To obtain a high-quality image — sufficient contrast and sharpness — the technique of conducting this examination (taking into account the voltage of the X-ray tube and the irradiation field), which is the responsibility of the x-ray technician or x-ray technician, must be followed.
In order to obtain adequate X-ray signs of diseases of bones and joints in the images in standard projections — frontal (front or back) and lateral — correct placement of the limb by a radiologist is especially important. Depending on the location of the examined structures and clinical data, oblique projections are also used, and X-rays of the leg joints can be made in a bent and unbent state. In most cases, the position of patients on an X-ray table is recumbent.
According to the methodological guideline for laying the examined limb, the fixation of the position of the bone or joint is ensured by placing rollers and sandbags.
Modern clinics use digital X-rays with an analog-to-digital converter, which gives very high-quality images in electronic form - for a shorter exposure time and with minimal radiation exposure on the body. 
In addition, taking into account certain problems with the detection of initial pathological joint disorders in osteoarthrosis and other joint diseases on a conventional X-ray, more sensitive microfocus X-ray machines are now used.
See more - Radiography
In difficult cases, for example, in case of suspected fracture of the femoral neck in elderly people who are difficult to deliver to the hospital, an x-ray of the leg at home is possible, which the relevant specialists carry out with a special mobile x-ray machine. 
X-ray of toes
In traumas, in patients with ankylosing spondylitis, Reiter's disease of psoriatic or gouty arthritis, in cases of osteo-articular panaritium, in case of defects of the toes (polydactyly or syndactyly), an x-ray of the toes - phalanges, metatarsophalangeal and interphalangeal joints.
To take a picture in a direct projection (rear-plantar) - the foot is placed on the sole in the lying position with the legs bent at the knees. A picture of each finger on the side is done with the lateral laying of the foot and fixing each finger in the designated position.
X-ray of shin
X-ray of the tubular bones of the tibia (fibular and tibial) is carried out in the straight (posterior) and lateral projections, capturing their ends with the tibial-fibular joint connecting them in the proximal part, and the fibrous ligament (syndesmosis) from the distal end.
A direct projection is provided by laying the patients on their backs (with their legs straightened), and the side requires placing the corresponding leg on the side, and the healthy limb should be bent.
X-ray of thigh
If it is necessary to conduct an x-ray of the thigh, the tubular femur is examined - in projections similar to those of the x-ray of the tibia. For a picture in a straight rear projection, the patient should lie on his back, straightening both legs. Side projection, respectively, requires the location of the body on its side; at the same time, the examined leg should be bent at the knee and pulled forward, while the other leg should be pulled back.
X-rays of the femoral neck are performed to detect injuries (cracks or fractures) of a narrowing area at the top of the femur, which goes at an angle and connects it to the epiphysis - the upper rounded portion, called the femoral head.
An X-ray is necessarily done in case of aseptic necrosis of the femoral head - avascular osteolysis of a section of bone tissue under the articular cartilage, the so-called epophysial subchondral plate, which develops due to lack of blood supply. In children, aseptic necrosis is called Legg-Calvet-Perthes disease.
With this pathology, an increase in the X-ray image in the frontal and lateral projections is practiced.
Since the early stages of osteolysis are not displayed on the X-ray, specialists use other methods of instrumental diagnostics: magnetic resonance imaging and bone scintigraphy.
X-ray of leg joints
X-rays of the leg joints (hip, knee, ankle, foot joints) or performed not only with the purpose of setting or clarifying the clinical diagnosis, but also before surgery (osteophyte removal, joint replacement), as well as to monitor the results of conservative therapy.
Details on how is carried out:
Standard x-rays of the hip joint are made in two projections: straight (lying on your back with legs aligned and rotating the feet towards each other, or also on the stomach with a raised part of the pelvis from the side of a healthy leg) and side - lying on its side with a bent leg. If the mobility of the joint is limited, X-rays are performed in the half-sitting position (the body is bent backward, relying on the hands taken away from the back).
A frontal snapshot of both joints is also taken to compare the anatomical structures of the damaged joint with the healthy one.
When taking pictures in the lateral projection, the patient should be laid when the limb is being withdrawn in the hip joint, and when it is contracted - without it. In addition, the back view of the hip joint is provided by irradiating the joint from the back at an angle (from top to bottom), for which the patient must sit.
If necessary, conduct an x-ray study of the condition of the periarticular tissues, resort to x-rays with the introduction of a contrast agent - arthrography of the joints.
See also - X - ray diagnosis of osteoarthritis of the hip joints (coxarthrosis).
To assess the severity of orthopedic pathology, determine the nature of violations of the structures of the hip joint, an x-ray is necessary for dislocation of the femur (the femoral head emerges from the acetabulum), as well as an x-ray of congenital dislocation of the hip - hip dysplasia in children. The radiograph of the joint in the frontal plane allows you to visualize the defect, make all the necessary measurements and on the basis of these data choose the most appropriate tactics to correct it.
It should be borne in mind that during the first three to four months of life, an x-ray of the baby’s feet is prohibited and, if necessary, an ultrasound of the hip joints of the newborn is performed .
More complete information in the material - Diagnosis of congenital hip dislocation.
X-ray soft tissue legs
The focused X-ray of the soft tissues of the leg, that is, the muscle, is not informative, since the X-rays of the soft tissues cannot be reflected, and they are not visible on the X-rays. But in some diseases, such as ossifying myositis, the presence of ossification sites is determined by the shadows along the fibers of the muscle tissue. And with the differential diagnosis using radiography in patients with an autoimmune disease of the connective tissue - systemic scleroderma - deposits of calcium salts (calcifications) are found in the periarticular soft tissues.
For myopathies affecting the muscle tissue of the lower limbs, ultrasound and MRI are the imaging instruments. For details, see - Muscle Examination.
X-ray of the leg vessels
X-ray of the blood vessels of the legs with contrasting is used in the diagnosis of diabetic or atherosclerotic angiopathy, venous insufficiency or deep venous thrombophlebitis of the lower extremities.
All the details in the material - Angiography
Currently, phlebography (x-ray veins for varicose veins) is replaced by a more modern, safer and most informative duplex scanning or ultrasound of the veins of the lower extremities.
Also, an x-ray of the lymphatic vessels with a contrast agent is made - lymphography.