A Prospective Trial to Compare Deep Inspiratory Breath Hold With Prone Breast Irradiation.

PURPOSE: To compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters. METHODS AND MATERIALS: Patients with left breast ductal carcinoma in situ or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon signed-rank and rank-sum tests were used to compare intrapatient differences between plans for the entire cohort and within BV groups defined by tertiles. RESULTS: Forty patients were enrolled. Thirty-four patients are included in the analysis owing to patient withdrawal or inability to hold breath. With WBI dose of 4005 to 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH and 77 cGy in P-FB (P = .08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH and 45 cGy in P-FB (P < .0001). Mean and max left anterior descending artery doses were 251 cGy and 551 cGy in S-DIBH, respectively (P = .1), and 324 cGy and 993 cGy in P-FB, respectively (P = .3). Hot spot and separation were 109% and 22 cm in S-DIBH, respectively, and 107% and 16 cm in P-FB, respectively (P < .0001). For patients with smallest BV, S-DIBH improved MHD and left anterior descending artery doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (P = .05), and max (P = .03) and mean (P = .02) left anterior descending artery doses, and the reduction in MLD, hot spot, and separation with P-FB increased (P < .05). CONCLUSIONS: MHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.

Radiation effect on late cardiopulmonary toxicity: An analysis comparing supine DIBH versus prone techniques for breast treatment.

Two commonly used whole breast irradiation (WBI) techniques, deep inspiration breath hold (DIBH) and prone positioning, are compared with regard to dosimetry and estimated late cardiac morbidity and secondary lung cancer mortality using published models. Forty patients with left-sided DCIS or breast cancer who underwent lumpectomy and required adjuvant WBI were enrolled on a prospective trial comparing supine DIBH (S-DIBH) with prone free breathing (P-FB) planning. Patients underwent CT simulation in both positions; two plans were generated for each patient. Comparative dosimetry was available for 34 patients. Mean cardiac and lung doses were calculated. Risk of death from ischemic heart disease (IHD), risk of at least one acute coronary event (ACE), and lung cancer mortality were estimated from published data. Difference between S-DIBH and P-FB plans was compared using paired two-tailed t test. Estimated mean risk of death from IHD by age 80 was 0.1% (range 0.0%-0.2%) for both plans (P = 1.0). Mean risk of at least one ACE was 0.3% (range 0.1%-0.6%) for both plans (P = .6). Mean lung cancer mortality risk was 1.4% (range 0.5%-15.4%) for S-DIBH and 1.0% (range 0.4%-9.8%) for P-FB (P = .008). Excess lung cancer mortality due to radiation was 0.5% (range 0.1%-6.0%) with S-DIBH and 0.0% (range 0.0%-0.4%) with P-FB (P = .008). Both S-DIBH and P-FB provide excellent cardiac sparing. Prone positioning results in lower lung dose than S-DIBH and leads to an absolute decrease of 0.5% in excess lung cancer mortality for patients receiving WBI.

Prospective Randomized Trial of Prone Accelerated Intensity Modulated Breast Radiation Therapy With a Daily Versus Weekly Boost to the Tumor Bed.

PURPOSE: To report the results of a prospective randomized trial comparing a daily versus weekly boost to the tumor cavity during the course of accelerated radiation to the breast with patients in the prone position. METHODS AND MATERIALS: From 2009 to 2012, 400 patients with stage 0 to II breast cancer who had undergone segmental mastectomy participated in an institutional review board-approved trial testing prone breast radiation therapy to 40.5 Gy in 15 fractions 5 d/wk to the whole breast, after randomization to a concomitant daily boost to the tumor bed of 0.5 Gy, or a weekly boost of 2 Gy, on Friday. The present noninferiority trial tested the primary hypothesis that a weekly boost produced no more acute toxicity than did a daily boost. The recurrence-free survival was estimated for both treatment arms using the Kaplan-Meier method; the relative risk of recurrence or death was estimated, and the 2 arms were compared using the log-rank test. RESULTS: At a median follow-up period of 45 months, no deaths related to breast cancer had occurred. The weekly boost regimen produced no more grade ≥2 acute toxicity than did the daily boost regimen (8.1% vs 10.4%; noninferiority Z = -2.52; P=.006). No statistically significant difference was found in the cumulative incidence of long-term fibrosis or telangiectasia of grade ≥2 between the 2 arms (log-rank P=.923). Two local and two distant recurrences developed in the daily treatment arm and three local and one distant developed in the weekly arm. The 4-year recurrence-free survival rate was not different between the 2 treatment arms (98% for both arms). CONCLUSIONS: A tumor bed boost delivered either daily or weekly was tolerated similarly during accelerated prone breast radiation therapy, with excellent control of disease and comparable cosmetic results.

Reducing excess radiation from portal imaging of pediatric brain tumors.

Previously we have shown that our routine portal imaging (PI) of the craniofacial region in pediatric brain tumor patients contributed an additional 2%-3% of the prescribed dose and up to 200 cGy to the planning target volume (PTV) and nearby organs at risk (OARs). The purpose of this study is to quantify the reduction in dose to PTV and OARs from portal imaging (PI) of the craniofacial region of pediatric patients treated after the implementation of changes in our portal imaging practices. Twenty consecutive pediatric patients were retrospectively studied since the implementation of changes to our portal imaging procedure. Each received portal imaging of treatment fields and orthogonal setup fields to the craniofacial region. PI modifications included a reduction in the field size of setup orthogonal fields without loss of radiographic information needed for treatment verification. In addition, treatment fields were imaged using a single exposure, rather than double exposure. Dose-volume histograms were generated to quantify the dose to the target and critical structures through PI acquisition. These results were compared with our previous cohort of 20 patients who were treated using the former portal imaging practices. The mean additional target dose from portal imaging following the new guidelines was 1.5% of the prescribed dose compared to 2.5% prior to the new portal image practices (p < 0.001). With the new portal imaging practices, the percentage decrease in portal imaging dose to the brainstem, optic structures, cochlea, hypothalamus, temporal lobes, thyroid, and eyes were 25%, 35%, 35%, 51%, 45%, 80%, and 55%, respectively. Reductions in portal imaging doses were significant in all OARs with exception of the brainstem, which showed a trend towards significance. Changes to portal imaging practices can reduce the radiation dose contribution from portal imaging to surrounding OARs by up to 80%. This may have implications on both late toxicity and second cancer development in pediatric brain tumors.

Dose to craniofacial region through portal imaging of pediatric brain tumors.

The purpose of this study was to determine dose to the planning target volume (PTV) and organs at risk (OARs) from portal imaging (PI) of the craniofacial region in pediatric brain tumor patients treated with intensity-modulated radiation therapy (IMRT). Twenty pediatric brain tumor patients were retrospectively studied. Each received portal imaging of treatment fields and orthogonal setup fields in the craniofacial region. The number of PI and monitor units used for PI were documented for each patient. Dose distributions and dose-volume histograms were generated to quantify the maximum, minimum, and mean dose to the PTV, and the mean dose to OARs through PI acquisition. The doses resulting from PI are reported as percentage of prescribed dose. The average maximum, minimum, and mean doses to PTV from PI were 2.9 ± 0.7%, 2.2 ± 1.0%, and 2.5 ± 0.7%, respectively. The mean dose to the OARs from PI were brainstem 2.8 ± 1.1%, optic nerves/chiasm 2.6 ± 0.9%, cochlea 2.6 ± 0.9%, hypothalamus/pituitary 2.4 ± 0.6%, temporal lobes 2.3 ± 0.6%, thyroid 1.6 ± 0.8%, and eyes 2.6 ± 0.9%. The mean number of portal images and the mean number of PI monitor units per patient were 58.8 and 173.3, respectively. The dose from PI while treating pediatric brain tumors using IMRT is significant (2%-3% of the prescribed dose). This may result in exceeding the tolerance limit of many critical structures and lead to unwanted late complications and secondary malignancies. Dose contributions from PI should be considered in the final documented dose. Attempts must be made in PI practices to lower the imaging dose when feasible.