Rectal volume variations and estimated rectal dose during 8 weeks of image-guided radical 3D conformal external beam radiotherapy for prostate cancer.

•Modern IGRT has given new insight regarding organ motion in radiotherapy.•Rectal volume variation may increase the risk of biochemical and local failure.•Rectal volume decreased significantly during eight weeks of radiotherapy.•The percentage of irradiated rectal volume did not change statistically significant.•Our study shows that IGRT ensures a close to stable dose to the rectum.

Dose to penile bulb is not associated with erectile dysfunction 18 months post radiotherapy: A secondary analysis of a randomized trial.

BACKGROUND: Erectile dysfunction is a common side effect of prostate cancer (PC) therapy. In this randomized study (The RIC-study) we used patient reported outcomes to evaluate sexual function 18 months after combined endocrine therapy and radical radiotherapy (RT) given with either wide or tight planning target volume (PTV) margins. We also analyzed the impact of radiation dose to penile bulb on sexual function. METHODS: The RIC-study included 257 men with intermediate and high-risk PC. All patients received 6 months of total androgen blockage started 3 months prior to randomization. In high-risk patients, an oral anti-androgen (Bicalutamide) was administered for an additional 2.5 years. Patients were randomized to receive 78 Gy in 39 fractions guided either by weekly offline orthogonal portal imaging or by daily online cone beam computed tomography image-guided RT. Sexual function was evaluated at 18 months after start of RT using the Questionnaire Umeå Fransson Widmark 1994. Ability to have an erection was assessed on an 11-point scale numerical rating scale (0 = no and 10 = very much) as the primary outcome. In addition, the association between penile bulb (PB) radiation dose and erectile function was analyzed. FINDINGS: Of 250 evaluable patients, 228 (mean age 71.8 years) returned the questionnaires. The patients reported a high degree of sexual related problems with mean scores to the primary outcome question (221 respondents) of 7.44 and 7.39 in the 2D weekly IGRT-arm and 3D daily IGRT-arm (p = 0.93) respectively. For four additional questions (scale 0-10) regarding sexual function resulted in mean scores >6.5 with no difference between study arms. The mean dose to PB was substantially larger in the 2D weekly IGRT-arm vs the 3D daily IGRT-arm (mean 59.8 Gy vs mean 35.1 Gy).We found no effect of mean PB-dose on the primary outcome adjusted for study-site, risk-group and age. When adjusting for serum-testosterone level at 18 months in addition, the effect of mean PB-dose remained insignificant. INTERPRETATION: IGRT protocol or PB dose had no effect on ED 18 months after RT in this study population. The low potency rates can partly be explained by the prolonged use of anti-androgen in high risk patients. Longer follow-up is needed to confirm the results from the RIC-study.

Radiotherapy for prostate cancer - Does daily image guidance with tighter margins improve patient reported outcomes compared to weekly orthogonal verified irradiation? Results from a randomized controlled trial.

BACKGROUND: Novel cancer drugs are subject to strict scientific evaluation of safety and efficacy and usually undergo a cost effectiveness analysis before approval for use in clinical practice. For new techniques in radiotherapy (RT) such as image-guided radiotherapy (IGRT), this is often not the case. We performed a randomized controlled trial to compare daily cone beam computer tomography (CBCT) IGRT with reduced planning target volume (PTV) margins vs weekly orthogonal portal imaging with conventional PTV margins. The primary aim of the study was to investigate the effect of two different image guidance techniques on patient reported outcome (PRO) using early side effects as proxy outcome of late rectal side effects in patients receiving curative RT for prostate cancer. METHODS: This open label, phase 3 trial conducted at two RT centers in Norway enrolled men aged 18 years or older with previously untreated histologically proven intermediate or high-risk adenocarcinoma of the prostate. Patients eligible for radical RT received it after 3 months of total androgen blockage and were randomly assigned to 78 Gy in 39 fractions guided either by weekly offline orthogonal portal imaging (15 mm margins to PTV) or by daily online CBCT IGRT (7 mm margins to PTV). Based on previous results indicating that acute rectal side effects are a valid proxy outcome for late rectal side effects, the primary outcome was acute rectal toxicity at end of RT as evaluated by rectal bother scale (five of the items from PRO's QUFW94). The RIC-trial is registered with ClinicalTrials.gov, number NCT01550237. FINDINGS: Between October 2012 and June 2015, 257 patients were randomly assigned to weekly offline portal imaging (n = 129) or daily online CBCT IGRT (n = 128). Out of 250 evaluable patients, 96% completed PROs at baseline and 97% at end of RT. Baseline analyses demonstrated balance between groups for baseline characteristics as well as for PROs. In general, patients reported a small degree of side effects at end of RT, and there was no difference between groups for primary outcome (rectal bother scale of QUFW94 1.871 vs 1.884, p = 0.804). In addition, there were no significant differences between groups for any other gastrointestinal or urinary symptom as reported by QUFW94. Health related quality of life analyses (EORTC QLQ 30) demonstrated no differences between groups. INTERPRETATION: In radical RT for prostate cancer, daily CBCT IGRT with reduced PTV margins demonstrated no advantage with respect to patient reported side effects at end of RT as compared to weekly orthogonal offline portal imaging with standard PTV margins.

Robustness of VMAT and 3DCRT plans toward setup errors in radiation therapy of locally advanced left-sided breast cancer with DIBH.

PURPOSE: The aim of our study was to evaluate and compare the robustness of treatment plans produced using the volumetric modulated arc-therapy (VMAT) and the standard three-dimensional conformal radiotherapy (3DCRT) techniques by estimating perturbed doses induced by localization offsets for deep inspiration breath-hold (DIBH) in locally advanced breast cancer radiation therapy. METHODS: Twenty patients with left breast carcinoma requiring radiation therapy were analysed in this planning study. Robust VMAT plans regarding minimum CTV doses and standard 3DCRT plans were produced, and perturbed doses were calculated in accordance with localization values from the weekly offline imaging protocol. Offsets from 5 weeks were summed to a perturbed overall treatment plan. Dose criteria for evaluation were coverage and homogeneity of the target, as well as doses to organs at risk. RESULTS: VMAT plans resulted in significantly better target coverage compared to 3DCRT, as well as lowered doses to heart and left anterior descending artery, while the perturbed doses were less variable for VMAT than 3DCRT plans. Homogeneity was significantly improved in VMAT plans. The statistical analysis taking all organs into account found that VMAT plans were more robust than 3DCRT to localization offsets (p = .001). The overall mean setup-deviation for the DIBH-patients was less than 2 mm in all directions. CONCLUSIONS: VMAT plans were more robust on average than conventional 3DCRT plans for DIBH when localization errors were taken into consideration. The combination of robust VMAT planning and DIBH generally improves the homogeneity and target doses.

Intrafractional baseline drift during free breathing breast cancer radiation therapy.

BACKGROUND: Intrafraction motion in breast cancer radiation therapy (BCRT) has not yet been thoroughly described in the literature. It has been observed that baseline drift occurs as part of the intrafraction motion. This study aims to measure baseline drift and its incidence in free-breathing BCRT patients using an in-house developed laser system for tracking the position of the sternum. MATERIALS AND METHODS: Baseline drift was monitored in 20 right-sided breast cancer patients receiving free breathing 3D-conformal RT by using an in-house developed laser system which measures one-dimensional distance in the AP direction. A total of 357 patient respiratory traces from treatment sessions were logged and analysed. Baseline drift was compared to patient positioning error measured from in-field portal imaging. RESULTS: The mean overall baseline drift at end of treatment sessions was -1.3 mm for the patient population. Relatively small baseline drift was observed during the first fraction; however it was clearly detected already at the second fraction. Over 90% of the baseline drift occurs during the first 3 min of each treatment session. The baseline drift rate for the population was -0.5 ± 0.2 mm/min in the posterior direction the first minute after localization. Only 4% of the treatment sessions had a 5 mm or larger baseline drift at 5 min, all towards the posterior direction. Mean baseline drift in the posterior direction in free breathing BCRT was observed in 18 of 20 patients over all treatment sessions. CONCLUSIONS: This study shows that there is a substantial baseline drift in free breathing BCRT patients. No clear baseline drift was observed during the first treatment session; however, baseline drift was markedly present at the rest of the sessions. Intrafraction motion due to baseline drift should be accounted for in margin calculations.

Development of a deep inspiration breath-hold system for radiotherapy utilizing a laser distance measurer.

Deep inspiration breath-hold (DIBH) is a technique for treating left-sided breast cancer (LSBC). In modern radiotherapy, one of the main aims is to exclude the heart from the beam aperture with an individualized beam design for LSBC. A deep inhalation will raise the chest wall while the volume of the lungs increase, this will again push the heart away from the breast to be treated. There are a few commercial DIBH systems, both invasive and noninvasive. We present an alternative noninvasive DIBH system based upon an industrial laser distance measurer. This system can be installed in a treatment room at a low cost; it is very easy to use and requires limited amount of training for the personnel and the patient. The system is capable of measuring the position of the chest wall with high frequency and precision in real time. The patient views its breathing curve through video glasses, and gets instructions during the treatment session. The system is well tolerated by test subjects due to its noninvasiveness.