Dosimetric comparison between TomoDirect and Helical Tomotherapy in total body irradiation / 中华放射医学与防护杂志

Objective@#To investigate the dosimetric differences between TomoDirect (TD) and Helical Tomotherapy (HT) in total body irradiation (TBI), as well to evaluate the plan quality and delivery efficiency of TD.@*Methods@#Eight patients with acute leukemia at an average height of about 120 cm who had undergone TBI in the first affiliated hospital of Zhengzhou university were retrospectively reviewed and replanned with the TD and HT techniques for dosimetric comparison. Identical planning parameters were configured for both techniques except that TD plans were designed with 2-12 equally spaced odd number fields and with an initial angle of 180 or 0 degree. Dosimetric differences in mean dose of plan target volume (PTVDmean), homogeneity index (HI), dose of organs at risk (OARs), as well as delivery time were compared between the TD and HT plans.@*Results@#The TD plans with 9 fields or more had similar PTVDmeanand HI compared with HT plans, while TD plans with less than 9 fields had a significant different PTVDmean(t=-3.12, -5.41, -20.33, -4.56, -7.22, -11.27, P<0.05) and HI (t=-2.94, -5.18, -15.66, -4.31, -5.51, - 9.13, P<0.05) compared with those of HT. In terms of OARs, the TD plans with 7 fields or more had no significant dosimetric differences in the mean dose of left and right lung compared with the HT plans. The TD plans with 3 fields had significant different maximum dose in the left lens plan risk volume(PRV) (2.14±0.60) Gy and the right lens PRV (3.05±0.10) Gy (t=0.77, 0.63, P<0.05) compared with the HT plans. No significant difference in delivery time was observed. The initial angle of the TD plans had no effects on PTVDmean, HI, OAR dosimetry and delivery time.@*Conclusions@#The TD plans with 9 fields or more can achieve similar plan quality in terms of target coverage, OAR sparing and delivery time, but have an advantage in the maximum dose to lens PRV compared with the HT plans.

Dosimetric comparison between TomoDirect and Helical Tomotherapy in total body irradiation / 中华放射医学与防护杂志

Objective To investigate the dosimetric differences between TomoDirect ( TD) and Helical Tomotherapy ( HT ) in total body irradiation ( TBI ) , as well to evaluate the plan quality and delivery efficiency of TD. Methods Eight patients with acute leukemia at an average height of about 120 cm who had undergone TBI in the first affiliated hospital of Zhengzhou university were retrospectively reviewed and replanned with the TD and HT techniques for dosimetric comparison. Identical planning parameters were configured for both techniques except that TD plans were designed with 2-12 equally spaced odd number fields and with an initial angle of 180 or 0 degree. Dosimetric differences in mean dose of plan target volume ( PTVDmean ) , homogeneity index ( HI) , dose of organs at risk ( OARs) , as well as delivery time were compared between the TD and HT plans. Results The TD plans with 9 fields or more had similar PTVDmean and HI compared with HT plans, while TD plans with less than 9 fields had a significant different PTVDmean(t=-3. 12, -5. 41, -20. 33, -4. 56, -7. 22, -11. 27, P<0. 05) and HI ( t=-2. 94, -5. 18,-15. 66,-4. 31,-5. 51,- 9. 13, P<0. 05) compared with those of HT. In terms of OARs, the TD plans with 7 fields or more had no significant dosimetric differences in the mean dose of left and right lung compared with the HT plans. The TD plans with 3 fields had significant different maximum dose in the left lens plan risk volume(PRV) (2.14±0.60) Gy and the right lens PRV (3.05±0.10) Gy (t=0.77, 0.63, P<0.05) compared with the HT plans. No significant difference in delivery time was observed. The initial angle of the TD plans had no effects on PTVDmean , HI, OAR dosimetry and delivery time. Conclusions The TD plans with 9 fields or more can achieve similar plan quality in terms of target coverage, OAR sparing and delivery time, but have an advantage in the maximum dose to lens PRV compared with the HT plans.

Dosimetric comparison among TomoDirect, Helical Tomotherapy and VMAT in the treatment of upper thoracic esophageal carcinoma / 中华放射医学与防护杂志

Objective To compare the dosimetric difference among TomoDirect (TD) radiotherapy,Helical Tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in the treatment of upper thoracic esophageal carcinoma.Methods A total of 15 patients with cT2-4 N0-1 M0 upper thoracic esophageal squamous cell carcinoma were enrolled.Three plans were generated using the same dose objective for each patient:TD,HT and VMAT.Dose-volume histogram (DVH),homogeneity index (HI),conformal index (CI),dose at organ at risk (OAR),delivery time and monitor unit (MU) were compared among different plans.Results The D2 and D values in the HT and TD plans were significantly lower than those in the VMAT plans.The D98 value in the TD was similar to that in the HT,but lower than that in the VMAT.The HI of HT was significantly better than those of TD and VMAT (F =81.603,P ＜ 0.05).For the CI,there was no significant difference among the three techniques (P ＞ 0.05).For the V15 of lung,HT was significantly higher than TD (t =-2.626,P ＜0.05) and VMAT (t=3.547,P ＜ 0.05).The V20 of lung in TD was similar to that in HT,but higher than that in VMAT (t =2.824,3.052,P ＜ 0.05).The Dmax of spinal cord showed no significant difference among the three techniques.VMAT had a significantly shorter delivery time and lower MU compared with HT and TD (t =21.617,15.693,10.018,7.802,P ＜ 0.05).Conclusions HT and TD could gain a better planning target volume (PTV) coverage and HI than VMAT in the treatment of upper thoracic esophageal carcinoma.However,VMAT achieved the lowest lung V20,the least Mus and the shortest delivery time.HT achieved a better PTV coverage compared with TD,but TD had a lower lung V15 Mus and shorter delivery time compared with HT.

Dosimetric comparison of TomoDirect and TomoHelical modalities in Tomotherapy system for left-breast cancer radiotherapy after breast-conserving surgery / 中华放射医学与防护杂志

Objective To compare the dosimetric difference among plans designed by 4-field,6-field TomoDirect and TomoHelical techniques in Tomotherapy system for left-breast cancer patients with radiotherapy after breast-conserving surgery.Method A total of 16 patients with left-breast cancer following breast-conserving surgery and intensity-modulated radiation therapy were enrolled in this retrospective study.The 4-field TomoDirect (TD4),6-field TomoDirect (TD6),and TomoHelical (TH) techniques were applied to design simulation plans in tomotherapy system for each patient,respectively.The differences of dose distribution and treatment parameters were analyzed in this study.Results Three plans all met the clinical requirement.Thereinto,TD4 was superior to TH in the dose limitation of organs at risk (OARs),especially the max dose of cord and right-breast,thc 5 Gy radiation volume of lung,and the mean dose of heart(F =595.60,129.24,60.44,65.37,P ＜ 0.05),but inferior to TH in dose homogeneity (HI) and conformity (CI) (F =2.78,60.93,P ＜ 0.05).However,TD6 improved TD4's HI and CI when delivered the lower OARs dose compared to TH.Meanwhile,the number of monitor units was less in TD technique and reduced the treatment times (F =24.89,3.75,P ＜ O.05).Conclusions For the radiotherapy of left-breast cancer patients after breast-conserving surgery,TD6 technique appeared to be superior,with the lower radiation dose of OARs compared to TH technique,and the better target's HI and CI in comparison with TD4 technique,especially in patients with early stage breast cancer.

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study investigated setup error and effectiveness of weekly image-guided radiotherapy (IGRT) of TomoDirect for early breast cancer. MATERIALS AND METHODS: One hundred and fifty-one breasts of 147 consecutive patients who underwent breast conserving surgery followed by whole breast irradiation using TomoDirect in 2012 and 2013 were evaluated. All patients received weekly IGRT. The weekly setup errors from simulation to each treatment in reference to chest wall and surgical clips were measured. Random, systemic, and 3-dimensional setup errors were assessed. Extensive setup error was defined as 5 mm above the margin in any directions. RESULTS: All mean errors were within 3 mm of all directions. The mean angle of gantry shifts was 0.6degrees. The mean value of absolute 3-dimensional setup error was 4.67 mm. In multivariate analysis, breast size (odds ratio, 2.82; 95% confidence interval, 1.00 to 7.90) was a significant factor for extensive error. The largest significant deviation of setup error was observed in the first week of radiotherapy (p < 0.001) and the deviations gradually decreased with time. The deviation of setup error was 5.68 mm in the first week and within 5 mm after the second week. CONCLUSION: In this study, there was a significant association between breast size and significant setup error in breast cancer patients who received TomoDirect. The largest deviation occurred in the first week of treatment. Therefore, patients with large breasts should be closely observed on every fraction and fastidious attention is required in the first fraction of IGRT.

Current State of Radiation Therapy at Suzuka General Hospital Since Introduction of TomoTherapy / 日本農村医学会雑誌

  A new radiation system known as the TomoTherapy Hi-ART system was introduced into our hospital in October 2010. This system combines helical intensity-modulated radiotherapy (IMRT) with an integrated image guidance system by means of a megavoltage-CT. This image-guided IMRT enables us to deliver appropriate doses to tumors with good conformality while avoiding sensitive structures in an accurate manner. Patients having tumors in the head, neck, abdomen and pelvis would be good candidates for this treatment. In our hospital, a total of about 150 patients were treated with the helical tomotherapy in 2011. <br>  However, in the helical tomotherapy, low-dose areas would be spread wide, compared with conventional radiotherapy.Low dose irradiation to large volumes of the lung would increase the risk of radiation pneumonitis, thus planning for thoracic regions such as chest wall and mediastinum might be difficult. In such cases, another strategy “TomoDirect” might be more useful. That allows us to create treatment plans just like conventional radiotherapy using static gantry positions, combined with simultaneous couch movement. Over 20 patients were treated with TomoDirect in 2011.