The 9th chapter of Sutrasthana of Charaka Samhita explains in brief regarding the 4 basic elements of Ayurvedic treatment. This chapter is called as Khuddaka Chatushpada Adhyaya. These four elements are essential to fullfill the purpose of treatment.
4 elements of Ayurvedic treatment
The four aspects of treatment are –
1. Bhishak – Physician,
2. Dravya – Medicine
3. Upasthata – Attendant / nurse
4. Rogi – patient.
They are responsible for the cure of diseases, provided they have the requisite qualities.
Definition of health and disease
Any disturbance in the equilibrium of Dhatus (Tridosha, body tissues and waste products) is known as disease.
The state of their equilibrium is health. Happiness signals towards health and pain signals disease. 
Definition of treatment
The combined efforts of Physician, medicine, attendant and patient, who possess requisite qualities, for restoration of the equilibrium of Dhatus (Tridosha, body tissues and waste products) is known as treatment. 
4 essential qualities of physician
Shrute Paryavadatatvam – excellent medical knowledge, sound knowledge of text books / health literature
Bahusho Drushtakarmata – extensive practical knowledge and experience
Dakshya – Dakshata – proficiency, discipline
Shaoucha – Shuchi – cleanliness, clarity, purity of mind and body 
4 essential qualities of medicine / herb
Bahuta – availability in abundance. Ideally the herb or the herbal medicine should be easily available world over.
Yogyatvam – suitability. The herb / medicine should be suitable to the particular disease.
Aneka Vidha Kalpana – The herb should be usable in different forms and doses.
Sampat – the herb / medicine should be so prepared that it has all the desired therapeutic qualities. 
Shloka recitation video
4 essential qualities of nurse / attendant
Upachaarajnata – Knowledge of nursing,caring
Daakshya – Dakshata – accomplished, disciplined
Anuraga – affectionate and compassionate towards the patient
Shaucham – cleanliness, hygiene and purity 
4 essential qualities of patient
Smruti -Good memory power to learn about instructions about medicine and its intake.
Nirdeshakaritva – obedience, ability to follow instructions properly
Abhirutva – fearlessness, courage
Jnapakatvam cha roganaam – good memory about list of health complaints / diseases that he is suffering with.
and uninhibited expressing- these are the four qualities of a patient.
Importance of physician
These are the 4 factors in treatment, each with 4 essential qualities. These sixteen qualities together are responsible for success in treatment. But the physician,the virtue of his knowledge, administrative power and proficiency and capability is the most important among the four. 
Simile regarding physician
Vessels, fuel and fire are helping factors for the cook to make food;
Favourable topographical position, army and weapons are needed for a king to win the war;
similarly in the success of treatment the patient, attendant and medicament are helpers only to the physician. Thus the physician plays the most prominent role in treatment.[11-12]
In making a mud pot, the cold earth, the wheel, the thread, etc. are of no use without the help of the potter. Without the physician, other three factor,(viz, a patient, the attendant and the herbs) do not serve the purpose.
If the qualities of patient, attendant and herbs are kept constant, in the most difficult-to-treat diseases, the disease may vanish or may get aggravated very quickly, like the city of Gandharvas, depending on the quality of the physician.
Condemnation of quackery
Condemnation of quackery / bad clinical practices of the doctor:
It is better to die than to be treated by an ignorant physician. Because, like a blind person moving with help of his hands or like a boat being driven by the wind, a quack physician applies the course of treatment with anxiety and fear because of his ignorance. [15-16]
Such an inefficient physician may cure a few patients by chance, whose ailments might get cured automatically, but he is likely to kill patients in quick time, who would have otherwise survived if treated properly. 
A Good Ayurvedic doctor
A good ayurvedic doctor is the one, who is duly engaged in the study of the science, mastering the actual implications of the disease and the right application of the treatment with practical experience. Such a doctor is known as Pranabhisara Vaidya (saviour of life) 
Qualities of Royal Physician
One who possesses the knowledge of the below four factors is fit to become Royal physician. Those factors are –
Hetu – causative factors for diseases
Linga – characteristic features of diseases
Prashamana – treatment methods for diseases
Rogaanaam Apunarbhave – preventive measures for disease and to maintain health. 
A weapon, scripture and water have merits and demerits, depending upon who uses it for what. So, a physician should always have pure thoughts and intellect for the sake of giving proper treatment.
Six qualities of physician
For a physician who possesses below six qualities, no disease is incurable. Those six qualities are –
Vidya – Education,
Vitarka – critical approach, analytical mind
Vijnana – insightful understanding, special knowledge
Smruti – good memory
Tatparata – perseverance
Kriya – practical knowledge
Vidya – education, knowledge,
Mati – intellect,
Karmadrushti Abhyasa – practical experience and knowledge
Siddhi – expertise
Ashraya – accommodating mindset
– these words explains the qualities of “Vaidya – physician”
The one who combines in him all these good qualities will distribute happiness and comfort to all living beings.[21-23]
Simile about relation of intellect and literature
Knowledge of the medical science = light, which illuminates the room and relieves darkness.
Intellect of the physician can also be likened to light, which enlightens the patient about disease and treatment.
Such a physician having good knowledge and intellect will never commit mistakes in treatment.
As the remaining three factors (patient, medicine and nurse) of treatment depend on the quality of the physician, a physician should always thrive hard to have all the required good qualities. [24-25]
4 principles for physician
Doctor should be
Maitri – friendly,
Karunyam artheshu – sympathetic and kind to patients.
Shakye preetihi – He should concentrate on the diseases that can be cured and
upekshanam prakrutishteshu – should neglect the incurable diseases.
These are the four disciplines for physician.
In this brief chapter on 4 elements of treatment, all the four factors of therapeutics and their respective qualities, the importance and qualities of the physician, his knowledge and fourfold spiritual disposition in profession – all these are explained. [27-28]
Thus ends the ninth chapter of Sutrasthana of Charaka Samhita.