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To assess individual volumetric tumor regression pattern in cervical cancer during therapy using serial four-dimensional MRI and to define the regression parameters' prognostic value validated with local control and survival correlation.One hundred and fifteen patients with Stage IB(2)-IVA cervical cancer treated with radiation therapy (RT) underwent serial MRI before (MRI 1) and during RT, at 2-2.5 weeks (MRI 2, at 20-25 Gy), and at 4-5 weeks (MRI 3, at 40-50 Gy). Eighty patients had a fourth MRI 1-2 months post-RT. Mean follow-up was 5.3 years. Tumor volume was measured by MRI-based three-dimensional volumetry, and plotted as dose(time)/volume regression curves. Volume regression parameters were correlated with local control, disease-specific, and overall survival.Residual tumor volume, slope, and area under the regression curve correlated significantly with local control and survival. Residual volumesor=20% at 40-50 Gy were independently associated with inferior 5-year local control (53% vs. 97%, p0.001) and disease-specific survival rates (50% vs. 72%, p = 0.009) than smaller volumes. Patients with post-RT residual volumesor=10% had 0% local control and 17% disease-specific survival, compared with 91% and 72% for10% volume (p0.001).Using more accurate four-dimensional volumetric regression analysis, tumor response can now be directly translated into individual patients' outcome for clinical application. Our results define two temporal thresholds critically influencing local control and survival. In patients withor=20% residual volume at 40-50 Gy andor=10% post-RT, the risk for local failure and death are so high that aggressive intervention may be warranted.

The tumor oxygenation status is likely influenced by two major factors: local tumor blood supply (tumor perfusion) and its systemic oxygen carrier, hemoglobin (Hgb). Each has been independently shown to affect the radiotherapy (RT) outcome in cervical cancer. This study assessed the effect of local tumor perfusion, systemic Hgb levels, and their combination on the treatment outcome in cervical cancer.A total of 88 patients with cervical cancer, Stage IB2-IVA, who were treated with RT/chemotherapy, underwent serial dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) before RT, at 20-22 Gy, and at 45-50 Gy. The DCE-MRI perfusion parameters, mean and lowest 10th percentile of the signal intensity distribution in the tumor pixels, and the Hgb levels, including pre-RT, nadir, and mean Hgb (average of weekly Hgb during RT), were correlated with local control and disease-specific survival. The median follow-up was 4.6 years.Local recurrence predominated in the group with both a low mean Hgb (11.2 g/dL) and low perfusion (lowest 10th percentile of signal intensity2.0 at 20-22 Gy), with a 5-year local control rate of 60% vs. 90% for all other groups (p = .001) and a disease-specific survival rate of 41% vs. 72% (p = .008), respectively. In the group with both high mean Hgb and high perfusion, the 5-year local control rate and disease-specific survival rate was 100% and 78%, respectively.These results suggest that the compounded effects of Hgb level and tumor perfusion during RT influence the radioresponsiveness and survival in cervical cancer patients. The outcome was worst when both were impaired. The management of Hgb may be particularly important in patients with low tumor perfusion.

Purpose Intensity-modulated radiotherapy (IMRT) has been shown to reduce the radiation dose to small bowel in pelvic RT in gynecology patients. Prone positioning has also been used to decrease small bowel dose by displacement of small bowel from the RT field in these patients. The purpose of this study was to determine whether the combination of both IMRT and prone positioning on a belly board can reduce small bowel dose further in gynecologic cancer patients undergoing pelvic RT. Methods and materials IMRT plans for pelvic RT were computed in 16 patients with gynecologic cancer who had undergone planning CT scans in both the supine and the prone positions on a belly board. For the gross tumor volume, the uterus, cervix, and tumor (or postoperative region) were traced. The clinical target volume was defined as the vessels and lymph nodes from the obturator level to the aortic bifurcation, presacral region, and upper 4 cm of the vagina, in addition to gross tumor volume. The planning target volume was defined as a 2-cm margin in addition to the gross tumor volume and upper 4 cm of the vagina, and 1.5 cm for lymph nodes and vessels. Normal tissue regions of interest included small bowel, large bowel, and bladder. IMRT plans using ( 1 ) the limited arc technique (180° arc length) and ( 2 ) the extended arc technique (340° arc length) were computed. Dose–volume histograms for normal tissue structures and target were compared between the supine and prone IMRT plans using the paired t test. Results Prone positioning on a belly board decreased the small bowel dose in gynecologic pelvic IMRT, and the magnitude of improvement depended on the specific IMRT technique used. With the limited arc technique, prone positioning significantly decreased the irradiated small bowel volume at the 25–50-Gy dose levels compared with supine positioning. Small bowel volumes receiving ≥45 Gy decreased from 19% to 12.5% ( p = 0.005) with prone positioning. With the extended arc technique, the decrease in irradiated small bowel volume was less marked, but remained detectable in the 35–45-Gy dose levels. Small bowel volumes receiving ≥45 Gy decreased from 13.6% to 10.1% ( p = 0.03) with prone positioning. The effect of prone positioning on large bowel and bladder was variable. Large bowel volumes receiving ≥45 Gy increased with prone positioning from 16.5% to 20.6% ( p = 0.02) in the limited arc technique and was unaffected in the extended arc technique. Conclusion These preliminary data suggest that prone positioning on a belly board can reduce the small bowel dose further in gynecology patients treated with pelvic RT, and that the dose reduction depends on the IMRT technique used.

Purpose/Objective(s): With the development of molecular imaging technique, it is possible to define early stage tumors while their volume is very small. Therefore, there is an increasing need to understand the effectiveness of current Stereotactic Radiosurgery equipments in treating very small targets. In this study, we compared and evaluated treatment options for the highest physical resolution Stereotactic Radiosurgery equipments from 2.5mm Moduleaf Linac based IMRT (Moduleaf), Nomos MIMiC ARC tomotherapy with 4mm beak (Nomos) and Leksell Gamma Knife C Model with 4mm helmet size (GK). Materials/Methods: An isolated target with the size less than 50mm was identified and treatment plans were developed for Moduleaf, Nomos and GK respectively. First, the target was identified in the GK Treatment Planning System (TPS) and transferred to Nomos Covus 8.1 TPS and X-Knife RT TPS. Prescription was 50% isodose line covering the target in GK TPS, and the plugging pattern web engine was employed to generate a more conformal plan. The 2.5mm Moduleaf plan was computed using Xknife RT TPS with a twelve-field setup. For Nomos TPS, the arc length was set to 340 degrees. Comparisons of all 3 treatment plans was carried out using dose-volume histogram (DVH), target-volume ratio (TVR), which is defined as the ratio of volume that receives a dose higher than or equal to the minimum tumor dose and the tumor volume, maximum dose to the prescription dose ratio (MDPD), ratio PITV (PIV/TV), radiation conformity index (TVPIV/TV), and a combined conformity index (TVPIV /(TV×PIV)), where PIV is the prescription isodose surface volume, TV is target volume, and TVPIV is the intersection of TV and the PIV. Results: With normal treatment planning efforts, plan evaluation parameters from GK TPS, Nomos TPS and XKnife RT TPS are 1.0, 1.5, 2.0 for TVR, 2.0, 1.05, 1.05 for MPPD, 2.3, 1.5, 2.0 for PITV, 1.0, 1.0, 1.0 for TVPIV/TV, and 0.43, 0.67 and 0.5 for (TVPIV /(TV×PIV)), which is the inverse of the TVR for both plans from Nomos Covus 8.1 TPS and XKnife RT TPS because the prescription dose surface covered the target volume. Conclusions: For targets smaller than 50mm, the Gamma Knife treatment plan gave the best target volume ratio. Both Nomos arc Tomotherapy and X-Knife LINAC based IMRT gave better dose homogeneity. In addition to improvements in localization accuracy, smaller sizes of Nomos MLC and better IMRT planning algorithms for 2.5mm Moduleaf are needed to improve the plan comformality for very small targets.

The cases of 76 patients with chronic radiation dermatitis resulting from low-dose ionizing radiation for benign disease were reviewed retrospectively for risk factors leading to the development of neoplasia. The patients were studied with respect to original hair color, eye color, sun reactive skin type, benign disease treated, area treated, age at treatment, and age at development of first skin cancer. Analysis of data showed 37% of patients had sun-reactive skin type I, 27% had type II, and 36% had type III. Types IV through VI were not represented. There appeared to be an overrepresentation of types I and II. Increased melanin pigmentation may therefore be either directly or indirectly protective against the development of skin cancers in patients who have received low-dose superficial ionizing radiation for benign disease. The sun-reactive skin type of patients with chronic radiation dermatitis may be used as a predictor of skin cancer risk when the total dose of ionizing radiation is not known.