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Objective To study the dosimetric characteristics and plan quality of PTV-based intensity modulated proton radiotherapy (IMPT) and volumetric-modulated arc therapy (VMAT) plans for prostate cancer,so as to provide a reference for clinical application.Methods A total of 10 prostate cancer cases were included in this retrospective study.IMPT and RapidArc plans were designed by RayStation and Eclipse TPS based on PTV,respectively.For each case,IMPT plans were generated using multiple field optimization (MFO) technique with two parallel-opposed lateral fields,whereas RapidArc plans were generated using double-arc technique (two full arcs).Final dose calculation of IMPT was conducted by pencil beam (PB) and Monte Carlo (MC) algorithm,respectively,with adopted data model from the pencil beam scanning (PBS) proton therapy system of IBA Protues Plus (IBA Group,Belgium);The data model originated from the linear accelerator of Varian Clinac iX (Varian Medical Systems,America) was used for RapidArc plans.Dosimetric parameters of DVH and dose distribution were used to compare the dose differences in targets and organs at risk (OARs) between these two treatment techniques.Results For targets,HIs of PB-IMPT and MC-IMPT were slightly better than that of RapidArc,but CI of IMPT was slightly lower than that of RapidArc;D1 of PB-IMPT was significantly better than those of MC-IMPT and RapidArc (Z =-2.805,-2.803,P ＜ 0.05).PB-IMPT and MC-IMPT achieved better protection than RapidArc on rectum V30 (Z =-2.191,-1.988,P＜ 0.05) and D (Z =-2.599,-2.497,P＜0.05),bladder V30 (Z=-2.701,-2.701,P＜0.05),V40 (Z=-2.395,-2.395,P＜0.05) and D (Z =-2.701,-2.701,P ＜ 0.05).There was no significant difference between PB-IMPT and MC-IMPT plans for prostate cancer,except for the D1％ [(73.86t67.34) Gy vs.(75.45±2.01) Gy] (RBE) and HI [(0.040±0.010) vs.(0.058±0.020)] of the target.Conclusions Both techniques can meet the clinical requirements,but IMPT showed significant dosimetric advantages compared with RapidArch by reducing the dose to OARs and improving the plan quality.
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Objective@#To study the dosimetric characteristics and plan quality of PTV-based intensity modulated proton radiotherapy (IMPT) and volumetric-modulated arc therapy (VMAT) plans for prostate cancer, so as to provide a reference for clinical application.@*Methods@#A total of 10 prostate cancer cases were included in this retrospective study. IMPT and RapidArc plans were designed by RayStation and Eclipse TPS based on PTV, respectively. For each case, IMPT plans were generated using multiple field optimization (MFO) technique with two parallel-opposed lateral fields, whereas RapidArc plans were generated using double-arc technique (two full arcs). Final dose calculation of IMPT was conducted by pencil beam(PB) and Monte Carlo (MC) algorithm, respectively, with adopted data model from the pencil beam scanning (PBS) proton therapy system of IBA Protues Plus(IBA Group, Belgium); The data model originated from the linear accelerator of Varian Clinac iX (Varian Medical Systems, America) was used for RapidArc plans. Dosimetric parameters of DVH and dose distribution were used to compare the dose differences in targets and organs at risk (OARs) between these two treatment techniques.@*Results@#For targets, HIs of PB-IMPT and MC-IMPT were slightly better than that of RapidArc , but CI of IMPT was slightly lower than that of RapidArc; D1% of PB-IMPT was significantly better than those of MC-IMPT and RapidArc (Z=-2.805, -2.803, P<0.05). PB-IMPT and MC-IMPT achieved better protection than RapidArc on rectum V30(Z=-2.191, -1.988, P<0.05)and Dmean(Z=-2.599, -2.497, P<0.05), bladder V30(Z=-2.701, -2.701, P<0.05), V40(Z=-2.395, -2.395, P<0.05)and Dmean(Z=-2.701, -2.701, P<0.05). There was no significant difference between PB-IMPT and MC-IMPT plans for prostate cancer, except for the D1% [(73.86±67.34) Gy vs.(75.45±2.01) Gy] (RBE) and HI [(0.040±0.010) vs. (0.058±0.020)] of the target.@*Conclusions@#Both techniques can meet the clinical requirements, but IMPT showed significant dosimetric advantages compared with RapidArch by reducing the dose to OARs and improving the plan quality.
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Objective To study the effect of leaf movement speed on the setup error of multileaf collimator (MLC) in RapidArc mode,and to improve quality assurance and verify the reliability of RapidArc.Methods Referring to the PicketFenceStatic_M120.dcm and PicketFenceRA_Ml20.dcm files,the Tilt tests with different adjacent leaf speed were designed and setup errors of MLC were obtained by analyzing electronic portal imaging device images.Results In the Tilt tests,the setup errors gradually increased from gapl 1 to gapS0 in both static gantry mode and RapidArc mode.With a gantry angle of 270°,gap41 had the maximum setup error of-0.55 mm.In the RapidArc mode,gap46 had the maximum setup error of-0.67 mm.The deviation of gap width was no greater than 15％ in any mode.There was no significant difference in deviation pattern of gap width between four modes with different gantry angles.The same gaps in different stripes showed a consistent trend in gap width.The RapidArc mode had a larger variation in percentage deviation of gap width than the static gantry mode.Conclusions The setup error increases with the increase in the speed of MLC leaf.The variation in the leaf speed has no significant impact on the gap width.There is no correlation between the leaf speed and the deviation of gap width.Four different gantry angles give similar deviation patterns of gap width,suggesting that the deviation of gap width is related to the leaf rather than the gantry angle.The RapidArc mode has a greater impact on the gap width than the fixed gantry mode.
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Objective:To explore the dose distribution characteristics between RapidArc and five-field intensity modulated radiotherapy(5F-IMRT) plans in the treatment of locally advanced pancreatic carcinoma,and to provide reference for selecting the appropriate radiation technique in clinic.Methods:Ten patients with locally advanced pancreatic carcinoma were selected.The patients were scanned by simulation CT, and the targets and organs at risk were contoured. RapidArc plan and 5F-IMRT plan were designed respectively.The treatment time and the differences of dose distribution in the targets and organs at risk of RapidArc and 5F-IMRT plans were compared.Results:The conformal index (CI) of RapidArc plan was superior than that of 5F-IMRT plan(P=0.01).The homogeneity index (HI) of targets were similar between two plans (P>0.05).RapidArc plan decreased the maximum dose (Dmax) of the spinal cord(P=0.005);RapidArc plan decreased the mean dose(Dmean) of stomach(P=0.019);5F-IMRT plan decreased the V20 of kidney(P=0.043);RapidArc plan decreased the mean dose(Dmean) of small intestine(P=0.011).The small intestine V10 and V20 of RapidArc plan were lower than those of 5F-IMRT plan(P=0.015,P=0.14);the monitor unit (MU) of RapidArc plan was significantly lower than that of 5F-IMRT plan,with a 18% reduction from the MU level of the latter one,and the treatment time was reduced by 70.3%.RapidArc plan had the smaller doses at liver and kidney compared with 5F-IM RT plan.Conclusion:For the patients with locally advanced pancreatic carcinoma,RapidArc plan has higher CI. RapidArc plan shows the advantages in the protection of organs.Compared with 5F-IMRT,RapidArc plan has less treatment time and significantly improves the curative efficiency.In clinic, the RapidArc plan is recommended.
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Objective To explore the effect of the Jaw‐tracking with RapidArc(JT‐RapidArc) plans for upper thoracic e‐sophageal cancer .Methods Treatment planning was designed by using RapidArc and JT‐RapidArc techniques for 11 consecutive patients .The dose‐volume histogram parameters of PTV and the organs at risk ,conformity index(CI) ,heterogeneity index(HI) , low dose volume of normal tissue (B‐P ) and monitor units (MU ) were compared between the different techniques . Results Compared with the RapidArc plan ,JT‐RapidArc had increased coverage of PTV1(64) D98 and HI(P0 .05) .Plans with JT‐RapidArc had lower Lung(V5 ,V10 , V13 ,V20 ,V30 ,Dmean ,P0 .05) .JT‐RapidArc plans increaseed the MU by 1% (349 ± 29 vs .345 ± 16 ,P>0 .05) as compared with RapidArc plans .Conclusion All of the plans had met the requirements of clinical dosime‐try .JT‐RapidArc plans as compared with RapidArc plans ,showing better part of target coverage ,part of lung and heart and B‐P sparing ,which MU was slightly increased .
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Objective To analyze the difference of dosimetry and evaluate clinical efficacy and acute toxicity reaction between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (IMRT) in advanced cervical carcinoma.Methods A total of 43 patients with locally advanced cervical cancer were studied,including 22 patients treated with RapidArc and 21 patients with IMRT.All plans were prescribed 50.4 Gy in 28 fractions.The conformity index and homogeneity index of the targets,the monitor units(MUs) and delivery time were compared.Incidence of acute intestinal and bladder side effects and rates of efficacy were calculated.Results The conformity index of RapidArc was better compared to IMRT.The V40 and V50 of bladder and V30,V40 and V50 of rectum planned by RapidArc was significantly lower than that by IMRT(t =-2.386,-2.397,P ＜0.05;t =-5.525,-2.883,-2.686,P ＜0.05).The mean dose of femoral head planned by RapidArc was also significantly lower (t =-2.395,P ＜ 0.05).For RapidArc,mean MU and treatment time were reduced by 53.15％,and 62.14％,respectively.There was no difference in the incidence of acute intestinal and bladder toxicity and rates of complete remission and efficacy between the two groups.Conclusions In dosimetric analysis,RapidArc showed advantage in protecting organs at risk and reducing treatment time in radical radiotherapy for locally advanced cervical carcinoma.
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Objective To investigate the dosimetric characteristics and their clinical applications of volumetric modulated Arc therapy (RapidArc) with fixed-fields intensity modulated radiotherapy for early stage nasal NK/T-cell lymphoma.Methods Ten patients with stage Ⅰ E and Ⅱ E nasal NK/T-cell lymphoma were enrolled in the study.Five field coplanar plan (5F),nine field coplanar plan (9F),five field non-coplanar plan (5F-N) and RapidArc plans were designed for each patient,in which 5F plan was set as the control group.Conformity index (CI) and homogeneity index (HI) as well as the maximum dose of organs at risks were compared.Results The target CI of 5F,9F,5F-N and RapidArc plan was 0.419±0.159,0.478 ±0.181,0.465 ±0.121 and 0.518 ±0.111,respectively.Compared with 5F (0.136±0.038),the target HI of 9F and RapidArc plan was 0.111 ±0.027 and 0.112 ±0.031 (t =3.11,3.04,P ＜ 0.05).9F plan significantly increased the Dmax of lens in the contralateral side(t =2.82,P ＜ 0.05) and in ipsilateral side (t =3.25,P ＜ 0.05),while 5F-N plan decreased the Dmax of optical nerves by up to 9％.RapidArc plan effectively reduced the radiation to organs at risk in lens (t =3.25,P ＜0.05),eyes (t =3.25,P ＜0.05),optical nerve (t =2.57,P ＜0.05) and optical chaism(t =7.62,P ＜0.05).The delivery efficiency of four plans ranked as RapidArc ＞ 5F ＞ 5F-N ＞ 9F.Conclusions RapidArc produced statistically significant improvement in the dose distributions of targets,and also reduced the Dmax of organs at risk,which would be the better choice of radiotherapy for nasal NK/T-cell lymphoma.
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Objective To compare the planning quality and acute toxicity between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (IMRT) in the postoperative radiotherapy for cervical cancer patients.Methods All 35 patients with cervical cancer who had received postoperative radiotherapy were studied,including 17 patients with RapidArc and 18 patients with IMRT.All plans were prescribed 50 Gy in 25 fractions.The dose-volume histogram data,the conformity index and homogeneity index of the targets,the monitor units (MUs) and delivery time were compared.During the treatment,the incidence of acute intestinal and bladder side effects were also compared.Results Compared to IMRT,the conformity index of RapidArc was better(t =3.13,P ＜ 0.05),but the homogeneity index was slightly worse (t =-4.25,P ＜ 0.05).The V20 and V30 of femoral head planned by RapidArc was significantly lower than that by IMRT (t =2.56,2.34,P ＜ 0.05).The mean MU for RapidArc was reduced by 52.1％ compared with IMRT.The mean treatment time for RapidArc was decreased by 46.8％ compared with IMRT.There was no difference in the incidence of acute intestinal and bladder toxicity between the two groups.Conclusion For patients with cervical cancer who need prophylactic postoperative radiotherapy,both RapidArc and IMRT plan can achieve equal target coverage and organs at risk(OAR) sparing.There is no significant difference in dosimetric parameters and acute toxicity between the two groups.Compared with IMRT,RapidArc plan has fewer MUs and less treatment time and significantly improves the treatment efficiency.
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PURPOSE: Intensity modulated arc therapy (IMAT) is a form of intensity modulated radiation therapy (IMRT) that delivers dose in single or multiple arcs. We compared IMRT plans versus single-arc field (1ARC) and multi-arc fields (3ARC) IMAT plans in high-risk prostate cancer. MATERIALS AND METHODS: Sixteen patients were studied. Prostate (PTVP), right pelvic (PTVRtLN) and left pelvic lymph nodes (PTVLtLN), and organs at risk were contoured. PTVP, PTVRtLN, and PTVLtLN received 50.40 Gy followed by a boost to PTVB of 28.80 Gy. Three plans were per patient generated: IMRT, 1ARC, and 3ARC. We recorded the dose to the PTV, the mean dose (DMEAN) to the organs at risk, and volume covered by the 50% isodose. Efficiency was evaluated by monitor units (MU) and beam on time (BOT). Conformity index (CI), Paddick gradient index, and homogeneity index (HI) were also calculated. RESULTS: Average Radiation Therapy Oncology Group CI was 1.17, 1.20, and 1.15 for IMRT, 1ARC, and 3ARC, respectively. The plans' HI were within 1% of each other. The DMEAN of bladder was within 2% of each other. The rectum DMEAN in IMRT plans was 10% lower dose than the arc plans (p < 0.0001). The GI of the 3ARC was superior to IMRT by 27.4% (p = 0.006). The average MU was highest in the IMRT plans (1686) versus 1ARC (575) versus 3ARC (1079). The average BOT was 6 minutes for IMRT compared to 1.3 and 2.9 for 1ARC and 3ARC IMAT (p < 0.05). CONCLUSION: For high-risk prostate cancer, IMAT may offer a favorable dose gradient profile, conformity, MU and BOT compared to IMRT.
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Humans , Lymph Nodes , Organothiophosphorus Compounds , Organs at Risk , Prostate , Prostatic Neoplasms , Radiotherapy, Intensity-Modulated , Rectum , Urinary BladderABSTRACT
Objective To investigate the feasibility and potential advantages of RapidArc applied to the radiotherapy of the postoperative rectal cancer.Methods 8 postoperative patients with rectal cancer were selected to be treated with a dose of 50Gy in fraction of 2Gy every time and 5 times a week.IMRT and RapidArc were used respectively to compare different target conformities,homogeneity index,dose-volume histogram data,treatment times and monitor units.Results The conformal index by RapidArc was 0.89±0.02 which was better than those by 5F-IMRT,0.87±0.02 (t =3.286,P ＜ 0.05),while the homogeneity index of target volume (1.060±0.005) and average dose [(52.55±0.76) Gy] by RapidArc were a little less than the homogeneity index of target volume (1.064±0.007) and average dose [(52.90±0.82) Gy] by 5F-IMRT (t =-1.459,-1.000,P ＞ 0.05).The exposure dose and mean dose of bladder and small bowel in high dose region by RapidArc were lower than those by 5F-IMRT,as well as bone marrow.The differences were statistical significant (P ＜ 0.05).The monitor units by RapidArc and by 5F-IMRT were (631±68) MU and (1046±146) MU,respectively (t =-5.830,P ＜ 0.05),while the mean treatment times were (78±5) s and (348±29) s,respectively (t =-26.358,P ＜ 0.05).Conclusion Compared with 5F-IMRT,RapidArc improves the target conformities and lowers the exposure dose for the organs at risk in high dose region while using fewer monitor units and less treatment time,which helps comforting patients and improving the efficiency.
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Objective:To evaluate the performance of RapidArc technique on cervical cancer patients with various filling status of the bladder. Methods: Conventional fixed field intensity modulation radiated therapy (IMRT) is used as the benchmark. In 10 fe-males suffering from cervical cancer, two CT scans were performed for treatment planning:one with an empty bladder and the other with filled bladder. The prescribed dose was 50 Gy. The images of that with an evacuated bladder and that with filled bladder were planned in the dual-arc RapidArc and the 7-field IMRT, respectively. The implementor of the plan was the Varian TrueBeam linear ac-celerator. Dose-volume histogram was used to evaluate the data from each plan. Results:When the bladder was filled, IMRT and Rapi-dArc homogeneity were 1.05 and 1.04 (P>0.05), respectively. When the bladder was emptied, the homogeneity was 1.04 for both plans (P>0.05). With or without bladder filling, the conformity index was 0.71 and 0.73 for IMRT and RapidArc (P>0.05), respectively. The effect of V30 and V40 (volume for receiving doses of 30 and 40 Gy) on the intestine and the bladder was more favorable in a full than in an empty bladder. No significant difference between the two plans was observed. IMRT exhibited improved V30 on the rectum and on the bladder. RapidArc was much better in terms of monitor unit (MU) and deliver time. Conclusion:No significant differences in the homogeneity and conformity index between dual-arc RapidArc and 7-field IMRT were observed. Filled bladder is better than empty bladder in intestine and bladder protection in both RapidArc and IMRT. IMRT is better on V30 of the rectum and the bladder, whereas RapidArc improved MU and deliver time.
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Objective To compare the dosimetric differences between two plans of RapidArc and 5F-IMRT for breast cancer radiotherapy after breast-conserving surgery.Methods Eight female patients with left-sided breast cancer after breast-conserving surgery were selected.A dose of 50 Gy in 25 fractions was prescribed for plans of RapidArc and 5F-IMRT.Target conformity index (CI),homogeneity index (HI),target coverage,exposure dose volume delivered to organ at risk were compared between two plans.At the same time,treatment delivery time and monitor units (MU) were also compared.Results The target conformity index (CI) in RapidArc plan (·0.88 ±0.03) was higher than that in 5F-IMRT plan (0.79 ±0.02,t =8.28,P ＜ 0.05).The homogeneity index (HI) in RapidArc plan 9.01 ± 0.73 was significantly lower than that in 5F-IMRT plan10.44 ± 1.08 (t =-2.73,P ＜0.05).For the dose volume delivered to the ipsilateral lung in two plans,the values of V10,V20,V30,and Dmean in RapidArc plan were lower than those in 5F-IMRT plan(t =-7.53,-7.20,-8.39,-7.80,P ＜ 0.05).However,the value of V5 in RapidArc plan was higher than that in 5F-IMRT plan (t =5.67,P ＜0.05).For the heart,the values of V5,V10 and Dmean in RapidArc plan were higher than those in IMRT plan(t =10.46,28.76,5.40,P ＜ 0.05),while the value of V30 in RapidArc plan was lower than that in 5F-IMRT plan(t =-6.12,P ＜0.05).The values of V5 in contralateral lung and breast were higher in RapidArc plan than those in 5F-IMRT plan(lung:t =21.50,P ＜0.05;breast:t =5.44,P ＜0.05).The MU in RapidArc plan was decreased by 25％,and the average treatment delivery time was saved by 60％,compared with that of 5F-IMRT plan.Conclusions During breast cancer radiotherapy after breast-conserving surgery,compared with 5F-IMRT plan,the RapidArc plan could improve the target HI,and reduce both the irradiated dose in high-dose volume and MU,and shorten the treatment time,but increased the exposed volume in low-dose volume of normal tissues.
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Objective To compare and analyze the dosimetric characteristics of the intensity-modulated arc therapy (RapidArc) combined with active breathing coordinator (ABC) in the thoracic esophageal carcinoma radiation therapy. Methods Ten thoracic esophageal carcinoma patients undergoing radiotherapy were selected for this study.The CT simulations were performed under three breath patterns respectively:moderate deep inspiration breath-hold (mDIBH) with ABC aid; Set the trigger threshold to 80％ of the peak of the respiration curve; and free breathing (FB).Based on the corresponding CT image sets,three treatment plans were generated for each patient respectively:Arc-ABC( three small arcs),ArcFB (consisted of two coplanar full arcs) and IMRT-FB plan.The following dosimetric parameters were compared among different plans:D2％,D98％,V95,homogeneity index ( HI),conformal index ( CI ) the percentage of volume receiving dose of over x Gy (Vx),monitor unit (MU),control points and treatment time.Results The planning target volume ( PTV ) of FB was 376 cm3 which decreased to 260 cm3 after using ABC.For mDIBH and FB patients,the total lung volumes were 5964.6 cm3(35％ more than FB) and 3838.8 cm3 respectively; the heart volumes were 524.4 cm3 and 642.7 cm3 respectively. No significant difference was observed among Arc-ABC,IMRT-FB and Arc-FB in terms of D2,D98,V95,CI and HI.For Arc-ABC plans,there were significant decreases of radiation dose in total-lung's V10,V20,V30,V40 and mean lung dose ( F =4.38,5.34,4.07,3.89,4.28,P ＜0.05).Various dose decreases of heart V20,V3,V40,Dmean and spinal cord Dmax were observed,yet no statistically significant difference existed.The MUs and total control points of Arc-ABC plans were significantly lower than other plans ( F =26.86,12.56,P ＜ 0.05 ).Conclusions When thoracic esophageal carcinoma patients were treated with radiotherapy,the combined utilization of RapidArc and ABC can potentially decrease the volume of irradiated lung yet escalate the dose in target.
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We investigated the influence of photon energy, couch and collimator angle differences between arcs on dose distribution of RapidArc treatment planning for prostate cancer. RapidArc plans were created for 6 MV and 10 MV photons using 2 arcs coplanar and noncoplanar fields. The collimator angle differences between two arcs were 0degrees, 15degrees, 30degrees, 45degrees, 60degrees, 75degrees and 90degrees. The plans were optimized using same dose constrains for target and OAR (organ at risk). To evaluate the dose distribution, plans were analyzed using CI (conformity index), HI (homogeneity index), QOC (quality of coverage), etc. Photon energy, couch and collimator angle differences between arcs had a little influence on the target and OAR. The difference of dosimetric indices was less than 3.6% in the target and OAR. However, there was significant increase in the region exposed to low dose. The increase of V15% in the femur was 6.4% (left) and 5.5% (right) for the 6 MV treatment plan and 23.4% (left), 24.1% (right) for the noncoplanar plan. The increase of V10% in the Far Region distant from target was 54.2 cc for the 6 MV photon energy, 343.4 cc for the noncoplanar and 457.8 cc for the no collimator rotation between arcs.
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Femur , Photons , Prostate , Prostatic NeoplasmsABSTRACT
PURPOSE: To determine feasibility of RapidArc in sequential or simultaneous integrated tumor boost in whole brain radiation therapy (WBRT) for poor prognostic patients with four or more brain metastases. MATERIALS AND METHODS: Nine patients with multiple (> or =4) brain metastases were analyzed. Three patients were classified as class II in recursive partitioning analysis and 6 were class III. The class III patients presented with hemiparesis, cognitive deficit, or apraxia. The ratio of tumor to whole brain volume was 0.8-7.9%. Six patients received 2-dimensional bilateral WBRT, (30 Gy/10-12 fractions), followed by sequential RapidArc tumor boost (15-30 Gy/4-10 fractions). Three patients received RapidArc WBRT with simultaneous integrated boost to tumors (48-50 Gy) in 10-20 fractions. RESULTS: The median biologically effective dose to metastatic tumors was 68.1 Gy10 and 67.2 Gy10 and the median brain volume irradiated more than 100 Gy3 were 1.9% (24 cm3) and 0.8% (13 cm3) for each group. With less than 3 minutes of treatment time, RapidArc was easily applied to the patients with poor performance status. The follow-up period was 0.3-16.5 months. Tumor responses among the 6 patients who underwent follow-up magnetic resonance imaging were partial and stable in 3 and 3, respectively. Overall survival at 6 and 12 months were 66.7% and 41.7%, respectively. The local progression-free survival at 6 and 12 months were 100% and 62.5%, respectively. CONCLUSION: RapidArc as a component in whole brain radiation therapy for poor prognostic, multiple brain metastases is an effective and safe modality with easy application.
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Humans , Apraxias , Brain , Disease-Free Survival , Follow-Up Studies , Magnetic Resonance Imaging , Neoplasm Metastasis , Paresis , Radiotherapy, Intensity-ModulatedABSTRACT
Purpose: To validate a locally fabricated phantom of Imatrixx-2D Array by comparing its results with ArcCheck phantom and comparing portal dosimetry measurements with the two phantom studies. Materials and Methods: Electronic Portal Imaging Devices and Epiqa software were used for portal dosimetry. An Imatrixx-2D array with a locally fabricated phantom and ArcCheck cylindrical phantom were used for phantom studies. Eclipse-TPS with RapidArc treatment planning and portal dose prediction software was used for planar dose calculations. Three verification plans were created for each of the 15 patient plans of various sites, making a total of 45 plans to be delivered on 3 QA systems as above. Fifteen plans each with 2 arcs were delivered on the EPIDs of the Linacs, on Imatrixx-2D array phantom and on ArcCheck cylindrical phantom respectively. The planar dose matrices were analysed using global Gamma Index criteria of 3mm DTA and 3% dose difference. Results: The maximum deviations of percentage in dose points, in which γ>1, are 1.94, 1.89 and 1.5 in Imatrixx phantom, ArcCheck phantom and Portal dosimetry, respectively. Similarly, the mean deviations and SD values are less in portal dosimetry than that of phantom studies. The smaller deviations in portal dosimetry are attributed to closely embedded chambers in the EPID compared to the distance between the detectors placed in the phantom measurements. Conclusion: After carrying out the comparison of results, the locally fabricated phantom has been validated and accepted for the dosimetric studies. The conclusion is that all the three dosimetric QA systems are suitable for the patient-specific QA of RapidArc treatments.
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ObjectiveTo study the feasibility of RapidArc (RA) associated with active breath coordinator (ABC)for hepatocelluar carcinoma (HCC)radiotherapy comparing of three-dimensional conformal radiotherapy (3DCRT),intensity modulated radiotherapy (IMRT),RA treatment plans in different breath status.Methods12 HCC cases were selected.Three series CT scanning were completed in Free Breathing (FB),End Inspiration Hold (EIH) and End Expiration Hold (EEH) associated with ABC device.3DCRT,IMRT and RA (three 135° arcs) treatment plans were respectively designed on planning target volume (PTV) in different breath status.The dosimetric differences among 3 DCRT,IMRT and RA,among RA plans under different breath status were compared.ResultsThe PTV in FB was larger than in EEHand EIH (160.8 cm3,89.5 cm3,83.1 cm3,F=6.63,P=0.004). The conformity index and homogeneity index of RA plans were better than IMRT and 3DCRT ( 0.92,0.90,0.77,F =72.55,P =0.000 ;0.90,0.89,0.84,F =125.49,P =0.000 ) ;the V20,V30,V40 of normal liver in 3DCRT were higher than IMRT and RA (24％,20％,19％,F=3.56,P =0.032;13％,10％,10％,F=5.74,P =0.004;8％,5％,6％,F =3.72,P =0.027).The normal liver mean dose,V10,V20,V30,V40 of RA plans in FB were higher than in EEH and EIH ( 13.46 Gy,10.25 Gy,9.48 Gy,F =3.627,P =0.038 ;46％,35％,32％,F =2.96,P=0.066;24％,16％,16％,F=3.69,P=0.036;13％,8％,8％,F=4.28,P=0.022;8％,5％,5％,F =2.39,P =0.108 ).The duodenum D5 cm3 of RA in EEH was lower than in FB and EIH (8.78 Gy,19.35 Gy and 11.67 Gy,F =1.56,P =0.224 ).The mean monitor units for 3 DCRT,IMRT,RA was 254.06 MU,626.33 MU and 550.28 MU ( F =147.35,P =0.000 ),while the mean treatment time was 135 s,540 s and 130 s respectively (F =62.83,P =0.000).ConclusionsThe RapidArc applying three 135°arcs with ABC in HCC radiotherapy can achieve better PTV coverage than IMRT with fewer monitor units,shorter treatment time and sparing more normal liver.
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Objective To explore the advantages and disadvantages between the RapidArc plans and fixed-field IMRT plan (IMRT).Methods Ten cases of cervical cancer,aged 55 (36-70),who were to receive post-operative radiotherapy were selected randomly.Single arc (Arc 1),two arcs (Arc 2),and three arc (Arc 3) RapidArc plans and fixed-field IMRT plan were designed respectively in the Eclipse 8.6 planning system.The designing,treatment time,target area,and dose distribution of organs at risk by these 4 planning techniques were compared.Results The values of average planned treatment time by the Arc 1,Arc 2,and Arc 3 ten cases was 98,155,185,and 46 min,respectively.The values of average treatment time in the Varian IX accelerator were 2.15,3.32,4.48,and 6.95 min,respectively.The average mean doses were (48.99±1.08),(49.40±0.51) ,(49.51±0.62) ,and (48.65±0.92) Gy,respectively.The values of homogeneity index (HI) of target were 1.11±0.07,1.07±0.02,1.06±0.02,and 1.12±0.05,respectively.The values of eonformal index (CI) of target were 0.73±0.13,0.87±0.06,0.87±0.06,and 0.79±0.06,respectively.The doses at rectum,bladder,and small intestine calculated by IMRT plan were the lowest,and the doses at the femoral neck calculated by these 4 plans were similar.Conclusions The RapidArc plan is superior in dose distribution at target,HI,CI,and treatment time to IMRT,but IMRT plan is superior to RapidArc in planned dose calculation time and protection of organs at risk.However,in general,the RapidArc plan is better in clinical application than IMRT plan.
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Objective To compare the dosimetric difference between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (dIMRT) in developing the pre-operative radiotherapy for rectal cancer patients.Methods Two techniques,RapidArc and dIMRT,were used respectively to develop the synchronous intensity modulated plans for 10 stage Ⅱ and Ⅲ rectal cancer patients at the dose of gross tumor volume (GTV) of 50.6 Gy divided into 22 fractions and planning target volume (PTV) of 41.8 Gy divided into 22 fractions.Both plans satisfied the condition of 95% of PTV covered by 41.8 Gy.The dose-volume histogram data,isodose distribution,monitor units,and treatment time were compared.Results The two kinds of dose volume histogram (DVH) developed by these two techniques were almost the same.The conformal indexes of GTV and PTV by RapidArc were better than those by dIMRT (t =7.643,8.226 ,P < 0.05),while the homogeneity of target volume by dIMRT was better (t =-10.065,-4.235 ,P <0.05).The dose of rectum and small bowel planned by RapidArc was significantly lower than that by dIMRT (t =2.781 ,P <0.05).There were no significant differences in the mean doses of bladder and femoral head between these two techniques.The mean monitor units of RapidArc was 475.5,fewer by 48.5% in comparison with that by the dIMRT (924.6).The treatment mean time by RapidArc was 1.2min,shorter by 79.5% in comparison with that by dIMRT (5.58 min).Conclusions There is no significant dosimetric difference between the two plans of RapidArc and dIMRT.Compared with dIMRT,RapidArc achieves equal target coverage and organs at risk(OAR) sparing while using fewer monitor units and less time during radiotherapy for patient with rectal cancer.
ABSTRACT
Objective To compare the dosimetric difference between RapidArc and fixed gantry angle dynamic IMRT (dIMRT) for central-type lung cancer radiotherapy. Methods Therapy for 10 patients previously treated with dIMRT was replanned with RapidArc. Dose prescription was 66 Gy/33 fraction. Comparative endpoints were planning target volume (PTV) dose, doses to surrounding structures,number of monitor units, and treatment delivery time. Results There was no significant dosimetric difference between RapidArc and dIMRT. Compared with dIMRT, RapidArc slightly elevated target volume dose, lung V5, V10. The average values of lung V20, V30 and heart V30 were larger in dIMRT than those in RapidArc. The number of monitor units was reduced by 32% and the treatment time by 66% in RapidArc.Conclusions Both RapidArc and dIMRT plans could meet the clinical therapy needs. RapidArc could achieve similar target coverage and sparing of organs at risk, with fewer monitor units and shorter delivery time than dIMRT.