Patterns of dose variability in radiation prescription of breast cancer

Das, Indra J.; Cheng, Chee Wai; Fein, Douglas A.; Fowble, Barbara

doi:10.1016/s0167-8140(97)00054-6

Cited by 76 publications

(44 citation statements)

References 28 publications

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“…The subset of breast patients in whom these issues may be most relevant are women with large breast sizes and large separation measurements. In addition to our data relating dose inhomogeneity and breast volumes, Das et al have shown that the value of the maximum dose within a treated breast is related to chest wall separation distances [10]. These data offer a plausible explanation for the poorer cosmetic results noted in women with larger breast sizes [4,5,8].…”

Section: Discussionsupporting

confidence: 73%

Isoseparation curves:A mechanism for optimizing off-axis dose homogeneity of intact breast irradiation

Buchholz

Bilton

Gurgoze

et al. 1998

Radiat. Oncol. Investig.

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The purpose of this paper is to determine whether using off‐axis isoseparation curves to optimize the collimator rotation angle improves dose homogeneity. Eleven intact breast irradiation patients underwent computerized tomography (CT) treatment planning with 1 cm abutting slices. Central plane treatment planning, using 6 MV photons, tissue inhomogeneity corrections, and isocentric opposed tangent treatment fields, was performed. Collimators were rotated to match chest wall slope through the use of a beam's‐eye‐view setting. Patient separations were measured from the apex of the breast to the posterior field border on each axial CT slice. Sagittal‐plane isoseparation curves were constructed from these measurements. Using these curves, the collimator rotation that minimized off‐axis separation differences was determined. A comparison of off‐axis dose inhomogeneity was performed for patients with a ⩾10° difference between this optimized collimator angle and the angle determined by chest wall slope. These comparative treatment plans differed only with respect to collimator angle rotation. The mean optimal collimator rotation angle differed significantly from the mean rotation angle which matched the chest wall slope (5.4° vs. 11°, respectively, P < 0.001). Four of the 11 patients had rotation angle differences of 10°. In these patients, the optimization of collimator angle reduced the percentage of breast volume to “that” received ⩾110% of the prescribed dose. For the patient with the largest breast size to the patient with the smallest breast size the decreases were, respectively, 5% (15% to 10%), 3% (24% to 21%), 1% (4% to 3%), and 1% (0.9% to 0%). The mean reduction in dose inhomogeneity was greatest in the inferior breast quadrants. At 6 cm and 4 cm off axis, the mean reductions in the percentages of the breast tissue to “that” received 110% of the prescribed dose were respectively 15.1% and 5.3%. Optimizing the collimator angle through the use of isoseparation curves decreases dose inhomogeneity. The greatest improvements are in the inferior quadrants of the intact breast. The improved dose homogeneity may have clinical relevance in the treatment of patients with large breast sizes. Radiat. Oncol. Invest. 6:191–198, 1998. © 1998 Wiley‐Liss, Inc.

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Section: Discussionsupporting

confidence: 73%

Isoseparation curves:A mechanism for optimizing off-axis dose homogeneity of intact breast irradiation

Buchholz

Bilton

Gurgoze

et al. 1998

Radiat. Oncol. Investig.

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“…Other groups that have been studied for exposure to RT or for occupational exposure generally were exposed to fractionated doses delivered over a period of time. 23 In those instances, doses to parts of the lung in the radiation field would have been significantly higher than for the atomic bomb survivors, but the risks of subsequent lung carcinoma are approximately the same in all groups due to the cellular repair after dose fractionation. Although radiation type, energy, dose, dose-rate, and the volume of lung irradiated are different among A-bomb survivors, patients treated with RT, and occupationally exposed workers, their risks of lung carcinoma have been shown to be similar.…”

Section: Discussionmentioning

confidence: 99%

“…15,23 Inskip et al 15 estimated that the mean absorbed dose was 15.2 Gy to the ipsilateral lung, 4.6 Gy to the contralateral lung, and 9.8 Gy to both lungs combined. Adjuvant RT after breast-conserving surgery for primary breast carcinoma is believed by many to deliver the same incidental dose to the lung area as the adjuvant RT after mastectomy.…”

Section: Discussionmentioning

confidence: 99%

Lung carcinoma after radiation therapy in women treated with lumpectomy or mastectomy for primary breast carcinoma

Zablotska

Neugut

2003

Cancer

127

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BACKGROUNDPrior studies have demonstrated that women who receive adjuvant radiation therapy (RT) after mastectomy for breast carcinoma have an increased risk of a second primary lung carcinoma after 10 years, but, to the authors' knowledge, the risk associated with adjuvant RT after breast‐conserving surgery (lumpectomy) has yet to be determined. The purpose of the current study was to confirm and extend earlier findings of the effects of postmastectomy RT on second primary lung carcinoma and to investigate the impact of postlumpectomy RT on second primary lung carcinoma in the same population and to compare the results.METHODSThe authors used data from the population‐based Surveillance, Epidemiology, and End Results (SEER) program of the U.S. National Cancer Institute, encompassing approximately 10% of the U.S. population, from 1973 to 1998. Of the women with nonmetastatic invasive breast carcinoma, 194,981 had been treated with mastectomy and 65,560 were treated with lumpectomy. Cox regression analysis was used to estimate the relative risk (RR) of a second primary lung carcinoma among women treated with RT compared with those who received surgery alone as a function of time interval since treatment and laterality for both types of surgery.RESULTSAlthough no statistically significant elevation in risk for second primary lung carcinoma prior to 10 years was observed, the authors estimated a RR of 2.06 (95% confidence interval [95% CI], 1.53–2.78) and 2.09 (95% CI, 1.50–2.90) for ipsilateral lung carcinoma at 10–14 years and 15+ years after postmastectomy RT, respectively, whereas no increased risk was observed for the contralateral lung. The excess risk of ipsilateral lung carcinoma after postmastectomy RT was found for all three major histologic subtypes of lung carcinoma (adenocarcinoma, squamous cell carcinoma, and small cell carcinoma). No increased risk of lung carcinoma was observed at 10–14 years after postlumpectomy RT for either lung.CONCLUSIONSPostmastectomy RT was found to provide a moderate increase in risk for ipsilateral lung carcinoma starting 10 years after exposure; this increased risk is reported to persist to at least 20 years. Postlumpectomy RT does not appear to incur an increased risk. These findings should be reassuring to women treated with either type of RT, but the excess risk in the postmastectomy group should be considered in the choice between treatment options. Cancer 2003;97:1404–11. © 2003 American Cancer Society.DOI 10.1002/cncr.11214

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“…The conventional 3-dimensional conformal radiotherapy (3D-CRT) has been successful in improving local control (1,2). However, wedges can only provide 2-dimensional compensation of missing tissue, which could be suboptimal and result in an inhomogeneous dose distribution, particularly in the case of women with large breasts (3). Large breast size often deters homogeneous results in increased hot spots: these are located within both the target and the surrounding normal tissues.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric comparison of left-sided whole breast irradiation with 3D-CRT, IP-IMRT and hybrid IMRT

et al. 2014

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Abstract. The aim of this study was to compare the dosimetric characteristics of left-sided whole breast irradiation among 3-dimensional conformal radiotherapy (3D-CRT), 4-field inverse-planned intensity-modulated radiotherapy (IP-IMRT) and hybrid IMRT technique (combining 3D-CRT beams and IP-IMRT beams) with respect to target coverage and irradiation of organs at risk. The 3 different planning techniques were analyzed for 8 patients with left-sided breast conserving surgery. Plans were compared on the basis of planning target volume (PTV) dose conformity, homogeneity and the volumes of normal tissues treated based on dose-volume histograms (DVHs). DVHs were calculated for the PTV, heart, and the bilateral lungs, contralateral breast, and soft tissue surrounding the breast PTV (V OB ) volume. IP-IMRT and hybrid IMRT techniques comparably improved the PTV dose homogeneity and conformity (CI) significantly, compared to the conventional 3D-CRT technique (P<0.017); the IP-IMRT technique only could additionally benefit patients by decreasing the high-dose (40 Gy) volume for heart and ipsilateral lung compared with the hybrid IMRT technique (P<0.017); the hybrid IMRT plans achieved a further improvement by compromising the increase of low-dose volume (total lung V13, contralateral lung V5, heart V10 and soft tissue surrounding the breast V5) compared with IP-IMRT plans (P<0.017). Hybrid IMRT plans achieved equivalent PTV dose uniformity to IP-IMRT plans and compromised the low-dose volume and requirement of clinic resource between IP-IMRT and 3D-CRT plans, promoting it as a standard practice of left-sided breast irradiation for patients in good-ordered cardiopulmonary health.

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Patterns of dose variability in radiation prescription of breast cancer

Cited by 76 publications

References 28 publications

Isoseparation curves:A mechanism for optimizing off-axis dose homogeneity of intact breast irradiation

Isoseparation curves:A mechanism for optimizing off-axis dose homogeneity of intact breast irradiation

Lung carcinoma after radiation therapy in women treated with lumpectomy or mastectomy for primary breast carcinoma

Dosimetric comparison of left-sided whole breast irradiation with 3D-CRT, IP-IMRT and hybrid IMRT

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