Impact of intensity-modulated radiotherapy on acute hematologic toxicity in women with gynecologic malignancies

: To evaluate the impact of intensity-modulated whole pelvic radiotherapy (IM-WPRT) on acute hematologic toxicity (HT) in gynecology patients.

: Between February 2000 and June 2001, 36 patients (24 cervix, 12 uterus) received IM-WPRT. The target consisted of the upper vagina, parametria, uterus, and presacral and pelvic lymph nodes. Using commercially available software, seven or nine coplanar IM-WPRT plans were generated. The planning goals were to irradiate the target while minimizing the dose to the small bowel, bladder, and rectum. Pelvic bone marrow (BM) was not a constraint in the planning process. The variables analyzed included white blood count (WBC), absolute neutrophil count (ANC), platelets, and hemoglobin (Hgb) obtained before and weekly during RT. As a comparison, the HT in 88 patients (44 cervix, 44 uterus) treated to the same target volume and total dose (45 Gy) with conventional four-field WPRT was analyzed. In addition, the medullary spaces within the pelvic bones in 10 women were contoured and the average dose-volume histograms representing the pelvic BM were compared between the two groups.

: IM-WPRT patients had a lower median age (p = 0.008), higher percentage of squamous histologic features (p = 0.04), and were more likely to receive chemotherapy (CTX) (p = 0.02) than were the WPRT patients. No differences were seen in the baseline WBC, ANC, platelet, or Hgb levels between the two groups. Grade 2 or greater WBC, ANC, and Hgb toxicity was seen in 19.4%, 9.1%, and 8.6% of the IM-WPRT patients, respectively. Comparable rates were seen in the WPRT patients (WBC 21.6%, p = 0.79; ANC 8.3%, p = 0.91; Hgb 9.2%, p = 0.94). No Grade 2 or greater platelet toxicity was seen in either group. Significant HT was infrequent in women treated with RT alone and was comparable in the two groups. In contrast, WPRT + CTX patients experienced more Grade 2 or greater WBC toxicity (60% vs. 31.2%, p = 0.08) and developed lower median WBC (2.8 vs. 3.6 μg/dL, p = 0.05) and ANC (1874 vs. 2669, p = 0.04) nadirs than did IM-WPRT + CTX patients. Moreover, CTX was held more often in the WPRT group secondary to HT (40% vs. 12.5%, p = 0.06). Although Grade 2 or greater ANC (23.5% vs. 15.3%) and Hgb (35.2% vs. 15.2%) toxicity were lower in the IM-WPRT + CTX group, these differences did not reach statistical significance (p = 0.58 and p = 0.22, respectively). The comparison of pelvic BM dose-volume histograms revealed that IM-WPRT planning resulted in significantly less BM volume being irradiated compared with WPRT planning, particularly within the iliac crests.

: IM-WPRT has a favorable impact on the risk of acute HT in gynecology patients, particularly in those receiving CTX. Future work is needed to optimize BM sparing in these patients to reduce the risk of significant HT further.     

A dosimetric planning study comparing intensity-modulated radiotherapy with four-field conformal pelvic radiotherapy for the definitive treatment of cervical carcinoma

AimsTo compare the dose to organs at risk (OAR) between a conventional four-field whole pelvis radiotherapy (4F-WPRT) plan and an initial single intensity-modulated WPRT (IM-WPRT) plan for definitive treatment of cervical cancer. The magnitude of potential dose sparing of OAR is unknown when planning target volumes are defined to include potential organ motion and microscopic disease extent.Materials and MethodsPlanning computed tomography scans of 50 consecutive, previously treated patients were re-planned using 4F-WPRT and IM-WPRT. Margins compatible with the literature on organ motion were used to create the planning target volume. Dose–volume histograms for target and OAR were compared for each patient with paired t-tests and waterfall plots.ResultsThe mean target volume covered by 95% (V47.8) was 99.7% for 4F-WPRT and 98.8% for IM-WPRT (P > 0.05, ns). Intensity-modulated radiotherapy (IMRT) was associated with a significant reduction in the dose to OAR at the V50, V45, V40 and V30 level. There was a >20% difference in V50 in most patients: 84% (bladder), 58% (small bowel), 54% (sigmoid) and 84% (rectum).ConclusionsA single, initial IMRT plan with appropriate margins encompassing initial gross and potential microscopic pelvic disease leads to a reduction in the dose to OAR without compromising target coverage. This offers a potential ‘class solution’ for definitive treatment of patients with cervical cancer. Clinical outcome data are still needed to verify this planning study.     

Dosimetric comparison of bone marrow-sparing intensity-modulated radiotherapy versus conventional techniques for treatment of cervical cancer

PURPOSE: To compare bone marrow-sparing intensity-modulated pelvic radiotherapy (BMS-IMRT) with conventional (four-field box and anteroposterior-posteroanterior [AP-PA]) techniques in the treatment of cervical cancer. METHODS AND MATERIALS: The data from 7 cervical cancer patients treated with concurrent chemotherapy and IMRT without BMS were analyzed and compared with data using four-field box and AP-PA techniques. All plans were normalized to cover the planning target volume with the 99% isodose line. The clinical target volume consisted of the pelvic and presacral lymph nodes, uterus and cervix, upper vagina, and parametrial tissue. Normal tissues included bowel, bladder, and pelvic bone marrow (PBM), which comprised the lumbosacral spine and ilium and the ischium, pubis, and proximal femora (lower pelvis bone marrow). Dose-volume histograms for the planning target volume and normal tissues were compared for BMS-IMRT vs. four-field box and AP-PA plans. RESULTS: BMS-IMRT was superior to the four-field box technique in reducing the dose to the PBM, small bowel, rectum, and bladder. Compared with AP-PA plans, BMS-IMRT reduced the PBM volume receiving a dose >16.4 Gy. BMS-IMRT reduced the volume of ilium, lower pelvis bone marrow, and bowel receiving a dose >27.7, >18.7, and >21.1 Gy, respectively, but increased dose below these thresholds compared with the AP-PA plans. BMS-IMRT reduced the volume of lumbosacral spine bone marrow, rectum, small bowel, and bladder at all dose levels in all 7 patients. CONCLUSION: BMS-IMRT reduced irradiation of PBM compared with the four-field box technique. Compared with the AP-PA technique, BMS-IMRT reduced lumbosacral spine bone marrow irradiation and reduced the volume of PBM irradiated to high doses. Therefore BMS-IMRT might reduce acute hematologic toxicity compared with conventional techniques.     

Preliminary analysis of chronic gastrointestinal toxicity in gynecology patients treated with intensity-modulated whole pelvic radiation therapy

PURPOSE: To provide a preliminary analysis of chronic gastrointestinal (GI) toxicity in gynecology patients treated with intensity-modulated whole pelvic radiation therapy (IM-WPRT). METHODS AND MATERIALS: Between February 2000 and August 2001, 36 gynecology patients received IM-WPRT. All patients underwent a contrast-enhanced computed tomography scan, and a clinical target volume (CTV) was contoured consisting of the upper vagina, parametria, uterus (if present), and presacral and pelvic lymph node regions. The CTV was expanded by 1 cm to create a planning target volume (PTV). Seven or 9-field IM-WPRT plans were generated. IM-WPRT plans were highly conformal, providing excellent coverage of the PTV and considerable sparing of normal tissues, including the small bowel and rectum. Chronic GI toxicity was scored: 0 (no symptoms), 1 (mild symptoms, no medications required), 2 (moderate symptoms, medications required), and 3 (severe symptoms, hospitalization, surgery required). Chronic GI toxicity in 30 gynecology patients treated with conventional WPRT patients before the implementation of IM-WPRT was also evaluated. Median follow-up in the IM-WPRT and WPRT groups were 19.6 and 30.2 months, respectively. RESULTS: The IM-WPRT and WPRT groups were well balanced in terms of most patient and treatment factors, including age, site, stage, chemotherapy, WPRT dose, and brachytherapy, except for a higher frequency of surgery (75 vs. 54%, p = 0.02) in the IM-WPRT group. Overall, IM-WPRT patients had a lower rate of chronic GI toxicity (11.1 vs. 50.0%, p = 0.001) than WPRT patients. The percentage of IM-WPRT patients with Grade 1, 2, and 3 toxicity were 8.3%, 2.8%, and 0%, respectively. Corresponding percentages in the WPRT group were 30.0%, 16.7%, and 3.3%, respectively. The only other factor correlated with chronic GI toxicity was age (p = 0.02). On multivariate (logistic regression) analysis controlling for age and other clinical factors, IM-WPRT retained its statistical significance (p = 0.01; odds ratio 0.16; 95% confidence interval 0.04, 0.67) CONCLUSIONS: Our results suggest that IM-WPRT is associated with less chronic GI toxicity than conventional WPRT in patients with gynecologic malignancies. However, longer follow-up and more patients are clearly needed to ascertain whether the benefits of IM-WPRT treatment seen here translate into true long-term reductions in chronic GI toxicity.     

Reduction of irradiated small bowel volume with Trendelenburg position in gynecologic pelvic radiotherapy

The aim of this study was to assess the effect of Trendelenburg position in comparison to prone position on small bowel volume and treatment dose in gynecologic pelvic external beam radiotherapy using three-dimensional conformal treatment plans. Eight patients with gynecologic cancers, treated with definitive or postoperative pelvic radiotherapy were investigated. Pelvic computerized tomography (CT) scans for treatment planning were performed in prone and 25 degree Trendelenburg positions for each patient. The dose-volume histograms of small bowel within the treatment fields were obtained and compared for both positions. The clinical target volume (CTV) and the planning target volume (PTV) were also defined and evaluated in the subjects. Treatment dose was 5040 cGy to PTV with 180 cGy daily fraction doses in both techniques for all patients. The average irradiated small bowel volume was 726 cc for prone position and 458 cc for the Trendelenburg position. The average irradiated small bowel volume reduction in the Trendelenburg position was 38.0% (95% CI 19.5 ± 38%) compared with the prone position. The average small bowel percent dose was 25.4% (1280 cGy) for Trendelenburg position and 39.9% (2010 cGy) for prone position. PTV doses were similar in both techniques. The results of this dosimetric study suggest that gynecologic pelvic radiotherapy in the Trendelenburg position decreases the volume of irradiated small bowel compared to prone position and may decrease treatment related small bowel morbidity. Clinical benefit of this position should be evaluated in further clinical studies.     

The role and strategy of IMRT in radiotherapy of pelvic tumors: Dose escalation and critical organ sparing in prostate cancer

PURPOSE: To investigate the intensity-modulated radiotherapy (IMRT) strategy in dose escalation of prostate and pelvic lymph nodes. METHODS AND MATERIALS: Plan dosimetric data of 10 prostate cancer patients were compared with two-dimensional (2D) or IMRT techniques for pelvis (two-dimensional whole pelvic radiation therapy [2D-WPRT] or IM-WPRT) to receive 50 Gy or 54 Gy and additional prostate boost by three-dimensional conformal radiation therapy or IMRT (3D-PBRT or IM-PBRT) techniques up to 72 Gy or 78 Gy. Dose-volume histograms (DVHs), normal tissue complication probabilities (NTCP) of critical organ, and conformity of target volume in various combinations were calculated. RESULTS: In DVH analysis, the plans with IM-WPRT (54 Gy) and additional boost up to 78 Gy had lower rectal and bladder volume percentage at 50 Gy and 60 Gy, compared with those with 2D-WPRT (50 Gy) and additional boost up to 72 Gy or 78 Gy. Those with IM-WPRT (54 Gy) also had better small bowel sparing at 30 Gy and 50 Gy, compared with those with 2D-WPRT (50 Gy). In NTCP, those with IM-WPRT and total dose of 78 Gy achieved lower complication rates in rectum and small bowel, compared with those of 2D-WPRT with total dose of 72 Gy. In conformity, those with IM-WPRT had better conformity compared with those with 2D-WPRT with significance (p < 0.005). No significant difference in DVHs, NTCP, or conformity was found between IM-PBRT and 3D-PBRT after IM-WPRT. CONCLUSIONS: Initial pelvic IMRT is the most important strategy in dose escalation and critical organ sparing. IM-WPRT is recommended for patients requiring WPRT. There is not much benefit for critical organ sparing by IMRT after 2D-WPRT.     

Treatment planning evaluation of non-coplanar techniques for conformal radiotherapy of the prostate.

BACKGROUND AND PURPOSE: To evaluate the benefit of using non-coplanar treatment plans for irradiation of two different clinical treatment volumes: prostate only (PO) and the prostate plus seminal vesicles (PSV). MATERIAL AND METHODS: An inverse planning algorithm was used to produce three-field, four-field, five-field and six-field non-coplanar treatment plans without intensity-modulation in ten patients. These were compared against a three-field coplanar plan. A dose of 74 Gy was prescribed to the isocentre. Plans were compared using the minimum dose to the planning target volume (PTV), maximum dose to the small bowel, and irradiated volumes of rectum, bladder and femoral head. Biological indices were also evaluated. RESULTS: For the PO group, volume of rectum irradiated to 60 Gy (V(60)) was 22.5+/-3.7% for the coplanar plan, and 21.5+/-5.3% for the five-field non-coplanar plan, which was the most beneficial (p=0.3). For the PSV group, the five-field non-coplanar plan was again the most beneficial. Rectal V(60) was in this case reduced from 41.5+/-10.4% for the coplanar plan to 35.2+/-9.3% for the non-coplanar plan (p=0.02). CONCLUSIONS: The use of non-coplanar beams in conformal prostate radiotherapy provides a small increase in rectal sparing, more significantly with PSV volumes than for PO volumes.     

Analysis of Rapid arc-based Radiation Therapy on Dosimetric Parameters in Cervical Cancer Patients with and without Bone Marrow Sparing

Background: The standard treatment for cervical cancer is chemoradiation therapy. Pelvic radiation is associated with higher dose to bone marrow (BM) causing interrupted treatment due to haematologic toxicity with inferior outcomes. This study aims to evaluate rapid arc technique in sparing pelvic BM and dosimetric parameters for pelvis V5GY, V10GY, V20GY, V30GY, and V40GY dose. Method: Twenty one cervical cancer patients were selected for the analysis. Planning target volume (PTV) contours, total pelvic BM and surrounding structures contours were standardised. Two rapid arc based procedures were designed for individual patient. One was done using bone marrow sparing (BMS) constraints while other was performed without BMS constraints. Data for both plans was calculated with regard to PTV, normal structures and pelvic BM. Difference in dose distribution in both groups was analysed using Wilcoxon and Friedman ANOVA test. Results: In the presence of BM constraint a significant changes in pelvic BM dose for values of V10GY (p=0.002), V20GY (p=0.002) and V40GY (p=0.025) was observed. The coverage of PTV was found to be unaffected by adding BM constraint. Conclusion: The BM is radiosensitive structure so dosage is linked with haemtological toxicity. Increased dose is associated with higher grade of haematological toxicity in pelvic radiotherapy. The study suggests that adding BM constraint in plans reduced the pelvic BM dose while not affecting PTV coverage and dose to bowel, bladder and rectum. Bone marrow constraint in pelvic radiotherapy can be considered for better treatment toleration and to determine its role in decreasing haematological toxicity.     

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.     

静脉注射造影剂对妇科肿瘤全盆腔放疗剂量分布的影响

目的探讨静脉注射造影剂对妇科肿瘤术后全盆腔放疗剂量分布的影响。方法选择10例接受术后全盆腔放疗的子宫内膜癌和子宫颈癌患者。对每例患者静脉注射造影剂前后相同体位下行CT模拟定位扫描,在平扫图像和增强图像上为每例患者设计相同的三维适形全盆腔放疗计划。比较两组计划靶区、危及器官和正常组织剂量分布。结果增强计划的靶区、危及器官和正常组织平均剂量均低于平扫计划,但两组计划间差异均〈1.0Gy,危及器官和正常组织最大剂量差异均〈2.0 Gy,差异均无统计学意义。结论静脉注射造影剂对妇科肿瘤术后全盆腔适形放疗剂量分布影响很小,临床上可以忽略。     

胃癌术后放疗方式对肾脏剂量学影响的比较研究

目的:比较胃癌术后三维适形放疗(3D-CRT)与调强适形放疗(IMRT)对肾脏剂量学的分布影响.方法:选择9例根治术后的进展期胃癌患者,应用Pinnacal三维计划系统(TPS)分别为每例患者设计4野3D-CRT和5、7野IMRT,所有计划给予处方剂量95％的计划靶体积(PTV)＞45 Gy; IMRT同时要求99％的PTV体积＞42.75 Gy.应用等剂量曲线及剂量体积直方图(DVH)比较各个计划之间靶区剂量的分布和肾脏的剂量受量差异.结果:4野3D-CRT和5、7野IMRT的靶区V45分别为0.96±0.03、0.95±0.02和0.95±0.02.所有计划靶区均满足处方剂量,与4野3D-CRT相比,IMRT明显提高靶区的剂量的均匀性(HI)和适形度(CI),并且降低双侧肾脏18 Gy的剂量体积百分比(V18),但在低剂量(10 Gy)体积百分比(V10)3种放射方式之间差异无统计学意义,P＞0.05.5和7野IMRT之间不论在靶区剂量分布还是危及器官的剂量受量上均差异无统计学意义,P＞0.05.结论:与3D-CRT比较,IMRT明显提高靶区均匀性,降低肾脏剂量受量和剂量体积百分比,但在V10上3种计划间差异无统计学意义.     

颈段食管癌质子治疗与调强放疗计划对比研究

目的 比较质子治疗(PT)与X线调强放疗(IMRT)在颈段食管癌治疗中的剂量分布.方法 选取10例颈段食管癌患者CT图像,每例制定1个X线IMRT计划(7个野)与2个PT计划(PT1为前后对穿2个野,PT2为两前斜加后3个野).使用等剂量分布及剂量体积直方图进行计划间比较.结果 IMRT与PT1、PT2计划的计划靶体积(PTV)95%等剂量面适形指数分别为1.43与1.52、1.43(F=3.62,P<0.01),平均剂量分别为64.4 Gy与65.0、63.6 Gy(F=12.06,P<0.01);PTV周围正常组织平均剂量分别为20.7 Gy与10.5、10.6 Gy(F=77.60,P<0.01),全肺的为12.1 Gy与7.3、8.4 Gy(F:15.87,P<0.01),脊髓最大剂量分别为41.4 Gy与34.9、35.0 Gy(F=11.74,P<0.01).结论 3个计划均能满足覆盖靶区要求,但PT可明显降低肿瘤周围正常组织剂量,这为PT剂量提升或合并使用同期化疗提供了可能.PT计划中前后对穿2个野也可满足临床要求.

Abstract：

Objective To compare the dosimetric difference of proton therapy(PT)and X-ray intensity-modulated radiotherapy(IMRT)for cervical esophageal cancer.Methods The treatment planning of 10 patients with cervical esophageal cancer were selected for this study.One IMRT plan and 2 PT plans (PT1 plan:two opposed AP-PA beams;PT2 plan:two anterior-oblique beams and one posterior beam)were constructed for each patient.The isodose distribution and statistical data extracted from dose volume histograms were used for dose plan comparison.Results The conformal index(CI95%,defined as the ratio between the volume receiving at least 95%of the prescribed dose and the volume of PTV)of IMRT,PT1 and PT2 was 1.43,1.52 and 1.43(F=3.62,P<0.01),respectively.And the mean dose of PTV was 64.4 Gy,65.0 Gy and 63.6 Gy(F=12.06,P<0.01);the mean dose in normal tissue outside of PTV was 20.7 Gy,10.5 Gy and 10.6 Gy(F=77.60,P<0.01),in whole lung was 12.1 Gy,7.3 Gy and 8.4 Gy (F=15.87,P<0.01);the maximum dose in spinal cord was 41.4 Gy,34.9 Gy and 35.0 Gy(F=11.74,P<0.01),respectively.Conclusions Ail plans full file the requirements for PTV,however.PT plans can reduce radiation dose in surrounding normal significantly.The possibility is provided to escalate PT dose in PTV or to combine more aggressive chemotherapy.The PT1 plan full fills the clinical requirements.     

Reduction of dose delivered to the rectum and bulb of the penis using MRI delineation for radiotherapy of the prostate

PURPOSE: The prostate volume delineated on MRI is smaller than on CT. The purpose of this study was to determine the influence of MRI- vs. CT-based prostate delineation using multiple observers on the dose to the target and organs at risk during external beam radiotherapy. MATERIALS AND METHODS: CT and MRI scans of the pelvic region were made of 18 patients and matched three-dimensionally on the bony anatomy. Three observers delineated the prostate using both modalities. A fourth observer delineated the rectal wall and the bulb of the penis. The planning treatment volume (PTV) was generated from the delineated prostates with a margin of 10 mm in three-dimensions. A three-field treatment plan with a prescribed dose of 78 Gy to the International Commission on Radiation Units and Measurements point was automatically generated from each PTV. Dose-volume histograms were calculated of all PTVs, rectal walls, and penile bulbs. The equivalent uniform dose was calculated for the rectal wall using a volume exponent (n = 0.12). RESULTS: The equivalent uniform dose of the CT rectal wall in plans based on the CT-delineated prostate was, on average, 5.1 Gy (SEM 0.5) greater than in the plans based on the MRI-delineated prostate. For the MRI rectal wall, this difference was 3.6 Gy (SEM 0.4). Allowing for the same equivalent uniform dose to the CT rectal wall, the prescribed dose to the PTV could be raised from 78 to 85 Gy when using the MRI-delineated prostate for treatment planning. The mean dose to the bulb of the penis was 11.6 Gy (SEM 1.8) lower for plans based on the MRI-delineated prostate. The mean coverage (volume of the PTV receiving > or =95% of the prescribed dose) was 99.9% for both modalities. The interobserver coverage (coverage of the PTV by a treatment plan designed for the PTV delineated by another observer in the same modality) was 97% for both modalities. The MRI rectum was significantly more ventrally localized than the CT rectum, probably because of the rounded tabletop and no knee support on the MRI scanner. CONCLUSIONS: The dose delivered to the rectal wall and bulb of the penis is significantly reduced with treatment plans based on the MRI-delineated prostate compared with the CT-delineated prostate, allowing a dose escalation of 2.0-7.0 Gy for the same rectal wall dose. The interobserver coverage was the same for CT and MRI delineation of the prostate. A statistically significant difference in position between the CT- and MRI-delineated rectum was observed, probably owing to a different tabletop and use of knee support.     

子宫颈癌术后盆腔转移三维适形与调强放疗剂量学对比研究

目的 比较三维适形放疗(3DCRT)和调强放疗(IMRT)在子宫颈癌术后盆腔转移病灶靶区(PTY)剂量覆盖和危及器官(OAR)保护方面的差异,探讨子宫颈癌术后盆腔转移病灶的最佳治疗方案.方法 选择10例子宫颈癌根治术后盆腔转移患者,行CT模拟定位后将数据上传至Varian三维计划系统,勾画靶区,进行放疗计划设计后做下列研究:3DCRT计划与IMRT计划对计划靶区PTV的影响及比较;3DCRT计划与IMRT计划中危及器官受最比较分析.结果 采用95%可信区间,CTV至PTV的外放边界定为1 cm.3DCRT计划中3、4、5和6个射野下PTV适形指数分别为0.46、0.67、0.68、0.68,4个以上射野数日的增加不再显著改善靶区分布和减少正常组织受照射体积百分比.IMRT计划中5、7、9、11和13个射野下PTV适形指数分别为0.75、0.83、0.84、0.85、0.85,9个以上射野数目增加不再显著改善靶区分布和减少正常组织受照体积百分比.比较OAR最高照射剂量,IMRT计划中小肠脊髓的最高照射剂量低于3DCRT,直肠膀胱及股骨头的最大剂量差异无统计学意义.结论 子宫颈癌术后盆腔转移放疗者3DCRT以4个射野数计划为优,IMRT以9个射野数计划为优.高剂量范围内IMRT较3DCRT对脊髓及小肠的保护作用明显,IMRT较3DCRT减少了高剂量区直肠、膀胱的受照体积,从而有望减少OAR放射治疗并发症的发生概率.

Abstract：

Objective To compare the differences of target-volume(PTV) coverage and organ at risk (OAR) protection between three dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy(IMRT) for patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy. To explore the optimal treatment methods for pelvis metastasis of cervical cancer.Methods 10 patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy were selected for this study. The images scanned by CT were transferred to treatment planning system to generate 3DCRT and IMRT plans. The impacts of 3DCRT on PTV were compared with those of IMRT. Isodose line and dose volume histograms(DVH) were used to evaluate to the dose-distribution in PTV and OAR. Results For 95 % confidence interval, the margin from CTV to PTV was 1 cm. Conformal indexs (CIs) of PTV for 3, 4, 5 and 6 fields 3DCRT were 0.46, 0.67, 0.68 and 0.68, respectively. When beyond 4 fields, the advantage of adding fields was not significant. CIs of PTV for 5, 7, 9, 11 and 13 fields IMRT were 0.75, 0.83 0.84, 0.85 and 0.85, respectively. When beyond 9 fields, the advantage of adding fields was not significant. The maximum dose of the bowl and spine cord in IMRT plans were lower than that in the 3DCRT plans (P <0.05). Maximum dose of OAR had no significant differences (includingt the bone, recttum and bladder) between IMRT and 3DCRT plans. Conclusion For patients with pelvis metastasis of cervical cancer after radical surgery, 4 fields planning in 3DCRT and 9 fields planning in IMRT are feasible. At high dose levels, the IMRT plans can more significantly protect the bowl and spine cord and decrease the radiation volume of colorectal and urinary bladder at risk than 3DCRT, so IMRT may potentially diminish probability of the normal tissue complications.     

前列腺癌重碳离子放疗计划与调强放疗计划的比较

目的比较前列腺癌重碳离子放疗（C-ion RT）与调强放疗（IMRT）在剂量学方面的差异。方法随机选取5例前列腺癌患者,分别设计4野共面的C-ion RT计划和7野共面的IMRT计划。剂量均采用百分剂量,95％的等剂量面必须包括100％的计划靶体积（PTV）。比较靶区剂量分布的适形度指数（CI）和异质性指数（IC）,根据剂量体积直方图（DVH）,比较相同剂量水平下C-ion RT计划与IMRT计划中周围器官及非靶区正常组织的照射体积。结果在C—-ion RT计划中,CI50%、CI94%、IC分别为3．36、1．20和0．03,与IMRT计划比较差异有统计学意义（P均〈0．01）,靶区剂量分布的CI和IC均优于IMRT计划。除了95％的剂量水平外,在10％、30％、50％、70％和90％剂量水平,采用C—ion RT均可明显减少直肠的受照射体积（P均〈0．05）,同时完全保护直肠的后壁;在任何剂量水平,C—ion RT可明显减少膀胱和非靶区正常组织的受照射体积（P均〈0．05）;在10％、20％、30％和40％剂量水平,C—ion RT可明显减少双侧股骨头的受照射体积（P均〈0．05）。结论在前列腺癌的放射治疗中,与IMRT计划相比,C—ion RT计划在剂量学方面有明显优势,C—ion RT的这些优势将能够进一步提高前列腺癌的局部控制率,减少放疗引起的并发症。     

放疗计划自动分析系统的开发研究

目的开发一款放疗计划自动分析系统,通过智能解析Pinnacle3治疗计划系统(TPS)的治疗计划底层数据,实现放疗计划剂量参数的自动化分析。方法将12例接受放射治疗的食管癌患者的治疗计划纳入研究。自动分析系统自动检索Pinnacle3 TPS数据库,获取12例治疗计划原始数据,并自动解析底层原始数据,重建轮廓、射野和剂量参数,并重新计算剂量分布和"剂量-体积"直方图。通过与在线TPS中原始计划输出体积和剂量数据进行对比,来评估新系统重新计算体积和剂量数据的准确性。结果自动分析系统成功解析治疗计划的底层数据,并重建治疗计划参数。新系统计算轮廓的体积与原计划的体积偏差≤0.1%;重新计算GTV、PGTV、CTV和PTV的Dmax、Dmean、D95和D50等参数,与原计划的剂量偏差≤1.0%;重新计算ROIs的Dmax和Dmean,与原计划的剂量偏差<5%。结论自动分析系统可直接分析Pinnacle3 TPS治疗计划的底层数据,重建治疗计划,计算轮廓体积和剂量参数,与原计划的剂量偏差满足临床要求。