Dosimetric comparison of analytical anisotropic algorithm and the two dose reporting modes of Acuros XB dose calculation algorithm in volumetric modulated arc therapy of carcinoma lung and carcinoma prostate

Volumetric Modulated Arc Therapy (VMAT) is an important modality for radical radiotherapy of all major treatment sites. This study aims to compare Analytical Anisotropic Algorithm (AAA) and the two dose-reporting modes of Acuros XB (AXB) algorithm -the dose to medium option (D_m) and the dose to water option (D_w) in Volumetric Modulated Arc Therapy (VMAT) of carcinoma lung and carcinoma prostate. We also compared the measured dose with Treatment Planning System calculated dose for AAA and the two dose reporting options of Acuros XB using Electronic Portal Imaging Device (EPID) and ArcCHECK phantom. Treatment plans of twenty patients each who have already undergone radiotherapy for cancer of lung and cancer of prostate were selected for the study. Three sets of VMAT plans were generated in Eclipse Treatment Planning System (TPS), one with AAA and two plans with Acuros-D_m and Acuros-D_w options. The Dose Volume Histograms (DVHs) were compared and analyzed for Planning Target Volume (PTV) and critical structures for all the plans. Verification plans were created for each plan and measured doses were compared with TPS calculated doses using EPID and ArcCHECK phantom for all the three algorithms. For lung plans, the mean dose to PTV in the AXB-D_w plans was higher by 1.7% and in the AXB-D_m plans by 0.66% when compared to AAA plans. For prostate plans, the mean dose to PTV in the AXB-D_w plans was higher by 3.0% and in the AXB-D_m plans by 1.6% when compared to AAA plans. There was no difference in the Conformity Index (CI) between AAA and AXB-D_m and between AAA and AXB-D_w plans for both sites. But the homogeneity worsened in AXB-D_w and AXB-D_m plans when compared to AAA plans for both sites. AXB-D_w calculated higher dose values for PTV and all the critical structures with significant differences with one or two exceptions. Point dose measurements in ArcCHECK phantom showed that AXB-D_m and AXB-D_w options showed very small deviations with measured dose distributions than AAA for both sites. Results of EPID QA also showed better pass rates for AXB-D_w and AXB-D_m than AAA for both sites when gamma analysis was done for 3%/3 mm and 2%/2 mm criteria. With reference to the results, it is always better to choose Acuros algorithm for dose calculations if it is available in the TPS. AXB-D_w plans showed very high dose values in the PTV when compared to AAA and AXB-D_m in both sites studied. Also, the volume of PTV receiving 107% dose was significantly high in AXB-D_w plans compared to AXB-D_m plans in sites involving high density bones. Considering the results of dosimetric comparison and QA measurements, it is always better to choose AXB-D_m algorithm for dose calculations for all treatment sites especially when high density bony structures and complex treatment techniques are involved. For patient specific QA purposes, choosing AXB-D_m or AXB-D_w does not make any significant difference between calculated and measured dose distributions.     

The radiobiological effect of using Acuros XB vs anisotropic analytical algorithm on hepatocellular carcinoma stereotactic body radiation therapy

The purpose of this work was to study the radiobiological effect of using Acuros XB (AXB) vs Analytic Anisotropic Algorithm (AAA) on hepatocellular carcinoma (HCC) stereotactic body radiation therapy (SBRT). Seventy SBRT volumetric modulated arc therapy (VMAT) plans for HCC were calculated using AAA and AXB respectively with the same treatment parameters. Published tumor control probability (TCP) and normal tissue complication probability (NTCP) models were used to quantify the effect of dosimetric difference between AAA and AXB on TCP, NTCP and uncomplicated tumor control probability (UTCP). There was an average decrease of 2.5% in 6-month TCP. Normal liver has the largest average decrease in NTCP which was 59.7%. Bowels followed with 26.6% average decrease in NTCP. Duodenum, stomach and esophagus had 10.2%, 5.1%, and 4.3% average decrease in NTCP. There was an average decrease of 1.8% and up to 7.2% in 6-month UTCP. There was an overall decrease in TCP, NTCP, and UTCP for HCC SBRT plans calculated using AXB compared to AAA which could be clinically significant.     

Implementation of the three-field electron wraparound technique for extensive recurrent chest wall carcinoma: dosimetric and clinical considerations

Treatment of extensive recurrent chest wall carcinoma is a challenge for the radiation oncologist as well as the physics team responsible for setup, computer planning, and daily reproducibility. While electron arc therapy is desirable, unfortunately, most sites do not have this capability. The alternative method of treatment discussed here involves the use of a three-field electron wraparound technique for the chest wall when electron arc therapy is not available. This technique yields an excellent alternative treatment modality with flexibility to accommodate multiple electron energies to compensate for varying chest wall thickness. An additional anterior photon beam is used when skin lesions extend superiorly to the clavicle and along the proximal aspect of the arm. Computerized tomography (CT) interfaced radiotherapy computer planning is used to precisely calculate the sequential gantry angles, skin gaps for adjacent electron fields, and the appropriate junction moves to create a feathering effect of all overlap areas. Treatment aids include extensive shaping of electron and photon fields and the application of bolus material on all four fields. A Smithers Medical Products' Alpha Cradle is used to make this intricate setup possible, providing patient comfort and daily reproducibility for a more efficient treatment.     

Computed tomography and routine chest radiography in oat cell carcinoma of the lung

Computed tomography (CT) scans of the chest and routine postero-anterior and lateral chest films were compared in 32 patients with pathologically proven oat cell carcinoma of the lung. Nineteen of the 32 patients were examined prior to any form of therapy. Overall, CT gave more information about the extent of disease. The significance of this information may be of little value because the routine chest films also demonstrated mediastinal involvement, although to a lesser degree. Computed tomography of the chest should not be the initial diagnostic staging procedure in oat cell carcinoma, but used selectively. It can be quite useful in patients who have a partially opacified lung, possibly for the evaluation of mediastinum after therapy, and for the evaluation of possible abdominal metastases.     

肺肉瘤样癌的X线胸片和CT表现

目的探讨肺肉瘤样癌（LSC）的x线胸片、CT表现特点，提高对LSC的认识。方法对经病理证实的7例LSC的x线胸片、CT和临床资料进行回顾性分析。结果全部患者均表现为肺内直径3-11cm（平均7cm）的实质性肿块；均位于中下肺部，其中右下叶3例，右中叶2例，左下叶2例；7例中6例为周围型，1例为中央型。5例周围型者边缘清楚，3例呈分叶状；CT平扫见3例密度均匀，4例密度不均匀，内有空洞或钙化；增强cT上3例呈均匀、4例呈不均匀轻至中度强化，〉6cm的肿瘤呈边缘及肿瘤内斑片状强化。5例侵犯胸膜及胸壁组织，2例纵隔淋巴结肿大，1例有远处转移。结论LSC在x线胸片和CT上有相对的特征性表现，对定性诊断有价值。     

Image quality and dose evaluation in spiral chest CT examinations of patients with lung carcinoma

A study was undertaken to assess the quality of general chest CT examinations for indication of lung carcinoma according to the criteria proposed in the European Commission (EC) Guidelines, and to investigate their usefulness in the optimization of this practice. The criteria were evaluated for a sample of 100 examinations from five radiology departments in the Madrid area featuring single slice helical CT scanners with special emphasis on radiation dose and image quality. To determine the degree of compliance with the image criteria considered, the examinations were independently evaluated twice by five radiologists from the participating centres. A subsequent selection of the observers was made according to the consistency and independence of their readings. Dose measurements carried out in parallel supplied data to estimate the values of the CT dose indices (CTDI), dose-length product (DLP) and effective dose (E). The results show good compliance with the image criteria used - between 93% and 98% on average at the different sites, with variable degrees of internal deviation. 10 out of a total of 16 criteria proposed in the EC guidelines were met by practically all the examinations in the sample. The average weighted CTDI (CTDI(w)) values per site were in the range of 13-19 mGy; those of DLP were between 263 mGy cm and 577 mGy cm, and those of effective dose between 4 mSv and 9 mSv. The highest mean DLP value was below but close to the reference value proposed in the EC Document (650 mGy cm). In general, a weak correlation or no correlation at all was found between image quality scores and patient dose (DLP).     

基质金属蛋白酶-2、9在肺癌组织中的表达及与胸部CT部分征象的关系

目的 :通过基质金属蛋白酶 2 (MMP 2 )和 9(MMP 9)在肺癌组织不同病理分型及不同肺部CT征象中的表达情况的比较 ,探讨其与肺癌浸润转移的关系。方法 :采用免疫组化S P法检测 4 5例肺癌组织中金属蛋白酶的表达 ,所有病例均行胸部CT。结果 :MMP 2、9在小细胞肺癌及非小细胞肺癌中均有表达 ,低度分化、瘤体直径 >3cm、具有分叶征及有纵隔淋巴结转移者同高分化、瘤体直径≤ 3cm、无分叶征、无纵隔淋巴结转移者相比 ,MMP 2、MMP 9表达有显著性差异。结论 :MMP 2及MMP 9的测定 ,联合肺部CT检查 ,可以对肺癌浸润转移情况进行评价 ,预测预后。     

Detection and treatment of lung metastases of differentiated thyroid carcinoma in patients with normal chest X-rays

Lung metastases were demonstrated by total-body 131I scans in 23 patients with differentiated thyroid carcinoma, at a time when chest x-ray was normal. This total-body 131I scan was performed after the administration of 2 mCi (in 11 patients) or 100 mCi (in 12 patients). Overall uptake of 131I in lungs was less than 1% of the administered dose in 11 patients. All patients were treated with radioiodine. No lung uptake was found in 20 patients at the last 100 mCi post-therapy scan. Among them, Tg level became undetectable during T4 treatment in eight, lung CT scan showed the disappearance of the micronodules in seven, and lung biopsy did not show evidence of disease in two patients. No patient developed radiation lung fibrosis. In conclusion, favorable responses to radioiodine treatment were observed despite relatively low overall uptake, in relation to the small size of lung metastases. This provides high concentrations of radioiodine and therefore high radiation doses.     

肺腺癌的能谱CT参数与肿瘤浸润性及 Ki-67表达的相关性研究

目的：探究能谱CT成像参数与肺腺癌病理上的浸润性及Ki-67表达的相关性。材料与方法：收集我院2016年3月至2017年 7月经手术病理证实为肺腺癌患者的资料,共计60例,免疫组化均包含Ki-67,术前均已行宝石能谱成像（Gemstone spectral imaging,GSI）扫描。其中纯磨玻璃结节（pGGN）15例、混合磨玻璃结节（mGGN）组15例、实性结节组30例,采用spearman相关分析分别比较三组结节动、静脉期IC和Ki-67抗原表达的相关性。其中30例磨玻璃结节（GGN）分为A组,包括浸润前病变（2例）和微浸润腺癌（14例）,共计16例;B组为浸润性腺癌,共计14例。比较两组腺癌动、静脉期IC和Ki-67抗原表达的差异。结果：所有病例中,动、静脉期IC和Ki-67抗原表达呈负相关（r1=-0.749,P1=0.000;r2=-0.624,P2=0.000）;pGGN组动、静脉期IC和Ki-67抗原表达无相关性（P＞0.05）;mGGN组和实性结节组的动、静脉期IC和Ki-67抗原表达呈负相关（r1=-0.754、-0.617 ,P1＜0.05;r2=-6.09、-0.460,P2=＜0.05）。A组Ki-67抗原表达小于B组（P=0.001）,两组动、静脉IC的差异无统计学意义。结论：肺腺癌能谱CT相关参数和KI-67抗原表达有显著的负相关性,在评估肿瘤增殖能力方面具有潜在的价值,但在诊断GGN浸润程度的作用还有待进一步研究论证。     

食管癌MSCT灌注参数与微血管密度相关性研究

目的：观察食管癌多层螺旋CT（MSCT）灌注成像参数与组织学肿瘤微血管密度（MVD）之间的相关性,探讨MSCT灌注成像无创评价肿瘤血管生成的价值及可行性,并对CT灌注参数作为评价肿瘤生物学行为指标的可能性做初步探讨。方法：对经术后病理证实的31例食管癌患者进行MSCT灌注成像检查,绘制感兴趣区（ROI）的时间-密度曲线（TDC）,并计算血流量（BF）、血容量（BV）、平均通过时间（MTT）、毛细血管通透性（PS）数值;切取与CT灌注靶层面相同的肿瘤组织切片,经CD34单克隆抗体进行免疫组织化学染色,测定肿瘤组织微血管密度（MVD）,分析食管癌MSCT灌注成像各参数与MVD之间的相关性,并分析肿瘤组织不同分化程度、组织学分型和浸及深度的CT灌注参数差异有无统计学意义。结果：31例食管癌BF、BV、MTT、PS平均值分别为：（93.58±4.9）ml.100g-1.min-1、（6.57±1.70）ml.100g-1、（9.15±6.83）s（、12.99±7.30）ml.100g-1.min-1,MVD计数为：（24.80±8.63）。BF、PS与MVD呈正相关（P〈0.05）,r值分别为0.426、0.362,BV、MTT与MVD无相关性（P〉0.05）。不同肿瘤组织分化程度及组织学分型的CT灌注参数均无差异,BF在侵及深度差异有统计学意义（P=0.029）。结论：MSCT灌注成像可间接反映活体食管癌肿瘤血管生成情况,为治疗方案的确定、疗效的判定及预后评估提供依据。     

鼻咽癌磁共振灌注定量参数及ADC值与T分期的关系

目的：探讨鼻咽癌（NPC）磁共振灌注成像（PWI）定量参数及扩散加权成像（DWI）参数ADC 值与T 分期之间的相关性。方法：对94例NPC初治患者行PWI、DWI和T分期,分析PWI参数及ADC值与T分期之间的相关性,比较高低T分期NPC之间各 MR参数值的差异。结果：T 分期分别与 Ktrans （r＝0．226,P＝0．029）和 Ve （r＝0．553,P＝0．000）呈正相关,与Kep呈负相关（r＝－0．350,P＝0．001）。未发现T 分期与 fPV（r＝－0．122,P＝0．240）及 ADC 值（r＝－0．056,P＝0．592）之间存在线性相关。Ktrans、Kep和 Ve 值在 Thigh组（T3和 T4期 NPC）分别为（0．386±0．171）、（1．333±0．436）min－1和（0．302±0．107）,在 Tlow组（T1和 T2期 NPC）分别为（0．313±0．115）min－1、（1．552±0．472）min－1和0．219±0．102,两组间的差异有统计学意义。fPV和ADC值在Thigh组分别为（0．017±0．021）和（0．935±0．144）×10－3 s／mm2,在Tlow组分别为（0．019±0．018）和（0．950±0．196）×10－3 s／mm2,两组间的差异无统计学意义。与Ktrans和Kep值相比,Ve 值在判别Thigh组和Tlow组上诊断效能最大,其敏感性为91．8％、特异性为63．2％。结论：PWI定量参数可以反映不同T分期NPC在内部微循环灌注上的差异,而ADC值难以区分不同T分期NPC之间在水分子扩散方面的差别。     

Correlation of lymph node metastasis with CT perfusion parameters and angiogenesis in esophageal squamous cell carcinoma

目的:探讨食管鳞癌淋巴结转移与其CT灌注参数及血管生成的关系.方法.50例食管癌患者行MSCT灌注扫描,采用免疫组织化学SP法检测术后标本中MVD及VEGF的表达.分析食管癌淋巴结转移与CT灌注参教中血容量(BV)、血流量(BF)、平均通过时间(MTT)、表面通透性(PS)及MVD、VEGF表达之间的关系.结果:食管鳞癌CT灌注参数中BF、BV、MTT值在有和无淋巴结转移组中分别为(128.81±50.05)和(105.55±43.18))ml/(100g·min)、(7.64±3.11)和(6.33±1.71)ml/100g、(5.62±1.97)和(7.16±3.32)s,差异均无统计学意义(P＞0.05),而PS值在有和无淋巴结转移组分别为(18.32±5.39)和(9.66±2.46)ml/(100g.min),差异有高度统计学意义(P＜0.01);以PS值＞10ml/(100g·min)为阈值预测淋巴结转移的敏感度、特异度、阳性及阴性似然比分别为95.8％、65.4％、2.77和0.06;VEGF及MVD值与食管鳞癌淋巴结转移有显著正相关关系(r值分别为0.752和0.384,P＜0.01).结论:CT灌注成像有助于食管鳞癌淋巴结转移的术前诊断,其中PS值是最有价值的诊断指标.     

食管鳞癌淋巴结转移与CT灌注参数及血管生成的关系

目的:探讨食管鳞癌淋巴结转移与其CT灌注参数及血管生成的关系.方法.50例食管癌患者行MSCT灌注扫描,采用免疫组织化学SP法检测术后标本中MVD及VEGF的表达.分析食管癌淋巴结转移与CT灌注参教中血容量(BV)、血流量(BF)、平均通过时间(MTT)、表面通透性(PS)及MVD、VEGF表达之间的关系.结果:食管鳞癌CT灌注参数中BF、BV、MTT值在有和无淋巴结转移组中分别为(128.81±50.05)和(105.55±43.18))ml/(100g·min)、(7.64±3.11)和(6.33±1.71)ml/100g、(5.62±1.97)和(7.16±3.32)s,差异均无统计学意义(P＞0.05),而PS值在有和无淋巴结转移组分别为(18.32±5.39)和(9.66±2.46)ml/(100g.min),差异有高度统计学意义(P＜0.01);以PS值＞10ml/(100g·min)为阈值预测淋巴结转移的敏感度、特异度、阳性及阴性似然比分别为95.8％、65.4％、2.77和0.06;VEGF及MVD值与食管鳞癌淋巴结转移有显著正相关关系(r值分别为0.752和0.384,P＜0.01).结论:CT灌注成像有助于食管鳞癌淋巴结转移的术前诊断,其中PS值是最有价值的诊断指标.     

计量诊断在结核性与恶性胸液鉴别中的应用

目的:探讨结核性与恶性胸液的计量鉴别诊断方法。方法:(1)对结核性(168例)与恶性胸液(115例)的临床资料进行γ2统计,筛选出鉴别诊断价值较高的征象(20个)备用;(2)按极大似然法计算出各征象的计量鉴别诊断指数;(3)制定“结核性与恶性胸液非病检计量鉴别诊断表”,供临床使用。结果:拟合度考察:极大似然法诊断符合率为100.0％(40/40),临床初诊(经验性诊断)正确率为80.0％(32/40);准确度考察:极大似然法诊断符合率为100.0％(20/20),临床被诊断正确率为80.0％(32/40)。结论:极大似然法诊断符合率明显高于临床经验性诊断,二者差异显著,P<0.05。     

鼻咽癌CT灌注成像及其生物学相关性研究

目的研究鼻咽癌CT灌注值与肿瘤微血管密度（MVD）、肿瘤分期的关系，探讨多层螺旋CT灌注成像对鼻咽癌的临床应用价值。方法49例鼻咽部CT灌注检查中，鼻咽癌组30例，鼻咽癌放疗后组14例，正常鼻咽部5例，测量鼻咽癌和鼻咽黏膜位置的血流量（BF）、最大强化指数（PEI）、峰值到达时间（TTP）及血容量（BV）作为灌注指标，其中16例鼻咽癌活检组织行免疫组织化学CD34单抗染色后，Weidner方法计数MVD。各组灌注值比较行方差分析，CT灌注值、肿瘤分期与MVD之间行Spearman等级相关分析。结果49例中1例鼻咽癌灌注检查失败。鼻咽癌组（29例）肿瘤CT灌注值BF为（48．6±16．9）ml·100g^-1·min^-1，PEI为（32．3±7．9）HU，TTP为（17．5±4．9）s，BV为（12．8±4．4）ml·100g^-1；正常对照组（5例）BF、PEI、TTP、BV值分别为（15．9±5．9）ml·100g^-1·min^-1、（12.6±1．3）HU、（22．6±6．9）s、（3．5±0．5）ml·100g^-1；鼻咽癌放疗后组（14例）BF、PEI、TTP、BV值分别为（25．2±7．0）ml·100g^-1·min^-1、（19．8±5．9）HU、（22．6±4．3）s、（6．1±2．4）ml·100g^-1，三组各灌注值差异有统计学意义（P值均〈0．01）；相关分析显示，鼻咽癌组（29例）中TNM分期（其中Ⅰ期3例，Ⅱ期9例，Ⅲ期10例，Ⅳ期7例）与PEI和BV存在相关性（r值分别为0．48和0．50），与BF和TTP无明显相关性（r值分别为0．23和0．22）；16例鼻咽癌MVD为（30．8±12．6）个／高倍镜视野，与其BF（51．4±17．0）ml·100g^-1·min^-1、PEI（33．2±9．6）HU和TTP（16．3±4．1）8存在相关性（r值分别为0．85、0．60和0．78），与BV（13．2±5．6）ml·100g^-1弱相关（r=0．48）。结论鼻咽癌有着特征的CT灌注表现，多层螺旋CT灌注成像的灌注值可以反映鼻咽癌微血管密度特征，PEI和BV值与鼻咽癌的TNM分期存在一定的相关性。