous tissue. In the present study, we used three-dimensional, conformal, intensity-modulated radiation therapy to treat bilateral femoral hydatid disease in Meriones meridiani. The focus of the hydatid disease on the left femur was subjected to radiotherapy (40 Gy) for 14 days, and the right femur received sham irradiation. Hematoxylin-eosin staining, electron microscopy, and terminal deoxynucleotidyl transferase-dUTP nick end labeling assays on the left femurs showed that the left sciatic nerve cell structure was normal, with no obvious apoptosis after radiation. Trypan blue staining demonstrated that the overall protoscolex structure in bone parasitized with Echinococcus granulosus disappeared in the left femur of the animals after treatment. The mortality of the protoscolex was higher in the left side than in the right side. The succinate dehydrogenase activity in the protoscolex in bone parasitized with Echinococcus granulosus was lower in the left femur than in the right femur. These results suggest that three-dimensional conformal intensity-modulated radiation therapy achieves good therapeutic effects on the secondary bone in hydatid disease in Meriones meridiani without damaging the morphology or function of the sciatic nerve. PMID:25422645

  5. Bone Marrow Sparing in Intensity Modulated Proton Therapy for Cervical Cancer: Efficacy and Robustness under Range and Setup Uncertainties

    PubMed Central

    Dinges, Eric; Felderman, Nicole; McGuire, Sarah; Gross, Brandie; Bhatia, Sudershan; Mott, Sarah; Buatti, John; Wang, Dongxu

    2015-01-01

    Background and Purpose This study evaluates the potential efficacy and robustness of functional bone marrow sparing (BMS) using intensity-modulated proton therapy (IMPT) for cervical cancer, with the goal of reducing hematologic toxicity. Material and Methods IMPT plans with prescription dose of 45 Gy were generated for ten patients who have received BMS intensity-modulated x-ray therapy (IMRT). Functional bone marrow was identified by 18F-flourothymidine positron emission tomography. IMPT plans were designed to minimize the volume of functional bone marrow receiving 5–40 Gy while maintaining similar target coverage and healthy organ sparing as IMRT. IMPT robustness was analyzed with ±3% range uncertainty errors and/or ±3mm translational setup errors in all three principal dimensions. Results In the static scenario, the median dose volume reductions for functional bone marrow by IMPT were: 32% for V5GY, 47% for V10Gy, 54% for V20Gy, and 57% for V40Gy, all with p<0.01 compared to IMRT. With assumed errors, even the worst-case reductions by IMPT were: 23% for V5Gy, 37% for V10Gy, 41% for V20Gy, and 39% for V40Gy, all with p<0.01. Conclusions The potential sparing of functional bone marrow by IMPT for cervical cancer is significant and robust under realistic systematic range uncertainties and clinically relevant setup errors. PMID:25981130

  6. Quality of Intensity Modulated Radiation Therapy Treatment Plans Using a {sup 60}Co Magnetic Resonance Image Guidance Radiation Therapy System

    SciTech Connect

    Wooten, H. Omar Green, Olga; Yang, Min; DeWees, Todd; Kashani, Rojano; Olsen, Jeff; Michalski, Jeff; Yang, Deshan; Tanderup, Kari; Hu, Yanle; Li, H. Harold; Mutic, Sasa

    2015-07-15

    Purpose: This work describes a commercial treatment planning system, its technical features, and its capabilities for creating {sup 60}Co intensity modulated radiation therapy (IMRT) treatment plans for a magnetic resonance image guidance radiation therapy (MR-IGRT) system. Methods and Materials: The ViewRay treatment planning system (Oakwood Village, OH) was used to create {sup 60}Co IMRT treatment plans for 33 cancer patients with disease in the abdominal, pelvic, thorax, and head and neck regions using physician-specified patient-specific target coverage and organ at risk (OAR) objectives. Backup plans using a third-party linear accelerator (linac)-based planning system were also created. Plans were evaluated by attending physicians and approved for treatment. The {sup 60}Co and linac plans were compared by evaluating conformity numbers (CN) with 100% and 95% of prescription reference doses and heterogeneity indices (HI) for planning target volumes (PTVs) and maximum, mean, and dose-volume histogram (DVH) values for OARs. Results: All {sup 60}Co IMRT plans achieved PTV coverage and OAR sparing that were similar to linac plans. PTV conformity for {sup 60}Co was within <1% and 3% of linac plans for 100% and 95% prescription reference isodoses, respectively, and heterogeneity was on average 4% greater. Comparisons of OAR mean dose showed generally better sparing with linac plans in the low-dose range <20 Gy, but comparable sparing for organs with mean doses >20 Gy. The mean doses for all {sup 60}Co plan OARs were within clinical tolerances. Conclusions: A commercial {sup 60}Co MR-IGRT device can produce highly conformal IMRT treatment plans similar in quality to linac IMRT for a variety of disease sites. Additional work is in progress to evaluate the clinical benefit of other novel features of this MR-IGRT system.

  7. Cost-Effectiveness Analysis of Intensity Modulated Radiation Therapy Versus 3-Dimensional Conformal Radiation Therapy for Anal Cancer

    SciTech Connect

    Hodges, Joseph C.; Beg, Muhammad S.; Das, Prajnan; Meyer, Jeffrey

    2014-07-15

    Purpose: To compare the cost-effectiveness of intensity modulated radiation therapy (IMRT) and 3-dimensional conformal radiation therapy (3D-CRT) for anal cancer and determine disease, patient, and treatment parameters that influence the result. Methods and Materials: A Markov decision model was designed with the various disease states for the base case of a 65-year-old patient with anal cancer treated with either IMRT or 3D-CRT and concurrent chemotherapy. Health states accounting for rates of local failure, colostomy failure, treatment breaks, patient prognosis, acute and late toxicities, and the utility of toxicities were informed by existing literature and analyzed with deterministic and probabilistic sensitivity analysis. Results: In the base case, mean costs and quality-adjusted life expectancy in years (QALY) for IMRT and 3D-CRT were $32,291 (4.81) and $28,444 (4.78), respectively, resulting in an incremental cost-effectiveness ratio of $128,233/QALY for IMRT compared with 3D-CRT. Probabilistic sensitivity analysis found that IMRT was cost-effective in 22%, 47%, and 65% of iterations at willingness-to-pay thresholds of $50,000, $100,000, and $150,000 per QALY, respectively. Conclusions: In our base model, IMRT was a cost-ineffective strategy despite the reduced acute treatment toxicities and their associated costs of management. The model outcome was sensitive to variations in local and colostomy failure rates, as well as patient-reported utilities relating to acute toxicities.

  8. Risk of radiogenic second cancers following volumetric modulated arc therapy and proton arc therapy for prostate cancer.

    PubMed

    Rechner, Laura A; Howell, Rebecca M; Zhang, Rui; Etzel, Carol; Lee, Andrew K; Newhauser, Wayne D

    2012-11-07

    Prostate cancer patients who undergo radiotherapy are at an increased risk to develop a radiogenic second cancer. Proton therapy has been shown to reduce the predicted risk of second cancer when compared to intensity modulated radiotherapy. However, it is unknown if this is also true for the rotational therapies proton arc therapy and volumetric modulated arc therapy (VMAT). The objective of this study was to compare the predicted risk of cancer following proton arc therapy and VMAT for prostate cancer. Proton arc therapy and VMAT plans were created for three patients. Various risk models were combined with the dosimetric data (therapeutic and stray dose) to predict the excess relative risk (ERR) of cancer in the bladder and rectum. Ratios of ERR values (RRR) from proton arc therapy and VMAT were calculated. RRR values ranged from 0.74 to 0.99, and all RRR values were shown to be statistically less than 1, except for the value calculated with the linear-non-threshold risk model. We conclude that the predicted risk of cancer in the bladder or rectum following proton arc therapy for prostate cancer is either less than or approximately equal to the risk following VMAT, depending on which risk model is applied.

  9. Risk of radiogenic second cancers following volumetric modulated arc therapy and proton arc therapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Rechner, Laura A.; Howell, Rebecca M.; Zhang, Rui; Etzel, Carol; Lee, Andrew K.; Newhauser, Wayne D.

    2012-11-01

    Prostate cancer patients who undergo radiotherapy are at an increased risk to develop a radiogenic second cancer. Proton therapy has been shown to reduce the predicted risk of second cancer when compared to intensity modulated radiotherapy. However, it is unknown if this is also true for the rotational therapies proton arc therapy and volumetric modulated arc therapy (VMAT). The objective of this study was to compare the predicted risk of cancer following proton arc therapy and VMAT for prostate cancer. Proton arc therapy and VMAT plans were created for three patients. Various risk models were combined with the dosimetric data (therapeutic and stray dose) to predict the excess relative risk (ERR) of cancer in the bladder and rectum. Ratios of ERR values (RRR) from proton arc therapy and VMAT were calculated. RRR values ranged from 0.74 to 0.99, and all RRR values were shown to be statistically less than 1, except for the value calculated with the linear-non-threshold risk model. We conclude that the predicted risk of cancer in the bladder or rectum following proton arc therapy for prostate cancer is either less than or approximately equal to the risk following VMAT, depending on which risk model is applied.

  10. A model-aided segmentation in urethra identification based on an atlas human autopsy image for intensity modulated radiation therapy.

    PubMed

    Song, Yan; Muller, Boris; Burman, Chandra; Mychalczak, Borys; Song, Yulin

    2007-01-01

    In order to protect urethra in radiation therapy of prostate cancer, the urethra must be identified and localized as an organ at risk (OAR) for the inverse treatment planning in intensity modulated radiation therapy (IMRT). Because the prostatic urethra and its surrounding prostate tissue have similar physical characteristics, such as linear attenuation coefficient and density, it is difficult to distinct the OAR from the target in CT images. To localize the urethra without using contrast agent or additional imaging modalities other than planning CT images, a different approach was developed using a standard atlas of human anatomy image. This paper reports an investigation, in which an adult urethra was modeled based on a human anatomic image. An elastic model was build to account for a uniform tissue deformation of the prostate. This model was then applied to patients to localize their urethras and preliminary results are presented.

  11. Radiation efficacy and biological risk from whole-breast irradiation via intensity modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Desantis, David M.

    Radiotherapy is an established modality for women with breast cancer. During the delivery of external beam radiation to the breast, leakage, scattered x-rays from the patient and the linear accelerator also expose healthy tissues and organs outside of the breast, thereby increasing the patient's whole-body dose, which then increases the chance of developing a secondary, radiation-induced cancer. Generally, there are three IntensityModulated Radiotherapy (IMRT) delivery techniques from a conventional linear accelerator; forward planned (FMLC), inverse planned 'sliding window' (DMLC), and inverse planned 'step-and-shoot' (SMLC). The goal of this study was to determine which of these three techniques delivers an optimal dose to the breast with the least chance of causing a fatal, secondary, radiation-induced cancer. A conventional, non-IMRT, 'Wedge' plan also was compared. Computerized Tomography (CT) data sets for both a large and small sized patient were used in this study. With Varian's Eclipse AAA algorithm, the organ doses specified in the revised ICRP 60 publication were used to calculate the whole-body dose. Also, an anthropomorphic phantom was irradiated with thermoluminescent dosimeters (TLD) at each organ site for measured doses. The risk coefficient from the Biological Effects of Ionizing Radiation (BEIR) VII report of 4.69 x 10-2 deaths per Gy was used to convert whole-body dose to risk of a fatal, secondary, radiation-induced cancer. The FMLC IMRT delivered superior tumor coverage over the 3D conventional plan and the inverse DMLC or SMLC treatment plans delivered clinically equivalent tumor coverage. However, the FMLC plan had the least likelihood of inadvertently causing a fatal, secondary, radiation-induced cancer compared to the inverse DMLC, SMLC, and Wedge plans.

  12. Dosimetric effects of endorectal balloons on intensity-modulated radiation therapy plans for prostate cancer

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Sung; Chung, Jin-Beom; Kim, In-Ah; Eom, Keun-Yong

    2013-10-01

    We used an endorectal balloon (ERB) for prostate immobilization during intensity-modulated radiotherapy (IMRT) for prostate cancer treatment. To investigate the dosimetric effects of ERB-filling materials, we changed the ERB Hounsfield unit (HU) from 0 to 1000 HU in 200-HU intervals to simulate the various ERB fillings; 0 HU simulated a water-filled ERB, and 1000 HU simulated the densest material-filled ERB. Dosimetric data (coverage, homogeneity, conformity, maximal dose, and typical volume dose) for the tumor and the organs at risk (OARs) were evaluated in prostate IMRT treatment plans with 6-MV and 15-MV beams. The tumor coverage appeared to differ by approximately 1%, except for the clinical target volume (CTV) V100% and the planning target volume (PTV) V100%. The largest difference for the various ERB fillings was observed in the PTV V100%. In spite of increasing HU, the prostate IMRT plans at both energies had relatively low dosimetric effects on the PTV and the CTV. However, the maximal and the typical volume doses (D25%, D30%, and D50%) to the rectal wall and the bladder increased with increasing HU. For an air-filled ERB, the maximal doses to the rectal wall and the monitor units were lower than the corresponding values for the water-filled and the densest material-filled ERBs. An air-filled ERB spared the rectal wall because of its dosimetric effect. Thus, we conclude that the use of an air-filled ERB provides a dosimetric benefit to the rectal wall without a loss of target coverage and is an effective option for prostate IMRT treatment.

  13. Potential Benefits of Scanned Intensity-Modulated Proton Therapy Versus Advanced Photon Therapy With Regard to Sparing of the Salivary Glands in Oropharyngeal Cancer

    SciTech Connect

    Water, Tara A. van de; Bijl, Hendrik P.; Jong, Marije E. de; Schilstra, Cornelis; Langendijk, Johannes A.

    2011-03-15

    Purpose: To test the hypothesis that scanned intensity-modulated proton therapy (IMPT) results in a significant dose reduction to the parotid and submandibular glands as compared with intensity-modulated radiotherapy with photons (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for oropharyngeal cancer. In addition, we investigated whether the achieved dose reductions would theoretically translate into a reduction of salivary dysfunction and xerostomia. Methods and Materials: Ten patients with N0 oropharyngeal carcinoma were used. The intensity-modulated plans delivered simultaneously 70 Gy to the boost planning target volume (PTV2) and 54 Gy to the elective nodal areas (PTV1). The 3D-CRT technique delivered sequentially 70 Gy and 46 Gy to PTV2 and PTV1, respectively. Normal tissue complication probabilities were calculated for salivary dysfunction and xerostomia. Results: Planning target volume coverage results were similar for IMPT and IMRT. Intensity-modulated proton therapy clearly improved the conformity. The 3D-CRT results were inferior to these results. The mean dose to the parotid glands by 3D-CRT (50.8 Gy), IMRT (25.5 Gy), and IMPT (16.8 Gy) differed significantly. For the submandibular glands no significant differences between IMRT and IMPT were found. The dose reductions obtained with IMPT theoretically translated into a significant reduction in normal tissue complication probability. Conclusion: Compared with IMRT and 3D-CRT, IMPT improved sparing of the organs at risk, while keeping similar target coverage results. The dose reductions obtained with IMPT vs. IMRT and 3D-CRT varied widely per individual patient. Intensity-modulated proton therapy theoretically translated into a clinical benefit for most cases, but this requires clinical validation.

  14. Preliminary outcome and toxicity report of extended-field, intensity-modulated radiation therapy for gynecologic malignancies

    SciTech Connect

    Salama, Joseph K. . E-mail: jsalama@radonc.uchicago.edu; Mundt, Arno J.; Roeske, John; Mehta, Neil

    2006-07-15

    Purpose: The aim of this article is to report a preliminary analysis of our initial clinical experience with extended-field intensity-modulated radiotherapy for gynecologic malignancies. Methods and Materials: Between November 2002 and May 2005, 13 women with gynecologic malignancies were treated with extended-field radiation therapy. Of the women, 7 had endometrial cancer, 4 cervical cancer, 1 recurrent endometrial cancer, and 1 suspected cervical cancer. All women underwent computed tomography planning, with the upper vagina, parametria, and uterus (if present) contoured within the CTV. In addition, the clinical target volume contained the pelvic and presacral lymph nodes as well as the para-aortic lymph nodes. All acute toxicity was scored according to the Common Terminology Criteria for Adverse Events (CTCAE v 3.0). All late toxicity was scored using the Radiation Therapy Oncology Group late toxicity score. Results: The median follow-up was 11 months. Extended-field intensity-modulated radiation therapy (IMRT) for gynecologic malignancies was well tolerated. Two patients experienced Grade 3 or higher toxicity. Both patients were treated with concurrent cisplatin based chemotherapy. Neither patient was planned with bone marrow sparing. Eleven patients had no evidence of late toxicity. One patient with multiple previous surgeries experienced a bowel obstruction. One patient with bilateral grossly involved and unresectable common iliac nodes experienced bilateral lymphedema. Extended-field-IMRT achieved good local control with only 1 patient, who was metastatic at presentation, and 1 patient not able to complete treatment, experiencing in-field failure. Conclusions: Extended-field IMRT is safe and effective with a low incidence of acute toxicity. Longer follow-up is needed to assess chronic toxicity, although early results are promising.

  15. Optimization and quality assurance of an image-guided radiation therapy system for intensity-modulated radiation therapy radiotherapy.

    PubMed

    Tsai, Jen-San; Micaily, Bizhan; Miyamoto, Curtis

    2012-01-01

    To develop a quality assurance (QA) of XVI cone beam system (XVIcbs) for its optimal imaging-guided radiotherapy (IGRT) implementation, and to construe prostate tumor margin required for intensity-modulated radiation therapy (IMRT) if IGRT is unavailable. XVIcbs spatial accuracy was explored with a humanoid phantom; isodose conformity to lesion target with a rice phantom housing a soap as target; image resolution with a diagnostic phantom; and exposure validation with a Radcal ion chamber. To optimize XVIcbs, rotation flexmap on coincidency between gantry rotational axis and that of XVI cone beam scan was investigated. Theoretic correlation to image quality of XVIcbs rotational axis stability was elaborately studied. Comprehensive QA of IGRT using XVIcbs has initially been explored and then implemented on our general IMRT treatments, and on special IMRT radiotherapies such as head and neck (H and N), stereotactic radiation therapy (SRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Fifteen examples of prostate setup accounted for 350 IGRT cone beam system were analyzed. IGRT accuracy results were in agreement ± 1 mm. Flexmap 0.25 mm met the manufacturer's specification. Films confirmed isodose coincidence with target (soap) via XVIcbs, otherwise not. Superficial doses were measured from 7.2-2.5 cGy for anatomic diameters 15-33 cm, respectively. Image quality was susceptible to rotational stability or patient movement. IGRT using XVIcbs on general IMRT treatments such as prostate, SRT, SRS, and SBRT for setup accuracy were verified; and subsequently coordinate shifts corrections were recorded. The 350 prostate IGRT coordinate shifts modeled to Gaussian distributions show central peaks deviated off the isocenter by 0.6 ± 3.0 mm, 0.5 ± 4.5 mm in the X(RL)- and Z(SI)-coordinates, respectively; and 2.0 ± 3.0 mm in the Y(AP)-coordinate as a result of belly and bladder capacity variations. Sixty-eight percent of confidence was within

  16. Optimization and quality assurance of an image-guided radiation therapy system for intensity-modulated radiation therapy radiotherapy

    SciTech Connect

    Tsai, Jen-San; Micaily, Bizhan; Miyamoto, Curtis

    2012-10-01

    To develop a quality assurance (QA) of XVI cone beam system (XVIcbs) for its optimal imaging-guided radiotherapy (IGRT) implementation, and to construe prostate tumor margin required for intensity-modulated radiation therapy (IMRT) if IGRT is unavailable. XVIcbs spatial accuracy was explored with a humanoid phantom; isodose conformity to lesion target with a rice phantom housing a soap as target; image resolution with a diagnostic phantom; and exposure validation with a Radcal ion chamber. To optimize XVIcbs, rotation flexmap on coincidency between gantry rotational axis and that of XVI cone beam scan was investigated. Theoretic correlation to image quality of XVIcbs rotational axis stability was elaborately studied. Comprehensive QA of IGRT using XVIcbs has initially been explored and then implemented on our general IMRT treatments, and on special IMRT radiotherapies such as head and neck (H and N), stereotactic radiation therapy (SRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Fifteen examples of prostate setup accounted for 350 IGRT cone beam system were analyzed. IGRT accuracy results were in agreement {+-} 1 mm. Flexmap 0.25 mm met the manufacturer's specification. Films confirmed isodose coincidence with target (soap) via XVIcbs, otherwise not. Superficial doses were measured from 7.2-2.5 cGy for anatomic diameters 15-33 cm, respectively. Image quality was susceptible to rotational stability or patient movement. IGRT using XVIcbs on general IMRT treatments such as prostate, SRT, SRS, and SBRT for setup accuracy were verified; and subsequently coordinate shifts corrections were recorded. The 350 prostate IGRT coordinate shifts modeled to Gaussian distributions show central peaks deviated off the isocenter by 0.6 {+-} 3.0 mm, 0.5 {+-} 4.5 mm in the X(RL)- and Z(SI)-coordinates, respectively; and 2.0 {+-} 3.0 mm in the Y(AP)-coordinate as a result of belly and bladder capacity variations. Sixty-eight percent of confidence was

  17. A new Monte Carlo-based treatment plan optimization approach for intensity modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Li, Yongbao; Tian, Zhen; Shi, Feng; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

    2015-04-01

    Intensity-modulated radiation treatment (IMRT) plan optimization needs beamlet dose distributions. Pencil-beam or superposition/convolution type algorithms are typically used because of their high computational speed. However, inaccurate beamlet dose distributions may mislead the optimization process and hinder the resulting plan quality. To solve this problem, the Monte Carlo (MC) simulation method has been used to compute all beamlet doses prior to the optimization step. The conventional approach samples the same number of particles from each beamlet. Yet this is not the optimal use of MC in this problem. In fact, there are beamlets that have very small intensities after solving the plan optimization problem. For those beamlets, it may be possible to use fewer particles in dose calculations to increase efficiency. Based on this idea, we have developed a new MC-based IMRT plan optimization framework that iteratively performs MC dose calculation and plan optimization. At each dose calculation step, the particle numbers for beamlets were adjusted based on the beamlet intensities obtained through solving the plan optimization problem in the last iteration step. We modified a GPU-based MC dose engine to allow simultaneous computations of a large number of beamlet doses. To test the accuracy of our modified dose engine, we compared the dose from a broad beam and the summed beamlet doses in this beam in an inhomogeneous phantom. Agreement within 1% for the maximum difference and 0.55% for the average difference was observed. We then validated the proposed MC-based optimization schemes in one lung IMRT case. It was found that the conventional scheme required 106 particles from each beamlet to achieve an optimization result that was 3% difference in fluence map and 1% difference in dose from the ground truth. In contrast, the proposed scheme achieved the same level of accuracy with on average 1.2 × 105 particles per beamlet. Correspondingly, the computation time

  18. A new Monte Carlo-based treatment plan optimization approach for intensity modulated radiation therapy.

    PubMed

    Li, Yongbao; Tian, Zhen; Shi, Feng; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

    2015-04-07

    Intensity-modulated radiation treatment (IMRT) plan optimization needs beamlet dose distributions. Pencil-beam or superposition/convolution type algorithms are typically used because of their high computational speed. However, inaccurate beamlet dose distributions may mislead the optimization process and hinder the resulting plan quality. To solve this problem, the Monte Carlo (MC) simulation method has been used to compute all beamlet doses prior to the optimization step. The conventional approach samples the same number of particles from each beamlet. Yet this is not the optimal use of MC in this problem. In fact, there are beamlets that have very small intensities after solving the plan optimization problem. For those beamlets, it may be possible to use fewer particles in dose calculations to increase efficiency. Based on this idea, we have developed a new MC-based IMRT plan optimization framework that iteratively performs MC dose calculation and plan optimization. At each dose calculation step, the particle numbers for beamlets were adjusted based on the beamlet intensities obtained through solving the plan optimization problem in the last iteration step. We modified a GPU-based MC dose engine to allow simultaneous computations of a large number of beamlet doses. To test the accuracy of our modified dose engine, we compared the dose from a broad beam and the summed beamlet doses in this beam in an inhomogeneous phantom. Agreement within 1% for the maximum difference and 0.55% for the average difference was observed. We then validated the proposed MC-based optimization schemes in one lung IMRT case. It was found that the conventional scheme required 10(6) particles from each beamlet to achieve an optimization result that was 3% difference in fluence map and 1% difference in dose from the ground truth. In contrast, the proposed scheme achieved the same level of accuracy with on average 1.2 × 10(5) particles per beamlet. Correspondingly, the computation

  19. A fast algorithm for solving a linear feasibility problem with application to Intensity-Modulated Radiation Therapy.

    PubMed

    Herman, Gabor T; Chen, Wei

    2008-03-01

    The goal of Intensity-Modulated Radiation Therapy (IMRT) is to deliver sufficient doses to tumors to kill them, but without causing irreparable damage to critical organs. This requirement can be formulated as a linear feasibility problem. The sequential (i.e., iteratively treating the constraints one after another in a cyclic fashion) algorithm ART3 is known to find a solution to such problems in a finite number of steps, provided that the feasible region is full dimensional. We present a faster algorithm called ART3+. The idea of ART3+ is to avoid unnecessary checks on constraints that are likely to be satisfied. The superior performance of the new algorithm is demonstrated by mathematical experiments inspired by the IMRT application.

  20. Sparsity constrained split feasibility for dose-volume constraints in inverse planning of intensity-modulated photon or proton therapy

    NASA Astrophysics Data System (ADS)

    Penfold, Scott; Zalas, Rafał; Casiraghi, Margherita; Brooke, Mark; Censor, Yair; Schulte, Reinhard

    2017-05-01

    A split feasibility formulation for the inverse problem of intensity-modulated radiation therapy treatment planning with dose-volume constraints included in the planning algorithm is presented. It involves a new type of sparsity constraint that enables the inclusion of a percentage-violation constraint in the model problem and its handling by continuous (as opposed to integer) methods. We propose an iterative algorithmic framework for solving such a problem by applying the feasibility-seeking CQ-algorithm of Byrne combined with the automatic relaxation method that uses cyclic projections. Detailed implementation instructions are furnished. Functionality of the algorithm was demonstrated through the creation of an intensity-modulated proton therapy plan for a simple 2D C-shaped geometry and also for a realistic base-of-skull chordoma treatment site. Monte Carlo simulations of proton pencil beams of varying energy were conducted to obtain dose distributions for the 2D test case. A research release of the Pinnacle 3 proton treatment planning system was used to extract pencil beam doses for a clinical base-of-skull chordoma case. In both cases the beamlet doses were calculated to satisfy dose-volume constraints according to our new algorithm. Examination of the dose-volume histograms following inverse planning with our algorithm demonstrated that it performed as intended. The application of our proposed algorithm to dose-volume constraint inverse planning was successfully demonstrated. Comparison with optimized dose distributions from the research release of the Pinnacle 3 treatment planning system showed the algorithm could achieve equivalent or superior results.

  1. A Phase 1 Study of Everolimus + Weekly Cisplatin + Intensity Modulated Radiation Therapy in Head-and-Neck Cancer

    SciTech Connect

    Fury, Matthew G.; Lee, Nancy Y.; Sherman, Eric; Ho, Alan L.; Rao, Shyam; Heguy, Adriana; Shen, Ronglai; Korte, Susan; Lisa, Donna; Ganly, Ian; Patel, Snehal; Wong, Richard J.; Shaha, Ashok; Shah, Jatin; Haque, Sofia; Katabi, Nora; Pfister, David G.

    2013-11-01

    Purpose: Elevated expression of eukaryotic protein synthesis initiation factor 4E (eIF4E) in histologically cancer-free margins of resected head and neck squamous cell carcinomas (HNSCCs) is mediated by mammalian target of rapamycin complex 1 (mTORC1) and has been associated with increased risk of disease recurrence. Preclinically, inhibition of mTORC1 with everolimus sensitizes cancer cells to cisplatin and radiation. Methods and Materials: This was single-institution phase 1 study to establish the maximum tolerated dose of daily everolimus given with fixed dose cisplatin (30 mg/m{sup 2} weekly × 6) and concurrent intensity modulated radiation therapy for patients with locally and/or regionally advanced head-and-neck cancer. The study had a standard 3 + 3 dose-escalation design. Results: Tumor primary sites were oral cavity (4), salivary gland (4), oropharynx (2), nasopharynx (1), scalp (1), and neck node with occult primary (1). In 4 of 4 cases in which resected HNSCC surgical pathology specimens were available for immunohistochemistry, elevated expression of eIF4E was observed in the cancer-free margins. The most common grade ≥3 treatment-related adverse event was lymphopenia (92%), and dose-limiting toxicities (DLTs) were mucositis (n=2) and failure to thrive (n=1). With a median follow up of 19.4 months, 2 patients have experienced recurrent disease. The maximum tolerated dose was everolimus 5 mg/day. Conclusions: Head-and-neck cancer patients tolerated everolimus at therapeutic doses (5 mg/day) given with weekly cisplatin and intensity modulated radiation therapy. The regimen merits further evaluation, especially among patients who are status post resection of HNSCCs that harbor mTORC1-mediated activation of eIF4E in histologically negative surgical margins.

  2. A novel software and conceptual design of the hardware platform for intensity modulated radiation therapy

    PubMed Central

    Nguyen, Dan; Ruan, Dan; O’Connor, Daniel; Woods, Kaley; Low, Daniel A.; Boucher, Salime; Sheng, Ke

    2016-01-01

    Purpose: To deliver high quality intensity modulated radiotherapy (IMRT) using a novel generalized sparse orthogonal collimators (SOCs), the authors introduce a novel direct aperture optimization (DAO) approach based on discrete rectangular representation. Methods: A total of seven patients—two glioblastoma multiforme, three head & neck (including one with three prescription doses), and two lung—were included. 20 noncoplanar beams were selected using a column generation and pricing optimization method. The SOC is a generalized conventional orthogonal collimators with N leaves in each collimator bank, where N = 1, 2, or 4. SOC degenerates to conventional jaws when N = 1. For SOC-based IMRT, rectangular aperture optimization (RAO) was performed to optimize the fluence maps using rectangular representation, producing fluence maps that can be directly converted into a set of deliverable rectangular apertures. In order to optimize the dose distribution and minimize the number of apertures used, the overall objective was formulated to incorporate an L2 penalty reflecting the difference between the prescription and the projected doses, and an L1 sparsity regularization term to encourage a low number of nonzero rectangular basis coefficients. The optimization problem was solved using the Chambolle–Pock algorithm, a first-order primal–dual algorithm. Performance of RAO was compared to conventional two-step IMRT optimization including fluence map optimization and direct stratification for multileaf collimator (MLC) segmentation (DMS) using the same number of segments. For the RAO plans, segment travel time for SOC delivery was evaluated for the N = 1, N = 2, and N = 4 SOC designs to characterize the improvement in delivery efficiency as a function of N. Results: Comparable PTV dose homogeneity and coverage were observed between the RAO and the DMS plans. The RAO plans were slightly superior to the DMS plans in sparing critical structures. On average, the maximum and

  3. A novel software and conceptual design of the hardware platform for intensity modulated radiation therapy

    SciTech Connect

    Nguyen, Dan; Ruan, Dan; O’Connor, Daniel; Woods, Kaley; Low, Daniel A.; Sheng, Ke; Boucher, Salime

    2016-02-15

    Purpose: To deliver high quality intensity modulated radiotherapy (IMRT) using a novel generalized sparse orthogonal collimators (SOCs), the authors introduce a novel direct aperture optimization (DAO) approach based on discrete rectangular representation. Methods: A total of seven patients—two glioblastoma multiforme, three head & neck (including one with three prescription doses), and two lung—were included. 20 noncoplanar beams were selected using a column generation and pricing optimization method. The SOC is a generalized conventional orthogonal collimators with N leaves in each collimator bank, where N = 1, 2, or 4. SOC degenerates to conventional jaws when N = 1. For SOC-based IMRT, rectangular aperture optimization (RAO) was performed to optimize the fluence maps using rectangular representation, producing fluence maps that can be directly converted into a set of deliverable rectangular apertures. In order to optimize the dose distribution and minimize the number of apertures used, the overall objective was formulated to incorporate an L2 penalty reflecting the difference between the prescription and the projected doses, and an L1 sparsity regularization term to encourage a low number of nonzero rectangular basis coefficients. The optimization problem was solved using the Chambolle–Pock algorithm, a first-order primal–dual algorithm. Performance of RAO was compared to conventional two-step IMRT optimization including fluence map optimization and direct stratification for multileaf collimator (MLC) segmentation (DMS) using the same number of segments. For the RAO plans, segment travel time for SOC delivery was evaluated for the N = 1, N = 2, and N = 4 SOC designs to characterize the improvement in delivery efficiency as a function of N. Results: Comparable PTV dose homogeneity and coverage were observed between the RAO and the DMS plans. The RAO plans were slightly superior to the DMS plans in sparing critical structures. On average, the maximum and

  4. SU-E-J-274: Responses of Medulloblastoma Cells to Radiation Dosimetric Parameters in Intensity-Modulated Radiation Therapy

    SciTech Connect

    Park, J; Park, J; Rogalla, S; Contag, C; Woo, D; Lee, D; Park, H; Suh, T

    2015-06-15

    Purpose: To evaluate radiation responses of the medulloblastoma cell line Daoy in intensity-modulated radiation therapy (IMRT), quantitative variations to variable radiation dosimetic parameters were tracked by bioluminescent images (BLIs). Methods: The luciferase and green fluorescent protein positive Daoy cells were cultured on dishes. The medulloblastoma cells irradiated to different dose rate, interval of fractionated doses, field margin and misalignment, and dose uniformity in IMRT were monitored using bioluminescent images. The cultured cells were placed into a dedicated acrylic phantom to deliver intensity-modulated fluences and calculate accurate predicted dose distribution. The radiation with dose rate from 0.5 Gy/min to 15 Gy/min was irradiated by adjusting monitor unit per minute and source-to-surface distances. The intervals of fractionated dose delivery were changed considering the repair time of double strand breaks (DSB) revealed by straining of gamma-H2AX.The effect of non-uniform doses on the cells were visualized by registering dose distributions and BLIs. The viability according to dosimetric parameters was correlated with bioluminescent intensities for cross-check of radiation responses. Results: The DSB and cell responses due to the first fractionated dose delivery significantly affected final tumor control rather than other parameters. The missing tumor volumes due to the smaller field margin than the tumor periphery or field misalignment caused relapse of cell responses on BLIs. The dose rate and gradient had effect on initial responses but could not bring out the distinguishable killing effect on cancer cells. Conclusion: Visualized and quantified bioluminescent images were useful to correlate the dose distributions with spatial radiation effects on cells. This would derive the effective combination of dose delivery parameters and fractionation. Radiation responses in particular IMRT configuration could be reflected to image based-dose re-optimization.

  5. Intensity-Modulated Radiation Therapy for the Treatment of Squamous Cell Anal Cancer With Para-aortic Nodal Involvement

    SciTech Connect

    Hodges, Joseph C.; Das, Prajnan; Eng, Cathy; Reish, Andrew G.; Beddar, A. Sam; Delclos, Marc E.; Krishnan, Sunil; Crane, Christopher H.

    2009-11-01

    Purpose: To determine the rates of toxicity, locoregional control, distant control, and survival in anal cancer patients with para-aortic nodal involvement, treated with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy at a single institution. Methods and Materials: Between 2001 and 2007, 6 patients with squamous cell anal cancer and para-aortic nodal involvement were treated with IMRT and concurrent infusional 5-fluorouracil and cisplatin. The primary tumor was treated with a median dose of 57.5 Gy (range, 54-60 Gy), involved para-aortic, pelvic, and inguinal lymph nodes were treated with a median dose of 55 Gy (range, 50.5-55 Gy), and noninvolved nodal regions were treated with a median dose of 45 Gy (range, 43.5-45 Gy). Results: After a median follow-up of 25 months, none of the patients had a recurrence at the primary tumor, pelvic/inguinal nodes, or para-aortic nodes, whereas 2 patients developed distant metastases to the liver. Four of the 6 patients are alive. The 3-year actuarial locoregional control, distant control, and overall survival rates were 100%, 56%, and 63%, respectively. Four of the 6 patients developed Grade 3 acute gastrointestinal toxicity during chemoradiation. Conclusions: Intensity-modulated radiotherapy and concurrent chemotherapy could potentially serve as definitive therapy in anal cancer patients with para-aortic nodal involvement. Adjuvant chemotherapy may be indicated in these patients, as demonstrated by the distant failure rates. These patients need to be followed carefully because of the potential for treatment-related toxicities.

  6. Volumetric Modulated Arc Therapy (VMAT) Treatment Planning for Superficial Tumors

    SciTech Connect

    Zacarias, Albert S.; Brown, Mellonie F.; Mills, Michael D.

    2010-10-01

    The physician's planning objective is often a uniform dose distribution throughout the planning target volume (PTV), including superficial PTVs on or near the surface of a patient's body. Varian's Eclipse treatment planning system uses a progressive resolution optimizer (PRO), version 8.2.23, for RapidArc dynamic multileaf collimator volumetric modulated arc therapy planning. Because the PRO is a fast optimizer, optimization convergence errors (OCEs) produce dose nonuniformity in the superficial area of the PTV. We present a postsurgical cranial case demonstrating the recursive method our clinic uses to produce RapidArc treatment plans. The initial RapidArc treatment plan generated using one 360{sup o} arc resulted in substantial dose nonuniformity in the superficial section of the PTV. We demonstrate the use of multiple arcs to produce improved dose uniformity in this region. We also compare the results of this superficial dose compensation method to the results of a recursive method of dose correction that we developed in-house to correct optimization convergence errors in static intensity-modulated radiation therapy treatment plans. The results show that up to 4 arcs may be necessary to provide uniform dose to the surface of the PTV with the current version of the PRO.

  7. Proton-beam vs intensity-modulated radiation therapy. Which is best for treating prostate cancer?

    PubMed

    Nguyen, Paul L; Trofimov, Alexei; Zietman, Anthony L

    2008-06-01

    There is a growing interest in the use of proton therapy for the treatment of many cancers. With its unique dose-distribution properties, proton therapy has the potential to improve the therapeutic ratio of prostate radiation by allowing for an increase in dose without a substantial increase in side effects. While much evidence supports this notion in the context of many oncologic sites, only limited clinical data have compared protons to photons in prostate cancer. Therefore, the increasing enthusiasm for the use of protons in prostate cancer has aroused considerable concern. Some have questioned its ability to limit morbidity, and others have questioned its value relative to the cost. In addition, theoretical concerns have been raised about a potential additional risk for secondary malignancies. In this article, we review the current status of the evidence supporting the use of protons in prostate cancer and discuss the active controversies that surround this modality.

  8. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    SciTech Connect

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-26

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  9. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    NASA Astrophysics Data System (ADS)

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-01

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  10. SU-E-T-809: Volumetric Modulated Arc Radiotherapy Vs. Intensity-Modulated Radiotherapy for Locally Advanced Laryngeal Carcinoma: A Dosimetric Study

    SciTech Connect

    Lu, J-Y; Huang, B-T; Zhang, W-Z; Yan, L-J

    2015-06-15

    Purpose: To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed-gantry intensity-modulated radiotherapy (IMRT) technique for locally advanced laryngeal carcinoma. Methods: CT datasets of eleven patients were included. Dual-arc VMAT and 7-field IMRT plans, which were created based on the Eclipse treatment planning system, were compared in terms of dose-volume parameters, conformity index (CI) and homogeneity index (HI) of planning target volume (PTV), as well as organ-at-risk (OAR) sparing, planning time, monitor units (MUs) and delivery time. Results: Compared with the IMRT plans, the VMAT plans provided lower D2% and better CI/HI for the high-risk PTV (PTV1), and provided better CI and comparable HI for the low-risk PTV (PTV2). Concerning the OAR sparing, the VMAT plans demonstrated significantly lower Dmax of the spinal cord (planning OAR volume, PRV) and brainstem (PRV), as well as lower Dmean and V30Gy of the right parotid. No significant differences were observed between the two plans concerning the doses delivered to the thyroid, carotid, oral cavity and left parotid. Moreover, the VMAT planning (147 ± 18 min) consumed 213% more time than the IMRT planning (48 ± 10 min). The MUs of the VMAT plans (556 ± 52) were 64% less than those of the IMRT plans (1684 ± 409), and the average delivery time (2.1 ± 0.1 min) was 66% less than that of the IMRT plans (6.3 ± 0.7 min). Conclusion: Compared with the IMRT technique, the VMAT technique can achieve superior target dose distribution and better sparing of the spinal cord, brainstem and right parotid, with less MUs and less delivery time. It is recommended for the radiotherapy of locally advanced laryngeal carcinoma.

  11. SU-E-T-808: Volumetric Modulated Arc Radiotherapy Vs. Intensity-Modulated Radiotherapy for Early-Stage Nasopharyngeal Carcinoma: A Dosimetric Study

    SciTech Connect

    Lu, J-Y; Huang, B-T; Zhang, W-Z

    2015-06-15

    Purpose: To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed-gantry intensity-modulated radiotherapy (IMRT) technique for early-stage nasopharyngeal carcinoma. Methods: CT datasets of ten patients with early-stage nasopharyngeal carcinoma were included. Dual-arc VMAT and nine-field IMRT plans were generated for each case, and were then compared in terms of planning-target-volume (PTV) coverage, conformity index (CI) and homogeneity index (HI), as well as organ-at-risk (OAR) sparing, planning time, monitor units (MUs) and delivery time. Results: Compared with the IMRT plans, the VMAT plans provided comparable HI and CI of PTVnx (PTV of primary tumor of nasopharynx), superior CI and inferior HI of PTVnd (PTV of lymph nodes), as well as superior CI and comparable HI of PTV60 (high-risk PTV). The VMAT plans provided better sparing of the spinal cord, oral cavity and normal tissue, but inferior sparing of the brainstem planning OAR volume (PRV), larynx and parotids, as well as comparable sparing of the spinal cord PRV, brainstem, lenses, optic nerves, optic chiasm. Moreover, the average planning time (181.6 ± 36.0 min) for the VMAT plans was 171% more than that of the IMRT plans (68.1 ± 7.6 min). The MUs of the VMAT plans (609 ± 43) were 70% lower than those of the IMRT plans (2071 ± 262), while the average delivery time (2.2 ± 0.1 min) was 66% less than that of the IMRT plans (6.6 ± 0.4 min). Conclusion: Compared with the IMRT technique, the VMAT technique can achieve similar or slightly superior target dose distribution, with no significant advantages on OAR sparing, and it can achieve significant reductions of MUs and delivery time.

  12. SU-E-T-302: Dosimetric Comparison Between Volumetric Modulated Arc Radiotherapy and Intensity-Modulated Radiotherapy for Locally Recurrent Nasopharyngeal Carcinoma

    SciTech Connect

    Lu, J-Y; Huang, B-T; Zhang, J-Y; Ma, C-C

    2015-06-15

    Purpose: To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed-gantry intensity-modulated radiotherapy (IMRT) technique for locally recurrent nasopharyngeal carcinoma. Methods: CT datasets of eleven nasopharyngeal-carcinoma patients were included. Dual-arc VMAT and seven-field IMRT plans were created for each case, and were then compared in terms of conformity index (CI), homogeneity index (HI) of the planning target volume (PTV), organ-at-risk (OAR) sparing, monitor unit (MU) and delivery time. Results: The D98% (near-minimal dose) of PTV in the VMAT plans was slightly lower than that of the IMRT plans (P < 0.05), while the CI was higher than that of the IMRT plans (P < 0.05). No significant difference was found in the HI between the two plans (P > 0.05). Compared with the IMRT plans, the VMAT plans demonstrated lower Dmean (mean dose) of the bilateral temporal lobes and the whole surrounding normal tissue (P < 0.05), but slightly higher Dmean of brainstem (P < 0.05). In terms of the other OARs, no significant differences were found (P > 0.05). The MUs of the VMAT plans (672 ± 112) was significantly lower than that of the IMRT plans (917 ± 206), by 25 ± 13% (P < 0.05). The average delivery time of the VMAT plans (2.3 ± 0.1 min) was less than that of the IMRT plans (5.1 ± 0.4 min), by 54 ± 3%. Conclusion: For locally recurrent nasopharyngeal carcinoma, the VMAT technique could achieve equivalent or superior dose distribution of the target and better protect the bilateral temporal lobes, compared with the IMRT technique. Moreover, it could reduce the MU and delivery time effectively.

  13. Four-Week Course of Radiation for Breast Cancer Using Hypofractionated Intensity Modulated Radiation Therapy With an Incorporated Boost

    SciTech Connect

    Freedman, Gary M. . E-mail: Gary.Freedman@FCCC.edu; Anderson, Penny R.; Goldstein, Lori J.; Ma Changming; Li Jinsheng; Swaby, Ramona F.; Litwin, Samuel; Watkins-Bruner, Deborah; Sigurdson, Elin R.; Morrow, Monica

    2007-06-01

    Purpose: Standard radiation for early breast cancer requires daily treatment for 6 to 7 weeks. This is an inconvenience to many women, and for some a barrier for breast conservation. We present the acute toxicity of a 4-week course of hypofractionated radiation. Methods and Materials: A total of 75 patients completed radiation on a Phase II trial approved by the hospital institutional review board. Eligibility criteria were broad to include any patient normally eligible for standard radiation: age {>=}18 years, invasive or in situ cancer, American Joint Committee on Cancer Stage 0 to II, breast-conserving surgery, and any systemic therapy not given concurrently. The median age was 52 years (range, 31-81 years). Of the patients, 15% had ductal carcinoma in situ, 67% T1, and 19% T2; 71% were N0, 17% N1, and 12% NX. Chemotherapy was given before radiation in 44%. Using photon intensity-modulated radiation therapy and incorporated electron beam boost, the whole breast received 45 Gy and the lumpectomy bed 56 Gy in 20 treatments over 4 weeks. Results: The maximum acute skin toxicity by the end of treatment was Grade 0 in 9 patients (12%), Grade 1 in 49 (65%) and Grade 2 in 17 (23%). There was no Grade 3 or higher skin toxicity. After radiation, all Grade 2 toxicity had resolved by 6 weeks. Hematologic toxicity was Grade 0 in most patients except for Grade 1 neutropenia in 2 patients, and Grade 1 anemia in 11 patients. There were no significant differences in baseline vs. 6-week posttreatment patient-reported or physician-reported cosmetic scores. Conclusions: This 4-week course of postoperative radiation using intensity-modulated radiation therapy is feasible and is associated with acceptable acute skin toxicity and quality of life. Long-term follow-up data are needed. This radiation schedule may represent an alternative both to longer 6-week to 7-week standard whole-breast radiation and more radically shortened 1-week, partial-breast treatment schedules.

  14. Assessments of Sequential Intensity Modulated Radiation Therapy Boost (SqIB) Treatments Using HART

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-05-01

    A retrospective study was pursued to evaluate the SqIB treatments performed on ten head and neck cancer patients(n=10).Average prescription doses (PDs) of 39 Gy,15Gy and 17.8Gy were delivered consecutively from larger to smaller planning target volumes(ptvs) in three different treatment plans using 6 MV X-ray photon beams from a Linear accelerator (SLA Linac, Elekta) on BID weak on-weak off schedules. These plans were statistically evaluated on basis of plan indices (PIs),dose response of targets and critical structures, and dose tolerance(DT) of various organs utilizing the DVH analysis automated software known as Histogram Analysis in Radiation Therapy-HART(S.Jang et al., 2008, Med Phys 35, p.2812). Mean SqIB PIs were found consistent with the reported values for varying radio-surgical systems.The 95.5%(n=10)of each ptvs and the gross tumor volume also received 95% (n=10)of PDs in treatments. The average volume of ten organs (N=10) affected by each PDs shrank with decreasing size of ptvs in above plans.A largest volume of Oropharynx (79%,n=10,N=10) irradiated at PD, but the largest volume of Larynx (98%, n=10, N=10) was vulnerable to DT of structure (TD50).Thus, we have demonstrated the efficiency and accuracy of HART in the assessment of Linac based plans in radiation therapy treatments of cancer.

  15. Intensity Modulated Proton and Photon Therapy for Early Prostate Cancer With or Without Transperineal Injection of a Polyethylen Glycol Spacer: A Treatment Planning Comparison Study

    SciTech Connect

    Weber, Damien C.; Zilli, Thomas; Vallee, Jean Paul; Rouzaud, Michel; Miralbell, Raymond; Cozzi, Luca

    2012-11-01

    Purpose: Rectal toxicity is a serious adverse effect in early-stage prostate cancer patients treated with curative radiation therapy (RT). Injecting a spacer between Denonvilliers' fascia increases the distance between the prostate and the anterior rectal wall and may thus decrease the rectal radiation-induced toxicity. We assessed the dosimetric impact of this spacer with advanced delivery RT techniques, including intensity modulated RT (IMRT), volumetric modulated arc therapy (VMAT), and intensity modulated proton beam RT (IMPT). Methods and Materials: Eight prostate cancer patients were simulated for RT with or without spacer. Plans were computed for IMRT, VMAT, and IMPT using the Eclipse treatment planning system using both computed tomography spacer+ and spacer- data sets. Prostate {+-} seminal vesicle planning target volume [PTV] and organs at risk (OARs) dose-volume histograms were calculated. The results were analyzed using dose and volume metrics for comparative planning. Results: Regardless of the radiation technique, spacer injection decreased significantly the rectal dose in the 60- to 70-Gy range. Mean V{sub 70Gy} and V{sub 60Gy} with IMRT, VMAT, and IMPT planning were 5.3 {+-} 3.3%/13.9 {+-} 10.0%, 3.9 {+-} 3.2%/9.7 {+-} 5.7%, and 5.0 {+-} 3.5%/9.5 {+-} 4.7% after spacer injection. Before spacer administration, the corresponding values were 9.8 {+-} 5.4% (P=.012)/24.8 {+-} 7.8% (P=.012), 10.1 {+-} 3.0% (P=.002)/17.9 {+-} 3.9% (P=.003), and 9.7 {+-} 2.6% (P=.003)/14.7% {+-} 2.7% (P=.003). Importantly, spacer injection usually improved the PTV coverage for IMRT. With this technique, mean V{sub 70.2Gy} (P=.07) and V{sub 74.1Gy} (P=0.03) were 100 {+-} 0% to 99.8 {+-} 0.2% and 99.1 {+-} 1.2% to 95.8 {+-} 4.6% with and without Spacer, respectively. As a result of spacer injection, bladder doses were usually higher but not significantly so. Only IMPT managed to decrease the rectal dose after spacer injection for all dose levels, generally with no observed

  16. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    PubMed Central

    Hofmann, Kerstin M; Schell, Stefan; Wilkens, Jan J

    2012-01-01

    Abstract Laser-accelerated particles are a promising option for radiation therapy of cancer by potentially combining a compact, cost-efficient treatment unit with the physical advantages of charged particle beams. To design such a treatment unit we consider different dose delivery schemes and analyze the necessary devices in the required particle beam line for each case. Furthermore, we point out that laser-driven treatment units may be ideal tools for motion adaptation during radiotherapy. Reasons for this are the potential of a flexible gantry and the time structure of the beam with high particle numbers in ultrashort bunches. One challenge that needs to be addressed is the secondary radiation produced in several beam line elements. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) PMID:22930653

  17. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams.

    PubMed

    Hofmann, Kerstin M; Schell, Stefan; Wilkens, Jan J

    2012-11-01

    Laser-accelerated particles are a promising option for radiation therapy of cancer by potentially combining a compact, cost-efficient treatment unit with the physical advantages of charged particle beams. To design such a treatment unit we consider different dose delivery schemes and analyze the necessary devices in the required particle beam line for each case. Furthermore, we point out that laser-driven treatment units may be ideal tools for motion adaptation during radiotherapy. Reasons for this are the potential of a flexible gantry and the time structure of the beam with high particle numbers in ultrashort bunches. One challenge that needs to be addressed is the secondary radiation produced in several beam line elements.

  18. Shortening Delivery Times of Intensity Modulated Proton Therapy by Reducing Proton Energy Layers During Treatment Plan Optimization

    SciTech Connect

    Water, Steven van de; Kooy, Hanne M.; Heijmen, Ben J.M.; Hoogeman, Mischa S.

    2015-06-01

    Purpose: To shorten delivery times of intensity modulated proton therapy by reducing the number of energy layers in the treatment plan. Methods and Materials: We have developed an energy layer reduction method, which was implemented into our in-house-developed multicriteria treatment planning system “Erasmus-iCycle.” The method consisted of 2 components: (1) minimizing the logarithm of the total spot weight per energy layer; and (2) iteratively excluding low-weighted energy layers. The method was benchmarked by comparing a robust “time-efficient plan” (with energy layer reduction) with a robust “standard clinical plan” (without energy layer reduction) for 5 oropharyngeal cases and 5 prostate cases. Both plans of each patient had equal robust plan quality, because the worst-case dose parameters of the standard clinical plan were used as dose constraints for the time-efficient plan. Worst-case robust optimization was performed, accounting for setup errors of 3 mm and range errors of 3% + 1 mm. We evaluated the number of energy layers and the expected delivery time per fraction, assuming 30 seconds per beam direction, 10 ms per spot, and 400 Giga-protons per minute. The energy switching time was varied from 0.1 to 5 seconds. Results: The number of energy layers was on average reduced by 45% (range, 30%-56%) for the oropharyngeal cases and by 28% (range, 25%-32%) for the prostate cases. When assuming 1, 2, or 5 seconds energy switching time, the average delivery time was shortened from 3.9 to 3.0 minutes (25%), 6.0 to 4.2 minutes (32%), or 12.3 to 7.7 minutes (38%) for the oropharyngeal cases, and from 3.4 to 2.9 minutes (16%), 5.2 to 4.2 minutes (20%), or 10.6 to 8.0 minutes (24%) for the prostate cases. Conclusions: Delivery times of intensity modulated proton therapy can be reduced substantially without compromising robust plan quality. Shorter delivery times are likely to reduce treatment uncertainties and costs.

  19. Shortening delivery times of intensity modulated proton therapy by reducing proton energy layers during treatment plan optimization.

    PubMed

    van de Water, Steven; Kooy, Hanne M; Heijmen, Ben J M; Hoogeman, Mischa S

    2015-06-01

    To shorten delivery times of intensity modulated proton therapy by reducing the number of energy layers in the treatment plan. We have developed an energy layer reduction method, which was implemented into our in-house-developed multicriteria treatment planning system "Erasmus-iCycle." The method consisted of 2 components: (1) minimizing the logarithm of the total spot weight per energy layer; and (2) iteratively excluding low-weighted energy layers. The method was benchmarked by comparing a robust "time-efficient plan" (with energy layer reduction) with a robust "standard clinical plan" (without energy layer reduction) for 5 oropharyngeal cases and 5 prostate cases. Both plans of each patient had equal robust plan quality, because the worst-case dose parameters of the standard clinical plan were used as dose constraints for the time-efficient plan. Worst-case robust optimization was performed, accounting for setup errors of 3 mm and range errors of 3% + 1 mm. We evaluated the number of energy layers and the expected delivery time per fraction, assuming 30 seconds per beam direction, 10 ms per spot, and 400 Giga-protons per minute. The energy switching time was varied from 0.1 to 5 seconds. The number of energy layers was on average reduced by 45% (range, 30%-56%) for the oropharyngeal cases and by 28% (range, 25%-32%) for the prostate cases. When assuming 1, 2, or 5 seconds energy switching time, the average delivery time was shortened from 3.9 to 3.0 minutes (25%), 6.0 to 4.2 minutes (32%), or 12.3 to 7.7 minutes (38%) for the oropharyngeal cases, and from 3.4 to 2.9 minutes (16%), 5.2 to 4.2 minutes (20%), or 10.6 to 8.0 minutes (24%) for the prostate cases. Delivery times of intensity modulated proton therapy can be reduced substantially without compromising robust plan quality. Shorter delivery times are likely to reduce treatment uncertainties and costs. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. The Evaluation and Study of Modern Radiation Dosimetry Methods as Applied to Advanced Radiation Therapy Treatments Using Intensity Modulated Megavoltage Photon Beams

    NASA Astrophysics Data System (ADS)

    Stambaugh, Cassandra K. K.

    The purpose of this work is to evaluate quasi-3D arrays for use with intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) and to determine their clinical relevance. This is achieved using a Delta4 from Scandidos and ArcCheck from Sun Nuclear and the associated software. While certain aspects of these devices and software have been previously evaluated, the main goal of this work is to evaluate the new aspects, such as reconstructing dose on a patient CT set, and extending the capabilities. This includes the capability to reconstruct the dose based on a helical delivery as well as studying the dose to a moving target using measurement-guided motion simulations. It was found that Sun Nuclear's ArcCheck/3DVH system exhibited excellent agreement for dose reconstruction for IMRT/VMAT using a traditional C-arm linear accelerator and stringent 2%/2mm comparison constraints. It also is a powerful tool for measurement-guided dose estimates for moving targets, allowing for many simulations to be performed based on one measurement and the target motion data. For dose reconstruction for a helical delivery, the agreement was not as good for the stringent comparison but was reasonable for the clinically acceptable 3%/3mm comparison. Scandidos' Delta4 shows good agreement with stringent 2%/2mm constraints for its dose reconstruction on the phantom. However, the dose reconstruction on the patient CT set was poor and needs more work. Overall, it was found that quasi-3D arrays are powerful tools for dose reconstruction and treatment plan comparisons. The ability to reconstruct the dose allows for a dose resolution comparable to the treatment plan, which negates the previous issues with inadequate sampling and resolution issues found when just comparing the diodes. The ability to quickly and accurately compare many plans and target motions with minimum setup makes the quasi-3D array an attractive tool for both commissioning and patient specific

  1. Dosimetric and Radiobiological Consequences of Computed Tomography–Guided Adaptive Strategies for Intensity Modulated Radiation Therapy of the Prostate

    SciTech Connect

    Battista, Jerry J.; Johnson, Carol; Turnbull, David; Kempe, Jeff; Bzdusek, Karl; Van Dyk, Jacob; Bauman, Glenn

    2013-12-01

    Purpose: To examine a range of scenarios for image-guided adaptive radiation therapy of prostate cancer, including different schedules for megavoltage CT imaging, patient repositioning, and dose replanning. Methods and Materials: We simulated multifraction dose distributions with deformable registration using 35 sets of megavoltage CT scans of 13 patients. We computed cumulative dose–volume histograms, from which tumor control probabilities and normal tissue complication probabilities (NTCPs) for rectum were calculated. Five-field intensity modulated radiation therapy (IMRT) with 18-MV x-rays was planned to achieve an isocentric dose of 76 Gy to the clinical target volume (CTV). The differences between D{sub 95}, tumor control probability, V{sub 70Gy}, and NTCP for rectum, for accumulated versus planned dose distributions, were compared for different target volume sizes, margins, and adaptive strategies. Results: The CTV D{sub 95} for IMRT treatment plans, averaged over 13 patients, was 75.2 Gy. Using the largest CTV margins (10/7 mm), the D{sub 95} values accumulated over 35 fractions were within 2% of the planned value, regardless of the adaptive strategy used. For tighter margins (5 mm), the average D{sub 95} values dropped to approximately 73.0 Gy even with frequent repositioning, and daily replanning was necessary to correct this deficit. When personalized margins were applied to an adaptive CTV derived from the first 6 treatment fractions using the STAPLE (Simultaneous Truth and Performance Level Estimation) algorithm, target coverage could be maintained using a single replan 1 week into therapy. For all approaches, normal tissue parameters (rectum V{sub 70Gy} and NTCP) remained within acceptable limits. Conclusions: The frequency of adaptive interventions depends on the size of the CTV combined with target margins used during IMRT optimization. The application of adaptive target margins (<5 mm) to an adaptive CTV determined 1 week into therapy minimizes

  2. Dosimetric and radiobiological consequences of computed tomography-guided adaptive strategies for intensity modulated radiation therapy of the prostate.

    PubMed

    Battista, Jerry J; Johnson, Carol; Turnbull, David; Kempe, Jeff; Bzdusek, Karl; Van Dyk, Jacob; Bauman, Glenn

    2013-12-01

    To examine a range of scenarios for image-guided adaptive radiation therapy of prostate cancer, including different schedules for megavoltage CT imaging, patient repositioning, and dose replanning. We simulated multifraction dose distributions with deformable registration using 35 sets of megavoltage CT scans of 13 patients. We computed cumulative dose-volume histograms, from which tumor control probabilities and normal tissue complication probabilities (NTCPs) for rectum were calculated. Five-field intensity modulated radiation therapy (IMRT) with 18-MV x-rays was planned to achieve an isocentric dose of 76 Gy to the clinical target volume (CTV). The differences between D95, tumor control probability, V70Gy, and NTCP for rectum, for accumulated versus planned dose distributions, were compared for different target volume sizes, margins, and adaptive strategies. The CTV D95 for IMRT treatment plans, averaged over 13 patients, was 75.2 Gy. Using the largest CTV margins (10/7 mm), the D95 values accumulated over 35 fractions were within 2% of the planned value, regardless of the adaptive strategy used. For tighter margins (5 mm), the average D95 values dropped to approximately 73.0 Gy even with frequent repositioning, and daily replanning was necessary to correct this deficit. When personalized margins were applied to an adaptive CTV derived from the first 6 treatment fractions using the STAPLE (Simultaneous Truth and Performance Level Estimation) algorithm, target coverage could be maintained using a single replan 1 week into therapy. For all approaches, normal tissue parameters (rectum V(70Gy) and NTCP) remained within acceptable limits. The frequency of adaptive interventions depends on the size of the CTV combined with target margins used during IMRT optimization. The application of adaptive target margins (<5 mm) to an adaptive CTV determined 1 week into therapy minimizes the need for subsequent dose replanning. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Importance of Radiation Oncologist Experience Among Patients With Head-and-Neck Cancer Treated With Intensity-Modulated Radiation Therapy

    PubMed Central

    Boero, Isabel J.; Paravati, Anthony J.; Xu, Beibei; Cohen, Ezra E.W.; Mell, Loren K.; Le, Quynh-Thu

    2016-01-01

    Purpose Over the past decade, intensity-modulated radiation therapy (IMRT) has replaced conventional radiation techniques in the management of head-and-neck cancers (HNCs). We conducted this population-based study to evaluate the influence of radiation oncologist experience on outcomes in patients with HNC treated with IMRT compared with patients with HNC treated with conventional radiation therapy. Methods We identified radiation providers from Medicare claims of 6,212 Medicare beneficiaries with HNC treated between 2000 and 2009. We analyzed the impact of provider volume on all-cause mortality, HNC mortality, and toxicity end points after treatment with either conventional radiation therapy or IMRT. All analyses were performed by using either multivariable Cox proportional hazards or Fine-Gray regression models controlling for potential confounding variables. Results Among patients treated with conventional radiation, we found no significant relationship between provider volume and patient survival or any toxicity end point. Among patients receiving IMRT, those treated by higher-volume radiation oncologists had improved survival compared with those treated by low-volume providers. The risk of all-cause mortality decreased by 21% for every additional five patients treated per provider per year (hazard ratio [HR], 0.79; 95% CI, 0.67 to 0.94). Patients treated with IMRT by higher-volume providers had decreased HNC-specific mortality (subdistribution HR, 0.68; 95% CI, 0.50 to 0.91) and decreased risk of aspiration pneumonia (subdistribution HR, 0.72; 95% CI, 0.52 to 0.99). Conclusion Patients receiving IMRT for HNC had improved outcomes when treated by higher-volume providers. These findings will better inform patients and providers when making decisions about treatment, and emphasize the critical importance of high-quality radiation therapy for optimal treatment of HNC. PMID:26729432

  4. Predictors of radiation pneumonitis in patients receiving intensity modulated radiation therapy for Hodgkin and non-Hodgkin lymphoma.

    PubMed

    Pinnix, Chelsea C; Smith, Grace L; Milgrom, Sarah; Osborne, Eleanor M; Reddy, Jay P; Akhtari, Mani; Reed, Valerie; Arzu, Isidora; Allen, Pamela K; Wogan, Christine F; Fanale, Michele A; Oki, Yasuhiro; Turturro, Francesco; Romaguera, Jorge; Fayad, Luis; Fowler, Nathan; Westin, Jason; Nastoupil, Loretta; Hagemeister, Fredrick B; Rodriguez, M Alma; Ahmed, Sairah; Nieto, Yago; Dabaja, Bouthaina

    2015-05-01

    Few studies to date have evaluated factors associated with the development of radiation pneumonitis (RP) in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), especially in patients treated with contemporary radiation techniques. These patients represent a unique group owing to the often large radiation target volumes within the mediastinum and to the potential to receive several lines of chemotherapy that add to pulmonary toxicity for relapsed or refractory disease. Our objective was to determine the incidence and clinical and dosimetric risk factors associated with RP in lymphoma patients treated with intensity modulated radiation therapy (IMRT) at a single institution. We retrospectively reviewed clinical charts and radiation records of 150 consecutive patients who received mediastinal IMRT for HL and NHL from 2009 through 2013. Clinical and dosimetric predictors associated with RP according to Radiation Therapy Oncology Group (RTOG) acute toxicity criteria were identified in univariate analysis using the Pearson χ(2) test and logistic multivariate regression. Mediastinal radiation was administered as consolidation therapy in 110 patients with newly diagnosed HL or NHL and in 40 patients with relapsed or refractory disease. The overall incidence of RP (RTOG grades 1-3) was 14% in the entire cohort. Risk of RP was increased for patients who received radiation for relapsed or refractory disease (25%) versus those who received consolidation therapy (10%, P=.019). Several dosimetric parameters predicted RP, including mean lung dose of >13.5 Gy, V20 of >30%, V15 of >35%, V10 of >40%, and V5 of >55%. The likelihood ratio χ(2) value was highest for V5 >55% (χ(2) = 19.37). In using IMRT to treat mediastinal lymphoma, all dosimetric parameters predicted RP, although small doses to large volumes of lung had the greatest influence. Patients with relapsed or refractory lymphoma who received salvage chemotherapy and hematopoietic stem cell transplantation

  5. A comparison of liver protection among 3-D conformal radiotherapy, intensity-modulated radiotherapy and RapidArc for hepatocellular carcinoma

    PubMed Central

    2014-01-01

    Purpose The analysis was designed to compare dosimetric parameters among 3-D conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) and RapidArc (RA) to identify which can achieve the lowest risk of radiation-induced liver disease (RILD) for hepatocellular carcinoma (HCC). Methods Twenty patients with HCC were enrolled in this study. Dosimetric values for 3DCRT, IMRT, and RA were calculated for total dose of 50 Gy/25f. The percentage of the normal liver volume receiving >40, >30, >20, >10, and >5 Gy (V40, V30, V20, V10 and V5) were evaluated to determine liver toxicity. V5, V10, V20, V30 and Dmean of liver were compared as predicting parameters for RILD. Other parameters included the conformal index (CI), homogeneity index (HI), and hot spot (V110%) for the planned target volume (PTV) as well as the monitor units (MUs) for plan efficiency, the mean dose (Dmean) for the organs at risk (OARs) and the maximal dose at 1% volume (D1%) for the spinal cord. Results The Dmean of IMRT was higher than 3DCRT (p = 0.045). For V5, there was a significant difference: RA > IMRT >3DCRT (p <0.05). 3DCRT had a lower V10 and higher V20, V30 values for liver than RA (p <0.05). RA and IMRT achieved significantly better CI and lower V110% values than 3DCRT (p <0.05). RA had better HI, lower MUs and shorter delivery time than 3DCRT or IMRT (p <0.05). Conclusion For right lobe tumors, RapidArc may have the lowest risk of RILD with the lowest V20 and V30 compared with 3DCRT or IMRT. For diameters of tumors >8 cm in our study, the value of Dmean for 3DCRT was lower than IMRT or RapidArc. This may indicate that 3DCRT is more suitable for larger tumors. PMID:24502643

  6. Correlation between patients' anatomical characteristics and interfractional internal prostate motion during intensity modulated radiation therapy for prostate cancer.

    PubMed

    Maruoka, Shintaroh; Yoshioka, Yasuo; Isohashi, Fumiaki; Suzuki, Osamu; Seo, Yuji; Otani, Yuki; Akino, Yuichi; Takahashi, Yutaka; Sumida, Iori; Ogawa, Kazuhiko

    2015-01-01

    Intensity modulated radiation therapy (IMRT) is one of a standard treatment for localized prostate cancer. Although lower complication is expected for smaller target margin, determination of optimal margin is important. For bony-structure based registration, internal prostate motion is the main factor determining the margin from clinical target volume to planning target volume. The purpose of this study was to measure interfractional internal motion of the prostate and to identity the factors which enlarge or reduce the margin, with special focus on patients' anatomical characteristics. The 586 image sets of 16 patients acquired with megavoltage cone beam computed tomography were analyzed. For each patient, prostate shift in three directions was recorded for each fraction to calculate the required margin. Correlations between these values and patients' anatomical characteristics were evaluated. The posteriorly required margin correlated positively with rectal volume and rectal mean area (p = 0.015 and p = 0.008), while random error in lateral, craniocaudal and anteroposterior direction correlated negatively (p = 0.014, 0.04 and 0.0026, respectively) with body mass index (BMI). In addition to the previously identified factor of distended rectum, BMI was newly identified as another significant factor influencing interfractional internal prostate motion.

  7. Secondary radiation doses of intensity-modulated radiotherapy and proton beam therapy in patients with lung and liver cancer.

    PubMed

    Kim, Seonkyu; Min, Byung Jun; Yoon, Myonggeun; Kim, Jinsung; Shin, Dong Ho; Lee, Se Byeong; Park, Sung Yong; Cho, Sungkoo; Kim, Dae Hyun

    2011-03-01

    To compare the secondary radiation doses following intensity-modulated radiotherapy (IMRT) and proton beam therapy (PBT) in patients with lung and liver cancer. IMRT and PBT were planned for three lung cancer and three liver cancer patients. The treatment beams were delivered to phantoms and the corresponding secondary doses during irradiation were measured at various points 20-50 cm from the beam isocenter using ion chamber and CR-39 detectors for IMRT and PBT, respectively. The secondary dose per Gy (i.e., a treatment dose of 1Gy) from PBT for lung and liver cancer, measured 20-50 cm from the isocenter, ranged from 0.17 to 0.086 mGy. The secondary dose per Gy from IMRT, however, ranged between 5.8 and 1.0 mGy, indicating that PBT is associated with a smaller dose of secondary radiation than IMRT. The internal neutron dose per Gy from PBT for lung and liver cancer, 20-50 cm from the isocenter, ranged from 0.03 to 0.008 mGy. The secondary dose from PBT is less than or compatible to the secondary dose from conventional IMRT. The internal neutron dose generated by the interaction between protons and body material is generally much less than the external neutron dose from the treatment head. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  8. Optimal matching of 3D film-measured and planned doses for intensity-modulated radiation therapy quality assurance.

    PubMed

    Shin, Dongho; Yoon, Myonggeun; Park, Sung Yong; Park, Dong Hyun; Lee, Se Byeong; Kim, Dae Yong; Cho, Kwan Ho

    2007-01-01

    Intensity-modulated radiation therapy (IMRT) is one of the most complex applications of radiotherapy that requires patient-specific quality assurance (QA). Here, we describe a novel method of 3-dimensional (3D) dose-verification using 12 acrylic slabs in a 3D phantom (30 x 30 x 12 cm(3)) with extended dose rate (EDR2) films, which is both faster than conventionally used methods, and clinically useful. With custom-written software modules written in Microsoft Excel Visual Basic Application, the measured and planned dose distributions for the axial, coronal, and sagittal planes were superimposed by matching their origins, and the point doses were compared at all matched positions. Then, an optimization algorithm was used to correct the detected setup errors. The results show that this optimization method significantly reduces the average maximum dose difference by 7.73% and the number of points showing dose differences of more than 5% by 8.82% relative to the dose differences without an optimization. Our results indicate that the dose difference was significantly decreased with optimization and this optimization method is statistically reliable and effective. The results of 3D optimization are discussed in terms of various patient-specific QA data obtained from statistical analyses.

  9. A set cover approach to fast beam orientation optimization in intensity modulated radiation therapy for total marrow irradiation

    NASA Astrophysics Data System (ADS)

    Lee, Chieh-Hsiu Jason; Aleman, Dionne M.; Sharpe, Michael B.

    2011-09-01

    The beam orientation optimization (BOO) problem in intensity modulated radiation therapy (IMRT) treatment planning is a nonlinear problem, and existing methods to obtain solutions to the BOO problem are time consuming due to the complex nature of the objective function and size of the solution space. These issues become even more difficult in total marrow irradiation (TMI), where many more beams must be used to cover a vastly larger treatment area than typical site-specific treatments (e.g., head-and-neck, prostate, etc). These complications result in excessively long computation times to develop IMRT treatment plans for TMI, so we attempt to develop methods that drastically reduce treatment planning time. We transform the BOO problem into the classical set cover problem (SCP) and use existing methods to solve SCP to obtain beam solutions. Although SCP is NP-Hard, our methods obtain beam solutions that result in quality treatments in minutes. We compare our approach to an integer programming solver for the SCP to illustrate the speed advantage of our approach.

  10. A case study of radiotherapy planning for Intensity Modulation Radiation Therapy for the whole scalp with matching electron treatment

    SciTech Connect

    Sponseller, Patricia; Paravathaneni, Upendra

    2013-07-01

    The purpose of this report is to communicate a technique to match an electron field to the dose distribution of an Intensity-Modulated Radiation Therapy (IMRT) plan. A patient with multiple areas of squamous cell carcinoma over the scalp was treated using 60 Gy in 2.0-Gy fractions to the entire scalp and first echelon nodes with multiple 6-MV photon fields. To deliver an adequate dose to the scalp, a custom 1.0-cm bolus helmet was fashioned using a solid piece of aquaplast. Along with the IMRT scalp treatment, a left zygoma area was treated with electrons matching the anterior border of the IMRT dose distribution. The border was matched by creating a left lateral field with the multileaf collimator shaped to the IMRT dose distribution. The result indicated an adequate dose to the skin match between the IMRT plan and the electron field. Results were confirmed using optically stimulated luminescence placed at the skin match area, so that the dose matched the prescription within 10%.

  11. Early Outcome of Prostate Intensity Modulated Radiation Therapy (IMRT) Incorporating a Simultaneous Intra-Prostatic MRI Directed Boost

    PubMed Central

    Schild, Michael H; Schild, Steven E; Wong, William W; Vora, Sujay A; Silva, Alvin C; Silva, Annelise M; Daniels, Thomas B; Keole, Sameer R

    2015-01-01

    This study assessed the feasibility and outcomes of treating prostate cancer with intensity modulated radiotherapy (IMRT) incorporating a Magnetic Resonance Imaging (MRI) directed boost. Seventy-eight men received IMRT for localized prostate cancer. The entire prostate received 77.4Gy in 43 fractions and simultaneous intra-prostatic boosts (SIB) of 83Gy were administered to increase the dose to the MRI identified malignancy. In 16 (21%) patients, the MRI didn't detect a neoplasm and these patients received an SIB of 81Gy to the posterior prostate. Androgen Deprivation Therapy (ADT) was also administered to 32 (41%) patients. The 3-year rates of biochemical control, local control, distant control, and survival were 92%, 98%, 95%, and 95% respectively. While grade 1-2 toxicities were common, there were only 2 patients who suffered grade 3 toxicity. These patients developed strictures which were dilated resulting in improvement in symptoms such that both had grade 1-2 toxicity at last follow up examination. The results of this program of IMRT incorporating a MRI directed intra-prostatic boost suggest this technique is feasible and well tolerated. This technique appears to shift the therapeutic index favorably by boosting the malignancy to the highest dose without increasing the doses administered to the bladder and rectum. PMID:25717423

  12. Verification of the dose attenuation of a newly developed vacuum cushion for intensity-modulated radiation therapy of prostate cancer.

    PubMed

    Takakura, Toru; Ito, Yoshiyuki; Higashikawa, Akinori; Nishiyama, Tomohiro; Sakamoto, Takashi

    2016-07-01

    This study measured the dose attenuation of a newly developed vacuum cushion for intensity-modulated radiation therapy (IMRT) of prostate cancer, and verified the effect of dose-correction accuracy in a radiation treatment planning system (RTPS). The new cushion was filled with polystyrene foams inflated 15-fold (Sφ ≒ 1 mm) to reduce contraction caused by air suction and was compared to normal polystyrene foam inflated to 50-fold (Sφ ≒ 2 mm). The dose attenuation at several thicknesses of compression bag filled with normal and low-inflation materials was measured using an ionization chamber; and then the calculated RTPS dose was compared to ionization chamber measurements, while the new cushion was virtually included as region of interest in the calculation area. The dose attenuation rate of the normal cushion was 0.010 %/mm (R (2) = 0.9958), compared to 0.031 %/mm (R (2) = 0.9960) in the new cushion. Although the dose attenuation rate of the new cushion was three times that of the normal cushion, the high agreement between calculated dose by RTPS and ionization chamber measurements was within approximately 0.005 %/mm. Thus, the results of the current study indicate that the new cushion may be effective in clinical use for dose calculation accuracy in RTPS.

  13. Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image

    NASA Astrophysics Data System (ADS)

    Yeo, Inhwan Jason; Jung, Jae Won; Chew, Meng; Kim, Jong Oh; Wang, Brian; Di Biase, Steven; Zhu, Yunping; Lee, Dohyung

    2009-09-01

    A straightforward and accurate method was developed to verify the delivery of intensity-modulated radiation therapy (IMRT) and to reconstruct the dose in a patient. The method is based on a computational algorithm that linearly describes the physical relationship between beamlets and dose-scoring voxels in a patient and the dose image from an electronic portal imaging device (EPID). The relationship is expressed in the form of dose response functions (responses) that are quantified using Monte Carlo (MC) particle transport techniques. From the dose information measured by the EPID the received patient dose is reconstructed by inversely solving the algorithm. The unique and novel non-iterative feature of this algorithm sets it apart from many existing dose reconstruction methods in the literature. This study presents the algorithm in detail and validates it experimentally for open and IMRT fields. Responses were first calculated for each beamlet of the selected fields by MC simulation. In-phantom and exit film dosimetry were performed on a flat phantom. Using the calculated responses and the algorithm, the exit film dose was used to inversely reconstruct the in-phantom dose, which was then compared with the measured in-phantom dose. The dose comparison in the phantom for all irradiated fields showed a pass rate of higher than 90% dose points given the criteria of dose difference of 3% and distance to agreement of 3 mm.

  14. The radiobiological effect of intra-fraction dose-rate modulation in intensity modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Bewes, J. M.; Suchowerska, N.; Jackson, M.; Zhang, M.; McKenzie, D. R.

    2008-07-01

    Intensity-modulated radiation therapy (IMRT) achieves optimal dose conformity to the tumor through the use of spatially and temporally modulated radiation fields. In particular, average dose rate and instantaneous dose rate (pulse amplitude) are highly variable within a single IMRT fraction. In this study we isolate these variables and determine their impact on cell survival. Survival was assessed using a clonogenic assay. Two cell lines of differing radiosensitivity were examined: melanoma (MM576) and non-small cell lung cancer (NCI-H460). The survival fraction was observed to be independent of instantaneous dose rate. A statistically significant trend to increased survival was observed as the average dose rate was decreased, for a constant total dose. The results are relevant to IMRT practice, where average treatment times can be significantly extended to allow for movement of the multi-leaf collimator (MLC). Our in vitro study adds to the pool of theoretical evidence for the consequences of protracted treatments. We find that extended delivery times can substantially increase the cell survival. This also suggests that regional variation in the dose-rate history across a tumor, which is inherent to IMRT, will affect radiation dose efficacy.

  15. SU-E-T-07: 4DCT Robust Optimization for Esophageal Cancer Using Intensity Modulated Proton Therapy

    SciTech Connect

    Liao, L; Yu, J; Zhu, X; Li, H; Zhang, X; Li, Y; Lim, G

    2015-06-15

    Purpose: To develop a 4DCT robust optimization method to reduce the dosimetric impact from respiratory motion in intensity modulated proton therapy (IMPT) for esophageal cancer. Methods: Four esophageal cancer patients were selected for this study. The different phases of CT from a set of 4DCT were incorporated into the worst-case dose distribution robust optimization algorithm. 4DCT robust treatment plans were designed and compared with the conventional non-robust plans. Result doses were calculated on the average and maximum inhale/exhale phases of 4DCT. Dose volume histogram (DVH) band graphic and ΔD95%, ΔD98%, ΔD5%, ΔD2% of CTV between different phases were used to evaluate the robustness of the plans. Results: Compare to the IMPT plans optimized using conventional methods, the 4DCT robust IMPT plans can achieve the same quality in nominal cases, while yield a better robustness to breathing motion. The mean ΔD95%, ΔD98%, ΔD5% and ΔD2% of CTV are 6%, 3.2%, 0.9% and 1% for the robustly optimized plans vs. 16.2%, 11.8%, 1.6% and 3.3% from the conventional non-robust plans. Conclusion: A 4DCT robust optimization method was proposed for esophageal cancer using IMPT. We demonstrate that the 4DCT robust optimization can mitigate the dose deviation caused by the diaphragm motion.

  16. Intensity-modulated radiation therapy for early-stage breast cancer: is it ready for prime time?

    PubMed Central

    Chan, Tabitha Y; Tan, Poh Wee; Tang, Johann I

    2017-01-01

    Whole breast external beam radiotherapy (WBEBRT) is commonly used as an essential arm in the treatment management of women with early-stage breast cancer. Dosimetry planning for conventional WBEBRT typically involves a pair of tangential fields. Advancement in radiation technology and techniques has the potential to improve treatment outcomes with clinically meaningful long-term benefits. However, this advancement must be balanced with safety and improved efficacy. Intensity-modulated radiation therapy (IMRT) is an advanced technique that shows promise in improving the planning process and radiation delivery. Early data on utilizing IMRT for WBEBRT demonstrate more homogenous dose distribution with reduction in organs at risk doses. This translates to toxicities reduction. The two common descriptors for IMRT are forward-planning “fields in field” and inverse planning. Unlike IMRT for other organs, the aim of IMRT for breast planning is to achieve dose homogeneity and not organ conformality. The aim of this paper was to evaluate whether IMRT is ready for prime time based on these three points: 1) workload impact, 2) the clinical impact on the patient’s quality of life, and 3) the appropriateness and applicability to clinical practice. PMID:28360536

  17. Comparison of intensity-modulated radiotherapy with three-dimensional conformal radiation therapy planning for glioblastoma multiforme

    SciTech Connect

    Chan, Maria F.; Schupak, Karen; Burman, Chandra; Chui, C.-S.; Ling, C. Clifton

    2003-12-31

    This study was designed to assess the feasibility and potential benefit of using intensity-modulated radiotherapy (IMRT) planning for patients newly diagnosed with glioblastoma multiforme (GBM). Five consecutive patients with confirmed histopathologically GBM were entered into the study. These patients were planned and treated with 3-dimensional conformal radiation therapy (3DCRT) using our standard plan of 3 noncoplanar wedged fields. They were then replanned with the IMRT method that included a simultaneous boost to the gross tumor volume (GTV). The dose distributions and dose-volume histograms (DHVs) for the planning treatment volume (PTV), GTV, and the relevant critical structures, as obtained with 3DCRT and IMRT, respectively, were compared. In both the 3DCRT and IMRT plans, 59.4 Gy was delivered to the GTV plus a margin of 2.5 cm, with doses to critical structures below the tolerance threshold. However, with the simultaneous boost in IMRT, a higher tumor dose of {approx}70 Gy could be delivered to the GTV, while still maintaining the uninvolved brain at dose levels of the 3DCRT technique. In addition, our experience indicated that IMRT planning is less labor intensive and time consuming than 3DCRT planning. Our study shows that IMRT planning is feasible and efficient for radiotherapy of GBM. In particular, IMRT can deliver a simultaneous boost to the GTV while better sparing the normal brain and other critical structures.

  18. Limited Advantages of Intensity-Modulated Radiotherapy Over 3D Conformal Radiation Therapy in the Adjuvant Management of Gastric Cancer

    SciTech Connect

    Alani, Shlomo; Soyfer, Viacheslav; Strauss, Natan; Schifter, Dan; Corn, Benjamin W.

    2009-06-01

    Purpose: Although chemoradiotherapy was considered the standard adjuvant treatment for gastric cancer, a recent Phase III trial (Medical Research Council Adjuvant Gastric Infusional Chemotherapy [MAGIC]) did not include radiotherapy in the randomization scheme because it was considered expendable. Given radiotherapy's potential, efforts needed to be made to optimize its use for treating gastric cancer. We assessed whether intensity-modulated radiotherapy (IMRT) could improve upon our published results in patients treated with three-dimensional (3D) conformal therapy. Methods and Materials: Fourteen patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a noncoplanar four-field arrangement. Subsequently, a nine-field IMRT plan was designed using a CMS Xio IMRT version 4.3.3 module. Two IMRT beam arrangements were evaluated: beam arrangement 1 consisted of gantry angles of 0 deg., 53 deg., 107 deg., 158 deg., 204 deg., 255 deg., and 306 deg.. Beam arrangement 2 consisted of gantry angles of 30 deg., 90 deg., 315 deg., and 345 deg.; a gantry angle of 320 deg./couch, 30 deg.; and a gantry angle of 35{sup o}/couch, 312{sup o}. Both the target volume coverage and the dose deposition in adjacent critical organs were assessed in the plans. Dose-volume histograms were generated for the clinical target volume, kidneys, spine, and liver. Results: Comparison of the clinical target volumes revealed satisfactory coverage by the 95% isodose envelope using either IMRT or 3D conformal therapy. However, IMRT was only marginally better than 3D conformal therapy at protecting the spine and kidneys from radiation. Conclusions: IMRT confers only a marginal benefit in the adjuvant treatment of gastric cancer and should be used only in the small subset of patients with risk factors for kidney disease or those with a preexisting nephropathy.

  19. Breast Intensity-Modulated Radiation Therapy Reduces Time Spent With Acute Dermatitis for Women of All Breast Sizes During Radiation

    SciTech Connect

    Freedman, Gary M. Li Tianyu; Nicolaou, Nicos; Chen Yan; Ma, Charlie C.-M.; Anderson, Penny R.

    2009-07-01

    Purpose: To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT). Methods and Materials: The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment. Results: The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts. Conclusions: Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

  20. Predictors of Radiation Pneumonitis in Patients Receiving Intensity-Modulated Radiation Therapy for Hodgkin and Non-Hodgkin Lymphoma

    PubMed Central

    Pinnix, Chelsea C.; Smith, Grace L.; Milgrom, Sarah; Osborne, Eleanor M.; Reddy, Jay P.; Akhtari, Mani; Reed, Valerie; Arzu, Isidora; Allen, Pamela K.; Wogan, Christine F.; Fanale, Michele A.; Oki, Yasuhiro; Turturro, Francesco; Romaguera, Jorge; Fayad, Luis; Fowler, Nathan; Westin, Jason; Nastoupil, Loretta; Hagemeister, Fredrick B.; Rodriguez, Alma; Ahmed, Sairah; Nieto, Yago; Dabaja, Bouthaina

    2015-01-01

    Purpose Few studies to date have evaluated factors associated with the development of radiation pneumonitis (RP) in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), especially in patients treated with contemporary radiation techniques. These patients represent a unique group owing to the often large radiation target volumes within the mediastinum and to the potential to receive several lines of chemotherapy that add to pulmonary toxicity for relapsed or refractory disease. Our objective was to determine the incidence and clinical and dosimetric risk factors associated with RP in lymphoma patients treated with intensity modulated radiation therapy (IMRT) at a single institution. Methods We retrospectively reviewed clinical charts and radiation records of 150 consecutive patients who received mediastinal IMRT for HL and NHL from 2009 through 2013. Clinical and dosimetric predictors associated with RP per the Radiation Therapy Oncology Group (RTOG) acute toxicity criteria were identified in univariate analysis using the Pearson χ2 test and logistic multivariate regression. Results Mediastinal radiation was administered as consolidation therapy in 110 patients with newly diagnosed HL or NHL and in 40 patients with relapsed or refractory disease. The overall incidence of RP (RTOG grade 1–3) was 14% in the entire cohort. Risk of RP was increased for patients who received radiation for relapsed or refractory disease (25%) versus those who received consolidation (10%, P=0.019). Several dosimetric parameters predicted RP, including mean lung dose (MLD) >13.5 Gy, V20 >30%, V15 >35%, V10 >40% and V5>55%. The likelihood ratio (LR) χ2 value was highest for V5< 55% (LR χ2=19.37). Conclusions In using IMRT to treat mediastinal lymphoma, all dosimetric parameters predicted RP, although small doses to large volumes of lung had the greatest influence. Patients with relapsed or refractory lymphoma who received salvage chemotherapy and hematopoietic stem cell

  1. Limited Impact of Setup and Range Uncertainties, Breathing Motion, and Interplay Effects in Robustly Optimized Intensity Modulated Proton Therapy for Stage III Non-small Cell Lung Cancer.

    PubMed

    Inoue, Tatsuya; Widder, Joachim; van Dijk, Lisanne V; Takegawa, Hideki; Koizumi, Masahiko; Takashina, Masaaki; Usui, Keisuke; Kurokawa, Chie; Sugimoto, Satoru; Saito, Anneyuko I; Sasai, Keisuke; Van't Veld, Aart A; Langendijk, Johannes A; Korevaar, Erik W

    2016-11-01

    To investigate the impact of setup and range uncertainties, breathing motion, and interplay effects using scanning pencil beams in robustly optimized intensity modulated proton therapy (IMPT) for stage III non-small cell lung cancer (NSCLC). Three-field IMPT plans were created using a minimax robust optimization technique for 10 NSCLC patients. The plans accounted for 5- or 7-mm setup errors with ±3% range uncertainties. The robustness of the IMPT nominal plans was evaluated considering (1) isotropic 5-mm setup errors with ±3% range uncertainties; (2) breathing motion; (3) interplay effects; and (4) a combination of items 1 and 2. The plans were calculated using 4-dimensional and average intensity projection computed tomography images. The target coverage (TC, volume receiving 95% of prescribed dose) and homogeneity index (D2 - D98, where D2 and D98 are the least doses received by 2% and 98% of the volume) for the internal clinical target volume, and dose indexes for lung, esophagus, heart and spinal cord were compared with that of clinical volumetric modulated arc therapy plans. The TC and homogeneity index for all plans were within clinical limits when considering the breathing motion and interplay effects independently. The setup and range uncertainties had a larger effect when considering their combined effect. The TC decreased to <98% (clinical threshold) in 3 of 10 patients for robust 5-mm evaluations. However, the TC remained >98% for robust 7-mm evaluations for all patients. The organ at risk dose parameters did not significantly vary between the respective robust 5-mm and robust 7-mm evaluations for the 4 error types. Compared with the volumetric modulated arc therapy plans, the IMPT plans showed better target homogeneity and mean lung and heart dose parameters reduced by about 40% and 60%, respectively. In robustly optimized IMPT for stage III NSCLC, the setup and range uncertainties, breathing motion, and interplay effects have limited impact on

  2. TU-EF-304-07: Monte Carlo-Based Inverse Treatment Plan Optimization for Intensity Modulated Proton Therapy

    SciTech Connect

    Li, Y; Tian, Z; Jiang, S; Jia, X; Song, T; Wu, Z; Liu, Y

    2015-06-15

    Purpose: Intensity-modulated proton therapy (IMPT) is increasingly used in proton therapy. For IMPT optimization, Monte Carlo (MC) is desired for spots dose calculations because of its high accuracy, especially in cases with a high level of heterogeneity. It is also preferred in biological optimization problems due to the capability of computing quantities related to biological effects. However, MC simulation is typically too slow to be used for this purpose. Although GPU-based MC engines have become available, the achieved efficiency is still not ideal. The purpose of this work is to develop a new optimization scheme to include GPU-based MC into IMPT. Methods: A conventional approach using MC in IMPT simply calls the MC dose engine repeatedly for each spot dose calculations. However, this is not the optimal approach, because of the unnecessary computations on some spots that turned out to have very small weights after solving the optimization problem. GPU-memory writing conflict occurring at a small beam size also reduces computational efficiency. To solve these problems, we developed a new framework that iteratively performs MC dose calculations and plan optimizations. At each dose calculation step, the particles were sampled from different spots altogether with Metropolis algorithm, such that the particle number is proportional to the latest optimized spot intensity. Simultaneously transporting particles from multiple spots also mitigated the memory writing conflict problem. Results: We have validated the proposed MC-based optimization schemes in one prostate case. The total computation time of our method was ∼5–6 min on one NVIDIA GPU card, including both spot dose calculation and plan optimization, whereas a conventional method naively using the same GPU-based MC engine were ∼3 times slower. Conclusion: A fast GPU-based MC dose calculation method along with a novel optimization workflow is developed. The high efficiency makes it attractive for clinical

  3. The evaluation of the feasibility of carotid sparing intensity modulated radiation therapy technique for comprehensive breast irradiation.

    PubMed

    Erpolat, Ozge Petek; Akmansu, Muge; Catli Dinc, Serap; Akkan, Koray; Bora, Huseyin

    2017-04-01

    To investigate the feasibility of carotid sparing intensity modulated radiation therapy (CS-IMRT) to minimize the radiation dose to carotid arteries for comprehensive irradiation of breast cancer patients who have risk factors for atherosclerosis. The dose distribution of CS-IMRT technique and the conventional irradiation technique were also compared. Ten patients who were previously treated with comprehensive three-dimensional conformal radiation therapy (3DCRT) were selected. DICOM data were used to contour the carotid artery and to create the virtual CS-IMRT plans for each patient. 3DCRT and CS-IMRT plans were compared in terms of conformity index, homogeneity index, and the doses to organ at risk and carotid arteries. The homogeneity and conformity indices were better with CS-IMRT plans compared to 3DCRT plan. The homogeneity index was 1.13 vs 1.11 (p=0.007) for 3DCRT and CS-IMRT and the conformity index was 0.96 vs 0.97 (p=0.006) for 3DCRT and CS-IMRT. The radiation dose to the carotid arteries were reduced by applying CS-IMRT without compromising the target volume coverage. When the carotid artery was considered as organ at risk for CS-IMRT planning, the median of V50 was decreased to 0% from 12.5% compared to 3DCRT plans (p=0.017). The median of the maximum dose to the carotid artery was decreased under 50Gy with CS-IMRT. CS-IMRT can significantly reduce the unnecessary radiation dose to the carotid arteries compared with conventional 3DCRT technique while maintaining target volume coverage. CS-IMRT technique can be considered for breast cancer patient with high risk of atherosclerosis. Copyright © 2017. Published by Elsevier Ltd.

  4. Dosimetric evaluation of planning target volume margin reduction for prostate cancer via image-guided intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Hwang, Taejin; Kang, Sei-Kwon; Cheong, Kwang-Ho; Park, Soah; Yoon, Jai-Woong; Han, Taejin; Kim, Haeyoung; Lee, Meyeon; Kim, Kyoung-Joo; Bae, Hoonsik; Suh, Tae-Suk

    2015-07-01

    The aim of this study was to quantitatively estimate the dosimetric benefits of the image-guided radiation therapy (IGRT) system for the prostate intensity-modulated radiation therapy (IMRT) delivery. The cases of eleven patients who underwent IMRT for prostate cancer without a prostatectomy at our institution between October 2012 and April 2014 were retrospectively analyzed. For every patient, clinical target volume (CTV) to planning target volume (PTV) margins were uniformly used: 3 mm, 5 mm, 7 mm, 10 mm, 12 mm, and 15 mm. For each margin size, the IMRT plans were independently optimized by one medical physicist using Pinnalce3 (ver. 8.0.d, Philips Medical System, Madison, WI) in order to maintain the plan quality. The maximum geometrical margin (MGM) for every CT image set, defined as the smallest margin encompassing the rectum at least at one slice, was between 13 mm and 26 mm. The percentage rectum overlapping PTV (%V ROV ), the rectal normal tissue complication probability (NTCP) and the mean rectal dose (%RD mean ) increased in proportion to the increase of PTV margin. However the bladder NTCP remained around zero to some extent regardless of the increase of PTV margin while the percentage bladder overlapping PTV (%V BOV ) and the mean bladder dose (%BD mean ) increased in proportion to the increase of PTV margin. Without relatively large rectum or small bladder, the increase observed for rectal NTCP, %RDmean and %BD mean per 1-mm PTV margin size were 1.84%, 2.44% and 2.90%, respectively. Unlike the behavior of the rectum or the bladder, the maximum dose on each femoral head had little effect on PTV margin. This quantitative study of the PTV margin reduction supported that IG-IMRT has enhanced the clinical effects over prostate cancer with the reduction of normal organ complications under the similar level of PTV control.

  5. TH-C-BRD-12: Robust Intensity Modulated Proton Therapy Plan Can Eliminate Junction Shifts for Craniospinal Irradiation

    SciTech Connect

    Liao, L; Jiang, S; Li, Y; Wang, X; Li, H; Zhu, X; Sahoo, N; Gillin, M; Mahajan, A; Grosshans, D; Zhang, X; Lim, G

    2014-06-15

    Purpose: The passive scattering proton therapy (PSPT) technique is the commonly used radiotherapy technique for craniospinal irradiation (CSI). However, PSPT involves many numbers of junction shifts applied over the course of treatment to reduce the cold and hot regions caused by field mismatching. In this work, we introduced a robust planning approach to develop an optimal and clinical efficient techniques for CSI using intensity modulated proton therapy (IMPT) so that junction shifts can essentially be eliminated. Methods: The intra-fractional uncertainty, in which two overlapping fields shift in the opposite directions along the craniospinal axis, are incorporated into the robust optimization algorithm. Treatment plans with junction sizes 3,5,10,15,20,25 cm were designed and compared with the plan designed using the non-robust optimization. Robustness of the plans were evaluated based on dose profiles along the craniospinal axis for the plans applying 3 mm intra-fractional shift. The dose intra-fraction variations (DIV) at the junction are used to evaluate the robustness of the plans. Results: The DIVs are 7.9%, 6.3%, 5.0%, 3.8%, 2.8% and 2.2%, for the robustly optimized plans with junction sizes 3,5,10,15,20,25 cm. The DIV are 10% for the non-robustly optimized plans with junction size 25 cm. The dose profiles along the craniospinal axis exhibit gradual and tapered dose distribution. Using DIVs less than 5% as maximum acceptable intrafractional variation, the overlapping region can be reduced to 10 cm, leading to potential reduced number of the fields. The DIVs are less than 5% for 5 mm intra-fractional shifts with junction size 25 cm, leading to potential no-junction-shift for CSI using IMPT. Conclusion: This work is the first report of the robust optimization on CSI based on IMPT. We demonstrate that robust optimization can lead to much efficient carniospinal irradiation by eliminating the junction shifts.

  6. A dosimetric analysis of dose escalation using two intensity-modulated radiation therapy techniques in locally advanced pancreatic carcinoma

    SciTech Connect

    Brown, Michael W.; Ning, Holly; Arora, Barbara; Albert, Paul S.; Poggi, Matthew; Camphausen, Kevin; Citrin, Deborah . E-mail: citrind@mail.nih.gov

    2006-05-01

    Purpose: To perform an analysis of three-dimensional conformal radiation therapy (3D-CRT), sequential boost intensity-modulated radiation therapy (IMRTs), and integrated boost IMRT (IMRTi) for dose escalation in unresectable pancreatic carcinoma. Methods and Materials: Computed tomography images from 15 patients were used. Treatment plans were generated using 3D-CRT, IMRTs, and IMRTi for dose levels of 54, 59.4, and 64.8 Gy. Plans were analyzed for target coverage, doses to liver, kidneys, small bowel, and spinal cord. Results: Three-dimensional-CRT exceeded tolerance to small bowel in 1 of 15 (6.67%) patients at 54 Gy, and 4 of 15 (26.7%) patients at 59.4 and 64.8 Gy. 3D-CRT exceeded spinal cord tolerance in 1 of 15 patients (6.67%) at 59.4 Gy and liver constraints in 1 of 15 patients (6.67%) at 64.8 Gy; no IMRT plans exceeded tissue tolerance. Both IMRT techniques reduced the percentage of total kidney volume receiving 20 Gy (V20), the percentage of small bowel receiving 45 Gy (V45), and the percentage of liver receiving 35 Gy (V35). IMRTi appeared superior to IMRTs in reducing the total kidney V20 (p < 0.0001), right kidney V20 (p < 0.0001), and small bowel V45 (p = 0.02). Conclusions: Sequential boost IMRT and IMRTi improved the ability to achieve normal tissue dose goals compared with 3D-CRT. IMRTi allowed dose escalation to 64.8 Gy with acceptable normal tissue doses and superior dosimetry compared with 3D-CRT and IMRTs.

  7. Adaptive Planning in Intensity-Modulated Radiation Therapy for Head and Neck Cancers: Single-Institution Experience and Clinical Implications

    SciTech Connect

    Ahn, Peter H.; Chen, Chin-Cheng; Ahn, Andrew I.; Hong, Linda; Scripes, Paola G.; Shen Jin; Lee, Chen-Chiao; Miller, Ekeni; Kalnicki, Shalom; Garg, Madhur K.

    2011-07-01

    Purpose: Anatomic changes and positional variability during intensity-modulated radiation therapy (IMRT) for head and neck cancer can lead to clinically significant dosimetric changes. We report our single-institution experience using an adaptive protocol and correlate these changes with anatomic and positional changes during treatment. Methods and Materials: Twenty-three sequential head and neck IMRT patients underwent serial computed tomography (CT) scans during their radiation course. After undergoing the planning CT scan, patients underwent planned rescans at 11, 22, and 33 fractions; a total of 89 scans with 129 unique CT plan combinations were thus analyzed. Positional variability and anatomic changes during treatment were correlated with changes in dosimetric parameters to target and avoidance structures between planning CT and subsequent scans. Results: A total of 15/23 patients (65%) benefited from adaptive planning, either due to inadequate dose to gross disease or to increased dose to organs at risk. Significant differences in primary and nodal targets (planning target volume, gross tumor volume, and clinical tumor volume), parotid, and spinal cord dosimetric parameters were noted throughout the treatment. Correlations were established between these dosimetric changes and weight loss, fraction number, multiple skin separations, and change in position of the skull, mandible, and cervical spine. Conclusions: Variations in patient positioning and anatomy changes during IMRT for head and neck cancer can affect dosimetric parameters and have wide-ranging clinical implications. The interplay between random positional variability and gradual anatomic changes requires careful clinical monitoring and frequent use of CT- based image-guided radiation therapy, which should determine variations necessitating new plans.

  8. Comparison of a new noncoplanar intensity-modulated radiation therapy technique for craniospinal irradiation with 3 coplanar techniques

    SciTech Connect

    Hansen, Anders T.; Lukacova, Slavka; Lassen-Ramshad, Yasmin; Petersen, Jørgen B.

    2015-01-01

    When standard conformal x-ray technique for craniospinal irradiation is used, it is a challenge to achieve satisfactory dose coverage of the target including the area of the cribriform plate, while sparing organs at risk. We present a new intensity-modulated radiation therapy (IMRT), noncoplanar technique, for delivering irradiation to the cranial part and compare it with 3 other techniques and previously published results. A total of 13 patients who had previously received craniospinal irradiation with standard conformal x-ray technique were reviewed. New treatment plans were generated for each patient using the noncoplanar IMRT-based technique, a coplanar IMRT-based technique, and a coplanar volumetric-modulated arch therapy (VMAT) technique. Dosimetry data for all patients were compared with the corresponding data from the conventional treatment plans. The new noncoplanar IMRT technique substantially reduced the mean dose to organs at risk compared with the standard radiation technique. The 2 other coplanar techniques also reduced the mean dose to some of the critical organs. However, this reduction was not as substantial as the reduction obtained by the noncoplanar technique. Furthermore, compared with the standard technique, the IMRT techniques reduced the total calculated radiation dose that was delivered to the normal tissue, whereas the VMAT technique increased this dose. Additionally, the coverage of the target was significantly improved by the noncoplanar IMRT technique. Compared with the standard technique, the coplanar IMRT and the VMAT technique did not improve the coverage of the target significantly. All the new planning techniques increased the number of monitor units (MU) used—the noncoplanar IMRT technique by 99%, the coplanar IMRT technique by 122%, and the VMAT technique by 26%—causing concern for leak radiation. The noncoplanar IMRT technique covered the target better and decreased doses to organs at risk compared with the other techniques

  9. Multicriteria Optimization in Intensity-Modulated Radiation Therapy Treatment Planning for Locally Advanced Cancer of the Pancreatic Head

    SciTech Connect

    Hong, Theodore S. Craft, David L.; Carlsson, Fredrik; Bortfeld, Thomas R.

    2008-11-15

    Purpose: Intensity-modulated radiation therapy (IMRT) affords the potential to decrease radiation therapy-associated toxicity by creating highly conformal dose distributions. However, the inverse planning process can create a suboptimal plan despite meeting all constraints. Multicriteria optimization (MCO) may reduce the time-consuming iteration loop necessary to develop a satisfactory plan while providing information regarding trade-offs between different treatment planning goals. In this exploratory study, we examine the feasibility and utility of MCO in physician plan selection in patients with locally advanced pancreatic cancer (LAPC). Methods and Materials: The first 10 consecutive patients with LAPC treated with IMRT were evaluated. A database of plans (Pareto surface) was created that met the inverse planning goals. The physician then navigated to an 'optimal' plan from the point on the Pareto surface at which kidney dose was minimized. Results: Pareto surfaces were created for all 10 patients. A physician was able to select a plan from the Pareto surface within 10 minutes for all cases. Compared with the original (treated) IMRT plans, the plan selected from the Pareto surface had a lower stomach mean dose in 9 of 10 patients, although often at the expense of higher kidney dose than with the treated plan. Conclusion: The MCO is feasible in patients with LAPC and allows the physician to choose a satisfactory plan quickly. Generally, when given the opportunity, the physician w