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Das IJ, Compton JJ, Bajaj A, Johnstone PA. Intra- and inter-physician variability in target volume delineation in radiation therapy. JOURNAL OF RADIATION RESEARCH 2021:rrab080. [PMID: 34505151 DOI: 10.1093/jrr/rrab080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/17/2021] [Indexed: 06/13/2023]
Abstract
Reduction in setup errors is advocated through daily imaging and adaptive therapy, where the target volume is drawn daily. Previous studies suggest that inter-physician volume variation is significant (1.5 cm standard deviation [SD]); however, there are limited data for intra-physician consistency in daily target volume delineation, which is investigated in this study. Seven patients with lung cancer were chosen based on the perceived difficulty of contouring their disease, varying from simple parenchymal lung nodules to lesions with extensive adjacent atelectasis. Four physicians delineated the gross tumor volume (GTV) for each patient on 10 separate days to see the intra- and inter-physician contouring. Isocenter coordinates (x, y and z), target volume (cm3), and largest dimensions on anterior-posterior (AP) and lateral views were recorded for each GTV. Our results show that the variability among the physicians was reflected by target volumes ranging from +109% to -86% from the mean while isocenter coordinate changes were minimal; 3.8, 1.7 and 1.9 mm for x, y and z coordinates, respectively. The orthogonal image (AP and lateral) change varied 16.3 mm and 15.0 mm respectively among days and physicians. We conclude than when performing daily imaging, random variability in contouring resulted in isocenter changes up to ±3.8 mm in our study. The shape of the target varied within ±16 mm. This study suggests that when using daily imaging to track isocenter, target volume, or treatment parameters, physicians should be aware of personal variability when considering margins added to the target volume in daily decision making especially for difficult cases.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Julia J Compton
- Hancock Regional Hospital, Sue Ann Wortman Cancer Center, 801 N State St, Greenfield, IN 46410, USA
| | - Amishi Bajaj
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Peter A Johnstone
- Department of Radiation Oncology, Lee Moffitt Cancer Center, Magnolia Dr, Tampa, FL 33612, USA
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2
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Hadzipasic M, Giantini-Larsen AM, Tatsui CE, Shin JH. Emerging Percutaneous Ablative and Radiosurgical Techniques for Treatment of Spinal Metastases. Neurosurg Clin N Am 2020; 31:141-150. [DOI: 10.1016/j.nec.2019.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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3
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Gören M, Taşkın ZC. A column generation approach for evaluating delivery efficiencies of collimator technologies in IMRT treatment planning. Phys Med Biol 2015; 60:1989-2004. [DOI: 10.1088/0031-9155/60/5/1989] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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4
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Kim HJ, Kim S, Park YK, Kim JI, Park JM, Ye SJ. Multileaf collimator tongue-and-groove effect on depth and off-axis doses: A comparison of treatment planning data with measurements and Monte Carlo calculations. Med Dosim 2015; 40:271-8. [DOI: 10.1016/j.meddos.2015.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 11/03/2014] [Accepted: 01/22/2015] [Indexed: 10/23/2022]
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5
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Historical Development of Stereotactic Ablative Radiotherapy. STEREOTACTIC BODY RADIATION THERAPY 2012. [DOI: 10.1007/174_2012_540] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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6
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7
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Xu Q, Hamilton RJ, Schowengerdt RA, Alexander B, Jiang SB. Lung tumor tracking in fluoroscopic video based on optical flow. Med Phys 2009; 35:5351-9. [PMID: 19175094 PMCID: PMC2673603 DOI: 10.1118/1.3002323] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Respiratory gating and tumor tracking for dynamic multileaf collimator delivery require accurate and real-time localization of the lung tumor position during treatment. Deriving tumor position from external surrogates such as abdominal surface motion may have large uncertainties due to the intra- and interfraction variations of the correlation between the external surrogates and internal tumor motion. Implanted fiducial markers can be used to track tumors fluoroscopically in real time with sufficient accuracy. However, it may not be a practical procedure when implanting fiducials bronchoscopically. In this work, a method is presented to track the lung tumor mass or relevant anatomic features projected in fluoroscopic images without implanted fiducial markers based on an optical flow algorithm. The algorithm generates the centroid position of the tracked target and ignores shape changes of the tumor mass shadow. The tracking starts with a segmented tumor projection in an initial image frame. Then, the optical flow between this and all incoming frames acquired during treatment delivery is computed as initial estimations of tumor centroid displacements. The tumor contour in the initial frame is transferred to the incoming frames based on the average of the motion vectors, and its positions in the incoming frames are determined by fine-tuning the contour positions using a template matching algorithm with a small search range. The tracking results were validated by comparing with clinician determined contours on each frame. The position difference in 95% of the frames was found to be less than 1.4 pixels (approximately 0.7 mm) in the best case and 2.8 pixels (approximately 1.4 mm) in the worst case for the five patients studied.
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Affiliation(s)
- Qianyi Xu
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 19111, USA.
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8
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Siochi RAC. Optimized removal of the tongue-and-groove underdose via constrained partial synchronization and variable depth recursion. Phys Med Biol 2009; 54:1369-81. [PMID: 19204387 DOI: 10.1088/0031-9155/54/5/017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Full synchronization (FS) leaf sequencing removes tongue-and-groove underdosages (TGU) but increases the number of segments. Constrained partial synchronization (CPS) uses a minimum tongue-and-groove ratio (TGR) to reduce the number of segments while achieving acceptable TGUs. TGR is the ratio of non-overlapping intensities that irradiate a common junction. For TGRs of 1, 1.5 and 2, the TGUs were measured as 18%, 4% and 0%, respectively, for a 6 MV beam and a Siemens 82 leaf MLC. The extraction and sweep processes of the variable depth recursion (VDR) leaf-sequencing algorithm were constrained to satisfy a minimum TGR. For a Siemens MLC and 15 clinical cases, VDR with a TGR = 1.5 produced 7% more segments than the unsynchronized VDR, while a fully synchronized sweeping window algorithm produces 62% more segments. For random intensity maps, VDR with CPS produced significantly fewer segments than an unsynchronized sweeping window. Similar results can be obtained for MLCs that interdigitate. This has implications for direct aperture optimization algorithms (DAO) that use the sweeping window as a starting point (Pinnacle), for which a significant TGU has been observed. The concept of CPS can be applied to DAO by choosing appropriate levels for each of the segments in DAO.
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Affiliation(s)
- R Alfredo C Siochi
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
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9
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Liu Y, Shi C, Tynan P, Papanikolaou N. Dosimetric characteristics of dual-layer multileaf collimation for small-field and intensity-modulated radiation therapy applications. J Appl Clin Med Phys 2008; 9:15-29. [PMID: 18714277 PMCID: PMC5721708 DOI: 10.1120/jacmp.v9i2.2709] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 01/14/2008] [Accepted: 01/14/2008] [Indexed: 11/23/2022] Open
Abstract
The purpose of the present work was to measure the performance characteristics in the penumbra region and on the leaf‐end of an innovative dual‐layer micro multileaf collimator (DmMLC). The DmMLC consists of two orthogonal (upper and lower) layers of leaves; a standard MLC consists of one layer. The DmMLC provides unique performance characteristics in smoothing dose undulation, reducing leaf‐end transmission, and reducing MLC field dependence of the leaf stepping angle. Two standard MLCs (80‐leaf and 120‐leaf versions: Varian Medical Systems, Palo Alto, CA), a DmMLC (AccuKnife: Initia Medical Technology, Canton, MA), and a Cerrobend (Cerro Metal Products, Bellefonte, PA) block were used in performance studies involving a triangular field, a cross leaf‐end field, and a circular field. Measurements were made with 6‐MV X‐rays and extended dose range film at a depth of 5 cm in Solid Water (Gammex rmi, Middleton, WI) at a source–axis distance of 100 cm. The field penumbra width measured between the 20% and 80% isodose lines through the MLC‐80, MLC‐120, DmMLC, and Cerrobend block were 9.0, 5.0, 3.0, and 2.0 mm respectively. The dose undulation amplitude of the 50% isodose line was measured as 5.5, 2.0, and 0.5 mm for the MLC‐80, MLC‐120, and DmMLC respectively. The planar dose difference between the MLC‐80, MLC‐120, and DmMLC against Cerrobend block was measured as ranging at ±52.5%,±35.0%, and ±20.0% respectively. The leaf‐end transmission was measured at 22.4% in maximum and 15.4% in average when closing a single layer of the DmMLC, and at 2.4% in maximum and 2.1% in average when closing both layers. The MLC dependence of the leaf stepping angle with the DmMLC ranged from 45 degrees to 90 degrees. The standard MLC leaf stepping angle ranged from 0 degrees to 90 degrees. In conclusion, the dose undulation, leaf‐end transmission, and MLC field dependence of the leaf stepping angle with the DmMLC were remarkably reduced as compared with those of the standard MLCs. And as compared with Cerrobend block, the DmMLC provided very comparable performance in field‐edge smoothing and in the shaping of complex fields. PACS numbers: 87.56.Jk, 87.56.Nk, 87.56.Nj, 87.57.Nt
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Affiliation(s)
- Yaxi Liu
- Cancer Therapy and Research Center, Medical Physics Department, University of Texas Health Science Center, Radiation Oncology Department, San Antonio, Texas, U.S.A
| | - Chengyu Shi
- Cancer Therapy and Research Center, Medical Physics Department, University of Texas Health Science Center, Radiation Oncology Department, San Antonio, Texas, U.S.A
| | - Patricia Tynan
- Cancer Therapy and Research Center, Medical Physics Department, University of Texas Health Science Center, Radiation Oncology Department, San Antonio, Texas, U.S.A
| | - Niko Papanikolaou
- Cancer Therapy and Research Center, Medical Physics Department, University of Texas Health Science Center, Radiation Oncology Department, San Antonio, Texas, U.S.A
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10
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Agazaryan N, Tenn SE, Desalles AAF, Selch MT. Image-guided radiosurgery for spinal tumors: methods, accuracy and patient intrafraction motion. Phys Med Biol 2008; 53:1715-27. [DOI: 10.1088/0031-9155/53/6/015] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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11
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Tacke M, Nill S, Oelfke U. Real-time tracking of tumor motions and deformations along the leaf travel direction with the aid of a synchronized dynamic MLC leaf sequencer. Phys Med Biol 2007; 52:N505-12. [DOI: 10.1088/0031-9155/52/22/n01] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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12
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Xu Q, Hamilton RJ, Schowengerdt RA, Jiang SB. A deformable lung tumor tracking method in fluoroscopic video using active shape models: a feasibility study. Phys Med Biol 2007; 52:5277-93. [PMID: 17762086 DOI: 10.1088/0031-9155/52/17/012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A dynamic multi-leaf collimator (DMLC) can be used to track a moving target during radiotherapy. One of the major benefits for DMLC tumor tracking is that, in addition to the compensation for tumor translational motion, DMLC can also change the aperture shape to conform to a deforming tumor projection in the beam's eye view. This paper presents a method that can track a deforming lung tumor in fluoroscopic video using active shape models (ASM) (Cootes et al 1995 Comput. Vis. Image Underst. 61 38-59). The method was evaluated by comparing tracking results against tumor projection contours manually edited by an expert observer. The evaluation shows the feasibility of using this method for precise tracking of lung tumors with deformation, which is important for DMLC-based real-time tumor tracking.
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Affiliation(s)
- Qianyi Xu
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ 85721, USA
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13
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Dai J, Que W. Simultaneous minimization of leaf travel distance and tongue-and-groove effect for segmental intensity-modulated radiation therapy. Phys Med Biol 2005; 49:5319-31. [PMID: 15656280 DOI: 10.1088/0031-9155/49/23/009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This paper introduces a method to simultaneously minimize the leaf travel distance and the tongue-and-groove effect for IMRT leaf sequences to be delivered in segmental mode. The basic idea is to add a large enough number of openings through cutting or splitting existing openings for those leaf pairs with openings fewer than the number of segments so that all leaf pairs have the same number of openings. The cutting positions are optimally determined with a simulated annealing technique called adaptive simulated annealing. The optimization goal is set to minimize the weighted summation of the leaf travel distance and tongue-and-groove effect. Its performance was evaluated with 19 beams from three clinical cases; one brain, one head-and-neck and one prostate case. The results show that it can reduce the leaf travel distance and (or) tongue-and-groove effect; the reduction of the leaf travel distance reaches its maximum of about 50% when minimized alone; the reduction of the tongue-and-groove reaches its maximum of about 70% when minimized alone. The maximum reduction in the leaf travel distance translates to a 1 to 2 min reduction in treatment delivery time per fraction, depending on leaf speed. If the method is implemented clinically, it could result in significant savings in treatment delivery time, and also result in significant reduction in the wear-and-tear of MLC mechanics.
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Affiliation(s)
- Jianrong Dai
- Department of Radiation Oncology, Cancer Institute (Hospital), Chinese Academy of Medical Sciences, Beijing 100021, People's Republic of China.
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14
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Li S, Rashid A, He S, Djajaputra D. A new approach in dose measurement and error analysis for narrow photon beams (beamlets) shaped by different multileaf collimators using a small detector. Med Phys 2004; 31:2020-32. [PMID: 15305454 DOI: 10.1118/1.1760191] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Dose measurement for narrow stereotactic beams and intensity modulation radiotherapy beamlets is difficult and error-prone due to the lack of lateral electron equilibrium. A small detector position error and finite sensitive volume as well as the nonfocus collimation could result in considerable (> 10%) measurement errors. A new method is introduced here to measure the dose and error components so that the accuracy and precision of the dose measurement can be improved. Based on superposition principle, we can create exactly the small field of interest by subtraction of a reference open field (O-field) and two strip fields (S-fields) from the sum of four quadrant fields (Q-fields). The position effect on the dose measurement is determined by the standard deviation of the four Q-field readings. The collimator leaf-edge effect (LEE) is quantified by the difference between the readings of the two S-fields using a detector that has very small sensitive volume. The detector-volume effect can be analytically estimated from the integrals of the dose distributions of the two S-fields over the detector volume. Using a pinpoint ion chamber (PTW N31006) and a stereotactic silicon diode detector (Scanditronix, DEB050), we have measured scatter factors (SF) and tissue-maximum ratios for 6-MV x-ray fields with sizes of 3 x 3 and 6 x 6 mm2 shaped by a BrainLAB micromultileaf collimator (microMLC) (M3), 4.4 x 4.4 and 8.8 x 8.8 mm2 shaped by a 3DLine double-focus MLC, and 5 x 5 and 10 x 10 mm2 by a Varian Millennium MLC. Our experimental results demonstrate that the large errors are often caused by a small setup error or measuring point displacement from the central ray of the beam. The LEE is almost independent of the depth but closely related to the field size and the type of MLC. The volume effect becomes significant when the detector diameter is comparable to the half size of the small fields. Application of the new method using different detectors had achieved less than 8.3% total experiment error for all of the small fields of interest except for the SF of the 3 x 3 mm2 field from the pinpoint ion chamber that has 15% volume effect. Importantly, the new method using a solid water phantom is clinically convenient and highly reproducible.
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Affiliation(s)
- Shidong Li
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
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15
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Wang L, Movsas B, Jacob R, Fourkal E, Chen L, Price R, Feigenberg S, Konski A, Pollack A, Ma C. Stereotactic IMRT for prostate cancer: dosimetric impact of multileaf collimator leaf width in the treatment of prostate cancer with IMRT. J Appl Clin Med Phys 2004; 5:29-41. [PMID: 15738911 PMCID: PMC5723465 DOI: 10.1120/jacmp.v5i2.1989] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The focus of this work is the dosimetric impact of multileaf collimator (MLC) leaf width on the treatment of prostate cancer with intensity-modulated radiation therapy (IMRT). Ten patients with prostate cancer were planned for IMRT delivery using two different MLC leaf widths--4mm and 10mm--representing the Radionics micro-multileaf collimator (mMLC) and Siemens MLC, respectively. Treatment planning was performed on the XKnifeRT2 treatment-planning system (Radionics, Burlington, MA). All beams and optimization parameters were identical for the mMLC and MLC plans. All the plans were normalized to ensure that 95% of the planning target volume (PTV) received 100% of the prescribed dose. The differences in dose distribution between the two different plans were assessed by dose-volume histogram (DVH) analysis of the target and critical organs. We specifically compared the volume of rectum receiving 40 Gy (V40), 50 Gy (V50), 60 Gy (V60), the dose received by 17% and 35% of rectum (D17 and D35), and the maximum dose to 1 cm3 of the rectum for a prescription dose of 74 Gy. For the urinary bladder, the dose received by 25% of bladder (D25), V40, and the maximum dose to 1 cm3 of the organ were recorded. For PTV we compared the maximum dose to the "hottest" 1 cm3 (Dmax1 cm3) and the dose to 99% of the PTV (D99). The dose inhomogeneity in the target, defined as the ratio of the difference in Dmax1 cm3 and D99 to the prescribed dose, was also compared between the two plans. In all cases studied, significant reductions in the volume of rectum receiving doses less than 65 Gy were seen using the mMLC. The average decrease in the volume of the rectum receiving 40 Gy, 50 Gy, and 60 Gy using the mMLC plans was 40.2%, 33.4%, and 17.7%, respectively, with p < 0.0001 for V40 and V50 and p < 0.012 for V60. The mean dose reductions for D17 and D35 for the rectum using the mMLC were 20.4% (p < 0.0001) and 18.3% (p < 0.0002), respectively. There were consistent reductions in all dose indices studied for the bladder. The target dose inhomogeneity was improved in the mMLC plans by an average of 29%. In the high-dose range, there was no significant difference in the dose deposited in the "hottest" 1 cm3 of the rectum between the two plans for all cases (p > 0.78). In conclusion, the use of the mMLC for IMRT of the prostate resulted in significant improvement in the DVH parameters of the prostate and critical organs, which may improve the therapeutic ratio.
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Affiliation(s)
- L Wang
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
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Li K, Dai J, Ma L. Simultaneous minimizing monitor units and number of segments without leaf end abutment for segmental intensity modulated radiation therapy delivery. Med Phys 2004; 31:507-12. [PMID: 15070247 DOI: 10.1118/1.1644642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Leaf end abutment is seldom studied when delivering segmental intensity modulated radiation therapy (IMRT) fields. We developed an efficient leaf sequencing method to eliminate leaf end abutment for segmental IMRT delivery. Our method uses simple matrix and sorting operations to obtain a solution that simultaneously minimizes total monitor units and number of segments without leaf end abutment between segments. We implemented and demonstrated our method for multiple clinical cases. We compared the results of our method with the results from exhaustive search method. We found that our solution without leaf end abutment produced equivalent results to the unconstrained solutions in terms of minimum total monitor units and minimum number of leaf segments. We conclude that the leaf end abutment fields can be avoided without affecting the efficiency of segmental IMRT delivery. The major strength of our method is its simplicity and high computing speed. This potentially provides a useful means for generating segmental IMRT fields that require high spatial resolution or complex intensity distributions.
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Affiliation(s)
- Kaile Li
- Department of Radiation Oncology, University of Maryland, School of Medicine, Baltimore, Maryland 21201, USA
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Que W, Kung J, Dai J. Tongue-and-groove effect in intensity modulated radiotherapy with static multileaf collimator fields. Phys Med Biol 2004; 49:399-405. [PMID: 15012009 DOI: 10.1088/0031-9155/49/3/004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The 'tongue-and-groove problem' in step-and-shoot delivery of intensity modulated radiotherapy is investigated. A 'tongue-and-groove' index (TGI) is introduced to quantify the 'tongue-and-groove' effect in step-and-shoot delivery. Four different types of leaf sequencing methods are compared. The sliding window method and the reducing level method use the same number of field segments to deliver the same intensity map, but the TGI is much less for the reducing level method. The leaf synchronization method of Van Santvoort and Heijmen fails in step-and-shoot delivery, but a new method inspired by the method of Van Santvoort and Heijmen is shown to eliminate 'tongue-and-groove' underdosage completely.
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Affiliation(s)
- W Que
- MPCS, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3, Canada
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