Considerable Anatomical Variation Research Articles

Posterior auricular artery

Introduction: The posterior auricular artery (PAA) is the preterminal branch of the external carotid artery (ECA), arising superiorly to the occipital artery (OA). The PAA has quite a few anatomical variations and established neurosurgical applications. We conducted this study as an overview to illustrate all neurosurgical aspects regarding this artery, its reconstructive uses, and anatomical variation. Method: We performed a literature review in Google Scholar and PubMed medical databases for studies discussing the PAA, its anatomical variations, and neurosurgical applications. Results: We identified 30 articles that discuss the anatomical variations and neurosurgical applications of the PAA. While reviewing the available articles and original works regarding PAA. Conclusion: The PAA has considerable anatomical variations regarding its origin, course, branches, and length. The related neurosurgical applications of PAA include bypass, embolization, aneurysm, AVM, and reconstruction flaps.

3D anatomy of the supraorbital and greater occipital nerve trajectories.

This research aims to enhance understanding of the anatomy of the supraorbital nerve (SON) and greater occipital nerve (GON), focusing on their exit points, distal trajectories, and variability, utilizing a novel 3D representation. Ten cadaveric specimens underwent meticulous dissection, and 3D landmarks were registered. Models were generated from CT scans, and a custom 3D method was employed to visualize nerve trajectories. Measurements, including lengths and distances, were obtained for the SON and GON. The SON exhibited varied exit points, with the lateral branches being the longest. The GON showed distinct branching patterns, which are described relative to various anatomical reference points and planes. No systematic left-right differences were observed for either nerve. 3D analysis revealed significant interindividual variability in nerve trajectories. The closest approximation between the SON and GON occurred between lateral branches. The study introduces a novel 3D methodology for analyzing the SON and GON, highlighting considerable anatomical variation. Understanding this variability is crucial for clinical applications and tools targeting the skull innervation. The findings serve as a valuable reference for future research, emphasizing the necessity for personalized approaches in innervation-related interventions.

An assessment of the variation of the intramuscular innervation of the gracilis muscle, with the aim of determining its neuromuscular compartments.

Some muscles present neuromuscular compartments, one of which is the gracilis muscle. The aim of the present study is to determine the number of compartments present within the gracilis muscle based on its intramuscular innervation patterns; such knowledge could be of value in free functional muscle transfer. The study comprised 72 gracilis muscles (38 women, 34 men), fixed in 10% formalin solution. The muscles were removed and then stained using Sihler's method. When sufficient transparency was achieved, some measurements were made. Three different types of intramuscular innervation were distinguished. Type I (70.8%) was featured by at least one direct proximal nerve branch. Type II (23.6%) presented at least one indirect proximal nerve branch. Type III (5.6%) did not possess any proximal nerve branch. The median of descended nerve branches was five. Considerable anatomical variation is possible within the intramuscular innervation of the gracilis muscle. The muscle presents neuromuscular compartments, but the exact number depends on the type of its intramuscular innervation and the number of the main descendent nerve branches. All three types seem to be appropriate for free functional muscle transfer. Our findings may be of great value for surgeons carrying out complex reconstructions with the use of the gracilis muscle.

Sagittal femoral condylar shape varies along a continuum from spherical to ovoid: a systematic review and meta-analysis.

Considerable anatomic variations of sagittal femoral condylar shape have been reported, with a continuum between spherical (or single-radius) and ovoid (or multi-radius) condyles. The purpose of this systematic review and meta-analysis was to critically appraise and synthesise the available literature on the sagittal femoral profile. The hypothesis was that studies would reveal considerable variability among individuals, but also in their methodology to quantify sagittal profiles. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. On 10 September 2021 two authors searched for Level I to IV studies that reported on the sagittal curvature of the medial and/or lateral femoral condyles using the MEDLINE®, EMBASE® and Cochrane Library. Results were summarised by tabulating means, standard deviations and/or ranges for the reported radii-of-curvature, or ellipsoidal semi-major and semi-minor lengths of the condyles. To quantify sagittal 'ovoidicity' and asymmetry, results were stratified according to coordinate reference frame (posterior condylar axis (PCA), clinical and surgical transepicondylar axis (cTEA and sTEA), unified sagittal plane (USP), or unclear) and summarised in forest plots as standardised mean differences (SMD). Thirty-eight articles wereeligible for full text extraction, quantifyingsagittal radii-of-curvature by best-fit circles (BFC), ellipsoids, polynomials, spherical or cylindrical fitting. Studies with clear definition of the measurement plane revealed that both condyles were generally ovoid, with considerably greater 'ovoidicity' at the medial condyle (SMD, 4.09) versus the lateral condyle (SMD, 3.33). In addition, distal condylar radii were greater medially when measured normal to the TEA (cTEA: SMD, 0.81; sTEA: SMD, 0.79), but greater laterally when measured in a USP (SMD, -0.83). Posterior condylar radii were greater laterally when measured in a USP (SMD, -0.60). Studies reported considerable variability of sagittal femoral condylar radii-of-curvature, which arenot incremental, but rathera continuum that ranges from spherical to ovoid. Although this variation could be accommodated by single-, dual- and multi-radii femoral components, a surgeon typically uses only one or two TKA designs. Hence, there is a risk of mismatch between the native and prosthetic sagittal profile that could result in mid-flexion ligament imbalance unless other parameters are changed. These findings support the drive towards patient-specific implants to potentially achieve accurate sagittal bone-implant fit through implant customisation. IV.

Cone-Beam CT-assisted navigation for endovascular treatment of erection-related artery stenosis in patients with erectile dysfunction

BackgroundAngioplasty and stenting have emerged as endovascular treatment options for arteriogenic erectile dysfunction over the past few years. Considerable anatomical variation of the erection related pelvic arteries can be challenging during these procedures, leading to time-consuming repetitive super-selective angiograms for navigation.TechniqueWe report a novel technique of using C-arm Cone-Beam CT and vessel navigation software to facilitate super-selective catheterization.ConclusionCone-Beam CT-guided navigation for vascular assessment of arteriogenic ED is an optional approach compared to exclusive angiographic assessment. Compared to CT angiography, C-arm Cone-Beam CT offers benefits regarding usage of contrast media and radiation exposure. It has the advantage to combine imaging with endovascular procedures in a single session, reduces time to target navigation in complex pelvic arteries anatomy and may increase therapy safety in endovascular treatment of ED.

A new classification system for the anatomical variations of the human circle of Willis: A systematic review.

The circle of Willis (CoW) is an anastomotic arterial network located on the base of the brain. Studies have shown that it demonstrates considerable anatomical variation in humans. This systematic review aimed to identify and catalogue the described anatomical variations of the CoW in humans to create a new, comprehensive variation classification system. An electronic literature search of five databases identified 5899 studies. A two‐phase screening process was performed, and studies underwent quality assessment. A total of 42 studies were included in the review. Data were extracted and circles were reconstructed digitally using graphics software. The classification system contains 82 CoW variations in five continuous groups. Group one contains 24 circles with one or more hypoplastic segments only. Group two contains 11 circles with one or more absent segments only. Group three contains 6 circles with hypoplastic and absent segments only. Group four contains 26 circles with one or more accessory segments. Group five contains 15 circles with other types of anatomical variation. Within each group, circles were subcategorised according to the number or type of segments affected. An original coding system was created to simplify the description of anatomical variations of the CoW. The new classification system provides a comprehensive ontology of the described anatomical variations of the CoW in humans. When used with the coding system, it allows the description and categorisation of recorded and unrecorded variants identified in past and future studies. It is applicable to current clinical practice and the anatomical community, including human anatomy education and research.

Description of a safe doppler ultrasound-guided technique for hyaluronic acid filler in the face-A method to avoid adverse vascular events.

Knowledge of facial anatomy is essential for professionals intending to inject hyaluronic acid (HA) into that region, but due to the considerable anatomical variations in region, it does not guarantee the complete safety of the procedure. Similarly, procedures widely disseminated among professionals, such as aspiration and the use of cannulas, do not ensure total safety against vascular occlusion events caused by the filler. This article describes a technique for injecting hyaluronic acid into the face guided by Doppler ultrasonography (DUS) in order to ensure greater safety against vascular occlusion events secondary to the procedure. We describe a Doppler ultrasound-guided filling technique, with an 18MHZ transducer, consisting of three steps: arterial mapping, real-time ultrasound-guided filling, and assessing the perfusion. The described technique was performed in 480 patients and can be adopted in the routine of professionals who inject hyaluronic acid, especially in areas at high risk for vascular events. Its use results in greater safety against vascular occlusion events secondary to the procedure, without the need for prior aspiration. We conclude that there is a local vasodilation right after the filling that makes it difficult the possibility of extrinsic compression exerted by the filler on the vessel. Furthermore, the product moves to deep planes even with the bevel facing up (toward the epidermis). We believe that in the future the use of Doppler ultrasound-guided filling technique will be mandatory for professionals who intend to perform HA injection, to both ensure patient safety and provide legal protection for the professional.

Loss of the knee-ankle coupling and unrecognized elongation in Achilles tendon rupture: effects of differential elongation of the gastrocnemius tendon.

The biarticular anatomy of the gastrocnemii is an important mechanism of knee-ankle coupling and differential elongation may affect this function leading to weakness of the push-off phase during the gait. Achilles tendon ruptures may cause detachment of the gastrocnemius tendon from the soleus aponeurosis with subsequent differential elongation of the individual subtendons. This study investigated the effects of such detachment by investigating tendon fusion levels of the two muscle groups, and the effect of sequential differential elongation of the gastrocnemius on the Achilles tendon resting angle (ATRA) and to the knee-ankle coupling. Conjoined tendon length (CTL) was measured in 23 cadavers. ATRA in knee extension (ATRA 0) and 90-degree knee flexion (ATRA 90) was measured with the gastrocnemius tendons (GT) intact, transected and with the gap reduced in 5-mm increments. In 15 specimens, knee-ankle coupling was examined. Considerable anatomical variation was present with CTL ranging from 2 to 40% of fibular length. In the intact triceps, surae ATRA 0 differed from ATRA 90 by 6 degrees (p < 0.001). Cutting the gastrocnemius caused an immediate separation of the tendon ends by 19mm. ATRA 0 and ATRA 90 increased 8 and 4 degrees (p < 0.001), significantly larger increase for ATRA 0 (p < 0.001). Lengthening the gastrocnemius 10mm altered the coupling point 10 degrees towards dorsiflexion. Transfixing the gastrocnemius at the level of the gap where the Achilles was sectioned, decoupled the knee-ankle coupling in all but two specimens. A moderate correlation between CTL and length of the medial gastrocnemius tendon was found. A greater relative ATRA 0 than relative ATRA 90 indicates differential elongation of the gastrocnemius. By elongating the gastrocnemius the knee-ankle coupling point shifts dorsally, and 20mm elongation completely decouples the knee-ankle coupling. Independent lengthening of the gastrocnemius may explain the loss of power experienced by some patients following acute Achilles tendon rupture despite what would appear to be appropriate approximation of the ruptured tendon ends. Recognizing this occurrence is crucial when treating Achilles tendon ruptures and such patients require surgical correction in order to avoid long-term weakness of push-off strength.

Anatomical variations of the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve: A detailed electrophysiological study.

In this study we evaluated anatomic variations of the superficial branch of the radial nerve (SBRN) and the dorsal branch of the ulnar nerve (DBUN) electrophysiologically. Antidromic nerve conduction studies (NCS) of the SBRN and DBUN were performed on healthy individuals. To identify individual responses from the distal branches of the SBRN and DBUN, sensory nerve action potentials of each finger (lateral side/medial side) were recorded. NCS were performed in 50 hands of 27 healthy control subjects. The thumb and the index finger were supplied by the SBRN in all cases. The lateral and medial sides of the third finger were supplied by the SBRN in 94.0% and 74.0% of the cases, but the lateral and medial sides of the fourth finger were supplied by the SBRN in only 10.0% and 2.0% of cases. The fifth finger and the medial side of the fourth finger were always supplied by the DBUN. The lateral side of the fourth finger was supplied by the DBUN in 98.0% of cases, but the lateral and medial sides of the third finger were supplied by the DBUN in 40.0% and 70.0% of cases. Dual innervation by the SBRN and DBUN was found in 34.0% and 46.0% of the lateral and medial sides of the third finger, but in only 8.0% and 2.0% of the lateral and medial sides of the fourth finger. There are considerable anatomic variations of the SBRN and DBUN in healthy individuals.

Variations in the Circle of Willis in a large population sample using 3D TOF angiography: The Tromsø Study.

The main arteries that supply blood to the brain originate from the Circle of Willis (CoW). The CoW exhibits considerable anatomical variations which may have clinical importance, but the variability is insufficiently characterised in the general population. We assessed the anatomical variability of CoW variants in a community-dwelling sample (N = 1,864, 874 men, mean age = 65.4, range 40–87 years), and independent and conditional frequencies of the CoW’s artery segments. CoW segments were classified as present or missing/hypoplastic (w/1mm diameter threshold) on 3T time-of-flight magnetic resonance angiography images. We also examined whether age and sex were associated with CoW variants. We identified 47 unique CoW variants, of which five variants constituted 68.5% of the sample. The complete variant was found in 11.9% of the subjects, and the most common variant (27.8%) was missing both posterior communicating arteries. Conditional frequencies showed patterns of interdependence across most missing segments in the CoW. CoW variants were associated with mean-split age (P = .0147), and there was a trend showing more missing segments with increasing age. We found no association with sex (P = .0526). Our population study demonstrated age as associated with CoW variants, suggesting reduced collateral capacity with older age.

Anatomical variations of the circle of Willis and their prevalence, with a focus on the posterior communicating artery: A literature review and meta-analysis.

The circle of Willis is an anastomotic network of arteries surrounding the base of the brain, providing collateral circulation to prevent ischemia. It has, however, long been established that it exhibits considerable anatomical variation when compared to Thomas Willis' originally described circle. This study aimed primarily to determine an accurate prevalence of the variation of the circle of Willis in the general population and the prevalence of common posterior communicating artery variations. Additional aims were to explain why such a wide range of reported variations exist, and whether different types of studies report significantly different prevalence of variation. A comprehensive literature search identified 764 papers. A three-phase screening process was undertaken, involving a critical analysis of papers, and a total of 33 papers were selected for analysis and literature review. A descriptive statistics test with bootstrap was performed to estimate the average prevalence of variations. The estimated prevalence of general variation, unilateral, and bilateral posterior communicating artery hypoplasia or aplasia was 68.22 ± 14.32%, 19.45 ± 8.63%, and 22.83 ± 14.58%, respectively. Over half of the population exhibit a circle of Willis with some form of variation. To provide a more accurate estimation for the prevalence of variations, a universal classification system needs to be established, collating all the work from high-quality studies, to provide a comprehensive database of the circle's variations. Knowing the prevalence of variations and how they can impact neurosurgical approaches or patterns of ischemic pathology can be crucial in providing effective patient care.

Pulmonary vascular anatomy & anatomical variants.

The vessels supplying the lungs include the pulmonary arteries, pulmonary veins, and bronchial arteries. The segmental and sub segmental pulmonary arteries parallel the bronchi and are named according to the bronchopulmonary segments they supply. There are however considerable anatomic variations, particularly in the upper lobes with variations in number or presence of accessory arteries from adjacent segments. The subsegmental pulmonary vein branches, run within interlobular septa and do not parallel the segmental or sub segmental pulmonary artery branches and bronchi. They converge to form right and left superior and inferior pulmonary veins which drain into the left atrium. Knowledge of normal and variant anatomy on cross-sectional and angiographic images is essential for accurate diagnosis of vascular pathology and aids planning of interventional procedures.

Preoperative color Doppler ultrasound assessment in planning of SCIP flaps

Superficial circumflex iliac artery perforator (SCIP) flap is based on the perforator of superficial circumflex iliac artery (SCIA) system, and is a highly useful surgical tool with a wide variety of clinical applications. The SCIA system is associated with considerable anatomical variation, however, rendering transfer of a SCIP flap technically difficult. Using preoperative color Doppler ultrasound (US), we examined a total of 11 flaps of 11 patients who had undergone reconstruction with SCIP flap from April to August of 2014. The origin of SCIA from femoral artery and the bifurcation of its superficial branch and deep branch were easily identifiable in all patients. Perforator courses and their penetration points were marked to guide dissection. Although one patient required secondary revision and skin grafting because of partial necrosis, there were no serious postoperative complications such as total necrosis or resulting absorption of the transferred adiposal flap. In all cases, findings from the preoperative color Doppler US were useful in delineating the dominant vessel within the groin lesion. Using the technique described above, difficulties arising from the anatomical variation within the SCIA system are easily overcome, simplifying SCIP flap harvest. In addition to being relatively easy, the technique is also quick to administer and safe.

Anatomic variability of the vascularized composite osteomyocutaneous flap from the medial femoral condyle: an anatomical study

Aim: The anatomical study and clinical application for the vascularized corticoperiosteal flap from the medial femoral condyle have been performed and described previously. Although prior studies have described the composite osteomyocutaneous flap from the medial femoral condyle, a detailed analysis of the vascularity of this region has not yet been fully evaluated. Methods: This anatomical study described the variability of the arteries from the medial femoral condyle in 40 cadaveric specimens. Results: The descending genicular artery (DGA) was found in 33 of 40 cases (82.5%). The superomedial genicular artery (SGA) was present in 10 cases (25%). All 33 cases (100%) of the DGA had articular branches to the periosteum of the medial femoral condyle. Muscular branches and saphenous branches of the DGA were present in 25 cases (62.5%) and 26 cases (70.3%), respectively. Conclusion: The current study demonstrates that the size and length of the vessels to the medial femoral condyle are sufficient for a vascularized bone flap. A careful preoperative vascular assessment is essential prior to use of the vascularized composite osteomyocutaneous flap from the medial femoral condyle, because of the considerable anatomical variations in different branches of the DGA.

Análisis de espectros de resonancia magnética

ObjectiveTo study the performance in the use of metabolite ratios and the comparison of a contralateral volume of interest in order to determine which of these two techniques is most suitable for obtaining a ratio of the metabolite behaviour of a magnetic resonance spectrum. MethodsThe parietal lobe, the temporal lobe, and basal ganglions were analysed in the 10 healthy volunteers included in the study. ResultsThe direct quantification of the spectra showed a wide coefficient of variation within the analyses performed, which justified using techniques with endogenous references. The study of a contralateral volume showed to be a technique with a high dispersion and laterality index. The use of creatinine (Cr) as a control metabolite had a lower coefficient of variation than the first technique evaluated. The results obtained (basal ganglions: N-acetyl-aspartate/Cr: 3±6; choline/Cr: 2±4. Temporal lobe: N-acetyl-aspartate/Cr: 5±5; choline/Cr: 8±12. Parietal Lobe: N-acetyl-aspartate/Cr: 2.0±0.6; choline/Cr: 0.9±0.5) showed similar values to those obtained in the literature, with considerable anatomical region variations. ConclusionsThe technique that measures the ratio of the metabolites with Cr is the most suitable for use in the Instituto Nacional de Cancerología (National Oncology Institute), due to having a lower dispersion and producing results near those repo rted in the literature in the different anatomical regions studied.

Fibre wall and lumen fractions drive wood density variation across 24 Australian angiosperms

Wood density is considered a key plant trait, affecting mechanical and physiological performance, yet its biological meaning is still rather unclear. Accordingly we investigated the anatomical underpinnings of wood density in trees and shrubs. We measured wood density and anatomical traits in distal stems 4–10 mm diameter under bark in 24 Australian species. Proportions of wood components that are functionally distinct were analysed, including fibre wall and lumen, vessel wall and lumen, and axial and ray parenchyma. Wood density was mainly driven by the density of wood outside vessel lumens (densityNV) rather than by vessel lumen fraction. In turn, densityNV variation was chiefly affected by fibre wall and lumen fractions. Considerable anatomical variation was observed at a given densityNV, especially among medium-densityNV species (0.60–0.85 g cm−3); this range of medium densityNV roughly translates to 0.50–0.75 g cm−3 of overall density. The anatomy of these species formed a continuum from low fibre lumen and medium parenchyma fractions to medium fibre lumen and low parenchyma fractions. Our data suggest that wood density is an emergent property influenced by a complex anatomy rather than an unambiguous functional trait, particularly in medium-density species. With much anatomical variation, they likely represent a wide range of ecological strategies.

A case study for online plan adaptation using helical tomotherapy

Helical tomotherapy's ability to provide daily megavoltage (MV) computed tomography (CT) images for patient set-up verification allows for the creation of adapted plans. As plans become more complex by introducing sharper dose gradients in an effort to spare healthy tissue, inter-fraction changes of organ position with respect to plan become a limiting factor in the correct dose delivery to the target. Tomotherapy's planned adaptive option provides the possibility to evaluate the dose distribution for each fraction and subsequently adapt the original plan to the current anatomy. In this study, 30 adapted plans were created using new contours based on the daily MVCT studies of a bladder cancer patient with considerable anatomical variations. Dose to the rectum and two planning target volumes (PTVs) were compared between the original plan, the dose that was actually delivered to the patient, and the theoretical dose from the 30 adapted plans. The adaptation simulation displayed a lower dose to 35% and 50% of the rectum compared to no adaptation at all, while maintaining an equivalent dose to the PTVs. Although online adaptation is currently too time-consuming, it has the potential to improve the effectiveness of radiotherapy.

Patellar instability with increased knee flexion due to lateral femoral condyle distal dysplasia: A report of two cases

We present two case reports with clinical and radiological assessment of the anatomical features at the distal lateral end of trochlea and femur in patients with patellar instability in higher knee flexion and how these findings could possibly be involved in the genesis of this rare type of patellar instability. Both patients underwent several (nine and seven) surgical procedures, but the patellar instability could not be successfully eliminated. Our hypothesis was that a short and flattened lateral distal condyle/trochlea may cause lateral patellar instability in higher flexion. We found considerable anatomical variations at the distal lateral femoral condyle and trochlea in both patients. Individually tailored surgical procedures were selected for each patient according to the documented variations and the previous operations. Our surgical interventions consisted of different components, such as osteotomy of the distal lateral femoral condyle/trochlea with lengthening and elevation, balancing of the medial and lateral patellar soft tissue structures, MPFL reconstruction, transposition of the medialised tibial tubercle and the patellar tendon back to lateral to the normal initial anatomical position. With these procedures, lateral patellar instability with increased flexion could be completely eliminated in both patients at the 1- and 2-year follow-up. Our experience of assessment and treatment of these patients let us conclude that variations of the distal lateral femoral condyle/trochlea morphology may be responsible for patellar instability with increased flexion. This is another type of patellar instability caused by distal condyle/trochlea dysplasia compared to the well known and often described types of patellar instability close to extension caused by proximal trochlea dysplasia.

The contemporary management of chyle leak following cervical thoracic duct damage

The considerable anatomical variation of the thin walled cervical thoracic duct predisposes it to inadvertent damage during neck dissection. If this is not recognised at the time of surgery, a chyle leak can result in potentially serious complications as well as delaying the patient's discharge from hospital. This article summarises the basic anatomy of the terminal thoracic duct in the neck and discusses the pathophysiology of a chyle leak. We present the latest ideas for managing this problem when it is identified at the time of surgery, and review the diagnosis and contemporary management options available for dealing with this difficult problem when it is found to occur post-operatively.

SU-GG-T-454: Dosimetric Impact of Inter-Fractional Variations in Proton Therapy of Prostate Cancer: Assessment of Dose Accumulation and Plan Robustness Using Daily In-Room CT Images

Purpose: To quantify the dosimetric impact of inter-fractional anatomical variations during the course of fractionated proton therapy of prostate cancer, and assess the robustness of the standard treatment planning techniques. Method and Materials: We used pre-treatment simulation and daily in-room CT from ten prostate carcinoma patients. Treatment plans for proton therapy (39 fractions, 2 Gy/fraction) were created, with 25 fractions targeting PTV50Gy (expanded from prostate and seminal vesicles to account for intra-fraction motion) followed by 14 boost fractions targeting PTV78Gy (expanded from prostate). The plan was then applied to daily CT, with beams aligned to the prostate center. For three patients having sufficient daily imaging volume, contours were drawn and plans were evaluated for all CT sets. For the other seven patients, the plans were evaluated at the beginning, mid and end point of the treatment course. The daily CT was registered to the simulation CT through deformable registration, and fractional doses were summed to yield the accumulated dose. Results: The fractional PTV78Gy coverage fluctuated within ∼6% around the planned value, mainly due to the deformation of prostate. Loss of coverage was observed in the AP and SI direction, when PTV78Gy deformed and approached the field edge. Lateral coverage was stable even in the presence of considerable anatomical variations. The accumulated PTV78Gy coverage was slightly lower than planned, but remained acceptable. Although bladder dose per fraction increased in all three patients due to reduced daily volume, the accumulated dose remained within tolerance. No increase in the rectum dose was observed, most likely due to the smearing of the daily high-dose volumes. Conclusion: The results confirm that standard proton therapy planning techniques are generally robust to inter-fractional anatomical variations. Deviations in the dose to normal organs can be reduced with efforts aimed to maintain consistent levels of rectal and bladder filling.