Talking to children about their HIV status: a review of available resources, tools, and models for improving and promoting pediatric disclosure.

As children living with HIV (CLHIV) grow into adolescence and adulthood, caregivers and healthcare providers are faced with the sensitive challenge of when to disclose to a CLHIV his or her HIV status. Despite WHO recommendations for CLHIV to know their status, in countries most affected by HIV, effective resources are often limited, and national guidance on disclosure is often lacking. To address the need for effective resources, gray and scientific literature was searched to identify existing tools and resources that can aid in the disclosure process. From peer-reviewed literature, seven disclosure models from six different countries were identified. From the gray literature, 23 resources were identified including children's books (15), job aides to assist healthcare providers (5), and videos (3). While these existing resources can be tailored to reflect local norms and used to aid in the disclosure process, careful consideration must be taken in order to avoid damaging disclosure practices.

A predictive model to guide management of the overlap region between target volume and organs at risk in prostate cancer volumetric modulated arc therapy.

PURPOSE: The goal of this study is to determine whether the magnitude of overlap between planning target volume (PTV) and rectum (Rectumoverlap) or PTV and bladder (Bladderoverlap) in prostate cancer volumetric-modulated arc therapy (VMAT) is predictive of the dose-volume relationships achieved after optimization, and to identify predictive equations and cutoff values using these overlap volumes beyond which the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) dose-volume constraints are unlikely to be met. MATERIALS AND METHODS: Fifty-seven patients with prostate cancer underwent VMAT planning using identical optimization conditions and normalization. The PTV (for the 50.4 Gy primary plan and 30.6 Gy boost plan) included 5 to 10 mm margins around the prostate and seminal vesicles. Pearson correlations, linear regression analyses, and receiver operating characteristic (ROC) curves were used to correlate the percentage overlap with dose-volume parameters. RESULTS: The percentage Rectumoverlap and Bladderoverlap correlated with sparing of that organ but minimally impacted other dose-volume parameters, predicted the primary plan rectum V45 and bladder V50 with R(2) = 0.78 and R(2) = 0.83, respectively, and predicted the boost plan rectum V30 and bladder V30 with R(2) = 0.53 and R(2) = 0.81, respectively. The optimal cutoff value of boost Rectumoverlap to predict rectum V75 >15% was 3.5% (sensitivity 100%, specificity 94%, p < 0.01), and the optimal cutoff value of boost Bladderoverlap to predict bladder V80 >10% was 5.0% (sensitivity 83%, specificity 100%, p < 0.01). CONCLUSION: The degree of overlap between PTV and bladder or rectum can be used to accurately guide physicians on the use of interventions to limit the extent of the overlap region prior to optimization.

The dosimetric effects of photon energy on the quality of prostate volumetric modulated arc therapy.

PURPOSE: Studies comparing the dosimetric effects of high- and low-energy photons to treat prostate cancer using 3-dimensional conformal and intensity modulated radiation therapy have yielded mixed results. With the advent of newer radiation delivery systems like volumetric modulated arc therapy (VMAT), the impact of changing photon energy is readdressed. METHODS AND MATERIALS: Sixty-five patients treated for prostate cancer at our institution from 2011 to 2012 underwent CT simulation. A target volume encompassing the prostate and entire seminal vesicles was treated to 50.4 Gy, followed by a boost to the prostate and proximal seminal vesicles to a total dose of 81 Gy. The VMAT plans were generated for 6-MV and 10-MV photons under identical optimization conditions using the Eclipse system version 8.6 (Varian Medical Systems, Palo Alto, CA). The analytical anisotropic algorithm was used for all dose calculations. Plans were normalized such that 98% of the planning target volume (PTV) received 100% of the prescribed dose. Dose-volumetric data from the treatment planning system was recorded for both 6-MV and 10-MV plans, which were compared for both the entire cohort and subsets of patients stratified according to the anterior-posterior separation. RESULTS: Plans using 10-MV photons had statistically significantly lower relative integral dose (4.1%), gradient measure (4.1%), skin Dmax (16.9%), monitor units (13.0%), and bladder V(30) (3.1%) than plans using 6-MV photons (P < .05). There was no difference in rectal dose, high-dose-region bladder dose, PTV coverage, or conformity index. The benefit of 10-MV photons was more pronounced for thicker patients (anterior-posterior separation >21 cm) for most parameters, with statistically significant differences in bladder V(30), bladder V(65), integral dose, conformity index, and monitor units. CONCLUSIONS: The main dosimetric benefits of 10-MV as compared with 6-MV photons are seen in thicker patients, though for the entire cohort 10-MV plans resulted in a lower integral dose, gradient measure, skin Dmax, monitor units, and bladder V(30), possibly at the expense of higher rectum V(81).

Commissioning and clinical results utilizing the Gildenberg-Laitinen Adapter Device for X-ray in fractionated stereotactic radiotherapy.

BACKGROUND: The Gildenberg-Laitinen Adapter Device for X-Ray (GLAD-X/LS) frame is a positioning device that allows the use of the same fiducial points as the Brown-Robert-Wells (BRW) system. Thus it permits treatment planning to be accomplished by the Radionics X-knife Radiosurgery Program. We investigated the commissioning and clinical benefits of the GLAD-X/LS for fractionated stereotactic radiotherapy (FSRT) in patients who were unable to tolerate the Gill-Thomas-Cosman (GTC) frame. METHODS AND MATERIALS: Commissioning of the GLAD-X/LS system was done via use of a Rando Phantom. A target volume of 2 x 2 x 2 cm was drilled into the phantom head. An ion chamber and thermoluminescence dosimetric chips (TLDs) were implanted in the target. A simulated treatment course consisting of 5 stereotactic radiotherapy fractions (300 cGy, 30 mm collimator) was delivered to the phantom head. A total of 27 patients who could not tolerate the GTC frame were treated using the GLAD-X/LS system. A total of 35 isocenters were used; the median number of treatment fractions was eight. Reproducibility of the x, y, and z coordinates was examined and correlated to the same determined using orthogonal port films. Relocation accuracy and reproducibility were further assessed comparing the x, y, and z coordinates of the target center with multiplanar reconstructed coronal and sagittal images. Patient tolerance of the device was also evaluated daily throughout the treatment. RESULTS: The measured TLD and ion chamber doses were within 3% of the prescribed dose at the isocenter. The same dose accuracy was also found at incremental distances of 5 mm, 10 mm, and 15 mm from the isocenter. All patients tolerated the treatment and the device well. Six patients experienced mild ear canal pain, and softer or smaller earpieces were substituted. The mean relocation accuracy was 1.5 mm +/- 0.8. CONCLUSIONS: The GLAD-X/LS system has excellent accuracy and reproducibility with the mean relocation accuracy of 1.5 mm +/- 0.8. The device is well-tolerated by patients, with no significant complications. Larger scale studies are necessary before routine use can be recommended for the administration of FSRT.

Properties of the 18-MV photon beam from a dual energy linear accelerator.

The beam characteristics of the 18-MV photon beam of a Varian Clinac 1800 are presented. The clinically relevant parameters of central axis depth dose, tissue-phantom ratios, peak-scatter factors, and relative output factors are discussed and compared to 18-MV beam data previously reported. The nominal beam energy was found to be 18.3 +/- 0.8 MV on the central axis. The beam symmetry and uniformity meet the manufacturer's specifications. The inverse-square law is applicable within 1.4% over the clinically useful range of distances and field sizes. An empirical fit equation for the central axis depth dose is presented.

Characteristics of the 6-MV photon beam produced by a dual energy linear accelerator.

Clinical dosimetry data are presented for the lower-energy x-ray beam of a Varian Clinac 1800 linear accelerator. This beam has comparable characteristics to single energy linear accelerators with the same stated 6-MV x-ray energy. The nominal beam energy was found to be 5.3 +/- 0.3 MV on the central axis. Beam quality expressed in terms of half-value layer in water was found to vary by less than 10% over the entire field. The surface doses are only slightly, but consistently, larger than those reported in the literature for other 6-MV linacs. Dosimetric results presented include central axis percentage depth dose (% DD) and tissue-maximum ratio (TMR), surface and buildup doses, output factors, and inverse square law applicability. The flatness and symmetry characteristics are within the manufacturer's specifications for both large and small fields.