乳腺癌保乳术后常规、三维适形及两种调强放疗技术剂量学评估(英文)

Objective: The purpose of this study was to compare the dose distribution and dose volume histogram (DVH) of the planning target volume (PTV) and organs at risk (OARs) among conventional radiation therapy (CR), three-dimensional conformal radiation therapy (3DCRT), two-step intensity-modulated radiation therapy (TS-IMRT) and direct machine parameter optimization intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery. Methods: For each of 20 randomly chosen patients, 4 plans were designed using 4 irradiation techniques. The prescribed dose was 50 Gy/2 Gy/25 f, 95% of the planning target volume received this dose. The cumulated DVHs and 3D dose distributions of CR, 3DCRT, TS-IMRT and DMPO-IMRT plans were compared. Results: For the homogeneity indices, no statistically significant difference was observed among CR, 3DCRT, TS-IMRT and DMPO-IMRT while the difference of the conformality indices were statistically significant. With regard to the organs at risk, IMRT and 3DCRT showed a significantly fewer exposure dose to the ipsilateral lung than CR in the high-dose area while in the low-dose area, IMRT demonstrated a significant increase of exposure dose to ipsilateral lung, heart and contralateral breast compared with 3DCRT and CR. In addition, the monitor units (MUs) for DMPO-IMRT were approximately 26% more than those of TS-IMRT and the segments of the former were approximately 24% less than those of the latter. Conclusion: Compared with CR, 3DCRT and IMRT improved the homogeneity and conformity of PTV, reduced the irradiated volume of OARs in high dose area but IMRT increased the irradiated volume of OARs in low dose area. DMPO-IMRT plan has fewer delivery time but more MUs than TS-IMRT.     

Dosimetric comparison of left-sided whole breast irradiation with 3DCRT, forward-planned IMRT, inverse-planned IMRT, helical tomotherapy, and topotherapy

Background and purpose

To compare left-sided whole breast conventional and intensity-modulated radiotherapy (IMRT) treatment planning techniques.

Materials and methods

Treatment plans were created for 10 consecutive patients. Three-dimensional conformal radiotherapy (3DCRT), forward-planned IMRT (for-IMRT), and inverse-planned IMRT (inv-IMRT) used two tangent beams. For-IMRT utilized up to four segments per beam. For helical tomotherapy (HT) plans, beamlet entrance and/or exit to critical structures was blocked. Topotherapy plans, which used static gantry angles with simultaneous couch translation and inverse-planned intensity modulation, used two tangent beams. Plans were normalized to 50 Gy to 95% of the retracted PTV.

Results

Target max doses were reduced with for-IMRT compared to 3DCRT, which were further reduced with HT, topotherapy, and inv-IMRT. HT resulted in lowest heart and ipsilateral lung max doses, but had higher mean doses. Inv-IMRT and topotherapy reduced ipsilateral lung mean and max doses compared to 3DCRT and for-IMRT.

Conclusions

All modalities evaluated provide adequate coverage of the intact breast. HT, topotherapy, and inv-IMRT can reduce high doses to the target and normal tissues, although HT results in increased low doses to large volume of normal tissue. For-IMRT improves target homogeneity compared with 3DCRT, but to a lesser degree than the inverse-planned modalities.     

Dosimetric comparison of normal structures associated with accelerated partial breast irradiation and whole breast irradiation delivered by intensity modulated radiotherapy for early breast cancer after breast conserving surgery

Purpose

To assess the heart and lung dosimetry results associated with accelerated partial breast irradiation intensity-modulated radiotherapy (APBI-IMRT) and whole breast field-in-field intensity-modulated radiotherapy (WBI-FIF-IMRT).

Methods

A total of 29 patients with early-stage breast cancer after lumpectomy were included in this study. APBI-IMRT and WBI-FIF-IMRT plans were generated for each patient. The dosimetric parameters of ipsilateral lung and heart in both plans were then compared with and without radiobiological correction.

Results

With and without radiobiological correction, the volume of ipsilateral lung showed a substantially lower radiation exposure in APBI-IMRT with moderate to high doses (P < 0.05) but non-significant increases in volume of ipsilateral lung in 2.5 Gy than WBI-FIF-IMRT (P > 0.905).There was no significant difference in volume of ipsilateral lung receiving 1, 2.5, and 5 Gy between APBI-IMRT and WBI (P > 0.05) in patients with medial tumor location, although APBI-IMRT exposed more lung to 2.5 and 5 Gy. APBI-IMRT significantly decreases the volume of heart receiving low to high doses in left-sided breast cancer (P < 0.05).

Conclusion

APBI-IMRT can significantly spare the volume of heart and ipsilateral lung receiving moderate and high dose. Non-significant increases in volume of the ipsilateral lung exposed to low doses of radiation were observed for APBI-IMRT in comparison to WBI-FIF-IMRT, particularly in patients with medial tumor location. With the increasing interest in APBI-IMRT, our data may help clinicians individualize patient treatment decisions.     

光子束和电子束在早期乳腺癌患者放疗瘤床加量计划的剂量学研究

Objective

The aim of our study was to assess and compare the potential dosimetric advantages and drawbacks of photon beams and electron beams as a boost for the tumor bed in superficial and deep seated early-stage breast cancer.

Methods

We planned CTs of 10 women with early breast cancer underwent breast conservative surgery were selected. Tumor bed was defined as superficial and deep with a cut of point 4 cm, those with less than 4 cm were defined as superficial tumors representing 4 patients and those with depth of 4 cm or more were classified as deep tumors representing 6 patients. The clinical target volume (CTV) was defined as the area of architectural distortion surrounded by surgical clips. The planning target volume (PTV) was the CTV plus margin 1 cm. A dose of 10 Gy in 2 Gy fractions was given concurrently at the last week of treatment. Organs at risk (OARs) were heart, lungs, contra-lateral breast and a 5 mm thick skin segment of the breast surface. Dose volume histograms were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing OARs. The following treatment techniques were assessed: photon beam with 3D-conformal technique and a single electron beam.

Results

For superficial tumors better coverage for CTV and PTV with good homogeneity with better CI was found for the 3D conformal radiotherapy (3DCRT) but with no significant planning objectives over electron beam. For deep tumors, the 3DCRT met the planning objectives for CTV, PTV with better coverage and fewer hot spots with better homogeneity and CI. For superficial tumors, OARs were spared by both techniques with better sparing for the electron beam where as for deep tumors also OARs were well spared by both techniques.

Conclusion

Boosting the tumor bed in earlystage breast cancer with optimized photon may be preferred to electron beam for both superficial and deep tumors. The OARs dose sparing effect may allow for a potential long-term toxicity risk reduction and better cosmesis.     

Ionizing radiation and inhibition of angiogenesis in a spontaneous mammary carcinoma and in a syngenic heterotopic allograft tumor model: a comparative study

Background

To assess inter-observer variability in delineating target volume and organs at risk in benign tumor adjacent to optic tract as a quality assurance exercise.

Methods

We quantitatively analyzed 21 plans made by 11 clinicians in seven CyberKnife centers. The clinicians were provided with a raw data set (pituitary adenoma and meningioma) including clinical information, and were asked to delineate the lesions and create a treatment plan. Their contouring and plans (10 adenoma and 11 meningioma plans), were then compared. In addition, we estimated the influence of differences in contouring by superimposing the respective contours onto a default plan.

Results

The median planning target volume (PTV) and the ratio of the largest to the smallest contoured volume were 9.22 cm³ (range, 7.17 - 14.3 cm³) and 1.99 for pituitary adenoma, and 6.86 cm³ (range 6.05 - 14.6 cm³) and 2.41 for meningioma. PTV volume was 10.1 ± 1.74 cm³ for group 1 with a margin of 1 -2 mm around the CTV (n = 3) and 9.28 ± 1.8 cm³(p = 0.51) for group 2 with no margin (n = 7) in pituitary adenoma. In meningioma, group 1 showed larger PTV volume (10.1 ± 3.26 cm³) than group 2 (6.91 ± 0.7 cm³, p = 0.03). All submitted plan keep the irradiated dose to optic tract within the range of 50 Gy (equivalent total doses in 2 Gy fractionation). However, contours superimposed onto the dose distribution of the default plan indicated that an excessive dose 23.64 Gy (up to 268% of the default plan) in pituitary adenoma and 24.84 Gy (131% of the default plan) in meningioma to the optic nerve in the contours from different contouring.

Conclusion

Quality assurance revealed inter-observer variability in contour delineation and their influences on planning for pituitary adenoma and meningioma near optic tract.     

局部晚期宫颈癌调强和适形放疗的剂量学对比研究(英文)

Objective:This study was to compare 5 field conformal technique to the intensity modulated radiotherapy (IMRT) 8 fields technique in boosting locally advanced cancer cervix cases after external beam radiotherapy with respect to target volume coverage and dose to normal tissues. Methods:We conducted a single institutional comparative dosimetric analysis of 10 patients with cancer cervix who was presented to radiotherapy department in National Cancer Institute, Cairo in period between June 2012 to September 2012 and received a CRT boost in the place of planned brachytherapy after large field pelvic radiotherapy (PRT) with concurrent chemotherapy were retrospectively identified. All tumors were situated in the low central pelvis. Two plans were done for every patient; one using the 8 fields IMRT and the second one using 5 fields’ 3DCRT the two techniques were then compared using dose volume histogram (DVH) analysis for the PTV, bladder, rectum and both femoral heads. Results:Comparing different DVHs, it was found that the planning target volume (PTV) was adequately covered in both plans while it was demonstrates that the 8 fields IMRT technique carried less doses reaching OARs (rectum, bladder, both femoral heads). Conclusion:From the present study, it is concluded that IMRT technique spared more efficiently OARs than CRT technique but both techniques covered the PTV adequately so whenever possible IMRT technique should be used.     

三维适形放疗和调强放疗治疗原发性鼻咽癌的剂量学对比研究:来自埃及的经验报道

Objective

The study is a comparative study, the aim of which is to compare 3D conformal radiation therapy (3DCRT) and intensity modulated radiation therapy (IMRT) in treating nasopharyngeal carcinomas; dosimetrically evaluating and comparing both techniques as regard target coverage and doses to organs at risk (OAR).

Methods

Twenty patients with nasopharyngeal carcinoma were treated by 3D-CRT technique and another 20 patients were treated by IMRT. A dosimetric comparison was done by performing two plans for the same patient using Eclipse planning system (version 8.6).

Results

IMRT had a better tumor coverage and conformity index compared to 3D-CRT plans (P value of 0.001 and 0.004), respectively. As for the dose homogeneity it was also better in the IMRT plans and the reason for this was attributed to the dose inhomogeneity at the photon/electron junction in the 3D-CRT plans (P value 0.032). Also, doses received by the risk structures, particularly parotids, was significantly less in the IMRT plans than those of 3D-CRT (P value 0.001).

Conclusion

IMRT technique was clearly able to increase the dose delivery to the target volume, improve conformity and homogeneity index and spare the parotid glands in comparison to 3D-CRT technique.     

Stereotactic body radiation therapy for the treatment of early-stage minimally invasive adenocarcinoma or adenocarcnioma in situ (formerly bronchioloalveolar carcinoma): a patterns of failure analysis

Aims

Based on the hypothesis that first-line chemoradiation followed by chemotherapy was superior for primary tumor and non-inferior for distant lesions compared to chemotherapy alone in synchronous unresectable distant metastases rectal adenocarcinoma, this study was designed to assess the efficacy and safety of this strategy.

Materials and methods

Thirty two eligible patients received intensity modulated radiation therapy (45 Gy to the pelvis and a concomitant 10 Gy boost to the gross tumor), along with concurrent weekly capecitabine and oxaliplatin. Patients underwent radical surgery if all lesions were visually evaluated as resectable and received chemotherapy for a total of 6 months, whether pre- or post-operatively (definitive therapy group). The remaining patients received 6 months of consolidation chemotherapy followed by maintenance chemotherapy (non-definitive therapy group).

Results

The toxicities were acceptable, with radiation-induced dermatitis around the anal verge being the most common (18.8%). Fourteen patients underwent surgical resection of the rectal tumor, with 5 (35.7%) experiencing a pathological complete response. Nine out of 14 received definitive treatment, defined as R0 resections of all visible tumors. At a median follow-up of 12 months (range, 4–23 months), 2 cases were evaluated as local failure, and the median overall survival (OS) and progression free survival (PFS) for all 32 patients were 17.5 and 12 months, respectively. OS differed significantly in the definitive and non-definitive therapy groups (p=0.045), and PFS tended to differ (p=0.274).

Conclusion

It was demonstrated that the strategy of first-line chemoradiation followed by chemotherapy was effective and tolerable, especially for local control. OS and PFS were superior in patients who did than did not undergo curative therapy.     

Parotid gland sparing IMRT for head and neck cancer improves xerostomia related quality of life

Background

To compare two strategies of dynamic intensity modulated radiation therapy (dIMRT) with 3-dimensional conformal radiation therapy (3DCRT) in the setting of hypofractionated high-risk prostate cancer treatment.

Methods

3DCRT and dIMRT/Helical Tomotherapy(HT) planning with 10 CT datasets was undertaken to deliver 68 Gy in 25 fractions (prostate) and simultaneously delivering 45 Gy in 25 fractions (pelvic lymph node targets) in a single phase. The paradigms of pelvic vessel targeting (iliac vessels with margin are used to target pelvic nodes) and conformal normal tissue avoidance (treated soft tissues of the pelvis while limiting dose to identified pelvic critical structures) were assessed compared to 3DCRT controls. Both dIMRT/HT and 3DCRT solutions were compared to each other using repeated measures ANOVA and post-hoc paired t-tests.

Results

When compared to conformal pelvic vessel targeting, conformal normal tissue avoidance delivered more homogenous PTV delivery (2/2 t-test comparisons; p < 0.001), similar nodal coverage (8/8 t-test comparisons; p = ns), higher and more homogenous pelvic tissue dose (6/6 t-test comparisons; p < 0.03), at the cost of slightly higher critical structure dose (D_dose, 1–3 Gy over 5/10 dose points; p < 0.03). The dIMRT/HT approaches were superior to 3DCRT in sparing organs at risk (22/24 t-test comparisons; p < 0.05).

Conclusion

dIMRT/HT nodal and pelvic targeting is superior to 3DCRT in dose delivery and critical structure sparing in the setting of hypofractionation for high-risk prostate cancer. The pelvic targeting paradigm is a potential solution to deliver highly conformal pelvic radiation treatment in the setting of nodal location uncertainty in prostate cancer and other pelvic malignancies.     

Comparison of treatment results between surgery alone, preoperative short-course radiotherapy, or long-course concurrent chemoradiotherapy in locally advanced rectal cancer

Background

The aim of this study is to compare the results between surgery alone, preoperative radiotherapy (RT), or preoperative concurrent chemoradiotherapy (CCRT) followed by surgery in the treatment of locally advanced rectal cancer in Asian patients.

Methods

This study included 151 consecutive patients with clinical T3, T4 or node-positive rectal cancer from Jan. 2005 to Dec. 2007. Eighty-six patients underwent total mesorectal excision (TME) alone, 28 patients received preoperative RT (25?Gy in 5 fractions) followed by TME in 1?week, and 37 patients received preoperative CCRT (50.4?Gy in 28 fractions) followed by TME in 4–6?weeks.

Results

The 3-year loco-regional recurrence (LRR), distant metastasis, overall and disease-free survival rates are comparable among Surgery, RT and CCRT groups. By multivariate analysis, pT4, distal margin <2?cm, the ratio of positive lymph nodes to totally dissected lymph nodes ≥0.2, and non-R0 resection were significant factors for LRR. In subgroup analysis, TME alone produced comparable LRR to RT or CCRT (3.3 vs.. 4.8%) for favorable patients (0–1 risk factors). For unfavorable patients (2 or more risk factors), the LRR rose to 37% in patients receiving surgery alone as compared with 15% in the RT or CCRT patients.

Conclusions

Preoperative RT or CCRT followed by TME produced good local control in favorable and unfavorable patients with locally advanced rectal cancer. If preoperative RT or CCRT is not given, TME alone has a high incidence of local recurrence in unfavorable patients with 2 or more risk factors.     

Synchronous Occurrence of Neuroendocrine Colon Carcinoma and Hairy Cell Leukemia

Background—Purpose

The risk of secondary malignancy development in patients with hairy cell leukemia has been evaluated in several studies with varying results. The aim of this study is to describe a case of synchronous occurrence of neuroendocrine colon carcinoma and hairy cell leukemia.

Methods

A 69-year-old man presented with rectal bleeding. Colonoscopy revealed a rectal tumor, whereas biopsy specimens revealed a poorly differentiated carcinoma. During the preoperative evaluation, pancytopenia was detected.

Results

At laparotomy, a mass was detected 16 cm from the anal verge and an anterior resection of the rectum was performed. Detailed histological and immunohistochemical analyses revealed a poorly differentiated neuroendocrine carcinoma of the rectum. Postoperative evaluation of pancytopenia revealed hairy cell leukemia. The patient was initially treated with chemotherapy for hairy cell leukemia followed by chemotherapy for neuroendocrine colon carcinoma. Survival was 44 months.

Conclusions

To our knowledge, synchronous occurrence of neuroendocrine colon carcinoma and hairy cell leukemia has not been previously reported in the literature. Given the rare incidence of both entities in the general population, it is highly unlikely that they occurred together by chance. Further research is needed to determine what would be the optimal management options of patients with simultaneous hairy cell leukemia and a neuroendocrine colon cancer.     

Detailed dosimetric evaluation of intensity-modulated radiation therapy plans created for stage C prostate cancer based on a planning protocol

Background

Intensity-modulated radiation therapy (IMRT) has been employed as a precision radiation therapy with higher conformity to the target. Although clinical outcomes have been reported for many investigations, detailed treatment planning results have not been mentioned to date. The aim of this study was to evaluate the dose specifications of our IMRT treatment plans for locally advanced prostate cancer.

Methods

Seventy-seven clinically applied IMRT plans treated between September 2003 and December 2005, in which patients were irradiated with 78?Gy in the prone position, were retrospectively analyzed. Dosimetric data output from dose volume histograms were evaluated in detail.

Results

The mean dose?±?standard deviation, homogeneity index, and conformity index to the planning target volume (PTV) were 78.3?±?0.7?Gy (100.4?±?0.9%), 13.7?±?3.0, and 0.83?±?0.04, respectively. For the clinical target volume, the mean dose was 80.3?±?0.7?Gy (102.9?±?0.9%).The V40, V60, and V70?Gy of the rectal wall were 58.3?±?2.8, 29.6?±?2.7, and 15.2?±?3.0%, respectively. Planning difficulties were encountered in patients whose bowels were displaced downward, as constraints imposed by the bowel position altered the dose index of the PTV. In many cases, additional bowel optimization parameters were required to satisfy constraints for organs at risk. However, major deviation could be avoided by inverse planning with computer optimization.

Conclusion

IMRT allowed the creation of acceptable and practical treatment plans for locally advanced prostate cancer. Reports regarding detailed dosimetric evaluations are mandatory for interpreting clinical outcomes in the future.     

Cardiac Dose and Survival After Stereotactic Body Radiotherapy for Early-stage Non–Small-cell Lung Cancer

Introduction

Recent analyses have identified cardiac dose as an important predictor of overall survival (OS) after chemoradiation for locally advanced non–small-cell lung cancer (NSCLC). However, the survival influence of the cardiac dose after stereotactic body radiotherapy (SBRT) is unknown. We performed a dose–volume histogram (DVH) analysis of patients treated with SBRT for early stage NSCLC to examine survival and cardiac toxicity.

调强适形放疗对深部肿瘤皮肤剂量的影响(英文)

Objective: The purpose of this study was to investigate the impact of intensity modulated radiotherapy (IMRT) on surface doses for brain, abdomen and pelvis deep located tumors treated with 6 MV photon and to evaluate the skin dose calculation accuracy of the XIO 4.04 treatment planning system. Methods: More investigations for the influences of IMRT on skin doses would increase its applications for many treatment sites. Measuring skin doses in real treatment situations would reduce the uncertainty of skin dose prediction. In this work a pediatric human phantom was covered by a layer of 1 mm bolus at three treatment sites and thermoluminescent dosimeter (TLD) chips were inserted into the bolus at each treatment site before CT scan. Two different treatment plans [three-dimensional conformal radiation therapy (3DCRT) and IMRT] for each treatment sites were performed on XIO 4.04 treatment planning system using superposition algorism. Results: The results showed that the surface doses for 3DCRT were higher than the surface doses in IMRT by 1.6%, 2.5% and 3.2% for brain, abdomen and pelvis sites respectively. There was good agreement between measured and calculated surface doses, where the calculated surface dose was 15.5% for brain tumor calculated with 3DCRT whereas the measured surface dose was 12.1%. For abdomen site the calculated surface dose for IMRT treatment plan was 16.5% whereas the measured surface dose was 12.6%. Conclusion: The skin dose in IMRT for deep seated tumors is lower than that in 3DCRT which is another advantage for the IMRT. The TLD readings showed that the difference between the calculated and measured point dose is negligible. The superposition calculation algorism of the XIO 4.04 treatment planning system modeled the superficial dose well.     

Reduced late urinary toxicity with high-dose intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer

Background/purpose

To evaluate the impact of intensity-modulated radiotherapy (IMRT) with intra-prostate fiducial markers image-guided radiotherapy (IGRT) on the incidence of late urinary toxicity compared to 3D conformal radiotherapy (3DCRT) for patients with prostate cancer (PC).

Methods and materials

We selected 733 consecutive patients with localized PC treated with dose-escalation radiotherapy between 2001 and 2014. Eligibility criteria were radiation dose >72.0 Gy, no pelvic RT and minimum follow-up 24 months. 438 patients were treated with 3DCRT and 295 with IMRT. Acute and late urinary complications were assessed using the EORTC/RTOG and CTCAEs v3.0 definition. The Cox regression model was used to compare grade ≥2 urinary toxicity between both techniques. The median follow-up was 75 months (range 24–204).

Results

The median isocenter radiation dose was 78.7 Gy for 3DCRT and 80.7 Gy for IMRT/IGRT (p < 0.001). The 5-year incidence of late grade ≥2 urinary toxicity was 6.4% for IMRT and 10.8% for 3DCRT [hazard ratio (HR) 0.575, p = 0.056]. The corresponding 5-year estimates of late grade ≥2 hematuria were 2% for IMRT and 5.3% for 3DCRT (HR 0.296, p = 0.024). On multivariate analysis, the antecedent of prior transurethral resection of the prostate was also a strong predictor of a higher risk of urinary complications (HR 2.464, p = 0.002) and of hematuria (HR 5.196, p < 0.001).

Conclusion

Compared with 3DCRT, high-dose IMRT/IGRT is associated with a lower rate of late urinary complications in spite of higher radiation dose.