不同计划靶体积外扩界在三维适形放疗治疗复发性宫颈癌中的临床效果评价

目的 评价不同计划靶体积(PTV)外扩界在三维适形放疗治疗复发性宫颈癌中的临床效果.方法 随机选取温州市中心医院2013年1～12月收治的45例复发性宫颈癌患者作为研究对象,根据PTV外扩边界剂量不同分为三组,分别为PTV 0.5 cm组15例、PTV 1.0 cm组(常规对照组)15例、PTV 1.5 cm组15例,比较三组患者疗效及副作用发生情况.结果 PTV 1.5 cm组患者放疗后总有效率(93.33％)明显高于常规对照组(66.67％)和PTV0.5 cm组(60.00％);PTV 1.5 cm组患者放射性直肠炎发生率(0.00％)明显低于常规对照组(26.67％)和PTV 0.5 cm组(26.67％),差异有统计学意义(P＜0.05).三组患者的骨髓抑制发生率比较,差异无统计学意义(P＞0.05).结论 不同PTV外扩界在三维适形放疗治疗复发性宫颈癌中具有一定的差异性,PTV 1.5 cm临床总有效率更高,可明显降低放射性直肠炎的发生率,减少副作用的发生,属于最为安全的剂量范围,值得临床推广应用.     

Incertitudes inhérentes au concept actuel de volume cible prévisionnel en radiothérapie

The planning target volume is an essential notion in radiotherapy, that requires a new conceptualization. Indeed, the variability and diversity of the uncertainties involved or improved with the development of the new modern technologies and devices in radiotherapy suggest that random and systematic errors cannot be currently generalized. This article attempts to discuss these various uncertainties and tries to demonstrate that a redefinition of the concept of planning target volume toward its personalization for each patient and the robustness notion are likely an improvement basis to take into account the radiotherapy uncertainties.     

Marges en radiothérapie du cancer de la vessie

Radical cystectomy is the gold standard treatment of invasive bladder carcinoma, but conservative treatment is a serious option for selected patients. It comprises a transurethral resection, as complete as possible, before a radiation therapy of the whole bladder and pelvis, with a concomitant chemotherapy. Bladder wall movements during the treatment course lead to the use of wide margins to cover the clinical target volume. Planning target volume margins must be anisotropic to correspond to the mobility of each bladder zone: 10 mm in the inferior portion, 15 mm in lateral directions, and 20 to 25 mm in anterior and superior directions. The development of image-guided radiotherapy and adaptative radiotherapy should lead to a reduction of these margins. Besides, partial bladder radiotherapy is showing encouraging results, by reducing the clinical target volume in well-selected patients.     

Time of PTV is ending,robust optimization comes next

Continuous improvements have been made in the way to prescribe, record and report dose distributions since the therapeutic use of ionizing radiations. The international commission for radiation units and measurement (ICRU) has provided a common language for physicians and physicists to plan and evaluate their treatments. The PTV concept has been used for more than two decades but is becoming obsolete as the CTV-to-PTV margin creates a static dose cloud that does not properly recapitulate all planning vs. delivery uncertainties. The robust optimization concept has recently emerged to overcome the limitations of the PTV concept. This concept is integrated in the inverse planning process and minimizes deviations to planned dose distribution through integration of uncertainties in the planning objectives. It appears critical to account for the uncertainties that are specific to protons and should be accounted for to better exploit the clinical potential of proton therapy. It may also improve treatment quality particularly in hypofractionated photon plans of mobile tumors and more widely to photon radiotherapy. However, in contrast to the PTV concept, a posteriori evaluation of plan quality, called robust evaluation, using error-based scenarios is still warranted. Robust optimization metrics are warranted. These metrics are necessary to compare PTV-based photon and robustly optimized proton plans in general and in model-based NTCP approaches. Assessment of computational demand and approximations of robust optimization algorithms along with metrics to evaluate plan quality are needed but a step further to better prescribe radiotherapy may has been achieved.     

Concepts and terms for dose/volume parameters in carbon-ion radiotherapy: Conclusions of the ULICE taskforce

Purpose

The Union of Light Ion Centers in Europe (ULICE) program addressed the need for uniting scientific results for carbon-ion radiation therapy obtained by several institutions worldwide in different fields of excellence, and translating them into a real benefit to the community. Particularly, the concepts for dose/volume parameters developed in photon radiotherapy cannot be extrapolated to high linear energy transfer particles.

Three-dimensional flow analysis of a mechanical bileaflet mitral prosthesis

 The Jyros (JR) and the Advancing The Standard (ATS) valves were compared with the St. Jude Medical (SJM) valve in the mitral position to study the effects of design differences, installed valve orientation to the flow, and closing sounds using particle tracking velocimetry and particle image velocimetry methods utilizing a high-speed video flow visualization technique to map the velocity field. Sound measurements were made to confirm the claims of the manufacturers. Based on the experimental data, the following general conclusions can be made: On the vertical measuring plane which passes through the centers of the aortic and the mitral valves, the SJM valve shows a distinct circulatory flow pattern when the valve is installed in the antianatomical orientation; the SJM valve maintains the flow through the central orifice quite well; the newer curved leaflet JR valve and the ATS valve, which does not fully open during the peak flow phase, generates a higher but divergent flow close to the valve location when the valve was installed anatomically. The antianatomically installed JR valve showed diverse and less distinctive flow patterns and slower velocity on the central measuring plane than the SJM valve did, with noticeably lower valve closing noise. On the velocity field directly below the mitral valve that is normal to the previous measuring plane, the three valves show symmetrical twin circulations due to the divergent nature of the flow generated by the two inclined half discs; the SJM valve with centrally downward circulation is contrasted by the two other valves with peripherally downward circulation. These differences may have an important role in generation of the valve closing sound. Received: October 3, 2002 / Accepted: March 18, 2003