Variation in patient position and impact on carbon-ion scanning beam distribution during prostate treatment

Objective:

We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer.

Methods:

68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional–three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes.

Results:

Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D₉₅)-PTV1 was >98% of the prescribed dose.

Conclusion:

Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels.

Advances in knowledge:

Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.The depth dose distribution for a charged particle beam exhibits a Bragg peak at the end of range, which is particularly sensitive to variation in tissue density along its path length. For this reason, changes in patient position perturb charged particle beams more strongly than photon beams.¹ Of the two major treatment uncertainties, intrafractional motion and interfractional changes, treatment accuracy for the prostate appears more strongly affected by interfractional changes.^2–7 Clinical protocols now incorporate several approaches to overcoming these uncertainties, including acquisition of radiographs or cone beam CT images.However, despite these technical solutions to intra- and interfractional changes and improvements in patient positional accuracy during the patient set-up procedure, treatment accuracy may also be affected by positional changes during treatment. Most treatment centres do not check patient positional accuracy after treatment beam irradiation, because approaches to adjusting distribution in the next fraction to compensate for under-/overdosage in the preceding have not been developed and because patient position is assumed not to change during treatment. Our hospital has been providing carbon-ion scanning beam treatment since 2011.⁸ The average time from complete patient set-up to complete beam irradiation was 2.6 min. Although this is relatively short, we have no quantitative data on the effect of patient positional change on carbon-ion scanning dose distribution.In this study, we evaluated patient positional change during treatment and its impact on carbon-ion scanning dose distribution in treatment of the prostate.     

Infliximab treatment for refractory Kawasaki disease with coronary artery aneurysm.

Tumor necrosis factor-alpha (TNF-alpha) is considered to be 1 of the factors that induce vasculitis, including coronary artery aneurysm (CA), in Kawasaki disease (KD), because the blood concentration of TNF-alpha is higher in patients with CA compared with those without. Therefore, an anti-TNF-alphaagent (infliximab) was administered to a 1-month-old girl with refractory KD complicated by CA and subsequently, the CA improved and KD was controlled without complications 20 months after the onset.     

Salvage radiation therapy and chemoradiation therapy for postoperative locoregional recurrence of esophageal cancer

The purpose of this retrospective study was to assess the efficacy of salvage radiation therapy (RT) or chemoradiation therapy (CRT) for locoregional recurrence (LR) of esophageal cancer after curative surgery. Forty‐two patients who received salvage RT or CRT for LR of esophageal cancer after curative surgery between November 2000 and May 2012 were reviewed. The intended RT regimen was 60 Gy in 30 fractions combined with concurrent platinum‐based chemotherapy. Median follow‐up periods were 17.9 months for all evaluable patients and 28.2 months for patients still alive (19 patients) at analysis time. The 1‐, 2‐, and 3‐year survival rates were 81.2 ± 6.4%, 51.3 ± 8.6%, and 41.1 ± 8.7%, respectively, with a median survival time of 24.3 ± 4.1 months. Out of 41 evaluable patients, 16 patients (39%) were alive beyond 2 years from salvage therapy. However, univariate analyses for overall survival showed no significant prognostic factor. Grade 3 or higher leukocytopenia was observed in 46% of the patients. Salvage RT or CRT for LR after surgery for esophageal cancer was safe and effective. These therapies may offer long‐term survival to some patients. RT or CRT should be considered for LR.     

Digital Thermography of the Fingers and Toes in Raynaud's Phenomenon

The aim of this study was to determine whether skin temperature measurement by digital thermography on hands and feet is useful for diagnosis of Raynaud''s phenomenon (RP). Fifty-seven patients with RP (primary RP, n = 33; secondary RP, n = 24) and 146 healthy volunteers were recruited. After acclimation to room temperature for 30 min, thermal imaging of palmar aspect of hands and dorsal aspect of feet were taken. Temperature differences between palm (center) and the coolest finger and temperature differences between foot dorsum (center) and first toe significantly differed between patients and controls. The area under curve analysis showed that temperature difference of the coolest finger (cutoff value: 2.2℃) differentiated RP patients from controls (sensitivity/specificity: 67/60%, respectively). Temperature differences of first toe (cutoff value: 3.11℃) also discriminated RP patients (sensitivity/specificity: about 73/66%, respectively). A combination of thermographic assessment of the coolest finger and first toe was highly effective in men (sensitivity/specificity : about 88/60%, respectively) while thermographic assessment of first toe was solely sufficient for women (sensitivity/specificity: about 74/68%, respectively). Thermographic assessment of the coolest finger and first toe is useful for diagnosing RP. In women, thermography of first toe is highly recommended.

Graphical Abstract

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Skin toxicity predicts efficacy to sorafenib in patients with advanced hepatocellular carcinoma

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