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Showing 7 results for Helical Tomotherapy
Dr. G. Grigorov, J.c.l. Chow,
Volume 7, Issue 4 (3-2010)
Abstract
Background: In Helical Tomotherapy (HT), the
scaling factor (SF) is the time in seconds that each
leaf viewing a target would need to be open to deliver
the prescribed dose. The SF is patient-specific and is
used to calculate the rotational period of the gantry,
and the total treatment time (TTT) of the HT. The SF is
generally difficult to estimate. Currently, it takes
about one hour to fully optimize a prostate HT plan
and to calculate the corresponding TTT. The aim of
this study is to develop a method for estimation of
the SF directly using a patient-specific approximating
function. Materials and Methods: The SFs of ten
randomly selected patients were used to build the
approximation model. For the entire group of patients
the PTV1 ranged from 57 to 396 cm3 for PTV1 margins
from 2 to 10 mm. The discrete data for every patient
is represented by an individual function, SF=f (k×
PTV1). The values of the function were rescaled to a
special unit which represents the target volume irradiated
with the prescribed dose per second. The values
were normalized with two “geometric” parameters,
namely, the target-to-target and the body-to-body
ratios. After the normalization, the function for every
patient was ordered in the file by the volume of the
prostate and seminal vesicles. Results: For prostate
HT planning, it was found that the planning target
volume (PTV1) has a higher impact on the SF values
than the size of the patient's bodies. The function
SF=f (k×PTV1) was found smooth and continuous over
the given interval. The rescaled and normalized
functions for all patients were represented as delimiters
of a 2D field. Conclusion: The method proposed
for determination of the SF and TTT for HT prostate
planning covers PTV1 of four margins and a volume of
prostate and seminal vesicles ranging from 42.8 to
161 cm3. Using these approximations, the TTTs for a
second group of patients were determined in several
minutes with deviation ranging from −2.8% to +7.1%
compared to that of the TTTs calculated using the HT
planning system. Iran. J. Radiat. Res., 2010 7 (4): 177-185
Ph.d., M. Okutan, A. Franko, C. Köksal, E.o. Göksel, Ş. Karaman, Y. Emre Akpınar, N. Dağoğlu, B. Demir,
Volume 18, Issue 4 (10-2020)
Abstract
Background: Radiation Pneumonia (RP) is one of the most extensive side effects in Stereotactic Body Radiotherapy (SBRT) of lung cancer. SBRT are performed by means of Intensity Modulated Radiotherapy (IMRT), Intensity Modulated Arc Therapy (IMAT), CyberKnife (CK) or Helical Tomotherapy (HT) treatment methods. In this study, we performed a plan study to determine the plan parameter such as the Mean Lung Dose (MLD), V20Gy Lung Volume and V5Gy Lung Volume in the evaluation of RP risk in the treatment of lung with SBRT. Materials and Methods: Fifteen patients with Lung Cancer who had a tumor diameter of less than 5 cm and peripheral located were included to this study. Intensity Modulated Radiotherapy, Intensity Modulated Arc Therapy, CyberKnife and Helical Tomotherapy plans were separately created for each patients. For each plan, a total of 54 Gy dose were given to Planning Target Volume (PTV) in 3 fractions using a dose of 18 Gy per fraction. Results: In each technique for all parameters of PTV and critical organ doses (OAR) meet the required criteria. Total Lung MLD were found as 3.21 Gy and Total Lung V20Gy Volume were found as 4.05 cc, Total Lung V5Gy Volume were found as 14.06 cc as the lowest value in IMRT-SBRT plan. Conclusion: When treatment plans are evaluated in terms of RP risk, Total Lung MLD, Total Lung V20Gy Volume and Contralateral Lung V5Gy Volume are found the lower in IMRT- SBRT plan than other SBRT techniques. We suggest that IMRT-SBRT irradiation should be preferred in lung radiotherapy in case of high RP risk.
M.f. Guo, X.j. Zhao, Y. Huang, D.k. Chen, Dr. N. Zhang,
Volume 20, Issue 2 (4-2022)
Abstract
Background: To compare the dosimetric parameters, clinical complications, and efficacy of helical tomotherapy (HT) and fixed-field intensity-modulated radiotherapy (f-IMRT) in radical radiotherapy for cervical cancer. Materials and Method: From November 2016 to December 2018, 77 cervical cancer patients in radical irradiation were selected, 38 patients undergoing treatment with HT and 39 with f-IMRT. The dosimetic parameters, clinical complications, and efficacy were compared. Results: The homogeneity index (HI) and conformity index (CI) of HT plans were both superior to those of f-IMRT plans(P=0.000). HT plans resulted in a reduction in the dosimetric parameters of organs at risk (OARs) (P<0.05) except the V10 of small intestine (P=0.682). The incidence of myelosuppression showed no significant differences (P=0.265).The patients with HT had no radiocystitis, grade 2 or above radiation proctitis. The complete remission (CR) rates, efficacy rates (CR+PR) and local control rates of two years were 81.58%,100% and 97.37%. Conclusion: HT showed advantages in dosimetry, and provided more superior clinical results. It has a good application prospect in radical irradiation for cervical cancer.
Ph.d., N. Isık, E. Algül, G. Yaprak, A. Özen,
Volume 20, Issue 3 (7-2022)
Abstract
Background: We compare plans involving two different stereotactic radiotherapy devices: Cyberknife (CK) and Helical Tomotherapy (HTT) and their results on the lumbarvertebra targets. Materials and Methods: Ten simulation tomographs of the first lumbar vertebra were selected from among the tomographies of patients who had previously undergone SBRT for any reason. In each planning tomography, two separate clinical target volumes (CTV) were drawn at the first lumbar vertebra, we used 2%, 95% and 98% doses of the target volume (D2, D95, D98) in the plan evaluation. The 2% dose of the planning target volume (PTV) was used for comparison with the hot spot; the 95% dose coverage of CTV was used for the target coverage comparison, and the 98% dose of the target volume was used for the dose volume histogram "shoulder" metric definitionTheHomogeneity Index (HI), new Conformity Index (nCI) and Gradient Index (GI) were evaluated for each planning system and target. Results: In both groups, CTV1 and CTV2, when compared with D95, the coverage for HTT was found statistically significantly higher. D98 was found to be statistically significantly higher with HTT. In both targets, the CKplans were found to have a higher hot area (D2), and inhomogeneous plans were obtained when compared to HTT. The NCI results were similar, and GI was higher with HTT. Conclusion: In lumbar vertebra stereotactic radiotherapy, more inhomogeneous plans were obtained with Cyberknife than with the Helical Tomotherapy device. A better gradient index was achieved with Cyberknife, while better coverage was achieved on the HTT plan.
A. Watcharawipha, M.d., I. Chitapanarux, B. Jia-Mahasap,
Volume 20, Issue 3 (7-2022)
Abstract
Background: The Helical Tomotherapy (HT) technique has been introduced for use in Stereotactic Radiosurgery (SRS). Previously, the smallest field width (FW) has been recommended for optimum results, which would require a long beam-on time (BoT). The uncertainty of the intrafraction could be maximized during the delivery by this BoT. This study then investigated the plan qualities and dosimetric parameters among different FWs and treatment modes. Materials and Methods: Fifteen patients previously treated by the HT technique with fixed-FW 10 mm (FW10f) were selected. The treatment planning systems of TomoTherapy involved other plans that employed fixed-FW 25 mm (FW25f) and dynamic-FW 25 mm (FW25d). The plan quality indexes and the dosimetric parameters of the large FWs (FW 25 mm) were compared according to the FW10f benchmark and then analyzed by relevant statistics. Results: The plan quality indexes and the dosimetric parameters revealed no significant differences between FW10f and FW25d. Accordingly, FW25f revealed a significant difference in the FW10f values in some indexed parameters. The maximum dose on the right optic nerves and the value of the integral dose revealed a significant difference between FW10f and FW25f. The BoT of the FW10f presented the longest treatment time when compared with the other FWs. Conclusion: The outcomes of this investigation clearly ensure that the performance of FW25d is comparable with that of FW10f in terms of the plan qualities and the dosimetric parameters. Notably, the short BoT of this FW might benefit the minimization that is associated with intrafraction uncertainty.
N. Monadi, Ph.d., D. Shahbazi-Gahrouei, S. Monadi, L. Mahani, A. Shams, A. Akhavan, R. Mohammadi,
Volume 21, Issue 3 (7-2023)
Abstract
Background: This study aims to evaluate and compare Three-Dimensional Conformal Radiotherapy (3D-CRT) versus Helical Tomotherapy (HT) based on treatment planning and selection of the most appropriate method to reduce side effects. Materials and Methods: Treatment planning was performed on images of 20 patients with head and neck cancer with lymph node involvement by HT and 3D-CRT techniques in Seyed Al-Shohada hospital, Isfahan, Iran. The quality of target coverage, the exposure of normal tissue, and radiation delivery efficiency in two studied methods were compared. Results: Tomotherapy showed significant improvement over 3D-CRT in terms of D2%, D50% Dmean, V95%, CI (conformity index), and HI (homogeneity index) for PTV (planning target volume) and in terms of D2%, D98%, Dmean, V95%, CI and HI for PTV Nodal. The mean dose received by 98% of PTV (D98%) increased in HT compared to 3D-CRT. Whereas, higher doses received in organs at risk (OARs) in 3D-CRT compared to HT. Conclusion: Results showed improvements in target quality for HT over 3D-CRT, including dosimetric coverage of target volumes, homogeneity and conformity indices, and reduction of the volume of cold and hot spots. Tomotherapy also performed better than that of 3D-CRT in OARs. Overall, with the satisfactory results obtained here, HT technique has considerable promise for treating head and neck cancers with the involvement of regional lymph nodes.
A. Kazemzadeh, L. Mahani, M. Kianinia, Ph.d., A. Shanei,
Volume 22, Issue 4 (10-2024)
Abstract
Background: The main purpose of this study is to investigate different methods of radiotherapy (RT) using coplanar three-dimensional conformal RT (3D-CRT (cp)), non-coplanar 3D-CRT RT (3D-CRT (ncp)) and helical tomotherapy (HT) techniques to find the optimal method to treat gastric cancer patients. Materials and Methods: Twenty patients with gastric cancer were retrospectively enrolled. Three different treatment plans including HT, 3D-CRT (cp) and 3D-CRT (ncp) were generated and optimized for each patient. All plans were then evaluated with respect to dosimetric parameters exported from dose-volume histogram curves of target and organ-at-risk (OAR). SPSS software was used for statistical analysis. Results: The conformity index in the target was similar for all plans (p > 0.05), but HT showed significantly better homogeneity compared to the two 3D-CRT methods (p-value < 0.05). Compared to the 3D-CRT (cp) and 3D-CRT (ncp) plans, the HT plans significantly reduced the mean dose, V13 and V20 values of the kidneys (p-Value < 0.05); V5 values of both kidneys were lower in the 3D-CRT (ncp) plan compared to 3D-CRT (cp) and HT. The difference was statistically significant. Moreover, the results proved that the 3D-CRT (ncp) could better preserve kidneys rather than 3D-CRT (cp). Dmean of the liver for HT plans (20.03) was significantly higher than those for both coplanar and non-coplanar 3D-CRT plans (17.86 and 17.7, respectively). Conclusion: Generally, HT plans appear to be the best, but in the case of selecting an optimum method, it is necessary to pay attention to the location of tumors compared to OARs.
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