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Fukao M, Okamura K, Sabu S, Akino Y, Arimura T, Inoue S, Kado R, Seo Y. Repositioning accuracy of a novel thermoplastic mask for head and neck cancer radiotherapy. Phys Med 2020; 74:92-99. [PMID: 32450542 DOI: 10.1016/j.ejmp.2020.05.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 03/05/2020] [Accepted: 05/08/2020] [Indexed: 10/24/2022] Open
Abstract
PURPOSE The aim of this study was to assess the reproducibility of patient shoulder position immobilized with a novel and innovative prototype mask (E-Frame, Engineering System). METHODS The E-frame mask fixes both shoulders and bisaxillary regions compared with that of a commercial mask (Type-S, CIVCO). Thirteen and twelve patients were immobilized with the Type-S and E-Frame mask systems, respectively. For each treatment fraction, cone-beam CT (CBCT) images of the patient were acquired and retrospectively analyzed. The CBCT images were registered to the planning CT based on the cervical spine, and then the displacements of the acromial extremity of the clavicle were measured. RESULTS The systematic and random errors between the two mask systems were evaluated. The differences of the systematic errors between the two mask systems were not statistically significant. The mean random errors in the three directions (AP, SI and LR) were 2.7 mm, 3.1 mm and 1.5 mm, respectively for the Type-S mask, and 2.8 mm 2.5 mm and 1.4 mm, respectively for the E-Frame mask. The random error of the E-Frame masks in the SI direction was significantly smaller than that of the Type-S. The number of cases showing displacements exceeding 10 mm in the SI direction for at least one fraction was eight (61% of 13 cases) and three (25% of 12 cases) for Type-S and E-Frame masks, respectively. CONCLUSIONS The E-Frame masks reduced the random displacements of patient's shoulders in the SI direction, effectively preventing large shoulder shifts that occurred frequently with Type-S masks.
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Affiliation(s)
- Mari Fukao
- Department of Medical Technology, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Keita Okamura
- Department of Medical Technology, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shotaro Sabu
- Department of Medical Technology, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuichi Akino
- Oncology Center, Osaka University Hospital, 2-2 (D10), Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takehiro Arimura
- Department of Medical Technology, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shinichi Inoue
- Department of Medical Technology, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ryoko Kado
- Department of Nursing, Osaka University Hospital, 2-15, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10), Yamadaoka, Suita, Osaka 565-0871, Japan
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Lindsay C, Bazalova‐Carter M, Wang A, Shedlock D, Wu M, Newson M, Xing L, Ansbacher W, Fahrig R, Star‐Lack J. Investigation of combined
kV
/
MV CBCT
imaging with a high‐
DQE MV
detector. Med Phys 2018; 46:563-575. [DOI: 10.1002/mp.13291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 01/23/2023] Open
Affiliation(s)
- C. Lindsay
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - M. Bazalova‐Carter
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - A. Wang
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
| | - D. Shedlock
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
| | - M. Wu
- Department of Radiology Stanford University 1201 Welch Rd Stanford CA 94305‐5105 USA
| | - M. Newson
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - L. Xing
- Department of Radiation Oncology Stanford University 875 Blake Wilbur Dr Stanford CA 94305‐5847 USA
| | - W. Ansbacher
- Department of Medical Physics BC Cancer Agency ‐ Vancouver Island Centre Victoria BC Canada
| | - R. Fahrig
- Department of Radiology Stanford University 1201 Welch Rd Stanford CA 94305‐5105 USA
| | - J. Star‐Lack
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
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Hashido T, Nakasone S, Fukao M, Ota S, Inoue S. Comparison between manual and automatic image registration in image-guided radiation therapy using megavoltage cone-beam computed tomography with an imaging beam line for prostate cancer. Radiol Phys Technol 2018; 11:392-405. [PMID: 30242570 DOI: 10.1007/s12194-018-0476-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/15/2018] [Accepted: 09/15/2018] [Indexed: 12/25/2022]
Abstract
This study aimed to compare and assess the compatibility of the bone-structure-based manual and maximization of mutual information (MMI)-algorithm-based automatic image registration using megavoltage cone-beam computed tomography (MV-CBCT) images acquired with an imaging beam line. A total of 1163 MV-CBCT images from 30 prostate cancer patients were retrospectively analyzed. The differences between setup errors in three directions (left-right, LR; superior-inferior, SI; anterior-posterior, AP) of both registration methods were investigated. Pearson's correlation coefficients (r) and Bland-Altman agreements were evaluated. Agreements were defined by a bias close to zero and 95% limits of agreement (LoA) less than ± 3 mm. The cumulative frequencies of the absolute differences between the two registration methods were calculated to assess the distributions of the setup error differences. There were significant differences (p < 0.001) in the setup errors between both registration methods. There were moderate (SI, r = 0.45) and strong positive correlation coefficients (LR, r = 0.74; AP, r = 0.72), whereas the 95% LoA (bias ± 1.96 × standard deviation of the setup error differences) were - 1.61 ± 4.29 mm (LR), - 0.41 ± 5.45 mm (SI), and 0.67 ± 4.29 mm (AP), revealing no agreements in all directions. The cumulative frequencies (%) of the cases with absolute setup error differences within 3 mm in each direction were 80.83% (LR), 81.86% (SI), and 90.71% (AP), with all directions having large proportions of > 3-mm differences. The MMI-algorithm-based automatic registration is not compatible with the bone-structure-based manual registration and should not be used alone for prostate cancer.
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Affiliation(s)
- Takashi Hashido
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Shinya Nakasone
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Mari Fukao
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Seiichi Ota
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Shinichi Inoue
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Ding GX, Alaei P, Curran B, Flynn R, Gossman M, Mackie TR, Miften M, Morin R, Xu XG, Zhu TC. Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180. Med Phys 2018; 45:e84-e99. [PMID: 29468678 DOI: 10.1002/mp.12824] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. AIMS This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. MATERIALS & METHODS We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. RESULTS We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. DISCUSSION Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. CONCLUSION Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.
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Affiliation(s)
- George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Parham Alaei
- University of Minnesota, Minneapolis, MN, 55455, USA
| | - Bruce Curran
- Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ryan Flynn
- University of Iowa, Iowa City, IA, 52242, USA
| | | | | | | | | | - X George Xu
- Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Timothy C Zhu
- University of Pennsylvania, Philadelphia, PA, 19104, USA
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Bell K, Heitfeld M, Licht N, Rübe C, Dzierma Y. Influence of daily imaging on plan quality and normal tissue toxicity for prostate cancer radiotherapy. Radiat Oncol 2017; 12:7. [PMID: 28069053 PMCID: PMC5223448 DOI: 10.1186/s13014-016-0757-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/28/2016] [Indexed: 11/10/2022] Open
Abstract
Background Modern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP). Methods This study is based on treatment plans of 50 prostate patients. We evaluate the clinically performed IGRT and simulate the influence of different daily IGRT scenarios on plan quality. Imaging doses of planar and cone-beam-CT (CBCT) images for three different energies (6 MV, 1 MV and 121 kV) were added to the treatment plans. The plan quality of the different scenarios was assessed by a visual inspection of the dose distribution and dose-volume-histogram (DVH) and a statistical analysis of DVH criteria. In addition, an assessment of the normal tissue complication probability was performed. Results Daily 1MV-CBCTs result in undesirable high dose regions in the target volume. The DVH shows that the scenarios with actual imaging performed, daily kV-CBCT and daily 6MV imaging (1x CBCT, 4x planar images per week) do not differ exceedingly from the original plan; especially imaging with daily kV-CBCT has little influence to the sparing of organs at risk. In contrast, daily 1MV- CBCT entails an additional dose of up to two fraction doses. Due to the additional dose amount some DVH constraints for plan acceptability could no longer be satisfied, especially for the daily 1MV-CBCT scenario. This scenario also shows increased NTCP for the rectum. Conclusion Daily kV-CBCT has negligible influence on plan quality and is commendable for the clinical routine. If no kV-modality is available, a daily IGRT scenario with one CBCT per week and planar axial images on the other days should be preferred over daily MV-CBCT.
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Affiliation(s)
- Katharina Bell
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, D-66421, Homburg/Saar, Germany.
| | - Marina Heitfeld
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, D-66421, Homburg/Saar, Germany
| | - Norbert Licht
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, D-66421, Homburg/Saar, Germany
| | - Christian Rübe
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, D-66421, Homburg/Saar, Germany
| | - Yvonne Dzierma
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, D-66421, Homburg/Saar, Germany
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Tang G, Moussot C, Morf D, Seppi E, Amols H. Low-dose 2.5 MV cone-beam computed tomography with thick CsI flat-panel imager. J Appl Clin Med Phys 2016; 17:235-245. [PMID: 27455493 PMCID: PMC5690043 DOI: 10.1120/jacmp.v17i4.6185] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 03/22/2016] [Accepted: 03/16/2016] [Indexed: 11/29/2022] Open
Abstract
Most of the treatment units, both new and old models, are equipped with a megavoltage portal imager but its use for volumetric imaging is limited. This is mainly due to the poor image quality produced by the high‐energy treatment beam (>6 MV). A linac at our center is equipped with a prototype 2.5 MV imaging beam. This study evaluates the feasibility of low‐dose megavoltage cone‐beam imaging with the 2.5 MV beam and a thick cesium iodide detector, which is a high‐efficiency imager. Basic imaging properties such as spatial resolution and modulation transfer function were assessed for the 2.5 MV prototype imaging system. For image quality and imaging dose, a series of megavoltage cone‐beam scans were acquired for the head, thorax, and pelvis of an anthropomorphic phantom and were compared to kilovoltage cone‐beam and 6X megavoltage cone‐beam images. To demonstrate the advantage of MV imaging, a phantom with metallic inserts was scanned and the image quality was compared to CT and kilovoltage cone‐beam scans. With a lower energy beam and higher detector efficiency, the 2.5 MV imaging system generally yields better image quality than does the 6 MV imaging system with the conventional MV imager. In particular, with the anthropomorphic phantom studies, the contrast to noise of bone to tissue is generally improved in the 2.5 MV images compared to 6 MV. With an image quality sufficient for bony alignment, the imaging dose for 2.5 MV cone‐beam images is 2.4−3.4 MU compared to 26 MU in 6 MV cone‐beam scans for the head, thorax, and pelvis regions of the phantom. Unlike kilovoltage cone‐beam, the 2.5 MV imaging system does not suffer from high‐Z image artifacts. This can be very useful for treatment planning in cases where high‐Z prostheses are present. PACS number(s): 87.57.Q‐
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Held M, Sneed PK, Fogh SE, Pouliot J, Morin O. Feasibility of MV CBCT-based treatment planning for urgent radiation therapy: dosimetric accuracy of MV CBCT-based dose calculations. J Appl Clin Med Phys 2015; 16:458-471. [PMID: 26699575 PMCID: PMC5690985 DOI: 10.1120/jacmp.v16i6.5625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/18/2015] [Accepted: 08/25/2015] [Indexed: 11/23/2022] Open
Abstract
Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image‐based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit–to–density calibration curves for regular and extended field‐of‐view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole‐brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT‐based dose planning and delivery approach was feasible and time‐efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all treatment sites. PACS numbers: 87.55.D‐, 87.57.Q‐
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Alaei P, Spezi E. Imaging dose from cone beam computed tomography in radiation therapy. Phys Med 2015; 31:647-58. [PMID: 26148865 DOI: 10.1016/j.ejmp.2015.06.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/29/2015] [Accepted: 06/05/2015] [Indexed: 12/26/2022] Open
Abstract
Imaging dose in radiation therapy has traditionally been ignored due to its low magnitude and frequency in comparison to therapeutic dose used to treat patients. The advent of modern, volumetric, imaging modalities, often as an integral part of linear accelerators, has facilitated the implementation of image-guided radiation therapy (IGRT), which is often accomplished by daily imaging of patients. Daily imaging results in additional dose delivered to patient that warrants new attention be given to imaging dose. This review summarizes the imaging dose delivered to patients as the result of cone beam computed tomography (CBCT) imaging performed in radiation therapy using current methods and equipment. This review also summarizes methods to calculate the imaging dose, including the use of Monte Carlo (MC) and treatment planning systems (TPS). Peripheral dose from CBCT imaging, dose reduction methods, the use of effective dose in describing imaging dose, and the measurement of CT dose index (CTDI) in CBCT systems are also reviewed.
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Affiliation(s)
| | - Emiliano Spezi
- School of Engineering, Cardiff University, Cardiff, Wales, UK; Velindre Cancer Centre, Cardiff, Wales, UK
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9
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Gayou O, Colonias A. Imaging a moving lung tumor with megavoltage cone beam computed tomography. Med Phys 2015; 42:2347-53. [DOI: 10.1118/1.4917524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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10
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Liu L, Antonuk LE, El-Mohri Y, Zhao Q, Jiang H. Optimization of the design of thick, segmented scintillators for megavoltage cone-beam CT using a novel, hybrid modeling technique. Med Phys 2015; 41:061916. [PMID: 24877827 DOI: 10.1118/1.4875724] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Active matrix flat-panel imagers (AMFPIs) incorporating thick, segmented scintillators have demonstrated order-of-magnitude improvements in detective quantum efficiency (DQE) at radiotherapy energies compared to systems based on conventional phosphor screens. Such improved DQE values facilitate megavoltage cone-beam CT (MV CBCT) imaging at clinically practical doses. However, the MV CBCT performance of such AMFPIs is highly dependent on the design parameters of the scintillators. In this paper, optimization of the design of segmented scintillators was explored using a hybrid modeling technique which encompasses both radiation and optical effects. METHODS Imaging performance in terms of the contrast-to-noise ratio (CNR) and spatial resolution of various hypothetical scintillator designs was examined through a hybrid technique involving Monte Carlo simulation of radiation transport in combination with simulation of optical gain distributions and optical point spread functions. The optical simulations employed optical parameters extracted from a best fit to measurement results reported in a previous investigation of a 1.13 cm thick, 1016 μm pitch prototype BGO segmented scintillator. All hypothetical designs employed BGO material with a thickness and element-to-element pitch ranging from 0.5 to 6 cm and from 0.508 to 1.524 mm, respectively. In the CNR study, for each design, full tomographic scans of a contrast phantom incorporating various soft-tissue inserts were simulated at a total dose of 4 cGy. RESULTS Theoretical values for contrast, noise, and CNR were found to be in close agreement with empirical results from the BGO prototype, strongly supporting the validity of the modeling technique. CNR and spatial resolution for the various scintillator designs demonstrate complex behavior as scintillator thickness and element pitch are varied--with a clear trade-off between these two imaging metrics up to a thickness of ~3 cm. Based on these results, an optimization map indicating the regions of design that provide a balance between these metrics was obtained. The map shows that, for a given set of optical parameters, scintillator thickness and pixel pitch can be judiciously chosen to maximize performance without resorting to thicker, more costly scintillators. CONCLUSIONS Modeling radiation and optical effects in thick, segmented scintillators through use of a hybrid technique can provide a practical way to gain insight as to how to optimize the performance of such devices in radiotherapy imaging. Assisted by such modeling, the development of practical designs should greatly facilitate low-dose, soft tissue visualization employing MV CBCT imaging in external beam radiotherapy.
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Affiliation(s)
- Langechuan Liu
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109
| | - Larry E Antonuk
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109
| | - Youcef El-Mohri
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109
| | - Qihua Zhao
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109
| | - Hao Jiang
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109
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Image quality and dose distributions of three linac-based imaging modalities. Strahlenther Onkol 2014; 191:365-74. [PMID: 25527311 DOI: 10.1007/s00066-014-0798-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND PURPOSE Linac-based patient imaging is possible with a variety of techniques using different photon energies. The purpose of this work is to compare three imaging systems operating at 6 MV, flattening free filter (FFF) 1 MV, and 121 kV. PATIENTS AND METHODS The dose distributions of all pretreatment set-up images (over 1,000) were retrospectively calculated on the planning computed tomography (CT) images for all patients with prostate and head-and-neck cancer treated at our institution in 2013. We analyzed the dose distribution and the dose to organs at risk. RESULTS For head-and-neck cancer patients, the imaging dose from 6-MV cone beam CT (CBCT) reached maximum values at around 8 cGy. The 1-MV CBCT dose was about 63-79 % of the 6-MV CBCT dose for all organs at risk. Planar imaging reduced the imaging dose from CBCT to 30-40 % for both megavoltage modalities. The dose from the kilovoltage CBCT was 4-10 % of the 6-MV CBCT dose. For prostate cancer patients, the maximum dose from 6-MV CBCT reached 13-15 cGy, and was reduced to 66-73 % for 1 MV. Planar imaging reduces the MV CBCT dose to 10-20 %. The kV CBCT dose is 15-20 % of the 6-MV CBCT dose, slightly higher than the dose from MV axes. The dose distributions differ markedly in response to the different beam profiles and dose-depth characteristics.
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12
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Kaltwasser A, Dodt C. [Organizational models of inpatient emergency and acute care]. Med Klin Intensivmed Notfmed 2014; 109:478. [PMID: 25293596 DOI: 10.1007/s00063-013-0330-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A Kaltwasser
- Kreiskliniken Reutlingen GmbH, Steinenbergstr. 31 , 72764, Reutlingen, Deutschland,
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13
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Markwell T, Perera L, Trapp J, Fielding A. Evaluation of MegaVoltage Cone Beam CT image quality with an unmodified Elekta Precise Linac and EPID: a feasibility study. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:291-302. [DOI: 10.1007/s13246-014-0258-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 02/26/2014] [Indexed: 11/30/2022]
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Dzierma Y, Nuesken FG, Licht NP, Ruebe C. Dosimetric properties and commissioning of cone-beam CT image beam line with a carbon target. Strahlenther Onkol 2013; 189:566-72. [PMID: 23715886 DOI: 10.1007/s00066-013-0330-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 02/06/2013] [Indexed: 11/25/2022]
Abstract
BACKGROUND AND PURPOSE Accurate patient positioning before radiotherapy is often verified using advanced imaging techniques such as cone-beam computed tomography (CBCT). Even for dedicated imaging beam lines, the applied dose is not necessarily negligible with respect to the treatment dose and should be considered in the treatment plan. MATERIALS AND METHODS This study presents measurements of the beam properties of the Siemens kView (Siemens AG, Munich, Germany) image beam line (IBL) and the commissioning in the Philips Pinnacle(3) treatment planning system (TPS; Philips, Amsterdam, Netherlands). RESULTS The percent depth dose curve reaches its maximum at a depth of 10 mm, with a surface dose of 44 %. The IBL operates in flattening filter-free mode, showing the characteristic dose falloff from the central axis. Stability over several days to months is within less than 2 % dose deviation or 1 mm distance-to-agreement. Modelling of the IBL beam line was performed using the Pinnacle(3) automatic modelling routine, with absolute dosimetric verification and film measurements of the fluence distribution. CONCLUSION After commissioning of the IBL beam model, the dose from the imaging IBL CBCT can be calculated. Even if the absolute dose deposited is small, repeated imaging doses may sum up to significant amounts and can shift the position of the dose maximum by several centimetres.
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Affiliation(s)
- Y Dzierma
- Klinik für Strahlentherapie und Radioonkologie, Universitätsklinikum des Saarlandes, Kirrberger Str., Gebäude 6.5, 66421, Homburg/Saar, Germany.
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Fast MF, Koenig T, Oelfke U, Nill S. Performance characteristics of a novel megavoltage cone-beam-computed tomography device. Phys Med Biol 2012; 57:N15-24. [DOI: 10.1088/0031-9155/57/3/n15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Gayou O. Influence of acquisition parameters on MV-CBCT image quality. J Appl Clin Med Phys 2012; 13:3638. [PMID: 22231215 PMCID: PMC5716124 DOI: 10.1120/jacmp.v13i1.3638] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 07/21/2011] [Indexed: 12/04/2022] Open
Abstract
The production of high quality pretreatment images plays an increasing role in image‐guided radiotherapy (IGRT) and adaptive radiation therapy (ART). Megavoltage cone‐beam computed tomography (MV‐CBCT) is the simplest solution of all the commercially available volumetric imaging systems for localization. It also suffers the most from relatively poor contrast due to the energy range of the imaging photons. Several avenues can be investigated to improve MV‐CBCT image quality while maintaining an acceptable patient exposure: beam generation, detector technology, reconstruction parameters, and acquisition parameters. This article presents a study of the effects of the acquisition scan length and number of projections of a Siemens Artiste MV‐CBCT system on image quality within the range provided by the manufacturer. It also discusses other aspects not related to image quality one should consider when selecting an acquisition protocol. Noise and uniformity were measured on the image of a cylindrical water phantom. Spatial resolution was measured using the same phantom half filled with water to provide a sharp water/air interface to derive the modulation transfer function (MTF). Contrast‐to‐noise ratio (CNR) was measured on a pelvis‐shaped phantom with four inserts of different electron densities relative to water (1.043, 1.117, 1.513, and 0.459). Uniformity was independent of acquisition protocol. Noise decreased from 1.96% to 1.64% when the total number of projections was increased from 100 to 600 for a total exposure of 13.5 MU. The CNR showed a∓5% dependence on the number of projections and 10% dependence on the scan length. However, these variations were not statistically significant. The spatial resolution was unaffected by the arc length or the sampling rate. Acquisition parameters have little to no effect on the image quality of the MV‐CBCT system within the range of parameters available on the system. Considerations other than image quality, such as memory storage, acquisition speed, and individual projection image quality, speak in favor of the use of a coarse sampling rate on the short scan. PACS numbers: 87.57.C‐; 87.57.nf
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Affiliation(s)
- Olivier Gayou
- Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, PA 15212, USA.
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Beltran C. Image quality of an investigational imaging panel for use with the imaging beam line cone-beam CT. J Appl Clin Med Phys 2012; 13:3607. [PMID: 22231211 PMCID: PMC5716139 DOI: 10.1120/jacmp.v13i1.3607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 08/24/2011] [Accepted: 08/24/2011] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to measure and compare the contrast-to-noise ratio (CNR) as a function of dose for the cone-beam CT (CBCT) produced by the imaging beam line (IBL) for the standard and an investigational imaging panel. Two Siemens Artiste linear accelerators were modified at our institution such that the MV-CBCT would operate under an investigational IBL. The imaging panel from one of the machines was replaced with an investigational imaging panel. After the modification, a set of CBCT for a large and small phantom consisting of eight tissue-equivalent inserts was acquired for the standard imager and for the investigational imager with and without the standard copper plate. Ten dose settings for each phantom using the IBL in combination with the standard and investigational imaging panel were acquired. The CNR for each tissue-equivalent insert was calculated. Resolution measurements in line pairs per mm (lp/mm) of the CBCT for the various imaging panel setups were made. In addition, CBCT images of two patients that were imaged with each panel configuration were displayed for a group of physicians and therapists who were asked to identify the best and worst CBCT for each patient. This was used as a qualitative judge of practical image quality. The CNR of the muscle insert for the large phantom with 1.5 cGy at isocenter was 1.3 for the standard imager, 1.5 for the investigational imager with the copper plate, and 1.9 without the plate. Under the same conditions, the CNR of the trabecular bone insert was 5.9, 7.3, and 9.7, respectively. For the small phantom with the same dose to isocenter, the CNR for muscle was 1.7, 2.1, and 3.3, respectively. For the trabecular bone, the CNR was 8.1, 9.6, and 12.1 respectively. The resolution for 1 cGy at isocenter was 0.37 lp/mm for the standard imager, 0.32 and 0.33 for the investigational imager with and without the copper plate. The qualitative test ranked the CBCT of the investigational imager without the copper plate to be the best image, and the standard imager to be the worst. The investigational imaging panel improves image quality as compared to the standard imager for IBL CBCTs. A 1 cGy IBL CBCT, no matter which imager is used, is sufficient for bony anatomy localization. The investigational imager without the copper plate was judged clinically to produce the best IBL CBCT.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Beltran C, Merchant TE. Dependence of intrafraction motion on fraction duration for pediatric patients with brain tumors. J Appl Clin Med Phys 2011; 12:3609. [PMID: 22089020 PMCID: PMC5718741 DOI: 10.1120/jacmp.v12i4.3609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/14/2011] [Accepted: 05/17/2011] [Indexed: 12/22/2022] Open
Abstract
The purpose of this study was to quantify the intrafraction motion of pediatric patients with brain tumors during radiation therapy and investigate any correlation between motion, use of general anesthesia, and daily treatment duration. 100 pediatric patients with a mean age of 8.5 years (range: 1.0 to 17.8) were included in this prospective study. Forty-one patients required general anesthesia during treatment, mean age 4.8 years; 59 patients did not, mean age 11.2 years. Each patient had an intracranial tumor and was treated in the supine position with a thermoplastic facemask and headrest for immobilization. A pretreatment localization CBCT was acquired for each treatment fraction and a post-treatment CBCT was acquired every other fraction. If the magnitude of the patient's position pre-CBCT offset was ≥ 2 mm, the position was corrected. The difference between the patient's position based on the post-CBCT and the assumed position at the start of treatment (either the pre-CBCT offset if the magnitude was < 2 mm, or 0 offset due to correction) was determined and labeled intrafraction motion. Correlations between daily treatment duration and intrafraction motion were examined. There was an average of 14.2 post-CBCTs acquired per patient. The magnitude of the mean intrafraction motion was 1.2 ± 0.8 mm for patients requiring general anesthesia, and 1.5 ± 1.2 mm for those without (p < 0.001). The mean offset in each direction was less than 0.5 mm for both cohorts. There was no correlation between daily treatment duration and the magnitude of intrafraction motion. The intrafraction motion of pediatric patients undergoing external beam therapy for intracranial tumors is small, < 2 mm, and is independent of the daily treatment duration.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children’s Research Hospital, Memphis, TN, USA.
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Breitbach EK, Maltz JS, Gangadharan B, Bani-Hashemi A, Anderson CM, Bhatia SK, Stiles J, Edwards DS, Flynn RT. Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system. Med Phys 2011; 38:5969-79. [DOI: 10.1118/1.3651470] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Roberts DA, Hansen VN, Thompson MG, Poludniowski G, Niven A, Seco J, Evans PM. Comparative study of a low-Z cone-beam computed tomography system. Phys Med Biol 2011; 56:4453-64. [PMID: 21719950 DOI: 10.1088/0031-9155/56/14/014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Computed tomography images have been acquired using an experimental (low atomic number (Z) insert) megavoltage cone-beam imaging system. These images have been compared with standard megavoltage and kilovoltage imaging systems. The experimental system requires a simple modification to the 4 MeV electron beam from an Elekta Precise linac. Low-energy photons are produced in the standard medium-Z electron window and a low-Z carbon electron absorber located after the window. The carbon electron absorber produces photons as well as ensuring that all remaining electrons from the source are removed. A detector sensitive to diagnostic x-ray energies is also employed. Quantitative assessment of cone-beam computed tomography (CBCT) contrast shows that the low-Z imaging system is an order of magnitude or more superior to a standard 6 MV imaging system. CBCT data with the same contrast-to-noise ratio as a kilovoltage imaging system (0.15 cGy) can be obtained in doses of 11 and 244 cGy for the experimental and standard 6 MV systems, respectively. Whilst these doses are high for everyday imaging, qualitative images indicate that kilovoltage like images suitable for patient positioning can be acquired in radiation doses of 1-8 cGy with the experimental low-Z system.
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Affiliation(s)
- D A Roberts
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
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Beltran C, Pegram A, Merchant TE. Dosimetric consequences of rotational errors in radiation therapy of pediatric brain tumor patients. Radiother Oncol 2011; 102:206-9. [PMID: 21726913 DOI: 10.1016/j.radonc.2011.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 06/03/2011] [Accepted: 06/04/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE To quantify the rotational offsets and estimate the dose effect of rotation on the target volume and normal tissues in children with brain tumor. METHODS Twenty-one pediatric patients with brain tumors were included in this study. Cone-beam CT was performed before each treatment and at the end of every other treatment. Translational offsets were corrected before the treatment. An offline analysis was performed to quantify rotational errors. The treatment plans were altered and recalculated to simulate a rotation of 2° and 4°, and the dose changes were quantified. RESULTS 1016 CBCT datasets were analyzed for this report. The mean of the rotations were not meaningfully different from zero. 18.1% of the fractions had rotations with a magnitude ≥2°, 5.0% had rotations ≥3° and 0.9% had rotations ≥4°. For the 2° rotational simulation, the gEUD values of the PTV and critical structures changed by less than 2%. For the 4° simulation, parallel type normal structures had minor changes (<2%), but serial type normal structures and the PTV had changes of 10% and 5%, respectively. CONCLUSIONS The majority of rotational errors observed were less than 1°. A rotational error of 2° produced negligible changes in the gEUD to critical structures or target volumes. Rotational errors ≥4° produced undesirable results, therefore, at a minimum, errors >2° should be corrected.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN 38120, USA.
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Beltran C, Sharma S, Merchant TE. Role of adaptive radiation therapy for pediatric patients with diffuse pontine glioma. J Appl Clin Med Phys 2011. [PMCID: PMC5718676 DOI: 10.1120/jacmp.v12i2.3421] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences; St. Jude Children's Research Hospital; Memphis TN USA
| | - Saumya Sharma
- Department of Radiological Sciences; St. Jude Children's Research Hospital; Memphis TN USA
| | - Thomas E. Merchant
- Department of Radiological Sciences; St. Jude Children's Research Hospital; Memphis TN USA
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Yin FF, Oldham M, Cai J, Wu Q. Dosimetry challenges for implementing emerging technologies. ACTA ACUST UNITED AC 2010; 250:8-11. [PMID: 21617745 DOI: 10.1088/1742-6596/250/1/012002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
During the last 10 years, radiation therapy technologies have gone through major changes, mainly related introduction of sophisticated delivery and imaging techniques to improve the target localization accuracy and dose conformity. While implementation of these emerging technologies such as image-guided SRS/SBRT, IMRT/IMAT, IGRT, 4D motion management, and special delivery technologies showed substantial clinical gains for patient care, many other factors, such as training/quality, efficiency/efficacy, and cost/effectiveness etc. remain to be challenging. This talk will address technical challenges for dosimetry verification of implementing these emerging technologies in radiation therapy.
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Affiliation(s)
- Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27516, USA
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Beltran C, Naik M, Merchant TE. Dosimetric effect of target expansion and setup uncertainty during radiation therapy in pediatric craniopharyngioma. Radiother Oncol 2010; 97:399-403. [PMID: 21074883 DOI: 10.1016/j.radonc.2010.10.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 10/14/2010] [Accepted: 10/17/2010] [Indexed: 10/18/2022]
Abstract
PURPOSE Investigate the effect of tumor change and setup uncertainties on target coverage for pediatric craniopharyngioma during RT. METHODS AND MATERIALS Fifteen pediatric patients with craniopharyngioma (mean 5.1 years) were included in this study. MRI was performed before and a median of six times during RT to monitor changes in the tumor volume. IMRT plans were created and compared to the CRT plan used for treatment. The role of adaptive therapy based on GTV changes was investigated. Dosimetric effects of interfraction and intrafraction motion were examined. RESULTS The mean of the maximal change in the GTV was 28.5% [-20.7% to 82.0%]. For the standard margin IMRT plans, the mean D(95) of the base plan on the base target was 53.6 Gy [53.1-54.1]. The mean D(95) of the base plans on the adaptive targets was 52.1 Gy [47.9-54.1]. The D(95) for the adaptive plan on the adaptive target was 53.8 Gy [53.4-54.3]. A linear regression equation of y=-0.12x , r(2)=0.70, was found for the percent change in D(95) of the PTV (y) vs. the percent change in the GTV (x). Inter and intrafraction motion did not affect the target coverage for standard and reduced margin plans. CONCLUSIONS The GTV of pediatric craniopharyngioma patients change size during therapy and adaptive planning is critical for conformal plans; therefore early and regular surveillance imaging is required.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN 38120, USA.
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Beltran C, Pai Panandiker AS, Krasin MJ, Merchant TE. Daily image-guided localization for neuroblastoma. J Appl Clin Med Phys 2010; 11:3388. [PMID: 21081896 PMCID: PMC5720396 DOI: 10.1120/jacmp.v11i4.3388] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 08/02/2010] [Accepted: 08/01/2010] [Indexed: 12/25/2022] Open
Abstract
The purpose was to quantify the setup margin for pediatric patients with neuro-blastoma using cone beam CT imaging (CBCT) and ultrasound localization. Ten patients, with a median age of 4.3 years (1.8 to 7.9) underwent daily pretreatment localization CBCT and every other day post-treatment CBCT to calculate interfractional and intrafraction movement. Localization was based on CBCT to treatment planning CT registration in the lumbar spine region. Each subject was treated in the supine position under IV general anesthesia using intensity-modulated radiation therapy. Patients were repositioned based on the daily pretreatment CBCT. Required setup margins based on inter- and intrafraction positioning errors were calculated based on weekly and daily imaging scenarios. Four patients had ultra-sound localization of the kidneys performed before the CBCT. Correlation between daily CBCT and ultrasound was investigated. A lateral, longitudinal and vertical setup margin of 5.4, 5.6, and 5.9 mm is required without daily CBCT. When daily CBCT was incorporated, the setup margin was reduced to 1.5, 2.1, and 1.7 mm. There was no correlation between the suggested ultrasound shifts and the shifts based on the CBCT. Daily localization based on CBCT of the lumbar spine can reduce the required setup margin for neuroblastoma patients, thereby reducing normal tissue exposure for this young patient population. The internal margin needs further investigation before PTV reduction can be made. Ultrasound localization was highly variable and not correlated to CBCT shifts.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA.
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Million L, Anderson J, Breneman J, Hawkins DS, Laurie F, Michalski J, Rodeberg D, Wharam M, Wolden S, Donaldson SS. Influence of noncompliance with radiation therapy protocol guidelines and operative bed recurrences for children with rhabdomyosarcoma and microscopic residual disease: a report from the Children's Oncology Group. Int J Radiat Oncol Biol Phys 2010; 80:333-8. [PMID: 20646841 DOI: 10.1016/j.ijrobp.2010.01.058] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/28/2010] [Accepted: 01/31/2010] [Indexed: 11/26/2022]
Abstract
PURPOSE Postoperative radiation therapy (RT) is recommended for patients with rhabdomyosarcoma having microscopic disease. Sometimes RT dose/volume is reduced or omitted in an attempt to avoid late effects, particularly in young children. We reviewed operative bed recurrences to determine if noncompliance with RT protocol guidelines influenced local-regional control. METHODS AND MATERIALS All operative bed recurrences among 695 Group II rhabdomyosarcoma patients in Intergroup Rhabdomyosarcoma Study Group (IRS) I through IV were reviewed for deviation from RT protocol. Major/minor dose deviation was defined as >10% or 6-10% of the prescribed dose (40-60 Gy), respectively. Major/minor volume deviation was defined as tumor excluded from the RT field or treatment volume not covered by the specified margin (preoperative tumor volume and 2- to 5-cm margin), respectively. No RT was a major deviation. RESULTS Forty-six of 83 (55%) patients with operative bed recurrences did not receive the intended RT (39 major and 7 minor deviations). RT omission was the most frequent RT protocol deviation (19/46, 41%), followed by dose (17/46, 37%), volume (9/46, 20%), and dose and volume deviation (1/46, 2%). Only 7 operative bed recurrences occurred in IRS IV (5% local-regional failure) with only 3 RT protocol deviations. Sixty-three (76%) patients with recurrence died of disease despite retrieval therapy, including 13 of 19 nonirradiated children. CONCLUSION Over half of the operative bed recurrences were associated with noncompliance; omission of RT was the most common protocol deviation. Three fourths of children die when local-regional disease is not controlled, emphasizing the importance of RT in Group II rhabdomyosarcoma.
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Affiliation(s)
- Lynn Million
- Department of Radiation Oncology, University of Utah Health Sciences and Huntsman Cancer Institute, Salt Lake City, UT, USA.
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Beltran C, Krasin MJ, Merchant TE. Inter- and intrafractional positional uncertainties in pediatric radiotherapy patients with brain and head and neck tumors. Int J Radiat Oncol Biol Phys 2010; 79:1266-74. [PMID: 20605345 DOI: 10.1016/j.ijrobp.2009.12.057] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 12/11/2009] [Accepted: 12/14/2009] [Indexed: 12/25/2022]
Abstract
PURPOSE To estimate radiation therapy planning margins based on inter- and intrafractional uncertainty for pediatric brain and head and neck tumor patients at different imaging frequencies. METHODS Pediatric patients with brain (n = 83) and head and neck (n = 17) tumors (median age = 7.2 years) were enrolled on an internal review board-approved localization protocol and stratified according to treatment position and use of anesthesia. Megavoltage cone-beam CT (CBCT) was performed before each treatment and after every other treatment. The pretreatment offsets were used to calculate the interfractional setup uncertainty (SU), and posttreatment offsets were used to calculate the intrafractional residual uncertainty (RU). The SU and RU are the patient-related components of the setup margin (SM), which is part of the planning target volume (PTV). SU data was used to simulate four intervention strategies using different imaging frequencies and thresholds. RESULTS The SM based on all patients treated on this study was 2.1 mm (SU = 0.9 mm, RU = 1.9 mm) and varied according to treatment position (supine = 1.8 mm, prone = 2.6 mm) and use of anesthesia (with = 1.7 mm, without = 2.5 mm) because of differences in the RU. The average SU for a 2-mm threshold based on no imaging, once per week imaging, initial five images, and daily imaging was 3.6, 2.1, 2.2, and 0.9 mm, respectively. CONCLUSION On the basis of this study, the SM component of the PTV may be reduced to 2 mm for daily CBCT compared with 3.5 mm for weekly CBCT. Considering patients who undergo daily pretreatment CBCT, the SM is larger for those treated in the prone position or smaller for those treated under anesthesia because of differences in the RU.
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Affiliation(s)
- Chris Beltran
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA.
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Faddegon BA, Aubin M, Bani-Hashemi A, Gangadharan B, Gottschalk AR, Morin O, Sawkey D, Wu V, Yom SS. Comparison of patient megavoltage cone beam CT images acquired with an unflattened beam from a carbon target and a flattened treatment beama). Med Phys 2010; 37:1737-41. [DOI: 10.1118/1.3359822] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Sawkey D, Lu M, Morin O, Aubin M, Yom SS, Gottschalk AR, Bani-Hashemi A, Faddegon BA. A diamond target for megavoltage cone-beam CTa). Med Phys 2010; 37:1246-53. [DOI: 10.1118/1.3302831] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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