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Sasaki F. [2. Clinical Operations in a Helical Radiotherapy Unit with a Ring-based Gantry]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2024; 80:972-977. [PMID: 39313376 DOI: 10.6009/jjrt.2024-2404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
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Duan L, Qi W, Chen Y, Cao L, Chen J, Zhang Y, Xu C. Evaluation of complexity and deliverability of IMRT treatment plans for breast cancer. Sci Rep 2023; 13:21474. [PMID: 38052915 PMCID: PMC10698170 DOI: 10.1038/s41598-023-48331-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 11/25/2023] [Indexed: 12/07/2023] Open
Abstract
This study aimed to predict the outcome of patient specific quality assurance (PSQA) in IMRT for breast cancer using complexity metrics, such as MU factor, MAD, CAS, MCS. Several breast cancer plans were considered, including LBCS, RBCS, LBCM, RBCM, left breast, right breast and the whole breast for both Edge and TrueBeam LINACS. Dose verification was completed by Portal Dosimetry (PD). The receiver operating characteristic (ROC) curve was employed to determine whether the treatment plans pass or failed. The area under the curve (AUC) was used to assess the classification performance. The correlation of PSQA and complexity metrics was examined using Spearman's rank correlation coefficient (Rs). For LINACS, the most suitable complexity metric was found to be the MU factor (Edge Rs = - 0.608, p < 0.01; TrueBeam Rs = - 0.739, p < 0.01). Regarding the specific breast cancer categories, the optimal complexity metrics were as follows: MAD (AUC = 0.917) for LBCS, MCS (AUC = 0.681) for RBCS, MU factor (AUC = 0.854) for LBCM and MAD (AUC = 0.731) for RBCM. On the Edge LINAC, the preferable method for breast cancers was MCS (left breast, AUC = 0.938; right breast, AUC = 0.813), while on the TrueBeam LINAC, it became MU factor (left breast, AUC = 0.950) and MCS (right breast, AUC = 0.806), respectively. Overall, there was no universally suitable complexity metric for all types of breast cancers. The choice of complexity metric depended on different cancer types, locations and treatment LINACs. Therefore, when utilizing complexity metrics to predict PSQA outcomes in IMRT for breast cancer, it was essential to select the appropriate metric based on the specific circumstances and characteristics of the treatment.
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Affiliation(s)
- Longyan Duan
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Weixiang Qi
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yi Chen
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Lu Cao
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jiayi Chen
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yibin Zhang
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Cheng Xu
- Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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Yagihashi T, Inoue T, Shiba S, Yamano A, Minagawa Y, Omura M, Inoue K, Nagata H. Impact of delivery time factor on treatment time and plan quality in tomotherapy. Sci Rep 2023; 13:12207. [PMID: 37500671 PMCID: PMC10374581 DOI: 10.1038/s41598-023-39047-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/19/2023] [Indexed: 07/29/2023] Open
Abstract
Delivery time factor (DTF) is a new parameter introduced by the RayStation treatment planning system for tomotherapy treatment planning. This study investigated the effects of this factor on various tomotherapy plans. Twenty-five patients with cancer (head and neck, 6; lung, 9; prostate, 10) were enrolled in this study. Helical tomotherapy plans with a field width of 2.5 cm, pitch of 0.287, and DTF of 2.0 were created. All the initial plans were recalculated by changing the DTF parameter from 1.0 to 3.0 in increments of 0.1. Then, DTF's impact on delivery efficiency and plan quality was evaluated. Treatment time and modulation factor increased monotonically with increasing DTF. Increasing the DTF by 0.1 increased the treatment time and modulation factor by almost 10%. This relationship was similar for all treatment sites. Conformity index (CI), homogeneity index, and organ at risk doses were improved compared to plans with a DTF of 1.0, except for the CI in the lung cancer case. However, the improvement in most indices ceased at a certain DTF; nevertheless, treatment time continued to increase following an increase in DTF. DTF is a critical parameter for improving the quality of tomotherapy plans.
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Affiliation(s)
- Takayuki Yagihashi
- Department of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo, 116-8551, Japan
| | - Tatsuya Inoue
- Department of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan.
- Department of Radiation Oncology, Graduate School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Shintaro Shiba
- Department of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
| | - Akihiro Yamano
- Department of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
| | - Yumiko Minagawa
- Department of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
| | - Motoko Omura
- Department of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
| | - Kazumasa Inoue
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo, 116-8551, Japan
| | - Hironori Nagata
- Department of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa, 247-8533, Japan
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Kim C, Han MC, Lee YK, Shin HB, Kim H, Kim JS. Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy. Radiat Oncol 2022; 17:177. [DOI: 10.1186/s13014-022-02151-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/24/2022] [Indexed: 11/09/2022] Open
Abstract
Abstract
Background
Based on a previous study on the feasibility of TomoEQA, an exit detector-based patient-specific pre-treatment quality assurance (QA) method for helical tomotherapy, an in-depth clinical evaluation was conducted.
Methods
Data of one hundred patients were analyzed to evaluate the clinical usefulness of TomoEQA for patient-specific pre-treatment QA in comparison with the conventional phantom-based method. Additional investigations were also performed under unusual measurement conditions to validate the off-axis region. In addition to the clinical evaluation of TomoEQA, a statistical analysis was conducted to determine the plan parameters that affect the pass/failure results of pre-treatment QA.
Results
The average and standard deviations of the gamma passing rate and point dose error for TomoEQA were comparable to those of the conventional QA method. For TomoEQA, the average values of the gamma passing rate and point dose error were 96.32% (standard deviation (1 sigma) = 3.94; 95% confidence interval (CI), 95.55 to 97.09) and − 1.12% (standard deviation (1 sigma) = 1.04; CI, − 1.32 to − 0.92), respectively. For the conventional QA method, the average values of the gamma passing rate and point dose error were 95.95% (standard deviation (1 sigma) = 4.35; 95% confidence interval (CI), 95.10 to 96.80) and − 1.20% (standard deviation (1 sigma) = 1.61; CI, − 1.52 to − 0.88), respectively. Further experiments on the off-axis region demonstrated that TomoEQA can provide accurate results for 3D dose analysis, which is inherently difficult in the conventional QA method. Through a statistical analysis based on the results of TomoEQA, it was validated that the total fraction (Total Fx), monitor units, beam-on-time, leaf-of-time below 100 ms, and planning target volume diameter were statistically significant for the pass/failure of the pre-treatment QA results.
Conclusions
TomoEQA is a clinically beneficial alternative to the conventional phantom-based QA method.
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Shimizu H, Sasaki K, Aoyama T, Tachibana H, Koide Y, Iwata T, Kitagawa T, Kodaira T. Parotid gland dose reduction in the hippocampus avoidance whole-brain radiotherapy using helical tomotherapy. JOURNAL OF RADIATION RESEARCH 2022; 63:55-62. [PMID: 34850078 PMCID: PMC8776702 DOI: 10.1093/jrr/rrab107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/27/2021] [Indexed: 06/13/2023]
Abstract
The present study aimed to reduce the parotid gland dose in the hippocampus avoidance with whole-brain radiotherapy (HA-WBRT) using the helical tomotherapy (HT). Ten patients who had previously undergone WBRT were randomly selected and enrolled in this study. During the treatment planning, two different techniques to the jaw were applied for each patient, namely, 1.0 cm fixed jaw and 2.5 cm dynamic jaw. To efficiently reduce the dose in the bilateral parotid glands, directional block (DB) mode was set. The DB is a function of a treatment planning system for the dose reduction in organs at risk. The standard HA-WBRT plan which did not reduce the parotid gland dose was also designed to compare the plan quality. Compared with the standard HA-WBRT plan, the parotid gland dose could be reduced by approximately 70% without extending the delivery time by adding the parotid gland on the DB mode to the dose constraint. In addition, the differences in dosimetric parameters observed between the plans employing the 1.0 cm fixed jaw and 2.5 cm dynamic jaw were almost negligible. Moreover, delivery time in the 2.5 cm dynamic jaw could be greatly reduced by 60% compared with that in the 1.0 cm fixed jaw.
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Affiliation(s)
- Hidetoshi Shimizu
- Corresponding Author. Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-ku, Nagoya, Japan, Tel.: +81-52-762-6111, Fax: +81-52-752-8390;
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Ishibashi A, Kurosaki H, Miura K, Utsumi N, Sakurai H. Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy. Technol Cancer Res Treat 2021; 20:15330338211045497. [PMID: 34632876 PMCID: PMC8504207 DOI: 10.1177/15330338211045497] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Objectives: Hippocampus-sparing whole-brain radiotherapy (HS-WBRT) using tomotherapy is known to provide a better dose distribution than volumetric-modulated arc therapy but requires an extended irradiation time. The present study aimed to investigate whether irradiation time can be shortened by reducing the modulation factor (MF) without losing the target dose distribution. Methods: Using six tilted computed tomography images in the head area, the planning target volume (PTV) and hippocampal doses, and the irradiation time was investigated with a jaw width of 1 cm, a pitch of 0.200, and the MF changed from 3.0 to 2.6, 2.2, 1.8, and 1.4. Results: No significant changes in the PTV or hippocampus were found with MF in the range from 3.0 to 1.8, but marked deterioration was found with that of 1.4. The irradiation time showed a linear relationship with the MF within the range from 3.0 to 1.8, with 1334, 1158, 986, and 817 s at modulation factors of 3.0, 2.6, 2.2, and 1.8, respectively. However, when the MF was 1.4, the irradiation time was 808 s. Conclusions: When HS-WBRT is performed with a tilted body position and a jaw width of 1 cm, with a MF of 1.8, a favorable balance between dose parameters and irradiation time is achieved, whereas with a MF of 1.4, the quality of the radiotherapy plan deteriorates, and the irradiation time is approximately the same as that with a MF of 1.8.
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Affiliation(s)
- Akihiko Ishibashi
- 37004JCHO Tokyo Shinjuku Medical Center, Shinjuku-ku, Japan.,13081Suzuka University of Medical Science, Suzuka, Japan
| | - Hiromasa Kurosaki
- 37004JCHO Tokyo Shinjuku Medical Center, Shinjuku-ku, Japan.,13081Suzuka University of Medical Science, Suzuka, Japan
| | - Kosei Miura
- 37004JCHO Tokyo Shinjuku Medical Center, Shinjuku-ku, Japan.,13121University of Tsukuba, Tsukuba, Japan
| | - Nobuko Utsumi
- 37004JCHO Tokyo Shinjuku Medical Center, Shinjuku-ku, Japan
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Comparison of helical tomotherapy with multi-field intensity-modulated radiotherapy treatment plans using simultaneous integrated boost in high-risk prostate cancer. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2021. [DOI: 10.2478/pjmpe-2021-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Purpose: The aim of this study is to compare the dosimetric results of Helical Tomotherapy (HT) and Multi-field IMRT treatment plans using a Simultaneous Integrated Boost (SIB) technique in the treatment of High-Risk Prostate Cancer (HRPCa) with pelvic nodal radiation.
Methods: Seventeen patients planned with HT and 7,8 and 9 fields IMRT were investigated. All plans were designed with the prescribed dose of 54.0 Gy to the PTVln while simultaneously delivering 74.0 Gy to the PTVPS in 30 fractions. Dosimetric data of PTV and OARs were compared.
Results: HT gives a better CI and HI of PTVPS compared to multi-field IMRT plans. HT plans significantly improved target coverage (HT:0.95 vs multi-field IMRT: 0.52, 0.49 and 0.49 respectively, p < 0.001). Bladder mean dose(Gy) (HT: 45.6 vs multi-field IMRT: 53.6, 53.3 and 52.7 respectively, p = 0.004) and D66%(Gy) dose (HT: 35.3 vs multi-field IMRT: 46.7, 47.0 and 44.9 respectively, p = 0.006) were lower in HT. But multi-field IMRT plans significantly reduced the rectum volume receiving more than 75 Gy; (HT V75% (%) 2.7 vs multi-field IMRT 0.8, 1.4 and 0.9 respectively, p = 0.008). HT provided better sparing of the right and left femoral head receiving a mean dose. The penile bulb and small bowel doses were the highest in HT compared with multi-field IMRT.
Conclusions: HT achieved better dose distribution to target compared to multi-field IMRT. This study suggests HT as a reasonable option for the treatment of HRPCa patients.
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Muthuselvi CA, Bijina TK, Pichandi A. Evaluation of Optimal Combination of Planning Parameters (Field Width, Pitch, and Modulation Factor) in Helical Tomotherapy for Bilateral Breast Cancer. J Med Phys 2021; 45:234-239. [PMID: 33953499 PMCID: PMC8074714 DOI: 10.4103/jmp.jmp_31_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 11/23/2020] [Accepted: 12/03/2020] [Indexed: 11/05/2022] Open
Abstract
Aim: The aim of the study was to find the most balanced plan with an optimal combination of planning parameters in helical tomotherapy (HT) for bilateral breast irradiation by evaluating dosimetric indices and time factors. In particular, we investigated the best combination of field width (FW), pitch, and modulation factor (MF). Materials and Methods: A total of 90 plans (18 plans for each patient) was created in this study, with different combination of planning parameters (FW: 2.5 cm [F1] and 5 cm [F2]; pitch: 0.215 [P1], 0.287 [P2], and 0.43 [P3]; and MF: 2.0 [M1], 2.5 [M2], and 3.0 [M3]). Plans were analyzed using several dosimetric indices: homogeneity index, conformity index, dose near minimum D98%, dose near maximum D2%, and the coverage by D95% of the target. Organ at risk (OAR) doses were evaluated by mean dose, V5Gy and V25Gy for the heart and mean dose V5Gy and V20Gy for both the lungs. Treatment time was also reported for all plans. Results: Reducing FW from 5 cm to 2.5 cm increased the treatment time by 40%–50% and improved homogeneity of the target. Tightening the pitch value from 0.43 to 0.215 improved target as well as OAR doses without increasing the treatment time. Increasing MF from 2 to 3 improved all the dosimetric indices and also increased treatment time. Conclusions: On the basis of our analysis, a plan with FW 5 cm, pitch 0.215, and MF 2.5 can be considered as an optimal combination of planning parameters for bilateral breast irradiation in HT technique.
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Affiliation(s)
- C A Muthuselvi
- Department of Radiotherapy, Health Care Global Enterprises Ltd., Bengaluru, Karnataka, India
| | - T K Bijina
- Department of Radiotherapy, Health Care Global Enterprises Ltd., Bengaluru, Karnataka, India
| | - A Pichandi
- Department of Radiotherapy, Health Care Global Enterprises Ltd., Bengaluru, Karnataka, India
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Chang KH, Lee YH, Park BH, Han MC, Kim J, Kim H, Cho MS, Kang H, Lee H, Kim DW, Park K, Cho J, Kim YB, Kim JS, Hong CS. Statistical Analysis of Treatment Planning Parameters for Prediction of Delivery Quality Assurance Failure for Helical Tomotherapy. Technol Cancer Res Treat 2020; 19:1533033820979692. [PMID: 33302821 PMCID: PMC7734483 DOI: 10.1177/1533033820979692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Purpose: This study aimed to investigate the parameters with a significant impact on delivery quality assurance (DQA) failure and analyze the planning parameters as possible predictors of DQA failure for helical tomotherapy. Methods: In total, 212 patients who passed or failed DQA measurements were retrospectively included in this study. Brain (n = 43), head and neck (n = 37), spinal (n = 12), prostate (n = 36), rectal (n = 36), pelvis (n = 13), cranial spinal irradiation and a treatment field including lymph nodes (n = 24), and other types of cancer (n = 11) were selected. The correlation between DQA results and treatment planning parameters were analyzed using logistic regression analysis. Receiver operating characteristic (ROC) curves, areas under the curves (AUCs), and the Classification and Regression Tree (CART) algorithm were used to analyze treatment planning parameters as possible predictors for DQA failure. Results: The AUC for leaf open time (LOT) was 0.70, and its cut-off point was approximately 30%. The ROC curve for the predicted probability calculated when the multivariate variable model was applied showed an AUC of 0.815. We confirmed that total monitor units, total dose, and LOT were significant predictors for DQA failure using the CART. Conclusions: The probability of DQA failure was higher when the percentage of LOT below 100 ms was higher than 30%. The percentage of LOT below 100 ms should be considered in the treatment planning process. The findings from this study may assist in the prediction of DQA failure in the future.
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Affiliation(s)
- Kyung Hwan Chang
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Young Hyun Lee
- Eretec Inc. 401, Simin-daero, Dongan-gu, Anyang-si, Gyeonggi-do, South Korea
| | - Byung Hun Park
- Eretec Inc. 401, Simin-daero, Dongan-gu, Anyang-si, Gyeonggi-do, South Korea
| | - Min Cheol Han
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Jihun Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Hojin Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Min-Seok Cho
- Department of Radiation Oncology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, South Korea
| | - Hyokyeong Kang
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Ho Lee
- Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
| | - Dong Wook Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Kwangwoo Park
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Jaeho Cho
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Yong Bae Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Jin Sung Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Chae-Seon Hong
- Department of Radiation Oncology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, South Korea
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Boyd R, Jeong K, Tomé WA. Determining efficient helical IMRT modulation factor from the MLC leaf-open time distribution on precision treatment planning system. J Appl Clin Med Phys 2019; 20:64-74. [PMID: 30957967 PMCID: PMC6523016 DOI: 10.1002/acm2.12581] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 02/21/2019] [Accepted: 03/01/2019] [Indexed: 11/21/2022] Open
Abstract
Purpose Since the modulation factor (MF) impacts both plan quality and delivery efficiency in tomotherapy Intensity Modulated Radiation Therapy (IMRT) treatment planning, the purpose of this study was to demonstrate a technique in determining an efficient MF from the Multileaf Collimator (MLC) leaf‐open time (LOT) distribution of a tomotherapy treatment delivery plan. Methods Eight clinical plans of varying complexity were optimized with the highest allowed MF on the Accuracy Precision treatment planning system. Using a central limit theorem argument a range of reduced MFs were then determined from the first two moments of the LOT distribution. A step down approach was used to calculate the reduced‐MF plans and plan comparison tools available on the Precision treatment planning system were used to evaluate dose differences with the reference plan. Results A reduced‐MF plan that balanced delivery time and dosimetric quality was found from the set of five MFs determined from the LOT distribution of the reference plan. The reduced‐MF plan showed good agreement with the reference plan (target and critical organ dose‐volume region of interest dose differences were within 1% and 2% of prescription dose, respectively). Discussion Plan evaluation and acceptance criteria can vary depending on individual clinical expectations and dosimetric quality trade‐offs. With the scheme presented in this paper a planner should be able to efficiently generate a high‐quality plan with efficient delivery time without knowing a good MF beforehand. Conclusion A methodology for deriving a reduced MF from the LOT distribution of a high MF treatment plan using the central limit theorem has been presented. A scheme for finding a reduced MF from a set of MFs that results in a plan balanced in both dosimetric quality and treatment delivery efficiency has also been presented.
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Affiliation(s)
- Robert Boyd
- Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kyoungkeun Jeong
- Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Wolfgang A Tomé
- Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
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Shimizu H, Sasaki K, Kubota T, Fukuma H, Aoyama T, Iwata T, Tachibana H, Kodaira T. Interfacility variation in treatment planning parameters in tomotherapy: field width, pitch, and modulation factor. JOURNAL OF RADIATION RESEARCH 2018; 59:664-668. [PMID: 29868727 PMCID: PMC6151637 DOI: 10.1093/jrr/rry042] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/02/2018] [Indexed: 06/08/2023]
Abstract
Several studies have reported changes in dose distribution and delivery time based on the value of specific planning parameters [field width (FW), pitch, and modulation factor (MF)] in tomotherapy. However, the variation in the parameters between different facilities is unknown. The purpose of this study was to determine standard values of the above parameters for cases of head and neck cancer (HNC) and prostate cancer (PC) in Japan. In this survey, a web-based questionnaire was sent to 48 facilities performing radiation therapy with tomotherapy in March 2016. The deadline for data submission was April 2016. In the questionnaire, the values of the planning parameters usually used were requested and 23 responses were received, representing a response rate of 48% (23/48). The FW selected was 2.5 cm in most facilities, and facilities with a tomoEDGE license used dynamic FW rather than fixed FW. Facilities changed the pitch based on FW, dose per fraction, or target offset more frequently in HNC than in PC. In contrast, >50% of the facilities used the magic number proposed by Kissick et al. Median preset MFs (range, min to max) in HNC and PC were 2.4 (1.8-2.8) and 2.0 (1.8-3.0), respectively, and MF values showed large variations between the facilities. Our results are likely to be useful to several facilities designing treatment plans in tomotherapy.
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Affiliation(s)
- Hidetoshi Shimizu
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
- Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, 323-1 Kamioki, Maebashi, Gunma, Japan
| | - Koji Sasaki
- Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, 323-1 Kamioki, Maebashi, Gunma, Japan
| | - Takashi Kubota
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
| | - Hiroshi Fukuma
- Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, Aichi, Japan
| | - Takahiro Aoyama
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
| | - Tohru Iwata
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
| | - Hiroyuki Tachibana
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
| | - Takeshi Kodaira
- Department of Radiation Oncology, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-Ku, Nagoya, Aichi, Japan
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In regard to the paper: Patient performance-based plan parameter optimization for prostate cancer in tomotherapy [Cao YJ, Lee S, Chang KH, Shim JB, Kim KH, Park YJ, Kim CY. Med Dosim. 2015;40(4):285-9. doi: 10.1016/j.meddos.2015.03.005. Epub 2015 Apr 11.]. Med Dosim 2018; 43:351. [DOI: 10.1016/j.meddos.2017.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 11/14/2017] [Indexed: 11/19/2022]
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Shimizu H, Sasaki K, Tachibana H, Tomita N, Makita C, Nakashima K, Yokoi K, Kubota T, Yoshimoto M, Iwata T, Kodaira T. Analysis of modulation factor to shorten the delivery time in helical tomotherapy. J Appl Clin Med Phys 2017; 18:83-87. [PMID: 28444831 PMCID: PMC5689868 DOI: 10.1002/acm2.12075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 11/12/2022] Open
Abstract
A low modulation factor (MF) maintaining a good dose distribution contributes to the shortening of the delivery time and efficiency of the treatment plan in helical tomotherapy. The purpose of this study was to reduce the delivery time using initial values and the upper limit values of MF. First, patients with head and neck cancer (293 cases) or prostate cancer (181 cases) treated between June 2011 and July 2015 were included in the analysis of MF values. The initial MF value (MFinitial ) was defined as the average MFactual value, and the upper limit of the MF value (MFUL ) was defined according the following equation: MFUL = 2 × standard deviation of MFactual value + the average MFactual Next, a treatment plan was designed for patients with head and neck cancer (62 cases) and prostate cancer (13 cases) treated between December 2015 and June 2016. The average MFactual value for the nasopharynx, oropharynx, hypopharynx, and prostate cases decreased from 2.1 to 1.9 (p = 0.0006), 1.9 to 1.6 (p < 0.0001), 2.0 to 1.7 (p < 0.0001), and 1.8 to 1.6 (p = 0.0004) by adapting the MFinitial and the MFUL values, respectively. The average delivery time for the nasopharynx, oropharynx, hypopharynx, and prostate cases also decreased from 19.9 s cm-1 to 16.7 s cm-1 (p < 0.0001), 15.0 s cm-1 to 13.9 s cm-1 (p = 0.025), 15.1 s cm-1 to 13.8 s cm-1 (p = 0.015), and 23.6 s cm-1 to 16.9 s cm-1 (p = 0.008) respectively. The delivery time was shortened by the adaptation of MFinitial and MFUL values with a reduction in the average MFactual for head and neck cancer and prostate cancer cases.
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Affiliation(s)
- Hidetoshi Shimizu
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Koji Sasaki
- Department of radiation therapy education and research, Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, Maebashi, Gunma, Japan
| | - Hiroyuki Tachibana
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Natsuo Tomita
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Chiyoko Makita
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Kuniyasu Nakashima
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Kazushi Yokoi
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Takashi Kubota
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Manabu Yoshimoto
- Department of Radiology, Aichi Cancer Center Aichi Hospital, Okazaki, Aichi, Japan
| | - Tohru Iwata
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
| | - Takeshi Kodaira
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Aichi, Japan
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Buschmann M, Seppenwoolde Y, Wiezorek T, Weibert K, Georg D. Advanced optimization methods for whole pelvic and local prostate external beam therapy. Phys Med 2016; 32:465-73. [PMID: 27050171 DOI: 10.1016/j.ejmp.2016.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Radiation treatment planning inherently involves multiple conflicting planning goals, which makes it a suitable application for multicriteria optimization (MCO). This study investigates a MCO algorithm for VMAT planning (VMAT-MCO) for prostate cancer treatments including pelvic lymph nodes and uses standard inverse VMAT optimization (sVMAT) and Tomotherapy planning as benchmarks. METHODS For each of ten prostate cancer patients, a two stage plan was generated, consisting of a stage 1 plan delivering 22Gy to the prostate, and a stage 2 plan delivering 50.4Gy to the lymph nodes and 56Gy to the prostate with a simultaneous integrated boost. The single plans were generated by three planning techniques (VMAT-MCO, sVMAT, Tomotherapy) and subsequently compared with respect to plan quality and planning time efficiency. RESULTS Plan quality was similar for all techniques, but sVMAT showed slightly better rectum (on average Dmean -7%) and bowel sparing (Dmean -17%) compared to VMAT-MCO in the whole pelvic treatments. Tomotherapy plans exhibited higher bladder dose (Dmean +42%) in stage 1 and lower rectum dose (Dmean -6%) in stage 2 than VMAT-MCO. Compared to manual planning, the planning time with MCO was reduced up to 12 and 38min for stage 1 and 2 plans, respectively. CONCLUSION MCO can generate highly conformal prostate VMAT plans with minimal workload in the settings of prostate-only treatments and prostate plus lymph nodes irradiation. In the whole pelvic plan manual VMAT optimization led to slightly improved OAR sparing over VMAT-MCO, whereas for the primary prostate treatment plan quality was equal.
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Affiliation(s)
- Martin Buschmann
- Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.
| | - Yvette Seppenwoolde
- Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Tilo Wiezorek
- Department of Radiation Oncology, University Hospital Jena, Jena, Germany
| | - Kirsten Weibert
- Department of Radiation Oncology, University Hospital Jena, Jena, Germany
| | - Dietmar Georg
- Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
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Yawichai K, Chitapanarux I, Wanwilairat S. Helical tomotherapy optimized planning parameters for nasopharyngeal cancer. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/694/1/012002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Meyer P, Bouhours H, Dehaynin N, Jarnet D, Gantier M, Karamanoukian D, Niederst C. The optimal tomotherapy treatment planning parameters for extremity soft tissue sarcomas. Phys Med 2015; 31:542-52. [PMID: 26032005 DOI: 10.1016/j.ejmp.2015.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/30/2015] [Accepted: 05/07/2015] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND PURPOSE To determine the optimum combination of treatment parameters between pitch, field width (FW) and modulation factor (MF) for extremity sarcomas in tomotherapy. MATERIALS AND METHODS Six patients previously treated for extremity sarcomas (3 arms and 3 legs) with tomotherapy were included in this study. 288 treatment plans were recalculated, corresponding to all combinations between 2 FW (2.5 and 5 cm), 4 MF (1.5, 2, 2.5 and 3) and 6 pitches (0.215, 0.287, 0.43 and 3 off-axis pitches). The treatment parameters (MF, FW or pitch) are modified between each plan, and the calculation is relaunched for 400 iterations, without modifying the optimisation constraints of the plan under which the patient has been treated. RESULTS We suggest eliminating the 0.43 pitch and never combining a 0.215 pitch with an MF ≤ 2. We also do not recommend using an MF = 1.5 unless treatment time is an absolute priority over plan quality. We did not see any advantage in using Chen off-axis pitches, except for targets far from the axis (>15 cm) treated with a high pitch. A combination of MF = 2/FW = 5 cm/pitch = 0.287 gives plans of acceptable quality, combined with reduced treatment times. These conclusions are true only for extremity sarcomas treated in 2 Gy/fraction. CONCLUSIONS We have shown that the choice of pitch/MF/FW combination is crucial for the treatment of extremity sarcomas in tomotherapy: some produce good dosimetric quality with a reduced irradiation time, while others may increase the time without improving the quality.
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Affiliation(s)
- Philippe Meyer
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
| | - Hugo Bouhours
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
| | - Nicolas Dehaynin
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
| | - Delphine Jarnet
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
| | - Matthieu Gantier
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
| | - Diran Karamanoukian
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
| | - Claudine Niederst
- Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France
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Cao YJ, Lee S, Chang KH, Shim JB, Kim KH, Park YJ, Kim CY. Patient performance-based plan parameter optimization for prostate cancer in tomotherapy. Med Dosim 2015; 40:285-9. [PMID: 25869936 DOI: 10.1016/j.meddos.2015.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/17/2015] [Indexed: 11/18/2022]
Abstract
The purpose of this study is to evaluate the influence of treatment-planning parameters on the quality of treatment plans in tomotherapy and to find the optimized planning parameter combinations when treating patients with prostate cancer under different performances. A total of 3 patients with prostate cancer with Eastern Cooperative Oncology Group (ECOG) performance status of 2 or 3 were included in this study. For each patient, 27 treatment plans were created using a combination of planning parameters (field width of 1, 2.5, and 5cm; pitch of 0.172, 0.287, and 0.43; and modulation factor of 1.8, 3, and 3.5). Then, plans were analyzed using several dosimetrical indices: the prescription isodose to target volume (PITV) ratio, homogeneity index (HI), conformity index (CI), target coverage index (TCI), modified dose HI (MHI), conformity number (CN), and quality factor (QF). Furthermore, dose-volume histogram of critical structures and critical organ scoring index (COSI) were used to analyze organs at risk (OAR) sparing. Interestingly, treatment plans with a field width of 1cm showed more favorable results than others in the planning target volume (PTV) and OAR indices. However, the treatment time of the 1-cm field width was 3 times longer than that of plans with a field width of 5cm. There was no substantial decrease in treatment time when the pitch was increased from 0.172 to 0.43, but the PTV indices were slightly compromised. As expected, field width had the most significant influence on all of the indices including PTV, OAR, and treatment time. For the patients with good performance who can tolerate a longer treatment time, we suggest a field width of 1cm, pitch of 0.172, and modulation factor of 1.8; for the patients with poor performance status, field width of 5cm, pitch of 0.287, and a modulation factor of 3.5 should be considered.
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Affiliation(s)
- Yuan Jie Cao
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Suk Lee
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea.
| | - Kyung Hwan Chang
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Jang Bo Shim
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Kwang Hyeon Kim
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Young Je Park
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Chul Yong Kim
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
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Sterpin E. Monte Carlo evaluation of the dose calculation algorithm of TomoTherapy for clinical cases in dynamic jaws mode. Phys Med 2015; 31:273-80. [PMID: 25661978 DOI: 10.1016/j.ejmp.2015.01.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/14/2015] [Accepted: 01/19/2015] [Indexed: 10/24/2022] Open
Abstract
PURPOSE For the TomoTherapy(®) system, longitudinal conformation can be improved by selecting a smaller field width but at the expense of longer treatment time. Recently, the TomoEdge(®) feature has been released with the possibility to move dynamically the jaws at the edges of the target volume, improving longitudinal penumbra and enabling faster treatments. Such delivery scheme requires additional modeling of treatment delivery. Using a previously validated Monte Carlo model (TomoPen), we evaluated the accuracy of the implementation of TomoEdge in the new dose engine of TomoTherapy for 15 clinical cases. METHODS TomoPen is based on PENELOPE. Particle tracking in the treatment head is performed almost instantaneously by 1) reading a particle from a phase-space file corresponding to the largest field and 2) correcting the weight of the particle depending on the actual jaw and MLC configurations using Monte Carlo pre-generated data. 15 clinical plans (5 head-and-neck, 5 lung and 5 prostate tumors) planned with TomoEdge and with the last release of the treatment planning system (VoLO(®)) were re-computed with TomoPen. The resulting dose-volume histograms were compared. RESULTS Good agreement was achieved overall, with deviations for the target volumes typically within 2% (D95), excepted for small lung tumors (17 cm(3)) where a maximum deviation of 4.4% was observed for D95. The results were consistent with previously reported values for static field widths. CONCLUSIONS For the clinical cases considered in the present study, the introduction of TomoEdge did not impact significantly the accuracy of the computed dose distributions.
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Affiliation(s)
- E Sterpin
- Center of Molecular Imaging, Radiotherapy and Oncology, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Avenue Hippocrate 54, 1200 Brussels, Belgium.
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Piotrowski T, Kaczmarek K, Bajon T, Ryczkowski A, Jodda A, Kaźmierska J. Evaluation of image-guidance strategies for prostate cancer. Technol Cancer Res Treat 2014; 13:583-91. [PMID: 24000985 PMCID: PMC4527463 DOI: 10.7785/tcrtexpress.2013.600258] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 03/07/2013] [Accepted: 03/11/2013] [Indexed: 12/25/2022] Open
Abstract
In this study, set-up accuracy and time consumption of different image-guidance protocols used for prostate cancer patients were compared. Set-up corrections from 60 prostate cancer patients treated on helical tomotherapy (HT) were used to simulate four types of image-guidance protocols which were based on: (i) a limited number of imaging sessions (IG-1), (ii) reduced registration tasks during daily imaging (IG-2), or (iii) and (iv) mixed methods of imaging (IG-3, IG-4). Each protocol was evaluated for three referencing scenarios based on the first fraction, first three fractions and first five fractions. Residual set-up error, the difference between the average set-up correction and the actual correction required, was used to evaluate the accuracy of each protocol. The first five fractions referencing scenario provides the highest reduction of the margins for each image-guidance protocol evaluated in this study. The first type of protocol is the shortest way to the effective correction of the systematic component of set-up error. For the second type of the protocol, the control of the residual errors is better and, as a result, the reduction of the margins is more significant than that obtained for the first one. Moreover, the second type of the protocol provides the highest accuracy of delivered dose. The result obtained for the fourth type of protocol does not decrease the calculated margins or increase their accuracy in correspondence to the no image guidance scheme. The fourth type of the protocol is not recommended as a protocol to be used to increase the conformity of the dose. The choice of the rest protocols should be validated in the context of (i) institutional practice regarding patient set-up procedure and its time consumption, (ii) acceptable balance between the amount of the dose delivered to the organ at risk and the additional imaging dose and (iii) patient anatomical conditions.
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Affiliation(s)
- T Piotrowski
- Department of Electroradiology, University of Medical Sciences, Poznan, Poland.
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Takahashi Y, Verneris MR, Dusenbery K, Wilke C, Storme G, Weisdorf DJ, Hui SK. Peripheral dose heterogeneity due to the thread effect in total marrow irradiation with helical tomotherapy. Int J Radiat Oncol Biol Phys 2013; 87:832-9. [PMID: 24011657 PMCID: PMC3805769 DOI: 10.1016/j.ijrobp.2013.07.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/03/2013] [Accepted: 07/15/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To report potential dose heterogeneity leading to underdosing at different skeletal sites in total marrow irradiation (TMI) with helical tomotherapy due to the thread effect and provide possible solutions to reduce this effect. METHODS AND MATERIALS Nine cases were divided into 2 groups based on patient size, defined as maximum left-to-right arm distance (mLRD): small mLRD (≤47 cm) and large mLRD (>47 cm). TMI treatment planning was conducted by varying the pitch and modulation factor while a jaw size (5 cm) was kept fixed. Ripple amplitude, defined as the peak-to-trough dose relative to the average dose due to the thread effect, and the dose-volume histogram (DVH) parameters for 9 cases with various mLRD was analyzed in different skeletal regions at off-axis (eg, bones of the arm or femur), at the central axis (eg, vertebrae), and planning target volume (PTV), defined as the entire skeleton plus 1-cm margin. RESULTS Average ripple amplitude for a pitch of 0.430, known as one of the magic pitches that reduce thread effect, was 9.2% at 20 cm off-axis. No significant differences in DVH parameters of PTV, vertebrae, or femur were observed between small and large mLRD groups for a pitch of ≤0.287. Conversely, in the bones of the arm, average differences in the volume receiving 95% and 107% dose (V95 and V107, respectively) between large and small mLRD groups were 4.2% (P=.016) and 16% (P=.016), respectively. Strong correlations were found between mLRD and ripple amplitude (rs=.965), mLRD and V95 (rs=-.742), and mLRD and V107 (rs=.870) of bones of the arm. CONCLUSIONS Thread effect significantly influences DVH parameters in the bones of the arm for large mLRD patients. By implementing a favorable pitch value and adjusting arm position, peripheral dose heterogeneity could be reduced.
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Affiliation(s)
- Yutaka Takahashi
- Masonic Cancer Center, Division of Hematology, Oncology and Bone Marrow Transplantation
| | - Michael R. Verneris
- Department of Pediatrics, Division of Hematology, Oncology and Bone Marrow Transplantation
| | | | | | - Guy Storme
- Department of Radiotherapy, Universitair Ziekenhuis Brussel
| | | | - Susanta K Hui
- Masonic Cancer Center, Division of Hematology, Oncology and Bone Marrow Transplantation
- Department of Therapeutic Radiology, University of Minnesota
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Dosimetric consequences of prostate-based couch shifts on the precision of dose delivery during simultaneous IMRT irradiation of the prostate, seminal vesicles and pelvic lymph nodes. Phys Med 2013; 30:228-33. [PMID: 23860339 DOI: 10.1016/j.ejmp.2013.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/02/2013] [Accepted: 06/25/2013] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION To evaluate the impact interfraction prostate (CTV1) motion corrections on doses delivered to seminal vesicles (CTV2) and lymph nodes (CTV3), and to determine ideal planning target volume (PTV) margins for these targets with prostate-based position verification. MATERIAL AND METHODS Retrospective analysis based on 253 cone beam computed tomography (CBCT) studies of 28 patients. The isocenter-shift method was used to estimate the interfraction prostate and bony shift effects on the original plan coverage. Friedman's test was used to assess statistical significance between dose-volume histogram (DVH) parameters which were calculated for prostate-based sum plans, bony-based sum plans and original treatment plans. The van Herk formula was used to determine the set-up margin size for prostate-based verification. RESULTS The tracked shifts influenced the minimum, maximum and mean CTV2 and CTV3 doses, with a range differential of 0.17%-2.63% (prostate shifts) and 0.13%-1.92% (bony shifts) compared to the corresponding original parameters. Friedman's test revealed significant differences in the minimum doses to the CTV3 and maximum doses to both the CTV2 and CTV3. The calculated set-up margins of 1.22 cm (vertical), 0.19 cm (longitudinal) and 0.39 cm (lateral) should be added to CTV3 while performing prostate-based positioning. CONCLUSION To avoid geographical miss during simultaneous irradiation of independently moving targets (CTV1-3) appropriate margins should be used in accordance with the position verification method used. Based on our findings the following margin sizes should be used: 0.7 cm for the CTV1, 0.8-0.9 cm for the CTV2 , and asymmetric 1.0 cm (vertically) and 0.5 cm (other axes) for the CTV3.
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Empirical estimation of beam-on time for prostate cancer patients treated on Tomotherapy. Rep Pract Oncol Radiother 2013; 18:201-8. [PMID: 24416554 DOI: 10.1016/j.rpor.2012.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/04/2012] [Accepted: 12/30/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND AIM This study proposed a method to estimate the beam-on time for prostate cancer patients treated on Tomotherapy when FW (field width), PF (pitch factor), modulation factor (MF) and treatment length (TL) were given. MATERIAL AND METHODS THE STUDY WAS DIVIDED INTO TWO PARTS: building and verifying the model. To build a model, 160 treatment plans were created for 10 patients. The plans differed in combination of FW, PF and MF. For all plans a graph of beam-on time as a function of TL was created and a linear trend function was fitted. Equation for each trend line was determined and used in a correlation model. Finally, 62 plans verified the treatment time computation model - the real execution time was compared with our estimation and irradiation time calculated based on the equation provided by the manufacturer. RESULTS A linear trend function was drawn and the coefficient of determination R (2) and the Pearson correlation coefficient r were calculated for each of the 8 trend lines corresponding to the adequate treatment plan. An equation to correct the model was determined to estimate more accurately the beam-on time for different MFs. From 62 verification treatment plans, only 5 disagreed by more than 60 s with the real time from the HT software. Whereas, for the equation provided by the manufacturer the discrepancy was observed in 16 cases. CONCLUSIONS Our study showed that the model can well predict the treatment time for a given TL, MF, FW and it can be used in clinical practice.
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