Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope

PURPOSE

To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs.

MATERIALS AND METHODS

PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations.

RESULTS

Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover ∼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment.

CONCLUSION

A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.

Development and evaluation of a novel pre-operative surgery school and behavioural change intervention for patients undergoing elective major surgery: Fit-4-Surgery School

Group pre-operative education has usually been limited to conditioning expectations and providing education. Prehabilitation has highlighted modifiable lifestyle factors that are amenable to change and may improve clinical outcomes. We instituted a pre-operative 'Fit-4-Surgery School' for patients scheduled for major surgery, to educate and promote healthy behaviour. We evaluated patients' views having attended the school, and after surgery we asked how it had changed their behaviour with a lifestyle questionnaire. The school was launched in May 2016 and was attended by 586/1017 (58%) of invited patients. Patients who did not attend: lived further away, median (IQR [range]) 8 (4-19 [0-123]) miles vs. 5 (3-14 [0-172]) miles, p < 0.001; and were more deprived, Index of Multiple Deprivation Rank decile median (IQR [range]), 6 (4-8 [1-10]) vs. 7 (4-9 [1-10]), p = 0.04. Of the 492/586 (84%) participants who completed an evaluation questionnaire, 462 (94%) would recommend the school to a friend having surgery and 296 (60%) planned lifestyle changes. After surgery, 232/586 (40%) completed a behavioural change questionnaire, 106 (46%) of whom reported changing at least one lifestyle factor, most commonly by increasing exercise. The pre-operative school was acceptable to patients.

Poor Appetite Is Associated with Six Month Mortality in Hospitalised Older Men and Women

OBJECTIVES

Appetite loss is common in hospitalised older individuals but not routinely assessed. Poor appetite in hospital has previously been identified as predictive of greater mortality in the six months following discharge in a single study of female patients. The present study aimed to assess this association in a larger sample including both hospitalised men and women.

DESIGN

Longitudinal observational study with six month follow up.

SETTING

Acute hospital wards in a single large hospital in England.

PARTICIPANTS

Older inpatients aged over 70 years.

MEASUREMENTS

Appetite was assessed using the Simplified Nutritional Appetite Questionnaire (SNAQ) during hospital stay. Deaths during six month follow-up period were recorded. Association between SNAQ score during hospital admission and death 6 months post-discharge was assessed using binary logistic regression in unadjusted and adjusted analysis.

RESULTS

296 participants (43% female, mean age 83 years (SD 6.9)) were included in this study. Prevalence of poor appetite (SNAQ score <14) was 41%. In unadjusted analysis a SNAQ score of <14 was associated with a 2.47 increase in odds of mortality at six months (OR 2.47 (95% CI 1.27,4.82)). This association remained after adjusting for number of comorbidities (Charlson index), length of stay and gender (OR 2.62 (95% CI 1.30, 5.27)). In unadjusted continuous analysis, every one point decrease in SNAQ score led to a 1.20 fold increase in odds of mortality at six months (OR 1.20 (95% CI 1.06-1.36)). This association remained in adjusted analysis (OR 1.22 (95% CI 1.07-1.39)).

CONCLUSION

Poor appetite is common in hospitalised older people. We have confirmed the association, previously reported in older women, between poor appetite during hospital stay and greater mortality at six months post-discharge but in a larger study including older men and women. Further research is needed to understand the mechanisms of poor appetite, which lead to increased mortality.

Abstract P5-10-07: TACT2 Randomised Adjuvant Trial in Early Breast Cancer (EBC): Tolerability and Toxicity of Standard 3 Weekly Epirubicin (E) Versus Accelerated Epirubicin (aE) Followed by Capecitabine (X) or CMF in 129 UK Hospitals (CRUK/05/019)

Introduction: TACT2, a multicentre phase III trial with E-CMF as control (NEAT Poole NEJM 2006), tests 2 hypotheses in a 2x2 factorial design: A) accelerating chemotherapy (CT) offers superior benefits (CALGB9741 Citron JCO 2003); B) the oral 5FU prodrug X gives similar efficacy but preferential side-effect profile to CMF. Here, focus is on hypothesis B with results for compliance, QL & acute toxicities (physician & patient (pt) reported) during CMF vs. X

Materials &

Methods: 4391 pts (4371 women, 20 men) with node+ve/high risk node-ve invasive EBC were recruited between Dec 2005-08. Treatment was E(100mg/m2 x 4) q3wk vs q2wk aE(100mg/m2 x 4 + pegfilgrastim 6mg d2) followed by classical CMF q4wk x 4 vs X(2500mg/m2/day x 14) q3wk x 4. Detailed CTCAE toxicity was assessed in a subset (38 centres, 2086 pts receiving ≥1 cycle CMF or X). 1279/2086 also participated in substudy of pt-reported outcomes (EORTC QLQ-C30 and TACT2-specific toxicities). 826 had complete dataset (baseline, cycles 4&8). P-values are trend tests across all grades & %grade 3+ are reported. QL assessed via linear regression models adjusted for baseline, end cycle 4 score, & aE vs E. P&lt;0.01 classed as significant

QL in cycles 5-8 was better with X than CMF for global QL& fatigue (P&lt;0.001). Pts reporting clinically meaningful deterioration (&gt;10 points): global QL CMF 106/398 (27%), X 79/428 (18%); fatigue CMF 164/398 (41%), X 122/428 (29%)).

Conclusion: TACT2, the largest adjuvant EBC trial with X, confirms that X has preferential side-effect profile and global QL compared to CMF, with no evidence that prior aE compromised treatment delivery. Dose delivery data are consistent with advanced disease observations that for some pts, 2000mg/m2/day may be correct dose.

Results: 4264 (97%) pts continued on CT beyond cycle 4. 3726 completed all 8 cycles (E-CMF 951 (85%), aE-CMF 938 (86%), E-X 932 (84%), aE-X 905 (83%). For cycles 5-8, %RDI &gt; 85% was 69% after E and 68% after aE. Cycles delivered on time CMF 59%, X 63%; cycles without dose reduction CMF 75%, X 62%. 15 deaths in total within 30 days of CT: 9 on CMF, 6 on X. Worst grade toxicities which differed between CMF & X during cycles 5-8: