Interobserver Delineation Variation Using CT versus Combined CT + MRI in Intensity–Modulated Radiotherapy for Prostate Cancer

Purpose:  

To quantify interobserver variation of prostate and seminal vesicle delineations using CT only versus CT + MRI in consensus reading with a radiologist.     

Three-Dimensional Treatment Planning for Postoperative Radiotherapy in Patients with Node-Positive Cervical Cancer Comparison between a Conventional and a Conformal Technique

PURPOSE: Reduction of irradiated small bowel volume, using a conformal three-dimensional treatment planning technique in postoperative radiotherapy of cervical cancer patients. PATIENTS AND METHODS: Large gynecological treatment fields including the para-aortic nodes were analyzed in 15 patients. A conventional treatment plan with anterior and posterior (AP-PA) parallel opposed fields and a 3D 4-field conformal radiotherapy plan with a central blocking of small bowel were compared for each patient. Dose-volume histograms and dose parameters were established. Because of the tolerance constraints of the small bowel, the cumulative dose applied to the target was 48.6 Gy. RESULTS: The mean Tumor Control Probability (TCP) values for both the conventional and the conformal technique were 0.60 and 0.61, respectively, with ranges of 0.56 to 0.67 and 0.57 to 0.66, respectively. The mean volume receiving 95% or more of the prescribed dose (V95) of the small bowel was 47.6% (32.5 to 66.3%) in the AP-PA technique and 14.9% (7.0 to 22.5%) in the conformal technique (p < 0.001), indicating a significant reduction in irradiated volume of small bowel in the higher dose range. The mean Normal Tissue Complication Probability (NTCP) decreased from 0.11 to 0.03 with the conformal plan. In patients who received a pedicled omentoplasty during surgery, the mean V95 for small bowel could be reduced to 8.5% (7.0 to 9.9%). The mean median dose to the kidneys was only slightly elevated in the conformal treatment. Especially the mean dose to the right kidney in conventional vs conformal treatment was 3.3 vs 7.9 Gy. The mean near-minimum dose (D95) to the rectosigmoid decreased from 48.4 to 30.1 Gy in the conformal plan compared to the conventional plan. CONCLUSION: The small bowel dose can be significantly reduced with 3D treatment planning, particularly if a pedicled omentoplasty is performed. This allows dose escalation to the tumor region without unacceptable toxicity for the small bowel.     

Acute Side Effects during 3-D-Planned Conformal Radiotherapy of Prostate Cancer

BACKGROUND: Radiotherapy-induced side effects are often scored retrospectively according to the EORTC/RTOG scores for organs at risk by reviewing the medical records. Some studies could prove an over- or underestimation of side effects as assessed by the medical professionals. The aim of this study was to prospectively evaluate differences in side effects as described by the doctors and the patients. PATIENTS AND METHODS: 47 patients with prostate cancer were questioned about their side effects by a radiotherapist and asked to fill in a questionnaire at the start, in the middle and at the end of radiotherapy. The data of this questionnaire and the doctor's report were scored according to the German version of the EORTC/RTOG scores for gastrointestinal (GI) and genitourinary (GU) side effects and subsequently compared. We distinguished between "moderate" disagreement (better/worse by one grade, assessed by the doctor) and "pronounced" disagreement (better/worse by two grades, assessed by the doctor). RESULTS: The number of GI and GU side effects increased during radiotherapy both according to data obtained from the doctor and the patient questionnaire. Comparing doctors' reports with patients' questionnaires, for GI side effects an agreement was found in 22/47 patients, "moderately better" scores by the doctor's report were found in 13/47 patients, and "moderately worse" scores in 9/47 patients on average. "Pronouncedly better and worse" scores were found in 2/47 patients. For GU side effects an agreement was seen in 22/47 patients, "moderately better" scores in 17/47 patients and "moderately worse" scores in 3/47 patients. Regarding GU side effects, only pronouncedly better scores, as assessed by the doctor, were found in a mean of 4/47 patients. If the EORTC/RTOG score is used in its original English version, a difference is found, particularly in the assessment of GU side effects, resulting in an higher amount of agreement concerning GU side effects and a minor amount of "pronounced disagreement". CONCLUSION: In order to evaluate radiation-induced side effects, a patient's self-reported questionnaire should be included in the analysis of morbidity, above all for grade 0, 1, and 2 side effects. The validity of data seems to be questionable, particularly in the assessment of grade 0, 1 and 2 side effects, if only data from the doctors' reports are taken into account. The German version of the EORTC/RTOG score--not including the pretreatment status--leads to different results, particularly in the assessment of grade 0, 1, and 2 urinary side effects, which asks for a revision.     

Transabdominal Ultrasonography, Computed Tomography and Electronic Portal Imaging for 3-Dimensional Conformal Radiotherapy for Prostate Cancer

PURPOSE: To evaluate the feasibility and accuracy of daily B-mode acquisition and targeting ultrasound-based prostate localization (BAT) and to compare it with computed tomography (CT) and electronic portal imaging (EPI) in 3-dimensional conformal radiotherapy (3-D CRT) for prostate cancer. PATIENTS AND METHODS: Ten patients were treated with 3-D CRT (72 Gy/30 fractions, 2.4 Gy/fraction, equivalent to 80 Gy/40 fractions, for alpha/beta ratio of 1.5 Gy) and daily BAT-based prostate localization. For the first 5 fractions, CT and EPI were also performed in order to compare organ-motion and set-up error, respectively. RESULTS: 287 BAT-, 50 CT- and 46 EPI-alignments were performed. The average BAT-determined misalignments in latero-lateral, antero-posterior and cranio-caudal directions were -0.9 mm+/-3.3 mm, 1.0 mm+/-4.0 mm and -0.9 mm+/-3.8 mm, respectively. The differences between BAT- and CT-determined organ-motion in latero-lateral, antero-posterior and cranio-caudal directions were 2.7 mm+/-1.9 mm, 3.9+/-2.8 mm and 3.4 +/- 3.0 mm, respectively. Weak correlation was found between BAT- and CT-determined misalignments in antero-posterior direction, while no correlation was observed in latero-lateral and cranio-caudal directions. The correlation was more significant when only data of good image-quality patients were analyzed (8 patients). CONCLUSION: BAT ensures the relative positions of target are the same during treatment and in treatment plan, however, the reliability of alignment is patient-dependent. The average BAT-determined misalignments were small, confirming the prevalence of random errors in 3-D CRT. Further study is warranted in order to establish the clinical value of BAT.     

Sucralfate versus Mesalazine versus Hydrocortisone in the Prevention of Acute Radiation Proctitis during Conformal Radiotherapy for Prostate Carcinoma

PURPOSE: To assess whether the topical use of steroids or 5-aminosalicylic acid (5-ASA) is superior to sucralfate in preventing acute rectal toxicity during three-dimensional conformal radiotherapy (3DCRT) to 76 Gy. PATIENTS AND METHODS: Patients undergoing 3DCRT for prostate carcinoma at our institution were offered to be randomized to sucralfate 3 g in 15 ml suspension enema (Antepsin, mesalazine 4 g gel enema (Enterasyn, or hydrocortisone 100 mg foam enema (Colifoam. Randomization was blind to the treating physician but not to the patient. Sucralfate was chosen as control arm. Topical treatment had to be performed once daily, starting on day 1 of 3DCRT. Acute rectal toxicity was scored weekly according to RTOG criteria. Time to occurrence of grade 2+ acute rectal toxicity was taken as endpoint. RESULTS: The trial was opened in August 1999, and after the first 24 patients had been treated, arm 2 was discontinued because of eight patients receiving mesalazine, seven actually developed acute rectal toxicity (five patients grade 3 and two patients grade 2).Until May 2001, 134 consecutive patients were randomly assigned to sucralfate (63 patients), mesalazine (eight patients) or hydrocortisone (63 patients). The cumulative incidence of acute rectal toxicity at the end of treatment by arm is 61.9 +/- 6.1%, 87.5 +/- 11.7%, and 52.4 +/- 6.2% for arms 1, 2, and 3, respectively. The difference between the mesalazine group and the sucralfate group is highly significant (hazard ratio [HR] 2.5, 95% confidence interval [CI] 1.1-5.7; p = 0.03). At both uni- and multivariate analysis taking into account several patients and treatment covariates, the difference between hydrocortisone and sucralfate is not significant (HR 0.7, 95% CI 0.5-1.2; p = 0.2). CONCLUSION: Topical mesalazine is contraindicated during radiotherapy. Hydrocortisone enema is not superior to sucralfate in preventing acute rectal toxicity.     

CT模拟定位在食管癌放射治疗的临床应用

目的　探讨CT模拟定位在食管癌放射治疗的临床应用价值。方法　对 49例食管癌应用CT模拟定位技术进行定位扫描 ,将扫描数据传输至放射治疗计划系统计算机工作站 ,比较以食管腔为中心和以实体肿瘤为中心设置照射野的 90 %等剂量线分布情况。结果　以CT图像所示的非对称性肿瘤占 85 .7% ,以实体肿瘤为中心设置照射野的 90 %等剂量线分布能 10 0 %包全肿瘤病灶。结论　CT扫描能更多显示有治疗意义的征象 ,基于CT模拟定位的放射治疗计划使食管癌放疗照射野的设置更加精确合理     

The Effect of Registration Surrogate and Patient Factors on the Interobserver Variability of Electronic Portal Image Guidance During Prostate Radiotherapy

Intraprostatic fiducial markers (IPM) and electronic portal imaging (EPI) are commonly used to identify and correct for prostate motion during radiotherapy. However, little data is available on the precision of this image-guidance technique. This study quantified impact of different registration surrogates and patient factors on the interobserver variability of manual EPI alignment during prostate radiotherapy. For 50 prostate radiotherapy patients previously implanted with 3 IPM, five observers manually aligned 150 pairs of orthogonal EPI to the reference digital reconstructed radiograph using Varian Vision EPI analysis software. Images were aligned using: Bony anatomy (BA), single mid-prostate IPM (SM); and 2 strategies using 3 IPM: center of mass (COM) and rotate & translate (R&T). Intraclass correlation coefficients (ICCs) were calculated to quantify interobserver variability. The absolute displacements measured using SM and R&T were compared with those using COM. The impact of patients' pelvic diameter and adjuvant hormone therapy on interobserver variability were also evaluated. Twelve thousand displacement values were collected for analysis. The maximum discrepancy between the 5 observers was >2 mm in 47% of measurements using BA, 5% using SM, 4% using R&T, and 3% using COM. Both of the 3 IPM alignment strategies demonstrated lower interobserver variability than the single IPM strategy (ICC 0.94–0.97 vs. 0.82–0.94). BA had the highest interobserver variability (ICC = 0.43–0.90). Pelvic diameter and hormone therapy had no discernible impact on interobserver variability. Compared with COM, the absolute displacements measured using the other IPM strategies were statistically different (p < 0.001), but 95% of the absolute magnitude of differences between the strategies were ≤1 mm. The high reproducibility among the observers demonstrated the precision of prostate localization using multiple IPM and EPI, which was not influenced by the patient factors studied. Bony anatomy displayed the highest interobserver variability of the 4 alignment, likely because of the limited EPI field-of-view. Alignment using more than one IPM is recommended to minimize interobserver variability.     

Long-Term Results in Three-Dimensional Conformal Radiotherapy of Localized Prostate Cancer at Moderate Dose (66 Gy)

PURPOSE: Biochemical control (bNED), disease-specific survival (DSS), overall survival (OS), and late gastrointestinal (GI) and urogenital (UG) side effects (EORTC/RTOG) of patients with long-term follow-up were evaluated. PATIENTS AND METHODS: Three-dimensional radiotherapy up to 66 Gy with/without additional hormonal therapy was performed in 154 prostate cancer (T1-3 N0 M0) patients. According to T-stage, pretreatment prostate-specific antigen (PSA) and grading, patients were divided into a low-, intermediate-, and high-risk group. The 5-, 8-, and 10-year actuarial rates of bNED, DSS and OS and late side effects were calculated. RESULTS: Median follow-up was 80 months. Additional hormonal therapy was given in 57% of patients. Distribution concerning risk groups (low, intermediate, high) showed 15%, 49%, and 36% of patients, respectively. bNED 5-, 8-, and 10-year actuarial rates were 46%, 44%, and 44%. DSS 5-, 8- and 10-year rates amounted to 96%, 90%, and 82%. OS 5-, 8- and 10-year rates were 81%, 64%, and 56%. In uni- and multivariate analysis, only pretreatment PSA (<10 vs. >or=10 ng/ml; p<0.05) and PSA nadir (<0.5 vs. >or=0.5 ng/ml; p<0.0001) affected bNED significantly. Age, risk group, T-stage, grading, and hormonal therapy had no significant influence on bNED, DSS, and OS. Rates of late GI and UG side effects grade>or=2 at 5 years were 17% and 15%. CONCLUSION: Current dose escalation studies with better bNED rates may be able to further increase long-term clinical outcome.     

CT模拟定位在食管癌放射治疗中的临床应用

目的：探讨CT模拟定位在食管癌放射治疗的临床应用价值。方法：45例食管癌病例行CT模拟定位,全部病例以肿瘤中心为照射野的等中心点,照射野长度为肿瘤上、下缘放大3.5 cm,野宽为肿瘤边缘外放1.0 cm,总剂量为DT 60 Gy～70 Gy,2 Gy/次,5次/周。结果：CT模拟定位可以和X线模拟定位一样完成从定位到做体表标记的全过程。45例病例近期疗效显示完全缓解率达60.00%（27/45）,部分缓解率为40.00%（18/45）。结论：CT模拟定位可以准确提供食管癌病变情况,利用CT模拟定位,可提供更多的原始信息和提高模拟精度。     

Biochemical Response after 3-D Conformal Radiotherapy of Localized Prostate Cancer to a Total Dose of 66 Gy

BACKGROUND: Since the introduction of 3-D conformal radiotherapy (CRT) doses of /= 70 Gy should be considered. As a consequence of our earlier analysis a prospective multicenter treatment optimization protocol has been initiated in 1999. The protocol includes a risk-adapted dose increase from 70 Gy in low-risk patients to 74 Gy in high-risk patients including short-term androgen ablation.