On voxel-by-voxel accumulated dose for prostate radiation therapy using deformable image registration.

Since delivered dose is rarely the same with planned, we calculated the delivered total dose to ten prostate radiotherapy patients treated with rectal balloons using deformable dose accumulation (DDA) and compared it with the planned dose. The patients were treated with TomoTherapy using two rectal balloon designs: five patients had the Radiadyne balloon (balloon A), and five patients had the EZ-EM balloon (balloon B). Prostate and rectal wall contours were outlined on each pre-treatment MVCT for all patients. Delivered fractional doses were calculated using the MVCT taken immediately prior to delivery. Dose grids were accumulated to the last MVCT using DDA tools in Pinnacle3 TM (v9.100, Philips Radiation Oncology Systems, Fitchburg, USA). Delivered total doses were compared with planned doses using prostate and rectal wall DVHs. The rectal NTCP was calculated based on total delivered and planned doses for all patients using the Lyman model. For 8/10 patients, the rectal wall NTCP calculated using the delivered total dose was less than planned, with seven patients showing a decrease of more than 5% in NTCP. For 2/10 patients studied, the rectal wall NTCP calculated using total delivered dose was 2% higher than planned. This study indicates that for patients receiving hypofractionated radiotherapy for prostate cancer with a rectal balloon, total delivered doses to prostate is similar with planned while delivered dose to rectal walls may be significantly different from planned doses. 8/10 patients show significant correlation between rectal balloon anterior-posterior positions and some VD values

Does practice analysis agree with the ambulatory care sensitive conditions list of avoidable unplanned admissions: cross-sectional study in the East of England.

Objectives: To use Significant Event Audits (SEA) in primary care to determine which of a sample of emergency (unplanned) admissions were potentially avoidable; and compare to the NHS list of ambulatory care sensitive conditions (ACSCs). Design: Analysis of unplanned medical admissions randomly identified in secondary care. Setting: Primary Care in the East of England. Participants: 20 general practice teams trained to use SEA on unplanned admissions to identify potentially preventable factors. Interventions: SEA of admissions. Main outcome measures: Level of agreement between those admissions identified as potentially preventable by SEA and the NHS ACSC list. Results: 132 (26%) of randomly selected patients with unplanned admissions gave consent and an SEA was performed by their primary practice team. 130 SEA reports had sufficient data for our analysis. Practices concluded that 17 (13%) of admissions were potentially preventable. The NHS ACSC list identified 36 admissions (28%) as potentially preventable. There was a low level of agreement between the practices and the NHS list as to which admissions were preventable (Kappa = 0.253). The ACSC list consisted mainly of respiratory admissions whereas the practice list identified a wider range of cases and identified context-specific factors as important. Conclusions: There was disagreement between the NHS list and practice conclusions of potentially avoidable admissions. The SEAs suggest that the pathway into unplanned admission may be less dependent on the condition than on context-specific factors, and the assumption that unplanned admissions for ACSC conditions are reasonable indicators of performance for primary care may not be valid

In vivo real-time rectal wall dosimetry for prostate radiotherapy

Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for realtime in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70 μm. Two MOSFETs were combined in a face-to-face orientation. The reproducibility, sensitivity and angular dependence were measured for the dual MOSFET in a 6 MV photon beam. The dual MOSFET was combined with a rectal balloon and irradiated with hypothetical prostate treatments in a phantom. The anterior rectal wall dose was measured in real time and compared with the planning system calculated dose. The dual MOSFET showed angular dependence within ±2.5% in the azimuth and +2.5%/−4% in the polar axes. When compared with an ion chamber measurement in a phantom, the dual MOSFET agreed within 2.5% for a range of radiation path lengths and incident angles. The dual MOSFET had reproducible sensitivity for fraction sizes of 2–10 Gy. For the hypothetical prostate treatments the measured anterior rectal wall dose was 2.6 and 3.2% lower than the calculated dose for 3DCRT and IMRT plans. This was expected due to limitations of the dose calculation method used at the balloon cavity interface. A dual MOSFET combined with a commercial rectal balloon was shown to provide reproducible measurements of the anterior rectal wall dose in real time. The measured anterior rectal wall dose agreed with the expected dose from the treatment plan for 3DCRT and IMRT plans. The dual MOSFET could be read out in real time during the irradiation, providing the capability for real-time dose monitoring of the rectal wall dose during treatment

Surface dosimetry for breast radiotherapy in the presence of immobilization cast material

Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range ofwater equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions

Applicability and usage of dose mapping/accumulation in radiotherapy

Dose mapping/accumulation (DMA) is a topic in radiotherapy (RT) for years, but has not yet found its widespread way into clinical RT routine. During the ESTRO Physics workshop 2021 on "commissioning and quality assurance of deformable image registration (DIR) for current and future RT applications", we built a working group on DMA from which we present the results of our discussions in this article. Our aim in this manuscript is to shed light on the current situation of DMA in RT and to highlight the issues that hinder consciously integrating it into clinical RT routine. As a first outcome of our discussions, we present a scheme where representative RT use cases are positioned, considering expected anatomical variations and the impact of dose mapping uncertainties on patient safety, which we have named the DMA landscape (DMAL). This tool is useful for future reference when DMA applications get closer to clinical day-to-day use. Secondly, we discussed current challenges, lightly touching on first-order effects (related to the impact of DIR uncertainties in dose mapping), and focusing in detail on second-order effects often dismissed in the current literature (as resampling and interpolation, quality assurance considerations, and radiobiological issues). Finally, we developed recommendations, and guidelines for vendors and users. Our main point include: Strive for context-driven DIR (by considering their impact on clinical decisions/judgements) rather than perfect DIR; be conscious of the limitations of the implemented DIR algorithm; and consider when dose mapping (with properly quantified uncertainties) is a better alternative than no mapping

Dosimetric Consequences of 3D Versus 4D PET/CT for Target Delineation of Lung Stereotactic Radiotherapy

Introduction:Lung tumor delineation is frequently performed using 3D positron emission tomography (PET)/computed tomography (CT), particularly in the radiotherapy treatment planning position, by generating an internal target volume (ITV) from the slow acquisition PET. We investigate the dosimetric consequences of stereotactic ablative body radiotherapy (SABR) planning on 3D PET/CT in comparison with gated (4D) PET/CT.Methods:In a prospective clinical trial, patients with lung metastases were prescribed 26 Gy single-fraction SABR to the covering isodose. Contemporaneous 3D PET/CT and 4D PET/CT was performed in the same patient position. An ITV was generated from each data set, with the planning target volume (PTV) being a 5-mm isotropic expansion. Dosimetric parameters from the SABR plan derived using the 3D volumes were evaluated against the same plan applied to 4D volumes.Results:Ten lung targets were evaluated. All 3D plans were successfully optimized to cover 99% of the PTV by the 26 Gy prescription. In all cases, the calculated dose delivered to the 4D target was less than the expected dose to the PTV based on 3D planning. Coverage of the 4D-PTV by the prescription isodose ranged from 74.48% to 98.58% (mean of 90.05%). The minimum dose to the 4D-ITV derived by the 3D treatment plan (mean = 93.11%) was significantly lower than the expected dose to ITV based on 3D PET/CT calculation (mean = 111.28%), p < 0.01. In all but one case, the planned prescription dose did not cover the 4D-PET/CT derived ITV.Conclusions:Target delineation using 3D PET/CT without additional respiratory compensation techniques results in significant target underdosing in the context of SABR

The Effects of Enhancement Strategies of Beef Flanks on Composition and Consumer Palatability Characteristics

Beef rectus abdominis muscles (n = 100; 20/treatment) were assigned randomly to 1 of 5 treatments: untreated control (Control, No Treatment; CNT), vacuum tumbled control without marinade (Tumbled Control, No Treatment; TCNT), vacuum tumbled with marinade (TUMB), injected with marinade (INJ), and injected with marinade plus vacuum tumbled (IPT) to determine how enhancement techniques influence consumer palatability. After processing, flank samples were cooked (72°C), cut into 1.3-cm strips, and served as fajita strips for consumer evaluation (n = 200). Treatment influenced (P &lt; 0.01) the rating and acceptability of all palatability traits, overall liking, and willingness to pay (WTP). Consumers scored IPT and INJ more tender compared to all other treatments (P &lt; 0.05). Samples processed using IPT and INJ were juicier (P &lt; 0.05) than all other treatments, except INJ and TUMB were similar (P &gt; 0.05). Samples processed using TUMB and INJ were similar (P &gt; 0.05) for flavor and WTP, and INJ, IPT, and TUMB samples were similar (P &gt; 0.05) for overall liking. Thus, consumers were willing to pay more for IPT than TUMB (P &lt; 0.05). Consumers scored CNT and TCNT lower for all palatability traits which resulted in lower WTP (P &lt; 0.05). Inclusion of a marinade improved the eating quality of samples compared to CNT and TCNT. The delivery method of the brine solution was less important to palatability as the presence of a marinade, as IPT, INJ, and TUMB were all similar (P &gt; 0.05) for overall liking. Injection plus tumbling improved tenderness, juiciness, and flavor liking scores over tumbling alone, but not over injection alone. Injection influenced consumer tenderness more than tumbling, but tumbling had greater effects on cooked moisture than injection. While IPT did not surpass either TUMB or INJ in all sensory categories, IPT does excel when considering moisture retention along with palatability

Carcass Yield and Subprimal Cutout Value of Beef, High- and Low-Yielding Beef × Dairy, and Dairy Steers

This study compared carcass yield and cutout value of conventional beef and dairy cattle to high-yielding (HY) and low-yielding (LY) crossbred beef × dairy cattle and identified the contribution of carcass regions to carcass yield andcutout value among beef × dairy crossbreds. Carcasses of conventional beef, beef × dairy crossbred, and dairy cattle were selected according to industry-average slaughter endpoints for their cattle type. Carcasses were fabricated at a commercial processing facility, and weights of carcass components were obtained. Post hoc subsampling was used to segregate HY and LY beef × dairy crossbreds based on subprimal yield. Multiple linear regression was used to assess carcass yield and sub-primal cutout value between the 4 cattle types (n=21 to 26 per cattle type). Beef cattle and HY crossbreds produced 1.59 to 3.04 percentage units greater (P&lt;0.05) subprimal yield than LY crossbreds and dairy cattle. Dairy cattle produced at least 1.16 percentage units more (P&lt;0.05) bone than any other cattle type. Subprimal to bone was not different (P&gt;0.05) between HY crossbreds and beef cattle, and subprimal to fat was lesser (P&lt;0.05) in HY crossbreds than beef cattle. Subprimal cutout value was more than 5 US dollars (USD)/45.4 kg different (P&lt;0.05) between cattle types, which were ranked HY crossbreds &gt; beef cattle &gt; LY crossbreds &gt; dairy cattle. In beef × dairy cattle, subprimal to bone in the round contributed most greatly to an increase (P=0.02), by 3.79 USD/45.4 kg, in subprimal cutout value. Together, these results suggested carcass value of beef × dairy cattle may be maximized when cattle are harvested at a lesser overall fatness than conventional beef cattle and when considerable muscling, especially in the round, is achieved

NaF PET/CT for response assessment of prostate cancer bone metastases treated with single fraction stereotactic ablative body radiotherapy

Introduction: In prostate cancer patients, imaging of bone metastases is enhanced through the use of sodium fluoride positron emission tomography (18F-NaF PET/CT). This imaging technique shows areas of enhanced osteoblastic activity and blood flow. In this work, 18F-NaF PET/CT was investigated for response assessment to single fraction stereotactic ablative body radiotherapy (SABR) to bone metastases in prostate cancer patients. Methods: Patients with bone metastases in a prospective trial treated with single fraction SABR received a 18F-NaF PET/CT scan prior to and 6 months post-SABR. The SUVmax in the tumour was determined and the difference between before and after SABR determined. The change in uptake in the non-tumour bone was also measured as a function of the received SABR dose. Results: Reduction in SUVmax was observed in 29 of 33 lesions 6 months after SABR (mean absolute decrease in SUVmax 17.7, 95% CI 25.8 to - 9.4, p = 0.0001). Of the three lesions with increased SUVmax post-SABR, two were from the same patient and located in the vertebral column. Both were determined to be local progression in addition to one fracture. The third lesion (in a rib) was shown to be controlled locally but suffered from a fracture at 24 months. Progression adjacent to the treated volume was observed in two patients. The non-tumour bone irradiated showed increased loss in uptake with increasing dose, with a median loss in uptake of 23.3% for bone receiving 24 Gy. Conclusion: 18F-NaF PET/CT for response assessment of bone metastases to single fraction SABR indicates high rates of reduction of osteoblastic activity in the tumour and non-tumour bone receiving high doses. The occurrence of marginal recurrence indicates use of larger clinical target volumes may be warranted in treatment of bone metastases. Trial registration: POPSTAR, \u27Pilot Study of patients with Oligometastases from Prostate cancer treated with STereotactic Ablative Radiotherapy\u27, Universal Trial Number U1111-1140-7563, Registered 17th April 2013