共查询到20条相似文献,搜索用时 31 毫秒
1.
Elizabeth Forde Andrew Kneebone Regina Bromley Linxin Guo Peter Hunt Thomas Eade 《Medical Dosimetry》2013,38(3):262-267
The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68 Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40 Gy to 35% and >65 Gy to 17%, and bladder volumes >40 Gy to 50% and >65 Gy to 25%. Plans were averaged across the 10 patients and compared for mean dose, conformity, homogeneity, rectal and bladder doses, and monitor units. The mean dose to the clinical target volume and PTV was significantly higher (p<0.05) for SA compared with DA or IMRT. The homogeneity index was not significantly different: SA = 0.09; DA = 0.08; and IMRT = 0.07. The rectal V40 was lowest for the DA plan. The rectal V20 was significantly lower (p<0.05) for both the VMAT plans compared with IMRT. There were no significant differences for bladder V40 or rectal and bladder V65. The IMRT plans required 1400 MU compared with 745 for DA and 708 for SA. This study shows that for equivalent dose coverage, SA and DA VMAT plans result in higher mean doses to the clinical target volume and PTV. This greater dose heterogeneity is balanced by improved low-range rectal doses and halving of the monitor units. 相似文献
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《Medical Dosimetry》2014,39(3):256-260
Volumetric-modulated arc radiotherapy (VMAT) is an iteration of intensity-modulated radiotherapy (IMRT), both of which deliver highly conformal dose distributions. Studies have shown the superiority of VMAT and IMRT in comparison with 3-dimensional conformal radiotherapy (3D-CRT) in planning target volume (PTV) coverage and organs-at-risk (OARs) sparing. This is the first study examining the benefits of VMAT in pancreatic cancer for doses more than 55.8 Gy. A planning study comparing 3D-CRT, IMRT, and VMAT was performed in 20 patients with pancreatic cancer. Treatments were planned for a 25-fraction delivery of 45 Gy to a large field followed by a reduced-volume 8-fraction external beam boost to 59.4 Gy in total. OARs and PTV doses, conformality index (CI) deviations from 1.0, monitor units (MUs) delivered, and isodose volumes were compared. IMRT and VMAT CI deviations from 1.0 for the large-field and the boost plans were equivalent (large field: 0.032 and 0.046, respectively; boost: 0.042 and 0.037, respectively; p > 0.05 for all comparisons). Both IMRT and VMAT CI deviations from 1.0 were statistically superior to 3D-CRT (large field: 0.217, boost: 0.177; p < 0.05 for all comparisons). VMAT showed reduction of the mean dose to the boost PTV (VMAT: 61.4 Gy, IMRT: 62.4 Gy, and 3D-CRT: 62.3 Gy; p < 0.05). The mean number of MUs per fraction was significantly lower for VMAT for both the large-field and the boost plans. VMAT delivery time was less than 3 minutes compared with 8 minutes for IMRT. Although no statistically significant dose reduction to the OARs was identified when comparing VMAT with IMRT, VMAT showed a reduction in the volumes of the 100% isodose line for the large-field plans. Dose escalation to 59.4 Gy in pancreatic cancer is dosimetrically feasible with shorter treatment times, fewer MUs delivered, and comparable CIs for VMAT when compared with IMRT. 相似文献
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Rachit Kumar Aaron T. Wild Mark A. Ziegler Ted K. Hooker Samson D. Dah Phuoc T. Tran Jun Kang Koren Smith Jing Zeng Timothy M. Pawlik Erik Tryggestad Eric Ford Joseph M. Herman 《Medical Dosimetry》2013,38(3):243-250
Stereotactic body radiation therapy (SBRT) achieves excellent local control for locally advanced pancreatic cancer (LAPC), but may increase late duodenal toxicity. Volumetric-modulated arc therapy (VMAT) delivers intensity-modulated radiation therapy (IMRT) with a rotating gantry rather than multiple fixed beams. This study dosimetrically evaluates the feasibility of implementing duodenal constraints for SBRT using VMAT vs IMRT. Non–duodenal sparing (NS) and duodenal-sparing (DS) VMAT and IMRT plans delivering 25 Gy in 1 fraction were generated for 15 patients with LAPC. DS plans were constrained to duodenal Dmax of<30 Gy at any point. VMAT used 1 360° coplanar arc with 4° spacing between control points, whereas IMRT used 9 coplanar beams with fixed gantry positions at 40° angles. Dosimetric parameters for target volumes and organs at risk were compared for DS planning vs NS planning and VMAT vs IMRT using paired-sample Wilcoxon signed rank tests. Both DS VMAT and DS IMRT achieved significantly reduced duodenal Dmean, Dmax, D1cc, D4%, and V20 Gy compared with NS plans (all p≤0.002). DS constraints compromised target coverage for IMRT as demonstrated by reduced V95% (p = 0.01) and Dmean (p = 0.02), but not for VMAT. DS constraints resulted in increased dose to right kidney, spinal cord, stomach, and liver for VMAT. Direct comparison of DS VMAT and DS IMRT revealed that VMAT was superior in sparing the left kidney (p<0.001) and the spinal cord (p<0.001), whereas IMRT was superior in sparing the stomach (p = 0.05) and the liver (p = 0.003). DS VMAT required 21% fewer monitor units (p<0.001) and delivered treatment 2.4 minutes faster (p<0.001) than DS IMRT. Implementing DS constraints during SBRT planning for LAPC can significantly reduce duodenal point or volumetric dose parameters for both VMAT and IMRT. The primary consequence of implementing DS constraints for VMAT is increased dose to other organs at risk, whereas for IMRT it is compromised target coverage. These findings suggest clinical situations where each technique may be most useful if DS constraints are to be employed. 相似文献
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Katsuyuki Sakanaka Takashi Mizowaki Sayaka Sato Kengo Ogura Masahiro Hiraoka 《Medical Dosimetry》2013,38(2):204-208
This study evaluated the dosimetric difference between volumetric-modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (cIMRT) in whole-ventricular irradiation. Computed tomography simulation data for 13 patients were acquired to create plans for VMAT and cIMRT. In both plans, the same median dose (100% = 24 Gy) was prescribed to the planning target volume (PTV), which comprised a tumor bed and whole ventricles. During optimization, doses to the normal brain and body were reduced, provided that the dose constraints of the target coverage were satisfied. The dose-volume indices of the PTV, normal brain, and body as well as monitor units were compared between the 2 techniques by using paired t-tests. The results showed no significant difference in the homogeneity index (0.064 vs 0.065; p = 0.824) of the PTV and conformation number (0.78 vs 0.77; p = 0.065) between the 2 techniques. In the normal brain and body, the dose-volume indices showed no significant difference between the 2 techniques, except for an increase in the volume receiving a low dose in VMAT; the absolute volume of the normal brain and body receiving 1 Gy of radiation significantly increased in VMAT by 1.6% and 8.3%, respectively, compared with that in cIMRT (1044 vs 1028 mL for the normal brain and 3079.2 vs 2823.3 mL for the body; p<0.001). The number of monitor units to deliver a 2.0-Gy fraction was significantly reduced in VMAT compared with that in cIMRT (354 vs 873, respectively; p<0.001). In conclusion, VMAT delivers IMRT to complex target volumes such as whole ventricles with fewer monitor units, while maintaining target coverage and conformal isodose distribution comparable to cIMRT; however, in addition to those characteristics, the fact that the volume of the normal brain and body receiving a low dose would increase in VMAT should be considered. 相似文献
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《Brachytherapy》2014,13(3):263-267
PurposeTo compare the three-dimensional (3D) image (CT/MR)-based planning with a multichannel vaginal cylinder (MVC) to a single-channel vaginal cylinder (SVC) for the treatment of vaginal cancer.Methods and MaterialsA total of 20 consecutive patients were treated with 3D CT/MR image-based high-dose-rate (HDR) brachytherapy using an MVC. All patients received external beam radiation therapy before HDR brachytherapy. A brachytherapy dose of 20–25 Gy of more than five fractions was delivered to clinical target volume (CTV). Retrospectively, treatment plans for all patients were generated using the central channel only to mimic an SVC applicator. The SVC plans were optimized to match CTV coverage with MVC plans. Dose homogeneity index as well as bladder, rectum, sigmoid, and urethral doses were compared.ResultsThe mean D90 for CTV was 74.2 Gy (range: 48.8–84.1 Gy). The mean (±standard deviation) of dose homogeneity index for MVC vs. SVC was 0.49 (±0.19) and 0.52 (±0.23), respectively (p = 0.09). Mean bladder 0.1, 1, and 2 cc doses for MVC vs. SVC were 69 vs. 71.2 Gy (p = 0.35), 61.4 vs. 63.8 Gy (p = 0.1), and 59.5 vs. 60.9 Gy (p = 0.31), respectively. Similarly, mean rectum 0.1, 1, and 2 cc doses for MVC vs. SVC were 67.2 vs. 75.4 Gy (p = 0.005), 60.0 vs. 65.6 Gy (p = 0.008), and 57.3 vs. 62.0 Gy (p = 0.015), respectively, and mean sigmoid doses were 56.3 vs. 60.5 Gy (p = 0.10), 50.9 vs. 53.1 Gy (p = 0.09), and 49.1 vs. 50.7 Gy (p = 0.10), respectively.ConclusionThe 3D CT-/MR-based plan with MVC may provide better dose distribution in the management of certain clinical situations of vaginal cancer requiring intracavitary brachytherapy, especially in minimizing potential late rectal complications. 相似文献
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Mara W. Rosenberg Catherine M. Kato Kelly M.P. Carson Nathan M. Matsunaga Robert F. Arao Emily J. Doss Charles L. McCracken Lu Z. Meng Yiyi Chen Wolfram U. Laub Martin Fuss James A. Tanyi 《Medical Dosimetry》2013,38(4):407-412
To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non–small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations. The prescribed dose (PD) was 60 Gy in 5 fractions to 95% of the planning target volume (PTV) (maximum PTV dose ~ 150% PD) for a 6-MV photon beam. Plan conformality, R50 (ratio of volume circumscribed by the 50% isodose line and the PTV), and D2 cm (Dmax at a distance ≥2 cm beyond the PTV) were evaluated. For lungs, mean doses (mean lung dose [MLD]) and percent V30/V20/V10/V5 Gy were assessed. Spinal cord and esophagus Dmax and D5/D50 were computed. Chest wall (CW) Dmax and absolute V30/V20/V10/V5 Gy were reported. Sectored SBRT planning resulted in significant decrease in contralateral MLD and V10/V5 Gy, as well as contralateral CW Dmax and V10/V5 Gy (all p < 0.001). Nominal reductions of Dmax and D5/D50 for the spinal cord with sectored planning did not reach statistical significance for static-gantry IMRT, although VMAT metrics did show a statistically significant decrease (all p < 0.001). The respective measures for esophageal doses were significantly lower with sectored planning (p < 0.001). Despite comparable dose conformality, irrespective of planning configuration, R50 significantly improved with IMRT-s/VMAT-c (p < 0.001/p = 0.008), whereas D2 cm significantly improved with VMAT-c (p < 0.001). Plan delivery efficiency improved with sectored technique (p < 0.001); mean monitor unit (MU)/cGy of PD decreased from 5.8 ± 1.9 vs 5.3 ± 1.7 (IMRT) and 2.7 ± 0.4 vs 2.4 ± 0.3 (VMAT). The sectored configuration achieves unambiguous dosimetric advantages over circumferential arrangement in terms of esophageal, contralateral CW, and contralateral lung sparing, in addition to being more efficient at delivery. 相似文献
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《Medical Dosimetry》2023,48(2):67-72
To compare dosimetric parameters for the hippocampus, organs at risk (OARs), and targets of volumetric modulated arc therapy (VMAT), noncoplanar VMAT (NC-VMAT), and HyperArc (HA) plans in patients undergoing postoperative radiotherapy for primary brain tumors. For 20 patients, HA plans were generated to deliver 40.05 to 60 Gy for the planning target volume (PTV). In addition, doses for the hippocampus and OARs were minimized. The VMAT and NC-VMAT plans were retrospectively generated using the same optimization parameters as those in the HA plans. For the hippocampus, the equivalent dose to be administered in 2 Gy fractions (EQD2) was calculated assuming α/β = 2. Dosimetric parameters for the PTV, hippocampus, and OARs in the VMAT, NC-VMAT, and HA plans were compared. For PTV, the HA plans provided significantly lower Dmax and D1% than the VMAT and NC-VMAT plans (p < 0.05), whereas the D99% and Dmin were significantly higher (p < 0.05). For the contralateral hippocampus, the dosimetric parameters in the HA plans (8.1 ± 9.6, 6.5 ± 7.2, 5.6 ± 5.8, and 4.8 ± 4.7 Gy for D20%, D40%, D60% and D80%, respectively) were significantly smaller (p < 0.05) than those in the VMAT and NC-VMAT plans. Except for the optic chiasm, the Dmax in the HA plans (brainstem, lens, optic nerves, and retinas) was the smallest (p < 0.05). In addition, the doses in the HA plans for the brain and skin were the smallest (p < 0.05) among the 3 plans. HA planning, instead of coplanar and noncoplanar VMAT, significantly reduces the dosage to which the contralateral hippocampus as well as other OARs are exposed without compromising on target coverage. 相似文献
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《Medical Dosimetry》2014,39(2):169-173
To determine the effect of gross tumor volume of the primary (GTV-P) and nodal (GTV-N) disease on planned radiation dose to the brachial plexus (BP) in head and neck intensity-modulated radiotherapy (IMRT). Overall, 75 patients underwent definitive IMRT to a median total dose of 69.96 Gy in 33 fractions. The right BP and left BP were prospectively contoured as separate organs at risk. The GTV was related to BP dose using the unpaired t-test. Receiver operating characteristics curves were constructed to determine optimized volumetric thresholds of GTV-P and GTV-N corresponding to a maximum BP dose cutoff of > 66 Gy. Multivariate analyses were performed to account for factors associated with a higher maximal BP dose. A higher maximum BP dose (> 66 vs ≤ 66 Gy) correlated with a greater mean GTV-P (79.5 vs 30.8 cc; p = 0.001) and ipsilateral GTV-N (60.6 vs 19.8 cc; p = 0.014). When dichotomized by the optimized nodal volume, patients with an ipsilateral GTV-N ≥ 4.9 vs < 4.9 cc had a significant difference in maximum BP dose (64.2 vs 59.4 Gy; p = 0.001). Multivariate analysis confirmed that an ipsilateral GTV-N ≥ 4.9 cc was an independent predictor for the BP to receive a maximal dose of > 66 Gy when adjusted individually for BP volume, GTV-P, the use of a low anterior neck field technique, total planned radiation dose, and tumor category. Although both the primary and the nodal tumor volumes affected the BP maximal dose, the ipsilateral nodal tumor volume (GTV-N ≥ 4.9 cc) was an independent predictor for high maximal BP dose constraints in head and neck IMRT. 相似文献
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James Welsh Arya Amini Katherine Ciura Ngoc Nguyen Matt Palmer Hendrick Soh Pamela K. Allen Michael Paolini Zhongxing Liao Jaques Bluett Radhe Mohan Daniel Gomez James D. Cox Ritsuko Komaki Joe Y. Chang 《Medical Dosimetry》2013,38(4):442-447
Stereotactic body radiotherapy (SBRT) can produce excellent local control of several types of solid tumor; however, toxicity to nearby critical structures is a concern. We found previously that in SBRT for lung cancer, the chest wall (CW) volume receiving 20, 30, or 40 Gy (V20, V30, or V40) was linked with the development of neuropathy. Here we sought to determine whether the dosimetric advantages of protons could produce lower CW doses than traditional photon-based SBRT. We searched an institutional database to identify patients treated with photon SBRT for lung cancer with tumors within < 2.5 cm of the CW. We found 260 cases; of these, chronic grade ≥ 2 CW pain was identified in 23 patients. We then selected 10 representative patients from this group and generated proton SBRT treatment plans, using the identical dose of 50 Gy in 4 fractions, and assessed potential differences in CW dose between the 2 plans. The proton SBRT plans reduced the CW doses at all dose levels measured. The median CW V20 was 364.0 cm3 and 160.0 cm3 (p < 0.0001), V30 was 144.6 cm3 vs 77.0 cm3 (p = 0.0012), V35 was 93.9 cm3 vs 57.9 cm3 (p = 0.005), V40 was 66.5 cm3 vs 45.4 cm3 (p = 0.0112), and mean lung dose was 5.9 Gy vs 3.8 Gy (p = 0.0001) for photons and protons, respectively. Coverage of the planning target volume (PTV) was comparable between the 2 sets of plans (96.4% for photons and 97% for protons). From a dosimetric standpoint, proton SBRT can achieve the same coverage of the PTV while significantly reducing the dose to the CW and lung relative to photon SBRT and therefore may be beneficial for the treatment of lesions closer to critical structures. 相似文献
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《Medical Dosimetry》2014,39(3):242-245
Radiotherapy for epithelioid hemangioendothelioma (EHE) using volumetric intensity-modulated arc radiotherapy (VMAT). A 48-year-old woman was referred for curative irradiation of a vertebral EHE after failure of surgery. A comparison between VMAT and conventional conformal tridimensional (3D) dosimetry was performed and potential advantage of VMAT for sparing critical organs from irradiation׳s side effects was discussed. The total delivered dose on the planning target volume was 54 Gy in 27 fractions. The patient was finally treated with VMAT. The tolerance was excellent. There was no acute toxicity, including no increase in pain. With a follow-up of 18 months, no delayed toxicity was reported. The clinical response consisted of a decrease in the dorsal pain. The Dmax for the spinal cord was reduced from 55 Gy (3D-radiotherapy [RT]) (which would be an unacceptable dose to the spine because of the risk of myelopathy) to 42.8 Gy (VMAT), which remains below the recommended dose threshold (45 Gy). The dose delivered to 20% of organ volume (D20) was reduced from 47 Gy (3D-RT) to 3 Gy (VMAT) for the spinal cord. The study shows that VMAT allows the delivery of curative treatment for vertebral EHEs because of critical organ sparing. 相似文献
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Daya Nand Sharma Ajeet Kumar Gandhi Seema Sharma Goura Kisor Rath Pandjatcharam Jagadesan Pramod Kumar Julka 《Brachytherapy》2013,12(4):311-316
PurposeInterstitial brachytherapy (IBT) is the standard alternative treatment for patients with cervical carcinoma not suitable for intracavitary radiotherapy. There is an emerging belief that intensity-modulated radiotherapy (IMRT) has the potential to replace IBT. We aimed to compare the dosimetry achieved by IBT and IMRT in such patients.Methods and MaterialsThe CT imaging data, previously used for IBT planning of 12 patients with cervical carcinoma, were transferred to IMRT planning system to generate parallel IMRT plans. Prescribed dose to the planning target volume (PTV) was 20 Gy delivered in 2-weekly high-dose-rate fractions of 10 Gy each with IBT (biologically equivalent dose [BED10] 40 Gy) and 33 Gy/13 fractions/2.5 wk with IMRT (BED10 41 Gy). For comparison, dose–volume parameters for target and organs at risk were recorded and expressed in terms of BED10 and BED3, respectively.ResultsFor PTV, the mean D95 (dose received by 95% of PTV) was better with IBT (57.16 Gy vs. 41.47 Gy, p = 0.003). The mean conformity index was 0.94 and 0.90 with IBT and IMRT, respectively (p = 0.034). IBT delivered significantly reduced doses to 1.0 cc (Dmax), 5.0 cc (D5 cc), 50% (D50), and 75% (D75) of bladder volume as compared with IMRT. The mean rectal Dmax was significantly better with IBT as compared with IMRT (54.64 Gy vs. 62.63 Gy, p = 0.02).ConclusionsIBT provides superior PTV coverage and organs at risk sparing to IMRT. Thus, IBT remains the standard treatment for patients with cervical carcinoma unsuitable for intracavitary radiotherapy. 相似文献
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《Medical Dosimetry》2014,39(3):261-265
This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D100, PTV D99, and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D95 of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D99 was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D100 average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used. 相似文献
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Nelson N. Stone Jamie A. Cesaretti Barry Rosenstein Richard G. Stock 《Brachytherapy》2010,9(2):114-118
PurposeTo investigate the morbidity of higher radiation doses in prostate cancer patients.Methods and MaterialsFive hundred eighty-five men treated with seed implantation and external beam irradiation were followed a median of 5 years (range, 2–11). Hormonal therapy (HT) of 9 months duration was used in 504 (86.2%) patients. The biologic effective dose (BED) was calculated using an α/β of 2. Urinary incontinence (UI) and symptoms (IPSS) were prospectively collected. Rectal morbidity was scored according to the Radiation Therapy Oncology Group (RTOG) scale. Two BED dose groups of ≤220 Gy (n = 449) and >220 Gy (n = 136) were used. Comparisons of means were made by Student's t test, and the associations were tested by chi-square analysis (Pearson).ResultsUrinary retention developed in 36 (6.2%) and was not associated with BED or IPSS. Retention occurred more often with prostate volume >50 cc (17%, p = 0.001). The median change in urinary symptoms (IPSS) was 1. Sixty-one percent with high BED were more likely to have increased postimplant symptoms compared with 39% with lower BED (p = 0.025; odds ratio [OR], 1.107; 95% confidence interval [CI], 1.10–1.21). UI occurred in 25 patients (4.3%) and was only associated with a postimplant transurethral resection of the prostate (TURP) (n = 25), 16% vs. 2.3% for no TURP (p = 0.001; OR, 8; 95% CI, 2.4–27). Of the 373 patients initially potent, 204 (54.7%) maintained potency. Impotence was only associated with age at implant (p = 0.001) and HT (p = 0.004). Sixty-two (10.6%) patients had Grade 1–2 and 4 patients had Grade 3–4 (0.7%, 2 ulcers and 2 fistulas) rectal complications. Three of the Grade 3/4 complications occurred with a dose ≤220 Gy.ConclusionA BED >220 Gy does not seem to increase morbidity. 相似文献
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Malolan S. Rajagopalan Neeta Kannan Hayeon Kim Christopher J. Houser Sushil Beriwal 《Brachytherapy》2013,12(3):248-253
PurposeThe tolerance and complication rates of the urethra are unknown for the interstitial high-dose-rate brachytherapy (HDR-BT) for vaginal cancer.Methods and MaterialsPatients with vaginal cancer near/involving the urethra who were treated with HDR-BT between 2008 and 2011 were included. Patients received mean external beam dose of 48.0 Gy followed by mean HDR-BT dose of 4.5 Gy/fraction for five fractions. With CT-based planning, the urethra was contoured from the bladder neck to the meatus. Doses were converted to the biologically equivalent dose in 2 Gy/fraction (EQD2).ResultsA total of 16 patients were included, and the EQD2 D90 was 74.9 Gy. The urethral volume was 1.31 cm3, and the EQD2 to 0.1 and 1 cm3 were 76.2 and 48.9 Gy, respectively. Two of the 6 patients with urethral involvement developed urethral necrosis. The D90 for these 2 patients was 76.8 Gy, and the urethral doses to 0.1 and 1 cm3 were 95.1 and 45.8, respectively. Those who developed severe urethral toxicity had a trend to urethral EQD2 (95.1 Gy vs. 73.4 Gy, p = 0.1) and significantly higher dose per fraction of HDR-BT to 0.1 cm3 of the urethra (5.7 Gy vs. 3.7 Gy, p = 0.02) when compared with those who did not develop severe urethral toxicity.ConclusionsThis study is among the first to assess urethral dosimetry for patients treated with HDR-BT for vaginal cancer. Patients who received five fractions of higher than 5 Gy/fraction to 0.1 cm3 of urethra (estimated EQD2 of 85 Gy) are at increased risk of severe urethral toxicity. 相似文献
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Chirag Shah Thomas B. Lanni Mihai I. Ghilezan Gary S. Gustafson Kimberly S. Marvin Hong Ye Frank A. Vicini Alvaro A. Martinez 《Brachytherapy》2012,11(6):441-445
PurposeTo evaluate the cost-effectiveness and outcomes of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy compared with intensity-modulated radiation therapy (IMRT) in patients with low/intermediate risk of prostate cancer.Methods and MaterialsOne thousand three hundred twenty-eight patients with low or intermediate risk of prostate cancer were treated with LDR (n = 207), HDR with four fractions (n = 252), or IMRT (n = 869) between January 1992 and December 2008. LDR patients were treated with palladium seeds to a median dose of 120 Gy, whereas HDR patients were treated to a median dose 38.0 Gy (four fractions). IMRT patients received 42–44 fractions with a median dose of 75.6 Gy. Clinical outcomes were compared, including biochemical failure, cause-specific survival, and overall survival.ResultsOverall, no differences in 5-year biochemical control (BC) or cause-specific survival were noted among treatment modalities. The calculated reimbursement for LDR brachytherapy, HDR brachytherapy with four fractions, and IMRT was $9,938; $17,514; and $29,356, respectively. HDR and LDR brachytherapy were statistically less costly to Medicare and the institution than IMRT (p < 0.001), and LDR brachytherapy was less costly than HDR brachytherapy (p = 0.01 and p < 0.001). Incremental cost-effectiveness ratios for cost to Medicare for BC with IMRT were $4045 and $2754 per percent of BC for LDR and HDR brachytherapy, respectively. Incremental cost-effectiveness ratio using institutional cost comparing IMRT with LDR and HDR brachytherapy was $4962 and $4824 per 1% improvement in BC.ConclusionsIn this study of patients with low and intermediate risk of prostate cancer, comparable outcomes at 5 years were noted between modalities with increased costs associated with IMRT. 相似文献
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Zoltán Takácsi-Nagy Ferenc Oberna Pál Koltai Erika Hitre Tibor Major János Fodor Csaba Polgár 《Brachytherapy》2013,12(6):535-541
PurposeTo report the long-term results of a prospective, nonrandomized clinical trial using high-dose-rate (HDR) brachytherapy (BT) for the management of base of the tongue (BOT) tumors.Methods and MaterialsBetween January 1992 and June 2011, 60 patients (mean age, 57 years; range, 36–78 years) with T1–T4 and N0-3 carcinoma of BOT were treated. Fifty-six patients (93%) had advanced (Stage III-IV) disease. HDR BT boost (mean dose, 17 Gy; range, 12–30 Gy) was delivered after 50–70 Gy (mean 62 Gy) locoregional external beam irradiation. Seventeen patients (28%) received radiochemotherapy (RCT) with cisplatin.ResultsThe 5-year actuarial rate of local tumor control, locoregional tumor control, overall survival (OS), and cancer-specific survival (CSS) was 57%, 50%, 47%, and 61%, respectively. OS was significantly better in patients (n = 17) receiving RCT (69% vs. 39%; p = 0.005). Delayed soft-tissue ulceration occurred in seven patients (12%). Only one patient (<2%) developed osteoradionecrosis. In univariate analysis, the tumor size (T1–T2–T3 vs. T4) was found to have a significant effect on CSS (p = 0.043), whereas the nodal status (N0 vs. N+) affected locoregional tumor control (p = 0.042), OS (p = 0.002), and CSS (p = 0.015). Low histologic grade (1–2) was associated with better CSS (p = 0.020), whereas RCT significantly improved OS (p = 0.012).ConclusionsExternal beam irradiation combined with interstitial HDR BT boost results in good local tumor control with an acceptable rate of late side effects in patients with BOT carcinoma. RCT improves OS. Our results are similar to those reported with traditional low-dose-rate BT implants. 相似文献