Assessment of extended-field radiotherapy for stage IIIC endometrial cancer using three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and helical tomotherapy

PURPOSE: To perform a dosimetric comparison of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and helical tomotherapy (HT) plans for pelvic and para-aortic RT in postoperative endometrial cancer patients; and to evaluate the integral dose (ID) received by critical structures within the radiation fields. METHODS AND MATERIALS: We selected 10 patients with Stage IIIC endometrial cancer. For each patient, three plans were created with 3D-CRT, IMRT, and HT. The IMRT and HT plans were both optimized to keep the mean dose to the planning target volume (PTV) the same as that with 3D-CRT. The dosimetry and ID for the critical structures were compared. A paired two-tailed Student t test was used for data analysis. RESULTS: Compared with the 3D-CRT plans, the IMRT plans resulted in lower IDs in the organs at risk (OARs), ranging from -3.49% to -17.59%. The HT plans showed a similar result except that the ID for the bowel increased 0.27%. The IMRT and HT plans both increased the IDs to normal tissue (see Table 1 and text for definition), pelvic bone, and spine (range, 3.31-19.7%). The IMRT and HT dosimetry showed superior PTV coverage and better OAR sparing than the 3D-CRT dosimetry. Compared directly with IMRT, HT showed similar PTV coverage, lower Ids, and a decreased dose to most OARs. CONCLUSION: Intensity-modulated RT and HT appear to achieve excellent PTV coverage and better sparing of OARs, but at the expense of increased IDs to normal tissue and skeleton. HT allows for additional improvement in dosimetry and sparing of most OARs.     

螺旋断层放射治疗系统在中枢神经系统肿瘤中的应用

螺旋断层放射治疗系统（helical tomotherapy,HT）是利用一台6MV的医用直线加速器以螺旋CT旋转扫描方式,实现40 cm×160 cm范围的照射,是当今最先进的肿瘤放射治疗系统之一,集调强放射治疗（IMRT）、图像引导放射治疗（IGRT）、自适应放疗 (ART）和剂量引导放疗（DGRT）于一体。目前HT已初步应用于中枢神经系统良恶性肿瘤的治疗,照射精确、剂量分布均匀、能够有效保护危及器官,降低正常组织放疗毒性,应用前景广阔。现就HT在中枢神经系统肿瘤中的应用展开总结论述。     

Evaluation of trends in the use of intensity‐modulated radiotherapy for head and neck cancer from 2000 through 2005

BACKGROUND:

The current study was conducted to evaluate trends in utilization of intensity‐modulated radiotherapy (IMRT) for head and neck cancer (HNC).

METHODS:

Identified were 5487 patients from the Surveillance, Epidemiology, and End Results (SEER) ‐Medicare linked database with a diagnosis of HNC (aged ≥65 years) between 2000 and 2005, who received any type of radiotherapy (RT). Multivariate logistic regression analyses were performed to assess the influence of patient, tumor, treatment, and sociodemographic characteristics on receipt of IMRT versus conventional radiotherapy techniques.

RESULTS:

Overall, 21.3% of patients in the cohort received IMRT as the technique of irradiation. The use of IMRT increased significantly, with 1.3% of patients receiving it in 2000 compared with 46.1% in 2005 (P <.0001 for trend). Patients treated with RT in 2005 were 68 times more likely to receive IMRT than those treated in 2000. There was significant geographic variation observed in use of IMRT, ranging from 11.3% of cases in Kentucky to 40.4% of cases in Hawaii. Patients in the census tracks comprising the lowest quartile for socioeconomic status were 33% less likely to receive IMRT than patients in the highest quartile, even when adjusting for geographic area and year of diagnosis.

CONCLUSIONS:

The use of IMRT has rapidly become widespread for the delivery of RT for patients with HNC. However, there was significant geographic variation noted in the utilization of IMRT. Patients in census tracks comprising the lowest socioeconomic quartile were less likely to receive IMRT than their more affluent counterparts. Cancer 2010. © 2010 American Cancer Society.     

Optimisation of radiotherapy for carcinoma of the parotid gland: a comparison of conventional, three-dimensional conformal, and intensity-modulated techniques.

BACKGROUND AND PURPOSE: To compare external beam radiotherapy techniques for parotid gland tumours using conventional radiotherapy (RT), three-dimensional conformal radiotherapy (3DCRT), and intensity-modulated radiotherapy (IMRT). To optimise the IMRT techniques, and to produce an IMRT class solution. MATERIALS AND METHODS: The planning target volume (PTV), contra-lateral parotid gland, oral cavity, brain-stem, brain and cochlea were outlined on CT planning scans of six patients with parotid gland tumours. Optimised conventional RT and 3DCRT plans were created and compared with inverse-planned IMRT dose distributions using dose-volume histograms. The aim was to reduce the radiation dose to organs at risk and improve the PTV dose distribution. A beam-direction optimisation algorithm was used to improve the dose distribution of the IMRT plans, and a class solution for parotid gland IMRT was investigated. RESULTS: 3DCRT plans produced an equivalent PTV irradiation and reduced the dose to the cochlea, oral cavity, brain, and other normal tissues compared with conventional RT. IMRT further reduced the radiation dose to the cochlea and oral cavity compared with 3DCRT. For nine- and seven-field IMRT techniques, there was an increase in low-dose radiation to non-target tissue and the contra-lateral parotid gland. IMRT plans produced using three to five optimised intensity-modulated beam directions maintained the advantages of the more complex IMRT plans, and reduced the contra-lateral parotid gland dose to acceptable levels. Three- and four-field non-coplanar beam arrangements increased the volume of brain irradiated, and increased PTV dose inhomogeneity. A four-field class solution consisting of paired ipsilateral coplanar anterior and posterior oblique beams (15, 45, 145 and 170 degrees from the anterior plane) was developed which maintained the benefits without the complexity of individual patient optimisation. CONCLUSIONS: For patients with parotid gland tumours, reduction in the radiation dose to critical normal tissues was demonstrated with 3DCRT compared with conventional RT. IMRT produced a further reduction in the dose to the cochlea and oral cavity. With nine and seven fields, the dose to the contra-lateral parotid gland was increased, but this was avoided by optimisation of the beam directions. The benefits of IMRT were maintained with three or four fields when the beam angles were optimised, but were also achieved using a four-field class solution. Clinical trials are required to confirm the clinical benefits of these improved dose distributions.     

Comparison of radiation treatment delivery for pancreatic cancer: Linac intensity-modulated radiotherapy versus helical tomotherapy

Introduction: Intensity‐modulated radiotherapy (IMRT) has been shown to reduce dose to organs at risk (OAR) while adequately treating tumour volume. This study quantitatively compares the dosimetric differences from step‐and‐shoot IMRT compared with helical tomotherapy (HT) for pancreatic head cancer. Methods: Twelve consecutive patients with non‐metastatic, stage T3 or T4, unresectable pancreatic head cancer were planned for step‐and‐shoot IMRT as well as HT. Radiotherapy was planned to deliver 45.9 Gy to the clinical target volume in 30 fractions with an integrated boost to 54 Gy to the gross tumour volume (planning target volume 5400 including a 1‐cm set‐up margin). The uniformity index (UI) and conformity index (CI) were used to compare the quality of target coverage, while the quality index (QI) compared the dosimetric performance for OAR. Results: Both methods were effective at covering the tumour with no significant difference in UI or CI. However, HT dosimetry exhibited superior sparing of OAR with significantly less stomach (mean QI_StomV30 = 0.84, P = 0.006) and small bowel dosing (mean small bowel QI_SBV30 = 0.84, P = 0.005). HT reduced dose to the kidney receiving the highest dose but the overall volume of kidney receiving 18 Gy was not significantly different between the two systems, indicating that HT spread the dose more uniformly through the kidneys. Conclusions: Target coverage is equivalent between the two systems; however, HT shows significantly better sparing of the stomach and small bowel. The decreased dose to OAR with HT is likely to improve the therapeutic ratio in the radiotherapy of pancreatic head cancers.     

Fluorine-18-labeled fluoromisonidazole positron emission and computed tomography-guided intensity-modulated radiotherapy for head and neck cancer: a feasibility study

PURPOSE: Hypoxia renders tumor cells radioresistant, limiting locoregional control from radiotherapy (RT). Intensity-modulated RT (IMRT) allows for targeting of the gross tumor volume (GTV) and can potentially deliver a greater dose to hypoxic subvolumes (GTV(h)) while sparing normal tissues. A Monte Carlo model has shown that boosting the GTV(h) increases the tumor control probability. This study examined the feasibility of fluorine-18-labeled fluoromisonidazole positron emission tomography/computed tomography ((18)F-FMISO PET/CT)-guided IMRT with the goal of maximally escalating the dose to radioresistant hypoxic zones in a cohort of head and neck cancer (HNC) patients. METHODS AND MATERIALS: (18)F-FMISO was administered intravenously for PET imaging. The CT simulation, fluorodeoxyglucose PET/CT, and (18)F-FMISO PET/CT scans were co-registered using the same immobilization methods. The tumor boundaries were defined by clinical examination and available imaging studies, including fluorodeoxyglucose PET/CT. Regions of elevated (18)F-FMISO uptake within the fluorodeoxyglucose PET/CT GTV were targeted for an IMRT boost. Additional targets and/or normal structures were contoured or transferred to treatment planning to generate (18)F-FMISO PET/CT-guided IMRT plans. RESULTS: The heterogeneous distribution of (18)F-FMISO within the GTV demonstrated variable levels of hypoxia within the tumor. Plans directed at performing (18)F-FMISO PET/CT-guided IMRT for 10 HNC patients achieved 84 Gy to the GTV(h) and 70 Gy to the GTV, without exceeding the normal tissue tolerance. We also attempted to deliver 105 Gy to the GTV(h) for 2 patients and were successful in 1, with normal tissue sparing. CONCLUSION: It was feasible to dose escalate the GTV(h) to 84 Gy in all 10 patients and in 1 patient to 105 Gy without exceeding the normal tissue tolerance. This information has provided important data for subsequent hypoxia-guided IMRT trials with the goal of further improving locoregional control in HNC patients.     

The impact of introducing intensity modulated radiotherapy into routine clinical practice.

BACKGROUND AND PURPOSE: Intensity modulated radiotherapy (IMRT) at the Royal Marsden Hospital London was introduced in July 2001. Treatment delivery was dynamic using a single-phase technique. Concerns were raised regarding increased clinical workload due to introduction of new technology. The potential increased use of resources was assessed. PATIENTS AND METHODS: IMRT patient selection was within guidelines of clinical trials and included patients undergoing prostate plus pelvic lymph node (PPN) irradiation and head and neck cancer (HNC) treatment. Patient planning, quality assurance and treatment times were collected for an initial IMRT patient group. A comparative group of patients with advanced HNC undergoing two- or three-phase conventional radiotherapy, requiring matched photon and electron fields, were also timed. RESULTS: The median overall total planning time for IMRT was greater for HNC patients compared to the PPN cohort. For HNC the overall IMRT planning time was significantly longer than for conventional. The median treatment time for conventional two- or three-phase HNC treatments, encompassing similar volumes to those treated with IMRT, was greater than that for the IMRT HNC patient cohort. A reduction in radiographer man hours per patient of 4.8h was recorded whereas physics time was increased by 4.9h per patient. CONCLUSIONS: IMRT currently increases overall planning time. Additional clinician input is required for target volume localisation. Physics time is increased, a significant component of this being patient specific QA. Radiographer time is decreased. For HNC a single phase IMRT treatment has proven to be more efficient than a multiple phase conventional treatment. IMRT has been integrated smoothly and efficiently into the existing treatment working day. This preliminary study suggests that IMRT could be a routine treatment with efficient use of current radiotherapy resources.     

Results of a two-year quality control program for a helical tomotherapy unit.

BACKGROUND AND PURPOSE: Image-guided helical tomotherapy (HT) is a new modality for delivering intensity modulated radiation therapy (IMRT) with helical irradiation: the slip ring continuously rotates while the couch moves into the bore. The radiation source (Linac, 6 MV) is collimated into a fan beam and modulated by means of a binary multileaf collimator (MLC). A xenon detector array, opposite the radiation source, allows a megavoltage-CT (MVCT) acquisition of patient images for set-up verification. The aim of this paper is to report the results of a two-year quality control (QC) program for the physical and dosimetric characterization of an HT unit installed at our Institute and clinically activated in November 2004, in order to monitor and verify the stability and the reliability of this promising radiation treatment unit. MATERIALS AND METHODS: Conventional Linac acceptance protocols (ATP) and QC protocols were adapted to HT with the addition of specific items reflecting important differences between the two irradiation modalities. QC tests can be summarized as: (a) mechanical and geometrical characterization of the system's components: evaluation of alignment among radiation source-gantry rotation plan-jaws-MLC-MVCT; (b) treatment beam configuration in static condition: depth dose curves (PDD) and profiles, output factors, output reproducibility and linearity; (c) dynamic component characterization: accuracy and reproducibility of MLC positioning; rotational output reproducibility and linearity, leaf latency, couch movement constancy; (d) gantry-couch and MLC-gantry synchronization; and (e) MVCT image quality. Peculiar periodicity specific tolerance and action levels were defined. Ionization chambers (Exradin A1SL 0.056 cc), films (XOmat-V/EDR2), water and solid water phantoms were used to perform quality assurance measurements. RESULTS: Over a two-year period the final average output variation after possible beam output adjustment was -0.2+/-1% for the static condition and equal to 0+/-1% for the rotational condition: around 98% of the collected output data was within the action level compared to 94% if no beam output adjustment was considered. An average energy variation of -0.4+/-0.4% was found. The daily absolute dose verification of IMRT plans showed a dose reproducibility of -0.5+/-1.2% and -0.4+/-2.2%, for low and high dose gradient regions, respectively. Source-jaws-MLC and MVCT alignment results and jaw and leaf positioning accuracy were +/-1mm. Couch-gantry-MLC synchrony tests showed good stability level (相似文献   

Apports de la radiothérapie avec modulation d’intensité guidée par l’image dans les cancers prostatiques

External beam radiotherapy (RT) is used to treat all stages of localized prostate cancer. Using a 3D conformal RT (3DCRT) without any androgen deprivation, a clear dose–effect relationship has been shown in terms of both biochemical control and also unfortunately of rectal and urinary toxicity. Compared to a “standard” 3DCRT, intensity modulated RT (IMRT) improves the dose distribution by mainly providing concave dose distribution and tight dose gradients. Based on large clinical experiences for at least one decade, IMRT is widely used to increase the dose in the prostate and therefore local control, without increasing toxicity. Indeed, toxicity rates observed after high dose delivered in the prostate (80 Gy) with IMRT appear no different than those observed after a standard dose (70 Gy) delivered by a standard 3DCRT. Arc IMRT appears a new promising IMRT modality, decreasing dramatically treatment duration. However, this IMRT-based dosimetric benefit may not be translated into a full clinical benefit, if intra-pelvic prostate motion is not taken in account. Image-guided radiotherapy (IGRT) should be therefore associated with IMRT for a maximal clinical benefit. This article is a literature review showing the interest of both combined approaches.     

The Gray Lecture 2001: coming technical advances in radiation oncology

PURPOSE: To review the current limits on the efficacy of radiotherapy (RT) due to technical factors and to assess the potential for major improvements in technology. METHODS AND MATERIALS: The method of this review was to assess the efficacy of current RT in general terms; strategies for improving RT; historical record of technological advances; rationale for further reductions of treatment volume; and importance of defining and excluding nontarget tissues from the target volume. The basis for the interest in proton beam RT is developed, and the relative dose distributions of intensity-modulated radiotherapy (IMRT) and intensity-modulated proton RT (IMPT) are discussed. The discovery of the proton and the first proposal that protons be used in RT is described. This is followed by a brief mention of the clinical outcome studies of proton RT. Likely technical advances to be integrated into advanced proton RT are considered, specifically, four-dimensional treatment planning and delivery. Finally, the increment in cost of some of these developments is presented. RESULTS: For definitive RT, dose limits are set by the tolerance of normal tissues/structures adjacent or near to the target. Using imaging fusion of CT, MRI, positron emission tomography, magnetic resonance spectroscopic imaging, and other studies will result in improved definition of the target margins. Proton beams are likely to replace photon beams because of their physical characteristics. Namely, for each beam path, the dose deep to the target is zero, across the target it is uniform, and proximal to the target it is less. Proton therapy can use as many beams, beam angles, noncoplanar, and dynamic, as well as static, intensity modulation, as can photon plans. The ability for much greater accuracy in defining the target position in space and then maintaining the target in a constant position in the radiation beam despite target movement between and during dose fractions will be possible. The cost of proton RT will be modestly higher than comparable high technology photon therapy. CONCLUSION: The technology of RT is clearly experiencing intense and rapid technical developments as pertains to treatment planning and dose delivery. It is predicted that radical dose RT will move to proton beam technology and that the treatment will be four dimensional (the fourth dimension is time). The impact will be higher tumor control probability and reduced frequency and severity of treatment-related morbidity.     

Dosimetric comparison of intensity modulated radiotherapy techniques and standard wedged tangents for whole breast radiotherapy*

Prior to introducing intensity modulated radiotherapy (IMRT) for whole breast radiotherapy (WBRT) into our department we undertook a comparison of the dose parameters of several IMRT techniques and standard wedged tangents (SWT). Our aim was to improve the dose distribution to the breast and to decrease the dose to organs at risk (OAR): heart, lung and contralateral breast (Contra Br). Treatment plans for 20 women (10 right‐sided and 10 left‐sided) previously treated with SWT for WBRT were used to compare (a) SWT; (b) electronic compensators IMRT (E‐IMRT); (c) tangential beam IMRT (T‐IMRT); (d) coplanar multi‐field IMRT (CP‐IMRT); and (e) non‐coplanar multi‐field IMRT (NCP‐IMRT). Plans for the breast were compared for (i) dose homogeneity (DH); (ii) conformity index (CI); (iii) mean dose; (iv) maximum dose; (v) minimum dose; and dose to OAR were calculated (vi) heart; (vii) lung and (viii) Contra Br. Compared with SWT, all plans except CP‐IMRT gave improvement in at least two of the seven parameters evaluated. T‐IMRT and NCP‐IMRT resulted in significant improvement in all parameters except DH and both gave significant reduction in doses to OAR. As on initial evaluation NCP‐IMRT is likely to be too time consuming to introduce on a large scale, T‐IMRT is the preferred technique for WBRT for use in our department.     

胃食管交界腺癌术后静态IMRT、VMAT和HT剂量学比较

目的 评价胃食管交界腺癌根治术后不同照射技术对靶区和正常组织剂量分布的影响,为临床治疗方法提供优选方案。方法 对 9例行根治性食管近端胃切除术或全胃切除术后的胃食管交界腺癌患者分别进行5个野静态IMRT、双弧VMAT和HT计划设计,通过DVH评价不同照射技术对靶区CI、HI和对OAR受量影响。放疗剂量45 Gy (1.8 Gy/次),同期每天口服替吉奥80 mg/m²,放疗日分2次口服。结果 HT靶区CI和HI好于IMRT和VMAT。对肠道和骨髓保护HT亦优于IMRT和VMAT。VMAT左肾 V₂₀、V₃₀和心脏 V₃₀低于IMRT和HT,而IMRT双肺 V₅、V₁₀较低;V₂₀和 D_mean三种技术差异不大。子野跳数平均数VMAT相似文献   

Dose–volume and biological-model based comparison between helical tomotherapy and (inverse-planned) IMAT for prostate tumours

BACKGROUND AND PURPOSE: Helical tomotherapy (HT) and intensity-modulated arc therapy (IMAT) are two arc-based approaches to the delivery of intensity-modulated radiotherapy (IMRT). Through plan comparisons we have investigated the potential of IMAT, both with constant (conventional or IMAT-C) and variable (non-conventional or IMAT-NC, a theoretical exercise) dose-rate, to serve as an alternative to helical tomotherapy. MATERIALS AND METHODS: Six patients with prostate tumours treated by HT with a moderately hypo-fractionated protocol, involving a simultaneous integrated boost, were re-planned as IMAT treatments. A method for IMAT inverse-planning using a commercial module for static IMRT combined with a multi-leaf collimator (MLC) arc-sequencing was developed. IMAT plans were compared to HT plans in terms of dose statistics and radiobiological indices. RESULTS: Concerning the planning target volume (PTV), the mean doses for all PTVs were similar for HT and IMAT-C plans with minimum dose, target coverage, equivalent uniform dose (EUD) and tumour control probability (TCP) values being generally higher for HT; maximum dose and degree of heterogeneity were instead higher for IMAT-C. In relation to organs at risk, mean doses and normal tissue complication probability (NTCP) values were similar between the two modalities, except for the penile bulb where IMAT was significantly better. Re-normalizing all plans to the same rectal toxicity (NTCP=5%), the HT modality yielded higher TCP than IMAT-C but there was no significant difference between HT and IMAT-NC. The integral dose with HT was higher than that for IMAT. CONCLUSIONS: with regards to the plan analysis, the HT is superior to IMAT-C in terms of target coverage and dose homogeneity within the PTV. Introducing dose-rate variation during arc-rotation, not deliverable with current linac technology, the simulations result in comparable plan indices between (IMAT-NC) and HT.     

Intensity-modulated radiotherapy for lymphoma involving the mediastinum

PURPOSE: To determine the feasibility, potential advantage, and indications for intensity-modulated radiotherapy (IMRT) in the treatment of Hodgkin's lymphoma or non-Hodgkin's lymphoma involving excessively large mediastinal disease volumes or requiring repeat RT. METHODS AND MATERIALS: Sixteen patients with Hodgkin's lymphoma (n = 11) or non-Hodgkin's lymphoma (n = 5) undergoing primary radiotherapy or repeat RT delivered via an IMRT plan were studied. The indications for using an IMRT plan were previous mediastinal RT (n = 5) or extremely large mediastinal treatment volumes (n = 11). For each patient, IMRT, conventional parallel-opposed (AP-PA), and three-dimensional conformal (3D-CRT) plans were designed using 6-MV X-rays to deliver doses ranging from 18 to 45 Gy (median, 36 Gy). The plans were compared with regard to dose-volume parameters. The IMRT/AP-PA and IMRT/3D-CRT ratios were calculated for each parameter. RESULTS: For all patients, the mean lung dose was reduced using IMRT, on average, by 12% compared with AP-PA and 14% compared with 3D-CRT. The planning target volume coverage was also improved using IMRT compared with AP-PA but was not different from the planning target volume coverage obtained with 3D-CRT. CONCLUSION: In selected patients with Hodgkin's lymphoma and non-Hodgkin's lymphoma involving the mediastinum, IMRT provides improved planning target volume coverage and reduces pulmonary toxicity parameters. It is feasible for RT of large treatment volumes and allows repeat RT of relapsed disease without exceeding cord tolerance. Additional follow-up is necessary to determine whether improvements in dose delivery affect long-term morbidity and disease control.     

呼吸运动对调强放疗影响的实验研究

目的 :评价静态调强放疗治疗肺癌等运动幅度较大肿瘤的可行性。方法 :应用自行研制的运动体模系统模拟呼吸运动 ,测量不同运动幅度及不同运动方向对基于多叶光栅的静态调强放疗射束半影、剂量分布及绝对剂量的影响。结果 :靶区运动明显增加了射野在运动方向的半影 ,导致了低剂量区面积增大及高剂量区不确定性的增加 ,但70 %～ 90 %的等剂量线变化不显著。虽然不同情况下各测量点的剂量有不同程度的变化 ,但若将运动等不确定性因素考虑在内 ,多次测量后总体变化幅度均在允许的范围之内。结论 :靶区运动加宽了射束的半影 ,但在适当补偿运动等影响靶区确定的因素后 ,应用静态调强放疗治疗周期性运动的肿瘤是可行的     

Comparison of IMRT techniques in the radiotherapeutic management of head and neck cancer: is tomotherapy "better" than step-and-shoot IMRT?

Currently, the most common method of delivering intensity-modulated radiotherapy (IMRT) is through step-and-shoot, segmental multi-leaf collimator (SMLC)-based techniques. Although rotational delivery methods such as helical tomotherapy (HT) have been proposed as offering advantages in the treatment of head and neck cancer, a lack of clinical data exists on its potential utility. This study compared dosimetric, clinical, and quality-of-life endpoints among 149 patients treated by HT and SMLC-IMRT for head and neck cancer. Dosimetric analysis revealed that the use of HT resulted in significant improvements with respect to mean dose (23.5 versus 27.9 Gy, p = 0.03) and V30 (30.1 versus 43.9 Gy, p = 0.01) to the contralateral (spared) parotid gland. However, the incidence of grade 3+ xerostomia in the late setting was 10% and 8% among patients treated by HT and SMLC-IMRT, respectively (p = 0.46). There were no significant differences in any of the quality of life endpoints among patients treated by HT and SMLC-IMRT (p > 0.05, for all). Acknowledging the biases inherent in this retrospective analysis, we found that the dosimetric advantages observed with HT compared to SMLC-IMRT failed to translate into significant improvements in clinical outcome. Prospective studies are needed to further evaluate how HT may affect the therapeutic ratio.     

Clinical application of intensity-modulated radiotherapy for locally advanced cervical cancer

Intensity-modulated radiotherapy (IMRT) offers technical advantages over conventional external beam radiotherapy (CXRT) that might prove clinically advantageous in the management of gynecologic malignancies. Especially in the case of locally advanced cervical cancer, IMRT provides an opportunity to improve the therapeutic ratio by allowing a selective combination of normal tissue dose reduction and/or concomitant integrated boost dose to the tumor. The clinical and biologic rationale for IMRT in this setting is presented here, and pertinent technical considerations such as the delineation of relevant clinical and planning target volumes are discussed. The capacity for IMRT-mediated normal tissue sparing is illustrated by example and review of the literature. Furthermore, for a small cohort of patients with locally advanced or recurrent cervical cancer treated with concomitant integrated boost IMRT and concurrent chemotherapy, preliminary clinical observations of toxicity and tumor response are presented. Concomitant integrated boost IMRT appears clinically tolerable and efficacious in this setting, and formal clinical investigation is warranted as a means of exploiting the fraction-size dependence of radiosensitizers in common clinical use.     

New strategy in hepatic metastatic colorectal cancer: tomotherapy and capecitabine followed by hepatic surgical resection

The majority of patients who develop liver metastases in metastatic colorectal cancer (mCRC) has often unresectable disease. Several new methods of nonsurgical ablation have been tested with variable success. Helical tomotherapy (HT), such as intensity-modulated radiation therapy (IMRT) or stereotactic body radiotherapy therapy, is a recent radiation therapy technique which can provide simultaneous and precise targeting of multiple lesions, while sparing normal tissues. We retrospectively assess the feasibility and the tolerance of IMRT with capecitabine followed by hepatic surgery in mCRC patients. This original observation suggests that HT could be safely integrated in the multidisciplinary management of patients with metastatic colorectal cancer as an alternative to surgery or other local ablation therapies.     

A Dosimetric and Radiobiological Comparison of Intensity Modulated Radiotherapy,Volumetric Modulated Arc Therapy and Helical Tomotherapy Planning Techniques in Synchronous Bilateral Breast Cancer

Objective: The present investigation intends to identify the optimal radiotherapy treatment plan for synchronous bilateral breast cancer (SBBC) using dosimetric and radiobiological indexes for three techniques, namely, helical tomotherapy (HT), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT). Methods: Twenty SBBC treated female patients treatment planning data (average age of 52.5 years) were used as the sample for the present study. Three different plans were created using 50 Gy in a 25 fraction dose regime. Poisson, Niemierko, and LKB models were applied for calculating normal tissue complication probability (NTCP) and tumour control probability (TCP). Result: The target average dose comparison between IMRT with HT and VMAT with HT was highly substantial (P=0.001). The percentage of TCP for IMRT, VMAT, and HT in the Poisson model were 93.70±0.28, 94.68±0.30, and 94.34±0.57, respectively (p<0.05). The dose maximum was lower for the whole lung in the HT plan, with an average dose of 49.31Gy±3.9 (p<0.009). The NTCP values of both Niemierko and LKB models were lower for the heart, lungs, and liver for the IMRT plan. Conclusion: The sparing of organs at risk was higher in the HT plan dosimetrically, and the TCP was higher in the three techniques. The comparison between the three techniques shows that the IMRT and HT techniques could be considered for treating SBBC.